CN1242669A - Digital television receiver with adaptive filter circuitry for suppressing NTSC Co-channel interference - Google Patents

Abstract

A digital TV receiver for preventing NTSC co-channel interference and its symbol decoding method, wherein the multi-level symbols of co-channel interference in the digital TV signal are suppressed by the first comb filter before data limiting. The first comb filter processes the symbol decoding results produced by the data slicer. The second comb filter is used for post-coding. The symbol precoding is from the differential delay of the differential delay means and the postcoding of the symbol data stream from the first linear combination is from the second linear combination, one of the first and second linear combinations being subtractive and the other being additive. The result of the second linear combination is the result of the corrected symbol decoding.

Description

Anti-NTSC road altogether disturbs DTV receiver and symbol decoding method thereof

For example the present invention relates to be used to carry out the digital high definition television receiver of land route broadcast standard in the U.S. according to advanced television branch (ATSC), particularly those meet and disturb the digital television receiver of the sef-adapting filter that suppresses in the road altogether having for National Television System Committee NTSC of national television system committee (NTSC) standard.

In the digital television standard of announcing by ATSC September 16 nineteen ninety-five, stipulated at present in the wireless 6MHz bandwidth television channel of the NTSC of the U.S., to carry out residual sideband (VSB) signal that Digital Television (DTV) signal sends.The DTV signal of this VSB makes its frequency spectrum staggered with the frequency spectrum that is total to the NTSC analog tv signal that disturbs in the road in design.It is to realize on the position of the odd-multiple of 1/4th horizontal scan line speed of the NTSC anolog TV signals between the even-multiple of 1/4th horizontal sweep speed that fall within the NTSC anolog TV signals by the main amplitude-modulation sideband frequency localization pilot frequency carrier wave and DTV signal.In this position, the majority of the even multiple of the energy of the brightness of road interference NTSC analog tv signal and chromatic component will fall altogether.The video carrier of the TV analog signal of NTSC is from the low side skew 1.25MHz of television channel.The carrier wave of DTV signal is offset 59.75 times of horizontal scan line speed of the anolog TV signals of this NTSC from this video carrier, the carrier wave of this DTV signal is placed on the 309877.6KHz place of the low side frequency of television channel apart, therefore, the carrier wave of this DTV signal is 2690122.4Hz at a distance of the centre frequency of television channel.

Definite character rate in the digital television standard is 684/286 times of sound carrier of the 4.5MHz of the video carrier skew from the NTSC anolog TV signals.The number of symbols of the horizontal scan line in NTSC anolog TV signals is 684, and 286 are factors, and the speed of the horizontal scan line in NTSC anolog TV signals and this factor multiply each other and obtain sound carrier at a distance of the 4.5MHz of the video carrier skew of these NTSC anolog TV signals.Character rate is 10.762238M/S (million a symbol per second), can be included in from a VSB signal of DTV signal carrier 5.381119.In other words, this VSB signal can be limited to a frequency band limitting expansion 5.690997MHz from the low side of TV signal frequently.

The ATSC standard that is used for digital HDTV signal land transmission in the U.S. can send the one of any of two cover high definition (HDTV) standards with 16: 9 the ratio of width to height.A HDTV display format adopts 1920 samplings of every row and 1080 dynamic level scan lines of per 2: 1 intervals (field interlace) 30Hz hardwood.A DTV display format adopts 1280 brightness samplings of every scan line and 720 row of lining by line scan of every 60Hz hardwood TV image.The ATSC standard also allows the transmission of the display format DTV display format in addition of HDTV, for example parallel transmission of the quadruplet TV signal of comparing with a kind of NTSC anolog TV signals with single-definition.

The DTV that the residual sideband (VSB) of the amplitude modulation of broadcasting in U.S. land route (AM) is sent comprises the continuous data fields of continuous time, and each comprises the data segment of 313 continuous times, and this data fields can be to be considered to mould 2 serial numbers.Each is numbered as the data fields of odd number and the data fields that is numbered even number subsequently forms a Frame.Frame rate was 20.66 frame/seconds.Each data segment is 77.3 milliseconds time remaining phase.So character rate is 10.76MHz, each data segment has 832 symbols.Each data segment starts from having the synchronous code character of row of four symbols, and the continuous value that has respectively is+S ,-S ,-S ,+S.This value+S is at the level maximum under of correction data between the apparition, and be worth-S is negative data value on the maximum level between the apparition.The initial row of each data fields includes the field synchronization code character, is used to encode one be used for the training signal of channel equalisation and multipath process of inhibition.This training signal is the PN (pseudo noise) sequence (being the PN sequence) of 511 samplings, is the PN sequence of three 63 samplings subsequently.The transmission of this training signal is consistent with first first logic regulation of going and first second logic regulation of going in the data fields of each even-numbered in the data fields of each odd-numbered, and this first and second logic regulation is 1 complementation each other.

Data in data line are to adopt 12 staggered lattice sign indicating numbers (trellis code) and the lattice coding, and the lattice sign indicating number of each 2/3 speed has a uncoded bit.Lattice sign indicating number that should be staggered is proofreaied and correct and is come from noise source (for example closing on unscreened automotive ignition system) pulse error by one Saloman, Ruide (Ree-Solomon) positive error correction coding.The result of Ruide-Saloman coding is used for aerial transmission as 8 level (3 bit/symbol) one dimension graticule ticks coding, and finishing of this transmission do not depart from the symbol generation of lattice cataloged procedure.The result of this Ruide-Saloman coding sends as cable as the one dimension graticule ticks coding of 16 level (4 bit/symbol), and not finishing of this transmission encoded in advance.This VSB signal has its natural carrier wave, and the change of amplitude is arranged according to the ratio of modulation inhibition.

This nature carrier wave is replaced by the pilot frequency carrier wave of regulation amplitude, and its amplitude is corresponding to predetermined modulation ratio.The generation of the pilot frequency carrier wave of this regulation amplitude is to provide the VSB signal to realize for the modulation voltage of the balanced modulator of the filter amplitude-modulation sideband of response by a flip-flop mobile being incorporated into be added in to produce to deliver to.If 8 level of 4 bit symbols codings have normal value-7 ,-5 ,-3 ,-1 in carrier (boc) modulated signals ,+1 ,+3 ,+5 ,+7, this pilot frequency carrier wave has one 1.25 normal value.Should+normal value of S is+5, and-normal value of S is-5.

In the DVT technology in early days, consideration be to determine whether on transmitter to use the symbol precoder by the broadcasting station, this symbol precoder will be followed after symbol produces circuit and the precoding filtering of symbol will be provided.Whether this decision of being done by the broadcasting station will be depended on has from the interference of the NTSC broadcasting station in road altogether.Before the data sementation device in the symbol decoder circuit, this symbol precoder will be finished the postposition coding for the symbol of being introduced at random by the comb filter institute that uses in each DTV receiver, so that suppress the distortion that NTSC is total to the road interference signal.For the synchronous code character of data line or during the data sync data are sent out, the precoding of symbol will do not used.

Disturb in the common road at a distance of place far away, NTSC broadcasting station to be reduced, in the summer in violent time of solar activity, the common road that will occur very big possibility under the situation that certain ionosphere condition occurs disturbs.Certainly, if in the overlay area of broadcasting, be not total to the NTSC broadcasting station of road broadcasting, common road just can not occur and disturb.If might appear at the possibility of the interference of the NTSC broadcasting in this zone.Suppose that this HDTV broadcasting uses the precoder of symbol so that easier the interference with this NTSC of this HDTV signal separated mutually, and correspondingly in the DTV receiver, use a comb filter, so that realize the filtering of mating fully as the rearmounted encoder of symbol.If the possibility or the effect of realization interference that do not have NTSC to disturb, in order to make the minimum judgement for the value of symbol mistake that might cause in trellis decoder of noise of smooth frequency spectrum, suppose that this DTV broadcasting will be to use this symbol precoder discontinuously; And make that therefore the rearmounted encoder of symbol in each DTV receiver is prohibited.Owing to the leakage of abnormal jump condition, cable, in the NTSC receiver, have other the reason of improper condition of the residue signal of previous simulated television record or some for the deficiency of the inhibition of intermediate frequency image, the tape that is used for the Digital Television record, because such situation is not considered in the broadcasting station, the NTSC in actual common road disturbs a part that constitutes in the broadcast reception zone.

The DTV standard of current ATSC does not authorize transmitter to use the precoding of symbol.The inhibition of the analog tv signal of road interference is to carry out in the lattice decoding process after the fragmentation procedure of the data relevant with symbol decoding by hypothesis altogether.This process has avoided whether having carried out at the transmitter place process of the judgement of precoding.But the analog tv signal of road interference is incorporated into error the fragmentation procedure of data undesirably altogether, and this has just added extra burden to the process of error correction decoding, lattice decoding and Ruide-Saloman decoding.These errors will reduce the zone that broadcasting covers, and this will make commercial DTV broadcasting lose income.So, need before data sementation, provide for the inhibition of the analog tv signal of road interference altogether, although do not have by the DTV standard mandate of current ATSC in the symbol precoding of DTV.

Term " linear combination " is the addition of carrying out according to traditional arithmetic or pattern arithmetic or subtracts each other this expression.The linear combination that term " mode combinations " expression is carried out according to a pattern arithmetic.The rearmounted coding of the symbol of the demonstration row of use in the HDTV of prior art receiver, the data flow of the numerical chracter of recompile by differential delay and differential delay linear combination mutually is defined as " first kind that symbol is encoded again " in specification.For the result of the delay of mode combinations by its mode combinations for the numeric character data stream type of coding again, be encoded to example again with the symbol in the HDTV transmitter of prior art, be referred to as " second type that symbol is encoded again " in this manual.

The crowded angle that the problem of disturbing from the common road of anolog TV signals can the auto-adaptive filter circuit by receiver when it being considered as some television receiver solves is treated.So long as the dynamic range of system is not exceeded, just can make the channel that road interference altogether can capture system by the signal transmitting capacity that destruction is used for the DTV modulation, the performance of system can be considered a stack of signal problem.Filter circuit in the receiver is used for selecting digital signal from being disturbed by the caused road altogether of anolog TV signals.Rely on tangible correlation and anolog TV signals decorrelation, filter circuit in receiver is used to select digital signal from the caused road altogether of anolog TV signals disturbing, so that reduce their energy significantly, so as from them the channel of capture system.

With regard to the common road from anolog TV signals disturbed, it was to enter into the channel of system the DTV transmitter after with before the DTV receiver.For the common road from anolog TV signals disturbs, use or do not use precoding all not have to influence at the symbol at transmitter place.For the DTV receiver, as long as this common road disturb not have greatly to transship this receiver front end and occupy the channel of this system, then be to insert a slicing that has comb filter to reduce the energy of the high frequency spectrum composition that disturbs in common road at last, thereby be reduced in the appearance of the error in the data sementation.This DTV speech amplifier should be regulated its carrier frequency, usually this carrier frequency is the nominal value of the 310KHz on the lower limit of setting television channel, so that make carrier frequency depart from the frequency of the NTSC anolog TV signals in the common road that may occur disturbing best on frequency.Departing from of this best in carrier frequency is definite 59.75 times of horizontal line scanning frequency of these NTSC anolog TV signals.Common road interference in the DTV of demodulation signal will comprise the horizontal frequency f of the NTSC anolog TV signals that produced by the mixing between the carrier wave of the anolog TV signals of the HDTV carrier wave of numeral and the interference of common road _H59.75 beat, with by the HDTV carrier wave of numeral and 287.25 times f producing of the mixing between the colour subcarrier of the anolog TV signals that disturb of road altogether _HCadence signal, this beat quite approaches 59.75 times f _HThe quintuple harmonics of cadence signal.This interference will further comprise the 345.75 times of f that are approximately by the mixing generation between the sound carrier of the anolog TV signals of the HDTV carrier wave of numeral and the interference of common road _HCadence signal, this signal quite approaches the fifth overtone at the cadence signal of 59.75 times fH.Almost approximate harmonic relationships between these cadence signals makes them not suppressed by the suitable filters of several symbol phase of a suitably employing difference delay.The symbol that a NTSC inhibition comb filter of using before the data slicing in the DTV receiver is carried out the first kind is relatively encoded again, so that revise the symbol that is obtained by data slicing.

But, consider the transmission of data, the quantization level that is used for data is formulated to the level with symbol and is complementary, so, in this DTV receiver, be connected on data slicing after the precoding of first kind symbol and be a quantizing process that does not destroy the result that first precoding from symbol produces, this quantification identification be the surplus of the anolog TV signals that disturb at remaining road altogether after the relevant filtering of the symbol precoding of the first kind, still and the jump between the symbol level to compare be significantly little.This is a kind of seizure phenomenon, and one of them stronger signal is to be that cost obtains with a more weak signal in quantizing process.

About the transmission of data, the symbol data streams of this numerical data is through the whole length of this system channel.When the symbol recompile of second type being implemented as the precoding of symbol at DTV transmitter place, serve as that additional combination is done for the data symbol data flow of differential delay in the basis then with a module, this combination does not increase the power or the intersymbol average distance of transmitter, so that further help to overcome the anolog TV signals of obstruction.On the contrary, be used for overcoming the main mechanism of blocking anolog TV signals and be by the comb filter that the is provided at the DTV receiver corresponding DTV signal of decaying, make that remaining anolog TV signals are resisted immediately by the quantization effect of the data amplitude limiter after this comb filter in the response of comb filter.

Because the rules that not have to encode can be damaged the transmission energy of symbol data streams, thus the symbol of this first and second type again the execution order of encoding process can not cause tangible influence in the case for the signal that passes system channel.So long as the processing that the symbol of second type is encoded again is not to be inserted between the symbol precoding processing and data slicing subsequently of the first kind, then the order of the symbol of this first and second type execution of encoding again just can not impact for the ability of digital receiver, so that suppress the anolog TV signals that road altogether disturbs.The intension of these technology provides the basis of basic function of the present invention.

In digital receiver, for example in digital television receiver, be accompanied by the inhibition of disturbing in the common road of many level symbols and be by use before data slicing reduction altogether first comb filter of the energy that disturbs of road realize.First comb filter is provided with a data flow of 2N level symbol, the stationary phase that each symbol has a symbol of official hour length postpones, the data flow of 2N level symbol wherein easily is attended by the interference of common road interference simulation TV signal, and a response signal is provided, the interference of the common road of wherein these interference simulation TV signal is suppressed.

The symbol that first comb filter is side by side carried out the first kind is cataloged procedure again, it is incorporated into error among the symbol decoding result who is produced by data slicing, suppose specified number or amount that this first comb filter postpones the prescribed phases of the traffic latency symbol of 2N level symbol so that produce the delayed data stream of 2N level symbol, subsequently the data flow of the delay of the data flow of 2N level symbol and 2N level symbol is made up linearly and produce result as the linear combination of the response of first comb filter.This response, promptly (4N-1) level symbol is sent to first data amplitude limiter.

In the solution of the present invention, the symbol of the first kind of being carried out by first data amplitude limiter before data slicing cataloged procedure again is regarded as the process that prelists.After data slicing, second comb filter is carried out the encoding process again of one second type symbol, implements the process of encoding process again that a rearmounted processing procedure compensates first type, and produces the symbol decoding end of proofreading and correct.The processing procedure that first type symbol is encoded again is by differential delay with for encode the again symbol data streams of an input of first linear combination of the data item of differential delay.Second type symbol cataloged procedure is again encoded for the symbol decoding result work of the local filtering that is recovered by first data amplitude limiter again.Process that the symbol of this second type is encoded is again used symbol decoding result's second linear combination of this part filtering of the delay result with second linear combination, and carries out this combination according to a modular algorithm.The result of first and second linear combinations subtracts each other, other then addition.The result of second linear combination is rearmounted symbol decoding result.

The problem of the reality that the postposition coding of carrying out after following comb filtering closely has must solve, and carries out correct operation so that carry out rearmounted coding.In case an aspect of this problem is the error that has in the symbol decoding result of basic filtering, then this error will be fed back in the mode that postpones, and is tending towards propagating this error during the result's of rearmounted symbol decoding generation.The aspect of other of this problem relates to other the condition of how initialization in postponing feedback circuit, and in case when transmission error having occurred, how to reinitialize the condition in this delay feedback loop.

When the second type precoding being used for rearmounted coding is this problem to occur, because the feedback of using in this coding is again accumulated and a kind of overtime accumulation is provided.When the precoding of second type in coding again and the first kind in postposition coding coding is implemented again the time, the coding again of the first kind is provided at temporal a kind of difference, promptly suppresses the response of the initial condition of coding again for second type.Adding up or integrated initial condition of these two kinds of unnecessary considerations of precoding self.When realizing the coding again of the first kind and in the process of postposition coding, realizing the coding again of second class in the process at coding in advance, because accumulation that produces in the second type precoding process or the integrated caused error of incorrect initial condition can be propagated in the postposition coding voluntarily.This will cause that the kinematic error in final coding result is the mistake of a system, rather than a mistake at random, and in general, this kinematic error will can not proofreaied and correct voluntarily at any time.

One aspect of the present invention be the method for a symbol decoding of the data flow of decoding 2N level symbol, the stationary phase that each symbol of symbol has stipulated time length postpones, the data flow of the symbol of this 2N level is attended by the distortion (artifact) of common road interference simulation TV signal easily, and N wherein is a positive integer.This method produces the symbol decoding result who selects by several steps, comprising the step of carrying out comb filtering for the 2N level symbol, so that produce the comb filtering response of the pre-coded symbols with (4N-1) level, the distortion suppression of the anolog TV signals that the common road of any existence is disturbed is fallen thus.The step of this comb filtering comprises the experimental process step, sign convention phase delay with the symbol data flow delay defined amount of 2N level, so that produce the data flow of the 2N level symbol of a delay, and according to addition with subtract each other the data flow that the delay of the data flow of 2N level symbol and this 2N level symbol is made up in one of operating process linearly, so that produce the first linear combination result as the comb filter response with (4N-1) level pre-coded symbols, have the step of carrying out amplitude limit for the comb filter response of symbol, so that produce the result of the symbol decoding of precoding with the precoding of (4N-1) level.Have several steps, the symbol stationary phase that the result of the symbol decoding selected is postponed to be scheduled to postpones, so that produce the decoded result of the selection symbol that postpones.And linearly with the result of the symbol decoding of precoding and the selecteed symbol decoding result row combination of delay, so that produce the result of second linear combination.For the enforcement of this linear combination of producing second linear combination result is according to using realizing for the addition that produces first linear combination result or the opposite process of subtracting each other operating procedure that the substep of linear combination is realized, this operation realizes according to a modular algorithm, the step of determining to describe in the symbolic coding of the total synchrodata of 2N level symbol data flow the time that occurs is wherein arranged, when the symbolic coding description of said synchrodata appears in the 2N level symbol data flow, generation does not have the synchrodata of error, and the result of the symbol decoding of generation selection, when appearing in the 2N level symbol data flow with the denotational description of convenient synchrodata for the synchrodata that does not have error, and when the symbol time that is not the description of synchrodata appears in this 2N level symbol, be the result of corresponding second linear combination in the selecteed time at least.

Another aspect of the present invention is the combination of a circuit, as described in the specification, this circuit is included in the television receiver, this combination of circuits comprises that the checkout gear of digital television signal is to provide a data flow of 2N level symbol, the stationary phase that each symbol has official hour length postpones, and the data flow of the symbol of this 2N level is attended by the distortion of common road interference simulation TV signal easily.This combination of circuits comprises first and second deferred mounts, and each all shows the delay of first number of the regulation that said symbol stationary phase postpones.The combination of this circuit comprises first and second linear combiners, and one of them is an adder, and another is a subtracter, and second linearity given and closed the algorithm operating that device is a module 2N.First deferred mount connects the data flow of the 2N level symbol that responds the data flow with first 2N level symbol that postpones, thereby produces the data flow of first pair of differential delay of said 2N level symbol.First linear combiner is connected the 2N level symbol data flow that is used for first pair of differential delay and makes up linearly.The data flow of this first pair of differential delay is first and second other input signal of branch that is received as first linear combiner, respond these input signals, this first linear combiner produces the output signal of the data flow of one first (4N-1) level symbol as it.In this combination of circuits, comprise one first data amplitude limiter, by producing the first pre-coded symbols decoded result for decoding as first data flow of (4N-1) level symbol that divides other output signal from first linear combiner.Be used for thereby second linear combiner that first and second input signals that receive respectively carry out linear combination and provide other output signal of branchs is connected to receive result as the symbol decoding of first precoding of other first input signal of branch.This second deferred mount is connected and is used for postponing to divide other input signal, thereby produces second input signal of second linear combiner.This combinational circuit also comprises data synchronization circuit, be used for determining the time that data in synchronization occurs that is used for of present 2N level symbol data flow, also comprise a circuit, when the symbol that is used for data sync is determined the data flow that appears at the 2N level symbol, be used to produce the result of desirable symbol decoding, this combination of circuits also comprises first Port Multiplier of a plurality of inputs, connect and be used for dividing other output signal to be provided to second deferred mount as dividing other input signal, the result who is used to receive desirable symbol decoding is as first of input signal, and the output signal that is used to receive second linear combiner is as another of its input signal.In the presence of, and if only if when being used for the symbol of data sync and being determined the data flow that appears at the 2N level symbol, this first Port Multiplier is adjusted to regenerate as first signal of its input signal of its output signal.Otherwise this first Port Multiplier is adjusted, and is at least on the selected time, and regeneration is as the output signal of the symbol decoding result's of the first rearmounted coding second linear combination.

Fig. 1 is the block diagram according to a digital television signal receiver of the present invention, wherein before the decoding of symbol, use the comb filter of the comb filter of inhibition NTSC signal and a postposition decoding after symbol decoding, and use a relatively detector that is total to the road interference of base band energy.

Fig. 2 is to use the NTSC block diagram of road interference detector altogether in the digital television receiver in Fig. 1.

Fig. 3 is the block diagram of the part of digital television receiver, according to the present invention, before carrying out symbol decoding, use a NTSC to remove comb filter and carrying out symbol decoding after use a rearmounted coding comb filter, and use the common road interference detector of type described in the United States Patent (USP) of submission on March 21st, 1997 (lawyer's office's case number be 1500-1).

Fig. 4 is the block diagram of the part of digital television receiver, according to the present invention, before carrying out symbol decoding, use a NTSC to remove comb filter and carrying out symbol decoding after use a rearmounted coding comb filter, and use the common road interference detector of type described in the United States Patent (USP) of submission on March 21st, 1997 (lawyer's office's case number be 1501-1).

Fig. 5 is the schematic block diagram of the details of the part in the digital television signal receiver among Fig. 1, Fig. 3 or Fig. 4, relate to final symbol decoding result's selection, during data synchronization, from the decoded result of predetermined symbol, select and from data amplitude limiter, select at the baseband signalling coding that received other time response, perhaps from rearmounted data amplitude limiter response, select, do not carry out the selection of final decoding symbols so that whether in fact have the common road of NTSC to disturb according to the baseband signalling coding of having received.

Fig. 6 is the schematic block diagram of another circuit arrangement of Fig. 5.

Fig. 7 is the schematic block diagram of another circuit arrangement of Fig. 5.

Fig. 8 is the schematic diagram of the circuit block diagram of the digital television receiver part among presentation graphs 1, Fig. 3 or Fig. 4, is used for producing at the interval of data sync the decoded result of predetermined symbol.

Fig. 9 represents when the NTSC that adopts 12 symbol delays removes filter the schematic diagram of the circuit block diagram of the digital television receiver part among Fig. 1, Fig. 3 or Fig. 4.

Figure 10 represents when the NTSC that adopts 6 symbol delays removes filter the schematic diagram of the circuit block diagram of the digital television receiver part among Fig. 1, Fig. 3 or Fig. 4.

Figure 11 represents when the NTSC that adopts 2 video line to postpone removes filter the schematic diagram of the circuit block diagram of the digital television receiver part among Fig. 1, Fig. 3 or Fig. 4.

Figure 12 represents when NTSC removes 262 video line delays of filter employing the schematic diagram of the circuit block diagram of the digital television receiver part among Fig. 1, Fig. 3 or Fig. 4.

Figure 13 represents when the NTSC that adopts 2 video frame-delay removes filter the schematic diagram of the circuit block diagram of the digital television receiver part among Fig. 1, Fig. 3 or Fig. 4.

Figure 14 is to use a plurality of NTSC that are used to carry out the parallel symbol decoding to remove the block diagram of a digital television receiver of filter.

To be expression constitute the schematic diagram of single circuit to be described in detail below to can put together shown in Figure 15 A and Figure 15 B to Figure 15, and wherein Figure 15 is shown in greater detail in the symbolic code selection circuit that can use in the digital television receiver among Figure 14.

Figure 15 A is the schematic block diagram of the circuit of expression digital television receiver shown in Figure 14, is used for producing predetermined symbolic coding result at the interval of data sync.

Figure 15 B is the schematic block diagram of the circuit of expression digital television receiver shown in Figure 14, is used for selecting in the middle of the decoded results of carrying out between the interval of data sync at symbol.

Each point in shown these accompanying drawings must insert adjusting (shimming) for the correctness that realizes operating sequence and postpone, and understands as this professional those of ordinary skill.Only have relevant specific control lag request and make mistakes, detailed explanation is not done in following reference.

Fig. 1 shows the digital television signal receiver that is used to recover error correction data, these data be applicable to mpeg decode digital VTR record and in relevant television receiver, show.DTV signal receiver among Fig. 1 is illustrated for the television broadcasting signal from reception antenna 8 and receives, but also can receive the signal from cable network, and this television broadcasting signal is sent to electronic installation 10 as input signal.This electronic installation 10 generally includes radio frequency amplifier and relevant first detector, is used for converting this radio television signal to medium-frequency TV signal, is input to intermediate frequency (IF) amplifier chain 12 that is used for the DTV signal of residual sideband as input signal.The DTV receiver is the receiver with multiple translation type of IF amplifier chain 12 at last, comprise an intermediate frequency amplifier, when converting a UHF band to by first detector, the DTV signal is used to amplify this signal, a second detector, the DTV conversion of signals that is used for amplifying becomes the signal of a very-high frequency band, also comprise another intermediate frequency amplifier, when this DTV signal is converted into the signal of VHF frequency band, it is amplified.If be implemented to the demodulation of base band at numeric field, then IF amplifier chain 12 further comprises a third detector, and the DTV conversion of signals that is used for amplifying becomes the last intermediate frequency baseband signal near base band.

Preferably, in the IF amplifier, a SAW (Surface Acoustic Wave) filter (SAW) is used for the UHF frequency band, so that the many selection of moulding response and suppress adjacent channel.This SAW filter just sharply ends the suppressed carrier frequency and the pilot frequency carrier wave of the DTV signal of removing VSB outside 5.38MHz, these carrier waves have similar frequency and fixing amplitude.Therefore this SAW filter has removed the major part of the frequency modulation sound carrier of the anolog TV signals that disturb in any road altogether.The removal of the FM sound carrier of the anolog TV signals that disturb for any road altogether in IF amplifier chain 12 has prevented the artificial interference in generation when final IF signal is detected, so that recover the symbol of base band and prevent the interference of this artificial disturbance for the data slicing of these baseband signallings during the decoding of symbol.Prevent that during the decoding of symbol this artificial disturbance is better than the result who relied on comb filter to realize for the interference of the data slicing of baseband signalling before data slicing.

Final IF output signal from IF amplifier chain 12 is delivered to compound demodulator 14, the DTV signal of the amplitude modulation of the residual sideband of these compound demodulator 14 demodulation in this final midband, so that recover real baseband signal and mirror image baseband signal, demodulation can be to realize in the numeric field of several million Hz after the analog-digital conversion of final midband, resemble people such as C.B.Patel have described in the U.S. Pat 5479449 of on December 26th, 95 disclosed being entitled as " DIGITAL VSB DETECTOR WITH PHASE TRACKER, ASFOR INCLUSION IN AN HDTV RECEIVER " like that.In addition, demodulation can be to realize in the analog signal field, and result wherein normally will carry out the conversion of analog to digital, so that help further processing.Compound demodulation preferably realizes with homophase (I) synchronous demodulation and the synchronous demodulation of quadrature phase (Q).The numeric results of aforesaid demodulating process has 8 bits or higher accuracy usually and describes N other symbol of bit 2N level of coded data.DTV signal receiver in current Fig. 1 is 8 by the 2N in the situation of antenna reception radio broadcasting, and the 2N in the situation of the DTV signal receiver wired broadcasting in Fig. 1 is 16.The reception on the land that involved in the present invention is realizes by wireless mode, and Fig. 1 does not illustrate and is used for providing the decoding of symbol and the DTV of error correction decoding to receive to receiving wired transmission.

From compound demodulator 14, symbol synchronizer and equalizer 16 receive the digitized at least actual sampling of homophase (I channel) baseband signal at least; In Fig. 1, this symbol synchronizer of DTV and equalizer 16 also are illustrated the digitized mirror image sampling that receives quadrature phase (Q channel) base band.This symbol synchronizer and equalizer 16 comprise that is increased the weight of the adjustable digital filter of coefficient, so that distortion and the shake of compensation in received signal.This symbol synchronizer and equalizer 16 provide synchronous or " separating turn " of symbol, and the inhibition of the equilibrium of amplitude and distortion.This this synchronous symbol synchronizer of realizing symbol before the amplitude equalization and equalizer 16 in U.S. Pat 5479449 as can be known.In this design, compound demodulator 14 provides the baseband signal that comprises real and mirror image the response of the demodulator of oversampling to be provided to symbol synchronizer and equalizer 16.After sign synchronization, the data of this oversampling are extracted, so that extract the signal of the I channel of base band with normal character rate, by being used for the speed that digital filtering that amplitude equalization and distortion remove reduces sampling.For the professional and technical personnel in the design field of digital signal receiver, wherein symbol synchronously, this symbol synchronizer and equalizer 16 that " separating turn " or " Phase Tracking " carries out amplitude equalization before are known equally.

The output signal of each sampling of symbol synchronizer and equalizer 16 is broken down into ten or more bits, and is the expression of numeral that presents an analog symbol of one of (2N=8) on effect.By one of some kinds of known methods, the control that this output signal of symbol synchronizer and equalizer 16 is gained in earnest is so that learn the rank of the desirable stepping that is used for symbol.Because the response speed of its gain controlling is fast especially, the normal level of the flip-flop that a kind of method of gain controlling is provided by the actual baseband signal that provides from compound demodulator 14 to+1.25.The method of this gain controlling has been done general description in U.S. Patent application US 5479449.More detailed be described in people such as C.B.Patel in the U.S. Patent application US 5574454 that submits to December 15 nineteen ninety-five, be entitled as " AUTOMATIC GAIN CONTROL OF RADIO RECEIVER FORRECEIVING DIGITAL HIGH-DEFINITION TELEVISION SIGNALS ", the document is hereby incorporated by reference.

Output signal from symbol synchronizer and equalizer 16 is input to synchronizing indicator circuit 18 as input signal, and this synchronizing indicator circuit 18 is changed for the synchronizing information F of the data fields of making balanced baseband I-channel signals and the synchronizing signal S of data segment.The input signal that is input to synchronizing indicator circuit 18 in addition can obtain before equilibrium.

Be input to NTSC from the signal of the balanced I channel of the proper symbol speed that provides as output signal of symbol synchronizer and equalizer 16 as input signal and remove filter 20.This NTSC remove filter 20 comprise transmission 2N level symbol a pair of differential delay data flow first deferred mount 201 and be used for the symbol data streams of differential delay made up linearly and produce first linear combiner 202 that NTSC removes the response of filter 20.As figure was described in the U.S. Pat 5260793, first deferred mount 201 can provide the delay that equals the 2N level symbol, and this first linear combiner 202 can be a subtracter.Each sampling that NTSC removes the output signal of filter 20 all is broken down into ten or more bits, and is the description of a numeral of representing one of the analog symbol of (4N-1)=15 on effect.

Suppose that this symbol synchronizer and equalizer 16 suppress the biasing composition (representing with digital sampling) of its input signal in design, because the detection of pilot frequency carrier wave, direct current biasing composition wherein have+1.25 level and appearing at from the baseband signal that recombiner demodulator 14 provides.Therefore, remove the input signal of filter 20 as NTSC and each sampling of the output signal of this symbol synchronizer that adds and equalizer 16 on effect be expression following standardization level-7 ,-5 ,-3 ,-1 ,+1 ,+3 ,+5 and+one of 7 numeral.These symbol level are " odd number " symbol level, are detected by strange level data amplitude limiter 22, so that produce the structure of intermediate symbols decoding respectively: 000,001,011,100,101 and 111.

Each sampling that NTSC removes the output signal of filter 20 on effect be expression-14 ,-12 ,-10 ,-8 ,-6 ,-4 ,-2 ,+2 ,+4 ,+6 ,+8 ,+10 ,+12 and+description of a numeral of 14 normalized analog symbol.These symbol level surfaces go out " even number " level and are detected by an even level data amplitude limiter 24, so that produce 001,010,011,100,101,110,111,000,001,010,011,100,101,110 and 111 pre-coded symbols decoded results respectively.

As described in specification, this strange level data amplitude limiter 22 and even level data amplitude limiter 24 can be so-called " hard decision " type, or resemble use " soft decision " type in Viterbi decoder rules.Move the position in circuit and provide biasing to revise its amplitude limit scope by the connection of Port Multiplier, consistency in strange level data amplitude limiter 22 and even level data amplitude limiter 24 in the design may make these two amplitude limiters be replaced by a single data amplitude limiter, but these designs are owing to operational complexity is not to be the most desirable.

Symbol synchronizer in the description in front and equalizer 16 are the direct current biasing composition that is used for suppressing input signal (represented with digital form) in design, this direct current biasing composition has+1.25 normalized bias level, and the detection owing to for pilot frequency carrier wave appears in the true baseband signal from compound demodulator 14.In addition, symbol synchronizer and equalizer 16 are the direct current biasing composition that keeps this input signal in design, have so just simplified the design of equalization filter to a certain extent.For the direct current biasing composition of considering to follow in the data step in input signal, the data slicing level in strange level data amplitude limiter 22 in this kind situation is compensated.Suppose that first linear combiner 202 is subtracters, whether this symbol synchronizer and equalizer 16 are designed to suppress or keep the direct current biasing composition of input signal not influence digital width of cloth level in even level data amplitude limiter 24.But, if the differential delay signal of selecting first deferred mount 201 to provide, so that make the linear combiner 202 of winning become subtracter, then the data slicing level in even level data amplitude limiter 24 just should be compensated, so that with respect to the direct current biasing of the companion data step-length in its input signal.

Rearmounted coding comb filter 26 is used in after strange level data amplitude limiter 22 and the even level data amplitude limiter 24, produces the rearmounted coding filter response that response NTSC removes filter 20.This postposition coding comb filter 26 comprises that 3 ends input multichannel journey 261, second linear combiner 262 and its delay equal to remove at NTSC second deferred mount 263 of first deferred mount 201 in the filter 20.If first linear combiner 202 is subtracters, 262 of this second linear combiners are the adders of a mould 8, and if first linear combiner 202 is adders, 262 of this second linear combiners are the subtracters of a mould 8.First linear combiner 202 and second linear combiner 262 can be constituted read-only memory (ROM) respectively, thereby quicken linear combination operation fully, so that the sampling rate that support is adopted.Output signal improvement from 3 ends input Port Multiplier 261 is postponed from the response of postposition coding comb filter 26 and by second deferred mount 263.This second linear combiner 262 is making up from the pre-coded symbols decoded result of even level data amplitude limiter 24 and the output signal of second deferred mount 263.

One of come the selection of first, second and the 3rd control signal that are added to this 3 end input Port Multiplier 261 of self-controller 28 according to response, these Port Multiplier 261 these three institute's plus signals of regeneration.When from the data fields synchronizing information F of the signal of the I channel of equilibrium and data segment sync information S by the synchronizing indicator circuit between 18 convalescences, the first input end mouth of multiplier 261 receives the desirable symbol decoding result that slave controller 28 internal storages provide.During this period, controller 28 is provided to Port Multiplier 261 with first state of Port Multiplier control signal, repairs the ideal symbol decoded result that the memory block in the slave controller 28 provides according to the result of the coding of its final output signal.Strange level data amplitude limiter 22 is delivered to the decoded result of intermediate symbols second input port of Port Multiplier 261 as its output.By second status adjustment Port Multiplier 261 of Port Multiplier control signal, so that generation is as the intermediate symbols decoded result of the final coding result of output signal.Second linear combiner 262 is provided to rearmounted symbol decoding result the 3rd input port of Port Multiplier 261 as output signal.Port Multiplier 261 is subjected to the adjusting of this control signal, so that produce the symbol decoding result, as the final coding result of output signal.

By during the synchronizing information S of the synchronizing information F of data synchronization detector circuit 18 restore data fields and data segment the ideal symbol decoded result feedback of coming the memory block in the comfortable controller 28, deleting from the error among the rearmounted symbol decoding result of postposition coding comb filter 26, this is an important aspect of the present invention, will describe in more detail in this manual.

The output signal of the Port Multiplier 261 in postposition coding sulphur shape filter 26 comprises the result of the final symbol decoding in three end parallel bit groups that is collected by Data Assembler 30, be used for data analysis 32, the data transaction that this data-analyzing machine 32 will collect becomes parallel data, is used for trellis decoder circuit 334.This trellis decoder circuit 34 adopts 12 trellis decoders traditionally, and the trellis decoder decoded results is delivered to data from this trellis decoder circuit 34 and separated also wrong device circuit 36, so that separate conversion.Byte syntactic analysis circuit 38 converts the dateout of data release of an interleave circuit 36 to the byte of Ruide-Saloman error correction code, for use in Ruide-Solomon decoder circuit 40, this Ruide-Solomon decoder circuit 40 is carried out Ruides-Salomans decoding and is produced and be provided to the byte data stream that data are separated the error correction of random device 42.Data are separated other the circuit (not illustrating) that random device 42 is provided to the data of regeneration receiver.The circuit of other of a complete DTV comprises screening washer, audio decoder, MPEG-2 decoder of a packing data etc.Record with a digital magnetic tape/related circuit of the DTV that the machine of putting combines will comprise the form that is used for data transaction is become to be suitable for writing down.

NTSC altogether road interference detector 44 to controller 28 provide an indication with show this NTSC altogether the road disturb whether strong to can cause data slicing that 22 execution of level data amplitude limiter occur the error that can not proofread and correct.If decoder 44 these NTSC of indication road interference altogether do not have such intensity, then in other the time that does not belong to the field synchronization information F that recovered by synchronizing indicator circuit 18 and data segment sync information S, controller 28 is just delivered to Port Multiplier 261 to second kind of state of Port Multiplier control signal.This makes the decoded results of the output signal conduct of adjusting Port Multiplier 261 generations from the intermediate symbols of data amplitude limiter 22.If 44 these NTSC of indication road interference altogether are enough to by force to the uncorrectable error that causes in strange level data amplitude limiter 22, then in other the time that does not belong to the field synchronization information F that recovered by synchronizing indicator circuit 18 and data segment sync information S, this controller 28 is just delivered to Port Multiplier 261 to the third state of Port Multiplier control signal.This output signal that will regulate the rearmounted symbol decoding result that Port Multiplier 261 produces is as second combined result from second linear combiner 262.

NTSC shown in Fig. 2 form of road interference detector 44 altogether believes for prior art it is novel.Subtracter 441 differential set incompatible from data amplitude limiter 22 middle entry symbol decoding result and the rearmounted symbol decoding result who provides from the conduct second linear combination result of second linear combiner 262.If this NTSC altogether amount disturbed of road can ignore, and if the random noise in the I of base band channel be to ignore, then these data item just should be similar, thus feasible difference from 411 is low.If the total amount that NTSC disturbs in common road is obviously as seen, then the difference signal that illustrates from subtracter 441 will can not be very low, and normally high value.

From the measurement of the energy of the difference signal of subtracter 441 utilize square operation that squarer 442 carries out for this difference signal squared and field average circuit 443 in the predetermined short time interval, determine all corresponding obtaining in side.This squarer 442 can use read-only memory (ROM) to realize.This average average circuit 43 can realize with postponing line storage, be used for several continuous digital samplings and adder be used for to be stored in that the current data sampling that postpones line storage is got and.The energy short term average from the difference output signal of subtracter 441 by 443 decisions of average average circuit is sent to the digital comparator of connection, so that a threshold detector 444 is provided.The thresholding of threshold detector 444 is sufficiently high, but is no more than the mean value of the difference in the random noise that is accompanied by intermediate symbols decoded result and the rearmounted symbol decoding result who is added to subtracter 441.If NTSC road interference altogether is strong enough to a value of getting above door, then cause uncorrectable error in the data slicing process of in level data amplitude limiter 22, carrying out.This threshold detector 444 provides the indication whether this thresholding is exceeded to controller 28.

The difference of the digital television receiver shown in the digital television receiver shown in Fig. 3 and Fig. 1 is, being used for wherein determines that NTSC disturbs and whether is strong enough to the circuit types that can cause in the uncorrectable error of the data slicing of being carried out by level data amplitude limiter 22 and is illustrated in the inventor in 1997 U.S.'s patent application on March 21, (agent docket is 1501-1) in the road altogether, and exercise question is " USINGINTERCARRIER SIGNALS FOR DELECTING NTSC INTERFERENCE INDIGITAL TV RECEIVERS ".DTV signal as the IF signal of being changed by " front end " electronic installation 10 is added to the IF amplifier link 46 that is used for the NTSC signal.This IF amplifier link 46 that is used for the NTSC signal is different from use and amplifies link at the IF of common NTSC signal receiver, amplifier stage in IF amplifier link 46 has in fact linear gain and the residual sideband that has corresponding to the identical gain controlling NTSC signal in IF amplifier chain 12 and is not suppressed in IF amplifier link 46 corresponding to the amplifier stage at the IF amplifier chain 12 that is used for the DTV signal.Belonging to is that the full sideband of NTSC signal of the monolateral band in character preferably is suppressed in IF amplifier link 46, so that lower the energy of DTV signal.The reduction of the dynamic range of IF amplifier link 46 responses helps the additional amplification of video carrier, is used for locking the phase place of use at the local video carrier oscillator of compound demodulator 48.If use multiple conversion receiver circuit, the filtering that carries out for the bandwidth of setting up IF amplifier link 46 can be realized by the SAW filter in a UHF IF amplifier.The IF of the amplification of IF amplifier link 46 responds or directly or through some further is sent to the compound demodulator 48 that is used for the NTSC signal after the amplification.This compound demodulator 48 provides the response of a homophase I channel, comprises the sampling of ntsc video signal and follows the composition of the reality of this DTV distorted signal.This compound demodulator 48 also provides the response of the Q passage of quadrature phase, comprises the sampling of the imaginary part composition of DTV distortion, and this sampling is added to hilbert-transform filter 50.The response of this hilbert-transform filter 50 is added to linear synthesizer 52.Linear synthesizer 52 is with the response of hilbert-transform filter 50 and the suitably DTV distortion combination of the homophase I passage of delay.According to the phase place of using the associated video carrier wave in the synchronous demodulation process in compound demodulator 48, this linearity synthesizer 52 is an adder or a subtracter, so that produce I channel signal and Q channel signal.

Deliver to from the NTSC signal of the DTV distorted signal of in fact not following of linear synthesizer 52 that to have cut-off frequency be a 750KHz or a littler low pass filter 54.By carrying out square for the response of low pass filter 54 with a squarer 56 and utilizing 58 to carry out the average of response squared at interval at preset time average, be created in the estimation that common road disturbs the energy of the luminance signal in the NTSC signal.This estimation is sent to 58.If this NTSC altogether road disturbs by force to be enough to cause the error that can't eliminate in the data slicing that very comes data amplitude limiter 22 to carry out, then this thresholding in 58 will be exceeded, and this 58 will provide the indication whether this threshold level is exceeded.

The difference of the digital television receiver shown in the digital television receiver shown in Fig. 4 and Fig. 1 is, being used for wherein determine NTSC altogether the road disturb whether be strong enough to can cause the circuit description of the uncorrectable error of the data slicing of carrying out by data amplitude limiter 22 in the inventor in 1997 U.S.'s patent application on March 21, (agent docket is 1500-1), exercise question is " USING VIDEOSIGNALS FROM AUXILIARY ANALOG TV RECEIVERS FORDETECTING NTSC INTERFERENCE IN DIGITAL TV RECEIVERS ".DTV signal as the IF signal of being changed by " front end " electronic installation 10 is added to the approximate parallel IF amplifier link 62 that is used for the NTSC signal.At the amplifier stage at the IF amplifier chain 12 that is used for the DTV signal of the amplifier stage correspondence of the IF amplifier link 62 that is used for the NTSC voice signal, have in fact linear gain and have corresponding to the identical gain controlling in IF amplifier chain 12.The frequency of IF amplifier link 62 select be make strengthen NTSC sound carrier ± 250KHz increase the weight of respond and video carrier ± 250KHz at about NTSC signal in the response that increases the weight of, if use multiple conversion receiver circuit, the filtering that carries out for the bandwidth of setting up IF amplifier link 46 can be realized by the SAW filter in a UHF IF amplifier.Mean carrier decoder 64 is delivered in the IF response of the amplification of IF amplifier link 62, the ntsc video carrier wave that this mean carrier decoder 64 uses modulation is as a reinsertion of carrier that is used for this NTSC sound carrier is carried out difference frequency, so that produce the intercarrier IF signal that utilizes 4.5MHz carrier wave intermediate frequency.Sound intermediate frequency was put device 66 amplifications in the middle of this intercarrier IF signal was used for mean carrier, and this has 4.5MHz IF amplifier 66 the intercarrier sound accompaniment IF signals that amplify are delivered to a carrier amplitude detector 68.Utilize an average average circuit 70 preset time at interval on for the carrier amplitude detector 68 responses do on average, and the average averaged result delivered to threshold detector 72.If the road interference is by force to being enough to cause the error that can't eliminate in the data slicing that data amplitude limiter 22 is carried out altogether for this NTSC, then the thresholding in this threshold detector 72 will be exceeded.This threshold detector 72 will provide the controller that is indicated to that this threshold level whether is exceeded.

Fig. 5 is illustrated in the best mode of implementing Port Multiplier 261 in the rearmounted coding comb filter 26.This Port Multiplier 261 is represented as the combination of two two ends input Port Multipliers 2611 and 2612.Controller 28 is delivering to two ends input Port Multiplier 2611 as control signal from the output signal of road interference detector altogether (for example 44).

By force to be enough to data amplitude limiter 22 carry out produce the error that can't proofread and correct in the data slicings NTSC altogether the road disturb if, then from this NTSC altogether the output signal of " 1 " of road interference detector adjust this two ends input multiplier 2611, so that be added to second input port of two ends input Port Multiplier 2612, this postposition symbol decoding causes this second linear combiner 262 to be provided to the first input end mouth of two ends input Port Multiplier 2611.

By force to be enough to data amplitude limiter 22 carry out produce the error that can't proofread and correct in the data slicings NTSC altogether the road disturb if, then from this NTSC altogether the output signal of " 0 " of road interference detector adjust this two ends input multiplier 2611, so that produce the result of intermediate symbols decoding note, the result of symbol decoding that this data amplitude limiter 22 is added to this result these regeneration middle entries of two ends input Port Multiplier 2611 is added to second input port of two ends input Port Multiplier 2612.

Fig. 5, each of 6 and 7 all illustrates of being included in the controller 28 or 281.The appearance of the synchrodata section that data segment sync detector 181 response then and there is detected and provide one 1 o'clock, and when providing one 1 when the appearance of the detected data sync sign indicating number of data segment sync detector 182 responses.Should or door 281 provide one to be 1 response.In the time of all other, should or door 281 be provided as 0 response.

In Fig. 5, or the response of door 281 is delivered to two ends input Port Multiplier 2612 as control signal.Should or door 281 be that 0 situation is regulated the output that two ends input Port Multiplier 2612 produces as final symbol decoding result and is added to Data Assembler 30, the output signal of two ends input Port Multiplier 2611 is delivered to two ends input Port Multiplier 2612 as the better result of symbol decoding.Or door 281 response is that 1 situation is regulated the output that two ends input Port Multiplier 2612 produces as final symbol decoding result and is added to Data Assembler 30, as what will be described, from the memory controller 28, obtain desirable decoded result for Fig. 8.

Fig. 6 illustrates another kind of rearmounted coding comb filter 260, and it is the another kind of structure of rearmounted coding comb filter 26.The 3 ends input Port Multiplier 261 that comprises two two ends input Port Multipliers 2611 and 2612 is replaced by the three ends input Port Multiplier 2610 that comprises three two ends input multipliers 26101,26102 and 26103.

Fig. 7 is follow-on back coding comb filter 2600 of rearmounted coding comb filter 26, the Port Multiplier 261 that comprises two two ends input Port Multipliers 2611 and 2612 is wherein comprised that a Port Multiplier 26100 of two two ends input Port Multipliers 261001 and 261002 replaces, they respectively from or door 281 and NTSC altogether the road interference detector receive control signal, this postposition coding comb filter 2600 provides certain to be different from the operating result of rearmounted coding comb filter 26 and rearmounted coding comb filter 260.When or door 281 responses when being 1, two ends input Port Multiplier 261001 replaces the result of rearmounted symbol decoding with desirable symbol decoding result.When being total to the road interference detector, NTSC provides one 1, indicating this NTSC to disturb when being enough to by force to the uncorrectable error that causes in the data slicing process performed by data amplitude limiter 22 in the road altogether, this two ends input Port Multiplier 261002 will select the decoded results of the rearmounted coded identification of correction to deliver to Data Assembler 30 as the result of final symbol decoding.When being total to the road interference detector, NTSC provides one 0, to point out this NTSC to disturb when being not enough to by force to the uncorrectable error that causes in the data slicing process performed in the road altogether by data amplitude limiter 22, this two ends input Port Multiplier 261002 will be selected to deliver to Data Assembler 30 from the decoded results of the intermediate symbols of data amplitude limiter 22 as the result of final symbol decoding, and not carry out with any replacement of desirable decoded result for these intermediate symbols decoded results.

Fig. 8 is the details drawing of Fig. 5 Port Multiplier 2612, and the circuit that produces the ideal symbol decoded result on the loading wave Port Multiplier 2612.Port Multiplier 2612 comprises read-only memory 74,76, and 78 buffer register is selectively to read three bit width output buss 80 from Port Multiplier 2612.Port Multiplier 2612 comprises that also tristate buffer 82 is optionally to deliver to output bus 80 with the 3 bit widths output of Port Multiplier 2611.

The circuit that generation is added to the ideal symbol decoded result of two ends input Port Multiplier 2612 comprises ROM74, ROM76, ROM78; Symbol clock generator 84; Be used to address this ROM74, the address counter 86 of ROM76 and ROM78; Be used to produce the address decoder of reading enabling signal 94 address decoders 96 and the address decoder 98 that are used for ROM74, ROM76 and ROM78; And NOR door 92 that is used to control ternary data buffer 82.These address counter 86 countings are from the input pulse with the reception of symbol decoding speed of symbol clock generator 84, thereby generation is described in the continuation address of the symbol in the Frame respectively.The suitable part of these addresses is added to ROM74, and ROM76 and ROM78 are as their Input Address.Response is by Fig. 1, and synchronizing indicator circuit 18 data recovered field sync signals F and data segment sync information S in 3 or 4 disturb reset circuit 88 that address counter 86 is reset to suitable counting.

Best configuration address counter 86 configurations make the number of data segment of prior one group of each Frame of bit count, and make the number of symbol of unessential one group of each Frame of bit count, and this will simplify the circuit design of interference reset circuit 88; The bit width of input signal is reduced to the width of address decoder 94, address decoder 96 and address decoder 98; And helping ROM74, ROM76 and ROM78 are addressed by the local address from address counter 86, lower the bit width of ROM addressing.

ROM74 storage is used for the ideal symbol decoded result of odd number field sync data segment, and by receive from address decoder 94 1 and started selectively and received.Export the counting of number of the symbol of each data segment group by the ROM74 of the unessential bit group addressing of address counter 86; And the prior bit group of address decoder 94 responses, count the number of the data segment of each Frame, the data segment part of and if only if the address that address counter 86 provides is during corresponding to the address of an odd number field sync data segment, and this address decoder 94 just produces one 1.

ROM76 storage is used for the ideal symbol decoded result of even number field sync data segment, and by receive from address decoder 96 1 and started selectively and received.Export the counting of number of the symbol of each data segment group by the ROM76 of the unessential bit group addressing of address counter 86; And the prior bit group of address decoder 96 responses, count the number of the data segment of each Frame, the data segment part of and if only if the address that address counter 86 provides is during corresponding to the address of an even number field sync data segment, and this address decoder 96 just produces one 1.

ROM78 storage is used for the ideal symbol decoded result that is used for the start code group at the section start of each field sync data segment, and by receive from address decoder 98 1 and started selectively and received.The ROM78 response is by two least important bits of address counter 86 outputs, and the least important bit group of address decoder 98 response address counters 86, counts the number of symbols of each data segment group.The design symbol of the data segment part of and if only if the address that address counter 86 provides is during corresponding to the part address of an initial code character, and this address decoder 98 just produces one 1.

Or door 92 is received in the response of three address decoder 94, address decoder 96 and address decoders 98 on the input contact.When accessing desirable symbol decoding as a result the time, one of address decoder 94, address decoder 96 and address decoder 98 provide one 1 output signal as it, respond ternary data buffer 82 and regulate NOR door 92 and export one 0.Make it show high source impedance for the adjusting of ternary data buffer 82, will do not absorbed the output bus 80 of three bit widths from the signal of two ends input Port Multiplier 2611 feedforwards from two ends input Port Multiplier 2612 so that make for output bus 80.During the data segment part under the situation that desirable symbol decoding result can not predict, address decoder 94, address decoder 96 and address decoder 98 do not provide 1 at their output, regulate NOR door 92 and are provided to ternary data buffer 82 to one 1.This will regulate ternary data buffer 82 makes it show low source impedance for output bus 80, so as to make appear at output bus 80 from the signal of two ends input Port Multiplier 2611 feedforwards from three bit widths of two ends input Port Multiplier 2612 on.

The circuit that is used for producing the ideal symbol decoded result that is added to two ends input Port Multiplier 2612 among Fig. 8 is easy to be adopted and used at the configuration shown in Fig. 6 and 7 by the professional and technical personnel of Design of Digital Circuit.

Fig. 9 is a schematic block diagram, expresses the detail drawing of digital television signal receiver of postposition coding sulphur shape filter 126 that the NTSC that removes a kind of filter 20 at the use NTSC shown in Fig. 1, Fig. 3 and Fig. 4 removes a kind of filter 120 and rearmounted coding comb filter 26.Subtracter 1202 is as one first linear combiner of removing at NTSC in the filter 120.NTSC removes filter 120 and uses first deferred mount 1201 of showing that 12 symbol stationary phases postpone, and second deferred mount 1263 that rearmounted coding comb filter 126 is used shows that also the stationary phase of 12 symbols postpones.Postpone simulated television horizontal frequency f by the stationary phase of 12 symbols of each displaying of first deferred mount 1201 and second deferred mount 1263 at 59.75 times _HPeople near the simulated television video carrier is the delay of the one-period of distortion.The delay of these 12 symbols is at 287.25 times of f _HLook 5 cycles of the people of colourity width of cloth carrier wave near simulated television for distortion.The delay of 12 symbols is at 345.75 times of f _HLook 6 cycles of the people of look sound carrier near simulated television for distortion.Here it is why subtracter 1202 for sound carrier, image carrier and for level off to the reason that common road with minimizing disturbs near difference array response by the frequency of the colored width of cloth carrier wave of first deferred mount, 1201 differential delays.But in the part of the vision signal of horizontal scan line, the correlation of this distance in analog video signal in the horizontal space direction is very low in its intersect edge.

A kind of Port Multiplier 1261 of Port Multiplier 261 is controlled by a Port Multiplier control signal, be in second state in the most time when definite NTSC that does not cause the intensity of uncorrectable error in the output signal of data amplitude limiter 22 is total to the road interference, and be in the third state in the most time when the road disturbs altogether as the NTSC that defines the intensity of the uncorrectable error of initiation in the output signal of data amplitude limiter 22.Port Multiplier 1261 is controlled by the control signal that is in the third state, the result's of mould 8 adders 1262 that the stationary phase that has postponed 12 symbols as second deferred mount 1263 is postponed mould 8 get and be fed to mould 8 adders 1262 are got as one and.This is a pattern accumulation, and signal errors is wherein propagated as kinematic error, and the stationary phase of per 12 symbols of this error postpones to occur once.Blocked by Port Multiplier 1261 from the kinematic error among the rearmounted symbol decoding result of postposition coding comb filter 126, in the beginning of each data segment and on during comprising each data segment whole of field synchronization, each data segment is set to its first state.When control signal is during at first state, Port Multiplier 1261 regeneration come ideal symbol decoded result that the memory in the self-controller 28 the provides output signal as it.The decoded result of ideal symbol is incorporated into the error that has stopped operation in the Port Multiplier 1261.Because each data segment has the individual symbol of 4+69 (12), all these ideal symbol decoded results are postponed by the stationary phase that changes back to four symbols in each data segment, thereby make do not have kinematic error can continue to be longer than three data segments.

Figure 10 is a schematic block diagram, expresses the detail drawing of digital television signal receiver that a kind of NTSC that removes filter 20 at the use NTSC shown in Fig. 1, Fig. 3 and Fig. 4 removes a kind of rearmounted coding comb filter 226 of filter 220 and postfilter comb filter 26.NTSC removes filter 220 and uses first deferred mount 2201 of showing that six symbol stationary phases postpone, and second deferred mount 2263 that rearmounted coding comb filter 226 is used shows that also the stationary phase of six symbols postpones.Postpone simulated television horizontal frequency f by the stationary phase of six symbols of each displaying of first deferred mount 2201 and second deferred mount 2263 at 59.75 times _HPeople near the simulated television video carrier is the delay in 0.5 cycle of distortion.The delay of six symbols of fortune is at 287.25 times of f _HLook 2.5 cycles of the people of colourity width of cloth carrier wave near simulated television for distortion.The delay of six symbols is at 345.75 times of f _HLook 3 cycles of the people of look sound carrier near simulated television for distortion.Adder 2202 is as first linear combiner of removing at NTSC in the comb filter 220, and mould 8 subtracters 2262 are as second linear combiner in postposition coding comb filter 226.Because the delay that the delay deferred mount 1201 in the Dragon Boat Festival first that first deferred mount 2201 and second deferred mount 2263 are showed and second deferred mount 1263 are showed, although the clear area near the frequency of changing from the TV carrier frequency is an arrowband, more likely having in signal synthesizes by adder 2202 combinations will good decorrelation than in the good associated row of the signal that is made up by subtracter 1202 difference.The inhibition response of removing the sound carrier in the filter 220 at NTSC is the response that is worse than in NTSC removal filter 120.But, if altogether the carrier wave of the anolog TV signals that disturb of road SAW filter or the trapper in IF amplifier chain 12 suppress, the inhibition that this NTSC removes the relatively poor sound accompaniment of filter 220 is not an individual problem.Remove in the filter 220 rather than the synchronous notch response of using the NTSC of Fig. 9 to remove in duration in the filter 120 is lowered at the NTSC that uses Figure 10, thereby in carrying out lattice decoding and Ruide-Saloman coding, have the trend of actual inhibition error correction.

A kind of 2261 of Port Multiplier 261 is controlled by a Port Multiplier control signal, be in second state in the most time when definite intensity NTSC that does not cause uncorrectable error in the output signal of data amplitude limiter 22 is total to the road interference, and be in the third state in the most time when the road disturbs altogether as the NTSC that defines the intensity of the uncorrectable error of initiation in the output signal of data amplitude limiter 22.Port Multiplier 1261 is controlled by the control signal that is in the third state, the result's of mould 8 subtracters 2262 that the stationary phase that has postponed six symbols as second deferred mount 2263 is postponed mould 8 get and be fed to mould 8 subtracters 2262 are got as one and.This is a pattern accumulation, and signal errors is wherein propagated as kinematic error, and the stationary phase of per six symbols of this error postpones to occur once.Blocked by Port Multiplier 1261 from the kinematic error among the rearmounted symbol decoding result of postposition coding comb filter 226, in the beginning of each data segment and on during comprising each data segment whole of field synchronization, each data segment is set to its first state that four symbol stationary phases postpone that is used for.When control signal is during at first state, Port Multiplier 2261 regeneration come ideal symbol decoded result that the memory in the self-controller 28 the provides output signal as it.The decoded result of ideal symbol is incorporated into the error that has stopped operation in the Port Multiplier 2261.Because each data segment has the individual symbol of 4+138 (6), all these ideal symbol decoded results are postponed by the stationary phase that changes back to four symbols in each data segment, thereby make do not have kinematic error can continue to be longer than two data segments.The possibility in a retardation cycle of the kinematic error in postposition coding comb filter 226 is in fact less than the possibility in postposition coding comb filter 126, although the frequent rate that kinematic error occurs is 12 at interval two ones of lattice sign indicating number.

Figure 11 is a schematic block diagram, expresses the detail drawing of digital television signal receiver that a kind of NTSC that removes filter 20 at the use NTSC shown in Fig. 1, Fig. 3 and Fig. 4 removes a kind of rearmounted coding comb filter 326 of filter 320 and rearmounted coding comb filter 26.NTSC removes filter 320 and uses one first deferred mount 3201 showing that 1368 symbol stationary phases postpone, the as many as anolog TV signals of this delay two on the stationary phase of horizontal line postpone, and rearmounted coding comb filter 326 is also used second deferred mount 3263 of showing this delay, first linear combiner of removing in the comb filter 320 at NTSC is an adder 3202, and second linear combiner in postposition coding comb filter 326 is a mould 8 adders 3262.

A kind of Port Multiplier 3261 of Port Multiplier 261 is controlled by a Port Multiplier control signal, be in second state in the most time when definite NTSC that does not cause the intensity of uncorrectable error in the output signal of data amplitude limiter 22 is total to the road interference, and the most time when the road disturbs altogether as the NTSC that defines the intensity of the uncorrectable error of initiation in the output signal of data amplitude limiter 22 is in the third state together.This DTV receiver preferably includes and is used for detecting the circuit that is total to the variation between the interlacing scan of disturbing in the road at NTSC, so that make this controller 28 keep the third state of the control signal that Port Multiplier 3261 is provided under such condition.

As what supposed, Port Multiplier 3261 is subjected to being in the control of the control signal of the third state, and each result that gets of the mould 8 of mould 8 subtracters 3262 is delivered to mould 8 subtracters 3262 as postponed the signal that 1368 symbol stationary phases postpone by second deferred mount 3263.This is the process of a pattern accumulation, and single error is wherein propagated as the kinematic error of the reproduction that the stationary phase with per 1386 symbols postpones.This character-coded span is longer than the span of the single data block of Ruide-Saloman coding, so a single kinematic error is easy to proofread and correct in Ruide-Saloman decoding.During each data segment that is comprising field synchronization from the kinematic error among the rearmounted symbol decoding result of postposition coding comb filter 326 whole, block first state that is set to it by Port Multiplier 3261, and each data segment begin have four stationary phases and postpone.When control signal is in first state at it time, Port Multiplier 3261 regeneration come ideal symbol decoded result in the comfortable controller 28 as its output signal.The output signal that the ideal symbol decoded result is incorporated into Port Multiplier 3261 has stopped kinematic error, the 16.67ms of ntsc video field and duration show the duration of the even level data amplitude limiter 24.19ms that resists the DTV data fields, so that make the frame grating of the whole NTSC of the final scanning of the DTV data segment that comprises field synchronization.Each of 525 row in NTSC frame grating comprises that the stationary phase of 684 symbols postpones, and postpones as 35911 symbol stationary phases.Being used for this numerical value postpones less than 832 symbol stationary phases of 432 times at the DTV data segment that comprises field synchronization, will be deleted by Port Multiplier 3261 than 432 longer kinematic errors of data fields so can expect the duration naturally, be born the ideal symbol decoded result in comprising the DTV data segment of field synchronization again.Wherein be used for to access the initial code group of ideal symbol decoded result and the phase shifts between the NTSC horizontal scan line data segment in addition.359110 symbol stationary phases can estimating postpone, it is 896775 times that four symbol stationary phases in the initial group of a coding postpone, during 89775 continuous data segments, be scanned, because each DTV data fields has 313 data segments, all can expect naturally that the kinematic error of the duration longer than 287 data fields will be eliminated by the desirable symbol decoding result's of regeneration during coding beginning group Port Multiplier 3261.These two information sources that suppress kinematic error are considerably independently of one another, and the possibility of the kinematic error of the duration that 200 left and right sides data fields of feasible ratio are longer is very little.And, if disturb decline in the road altogether, come the output signal of the response of playback of data amplitude limiter 222 as it so that regulate Port Multiplier 3261 at the NTSC when kinematic error reappears, then this error is possibly than earlier being corrected in other situation.

NTSC shown in Figure 11 removes aspect the demodulation distortion that filter 320 produces suppressing response simulation TV horizontal synchronization pulse and suppresses multiple fairly good in the performance aspect the distortion of response simulation TV vertical sync pulse and equalizing pulse.These interference are that the common road with quite high energy disturbs.Remove in the video content of the anolog TV signals on the cycle of two scan lines scan line outside the interference of scan line, and though this NTSC remove filter 320 also provide goodish for picture material inhibition and its colored what state.Its also removed by the tracking in symbol synchronizer and equalizer 16 filter under the condition that suppressed, be considerably good for the inhibition of the FM sound carrier of anolog TV signals.Interference in the burst signal of most simulated televisions also is suppressed in the response of NTSC removal filter 320.And the filtering that is provided by NTSC removal filter 320 is " quadrature " for the removal that is based upon the NTSC in the lattice decoding process.

Figure 12 is a schematic block diagram, expresses the fragmentary detail view of digital television signal technology receiver of postposition coding comb filter 426 that a kind of NTSC that removes filter 20 at the use NTSC shown in Fig. 1, Fig. 3 and Fig. 4 removes a kind of filter 420 and rearmounted coding comb filter 26.NTSC removes filter 420 and uses one first deferred mount 4201 showing that 179208 symbol stationary phases postpone, the stationary phase of 262 horizontal line of second linear combiner of the as many as anolog TV signals of this delay postpones, and rearmounted coding comb filter 426 is also used second deferred mount, 4263 subtracters 4202 of showing this delay to remove in the filter 420 at NTSC and is used as first linear combiner, and second linear combiner in postposition coding comb filter 426 is a mould 8 adders 4262.

A kind of Port Multiplier 4261 of Port Multiplier 261 is controlled by a Port Multiplier control signal, be in second state in the most time when definite NTSC that does not cause the intensity of uncorrectable error in the output signal of data amplitude limiter 22 is total to the road interference, and be in the third state in the most time when the road disturbs altogether as the NTSC that defines the intensity of the uncorrectable error of initiation in the output signal of data amplitude limiter 22.This NTSC receiver preferably includes to be used for detecting at NTSC and is total to the circuit by the field variation that the road disturbs, so that make this controller 28 keep the third state of the control signal that Port Multiplier 4261 is provided under such condition.

Port Multiplier 4261 is subjected to being in the control of the control signal of the third state, mould 8 adders 4262 moulds 8 get and the result makes the signals that the position postpones and delivers to adder 4262 as a summand as postponed 179208 symbol immobile phase by deferred mount 4263.This is the process of pattern accumulation, and single error wherein is that the kinematic error with reproduction that the stationary phase of per 179208 symbols postpones is propagated.This character-coded span is longer than the span of the single data block of Ruide-Saloman coding, so a single kinematic error is easy to proofread and correct in Ruide-Saloman decoding.During each data segment that is comprising field synchronization from the kinematic error among the rearmounted symbol decoding result of postposition coding comb filter 426 whole, block first state that is set to it by Port Multiplier 4261, and each data segment begin have four stationary phases and postpone.When control signal is in first state at it time, Port Multiplier 4261 regeneration come ideal symbol decoded result in the comfortable controller 28 as its output signal.The output signal that the ideal symbol decoded result is incorporated into Port Multiplier 4261 has stopped kinematic error.The number of in the output signal of Port Multiplier 4261, eliminating the maximum of the desired data fields of kinematic error be suppose in fact identical with the number that requires in the output signal of Port Multiplier 3261, to eliminate kinematic error.But the number of times that appears at error has during this period reduced coefficient 131.

NTSC shown in Figure 12 removes that filter 420 has suppressed response simulation TV horizontal synchronization pulse and the demodulation distortion that produces and suppress all majorities in the distortion of response simulation TV horizontal synchronization pulse.These interference are that the common road with quite high energy disturbs.And this NTSC removes the distortion that filter 420 also comes from not the picture material of the anolog TV signals that become with CY to CY and row to row, obtains the elimination for fixed pattern, no matter and the what state of its horizontal space and colour.Interference in the burst signal of most simulated televisions is also resisted in the response of NTSC removal filter 420.

Figure 13 is a schematic block diagram, expresses the fragmentary detail view of digital television signal receiver of postposition coding comb filter 526 that a kind of NTSC that removes filter 20 at the use NTSC shown in Fig. 1, Fig. 3 and Fig. 4 removes a kind of filter 520 and rearmounted coding comb filter 26.NTSC removes filter 520 and uses one first deferred mount 5201 showing that 718200 symbol stationary phases postpone.The cycle of two frames of the as many as anolog TV signals of this delay, and rearmounted coding comb filter 526 is also used second deferred mount 5263 of showing this delay.Subtracter 5202 is removed in the filter 520 at NTSC and is used as first linear combiner, and second linear combiner in postposition coding comb filter 526 is a mould 8 adders 5262.

A kind of Port Multiplier 5261 of Port Multiplier 261 is controlled by a Port Multiplier control signal, be in second state in the most time when definite NTSC that does not cause the intensity of uncorrectable error in the output signal of data amplitude limiter 22 is total to the road interference, and be in the third state in the most time when the road disturbs altogether as the NTSC that defines the intensity of the uncorrectable error of initiation in the output signal of data amplitude limiter 22.This DTV receiver preferably includes and is used for detecting the circuit of the variation of the frame of the alternation that disturbs of road altogether at NTSC, so that make this controller 28 keep the third state of the control signal that Port Multiplier 5261 is provided under such condition.

Port Multiplier 5261 is subjected to being in the control of the control signal of the third state, the mould 8 of mould 8 adders 5262 get and the result delivers to adder 5262 as summand as postponed the signal that 718200 symbol stationary phases postpone by deferred mount 5263.This is the process of a pattern accumulation, and single error is wherein propagated as the kinematic error of the reproduction that the stationary phase with per 718200 symbols postpones.This character-coded span is longer than the span of the single data block of Ruide-Saloman coding, so a single kinematic error is easy to proofread and correct in Ruide-Saloman decoding.Kinematic error in the rearmounted symbol decoding result who is combing filter 526 from postposition coding blocks first state that is set to it by Port Multiplier 5261 during comprising each data segment whole of field synchronization, and first data segment begin have four stationary phases and postpone.When control signal was first state at it, Port Multiplier 5261 regeneration came ideal symbol decoded result in the comfortable controller 28 as its output signal, and the output signal that the ideal symbol decoded result is incorporated into Port Multiplier 5261 has stopped kinematic error.The number of in the output signal of Port Multiplier 5261, eliminating the maximum of the desired data fields of kinematic error be suppose in fact identical with the number that requires in the output signal of Port Multiplier 3261, to eliminate kinematic error.But the number of times that appears at error has during this period reduced coefficient 525.

NTSC shown in Figure 13 removes that filter 520 has suppressed response simulation TV vertical sync pulse and equalizing pulse and all demodulation of producing are disturbed and suppress all whole in the interference of response simulation TV horizontal synchronization pulse.The common road that these interference have quite high energy disturbs.And, the interference of this NTSC removal filter 520 picture material of constant anolog TV signals in also coming from during two frames.Obtain removing, no matter and its horizontal space frequency and colored what state for this highly stable pattern.All the interference in the burst signal of simulated television also is suppressed in the response of NTSC removal filter 520.

The technical staff of television system can predict employing and the exploitation in the NTSC rejects trap of correlation in anolog TV signals and other type of irrelevance in being different from Fig. 9-13.The scheme of using two such NTSC removal filters to carry out cascade is open, and the 2N level that increases this baseband signal is to (8N-1) data level.This filter can be used to overcome the problem that a plurality of bad especially common roads disturb, and let it be to the greatest extent, and shortcoming is the signal to noise ratio that has lowered when carrying out symbol decoding for random noise disturbance.

Figure 14 illustrates the modified model according to the digital television signal receiver of a further aspect according to the present invention formation, utilize different odd number level data amplitude limiters to operate a plurality of symbol decoders concurrently, be connected to before each data amplitude limiter dissimilar NTSC remove filter and after be connected to separately postposition decoding comb filter so that compensate for remove the preposition decoding that filter carries out by preposition NTSC.A24 removes filter A20 response to first type NTSC and converts the postposition coding comb filter A26 that first kind of prime notation decoded result is used to be added to first type to.B24 removes filter B20 response to second type NTSC and converts the B26 that second kind of prime notation decoded result is used to be added to second type to.C24 removes filter C20 response to the NTSC of the third type and converts the postposition coding comb filter C26 that the third prime notation decoded result is used to be added to the third type to.Data amplitude limiter 22 is delivered to these rearmounted coding comb filter A26, B26 and C26 with the result of the symbol decoding of centre.Wherein the prefix A of parts, B are different integers with C among Figure 14.When adopting the receiver section of Fig. 9-13 expression, these integers are corresponding to one of 1,2,3,4 and 5.

The estimation that symbol decoding among Figure 14 selects circuit 90 to form the best of a correct symbol decoding is used to be added to trellis decoder circuit 34, selects at the intermediate symbols decoded result that receives from data amplitude limiter 22 with from the various rearmounted symbolic coding result that postposition coding comb filter A26, A28, C26 receive.The estimation of the best of this symbolic coding result is used to proofread and correct getting and process in postposition coding comb filter A26, B26, C26.

Comprise and realize shown in Figure 15 of Figure 15 A and 15B that symbol decoding selects the mode of more detailed current the best of circuit 90.Figure 15 A illustrates the details of the circuit that is used to produce aforesaid symbol decoding result.Be used for being added to the three bit width output data bus 800 that symbol decoding is selected circuit 90 at interval in data sync.The class of operation of this Figure 15 A circuit is similar to above-mentioned circuit with reference to figure 8 descriptions.

Figure 15 B is illustrated in and is used for selecting symbol decoding to select the detail circuits of circuit 90 to constitute at intermediate symbols decoded result and various rearmounted symbol decoding result, is used for producing at interval in data sync the result of final symbol decoding.Removing NTSC altogether in the road interfering process from the DTV signal, the effectiveness of this postposition coding comb filter A26, B26, C26 is to remove filter A100, B100, C100 and reduce the NTSC relevant degree of the energy that disturbs of road and DTV signal interference separation and fixed altogether that is transferred to base band by observing NTSC.As in front with reference to as described in the figure 3, NTSC is total to the road interference to be separated from the DTV signal, low pass filter 54 response baseband video signals, this vision signal detects disturbing in the road altogether from NTSC, is used as input signal and delivers to NTSC removal filter A100, B100, C100.Aspect used linear combination, this NTSC removes the NTSC removal filter A20 that filter A100 difference is used for first type, and the combination of removing the linearity among one of filter A20 and NTSC removal filter A100 at NTSC is a subtracter.This is because this NTSC removes that filter A100 is provided is the vision signal of base band, and the ntsc video carrier wave of delivering in the DTV signal that NTSC removes filter A20 is not the baseband signal that is used for video carrier.For similar reason, aspect used linear combination, this NTSC removes the NTSC removal filter B20 that filter B100 is different from second type, and aspect used linear combination, this NTSC removes the NTSC removal filter A20 that filter C100 is different from the third type.The response that NTSC removes filter A100, B100, C100 has squarer A102, B102, C102 institute square respectively, so that determine the energy of these responses.The response of low pass filter 54 is by 104 squares of squarers, so that determine its energy.

The circuit modification of Figure 15 B the circuit of Fig. 8, replace two ends input Port Multiplier 2611 and ternary data buffer 82 with four ternary data buffers 082, A82, B82 and C82.Ternary data buffer 082 is selected on the three bit width output data bus 800 of circuit 90 deliver to symbol decoding from the intermediate symbols decoded results of data amplitude limiter 22 selectively.This three-state data buffer A82 and B82 and C82 are used to selectively the result of the rearmounted symbol decoding of encode from postposition comb filter A26, B26 and C26 be delivered to data/address bus 800 respectively.

Determine whether that one of any response energy with actual specific low pass filter 54 that NTSC removes filter A100, B100 and C100 wants little response, so that determine one of these three ternary data buffer A82, B82 and C82, rather than ternary data buffer 082 is conditioned, and is that low information source impedance was provided in 1 o'clock with the response of convenient NOR door 92.If made such determining, determine whether further that then which of response that NTSC removes filter A100, B100, C100 has minimum energy therein, be conditioned when the response of NOR door 92 is 1, to provide low information source impedance so that control in the middle of ternary data buffer 082, A82, B82, the C82 which.In order to realize such target, the response of squarer 104 and squarer B102 by comparator 108 relatively; The response of squarer 104 and squarer C102 by comparator 110 relatively; The response of squarer A102 and D102 by comparator 112 relatively; The response of squarer A102 and squarer C102 by comparator 114 relatively; Compare by comparator 112 with the response of squarer B102 and squarer C102.

The squarer C102 of one of any response of the response NOR door 118 of three ends inputs surpasses comparator 106, comparator 108 and the comparator 110 of squarer A102, squarer B102 and to(for) the response of indication squarer 104 is not responded, so that produce one 1 as output signal; Otherwise the signal of these NOR door 118 outputs is zero.Two ends inputs provides 1 response of regulating ternary data buffer 082 with door 120, is used for response at and if only if NOR door 92 and is 1 and meanwhile NOR door 118 is that low information source impedance was provided at 1 o'clock.

The output signal that three ends inputs and door 122 provide 1 response is to the output that is 1 comparator 106, indication squarer A102 has the energy of the response that is not more than squarer 104, the output of the complementation of comparator 112 and comparator 114 meanwhile all is 1, and the response of expression squarer 104 has the energy of the response of no more than squarer B102 and squarer C102; Otherwise with the output signal of door 122 be 0.124 provide one 1 response, regulate ternary data set buffer A82, so that 92 responses of and if only if NOR door are 1 and being with door 122 responses a low information source impedance was provided in 1 o'clock at this moment.

The output signal that three ends inputs and door 126 provide 1 response is to the complementary output end that is 1 comparator 116, indication squarer B102 has the energy of the response that is not more than flat upright device C102, the output of comparator 108 and comparator 112 meanwhile all is 1, and the response of expression squarer B102 does not have the energy more than the response of squarer 104 and squarer A102; Otherwise with the output signal of door 126 be 0.Two ends inputs provides one 1 response with door 128, regulates ternary data set buffer B82, and 92 responses of NOR door are 1 and responding with door 126 at this moment is one a low information source impedance was provided in 1 o'clock so that and if only if.

When the output of comparator 110,114 and 116 all was 1, the input of three ends provided 1 output signal that responds with door 130, and the response of indication squarer C102 has the energy less than the response of squarer 104, A102 and B102; Otherwise exporting with door 130 is 0 signal.Two ends inputs provides one 1 response with door 132, regulates ternary data buffer C82, and 92 responses of NOR door are 1 and responding with door 130 at this moment is one a low information source impedance was provided in 1 o'clock so that and if only if.

With reference to Figure 14, the circuit that NTSC removes filter A20 and rearmounted coding comb filter A26 preferably is chosen to the type that NTSC among Figure 13 removes filter 520 and rearmounted coding comb filter 526.The result needs considerable memory like this, because need 718200 symbols of memory in the delay of first deferred mount 5201 and second deferred mount, 5263 these two frame of video.(still, the signal of storing in first deferred mount 5201 provides the storage demand of the common road interference detector A44 among Figure 15.And the same memory can be used to realize shorter delay first deferred mount 4201, first deferred mount 3201, first deferred mount 2201, first deferred mount 1201, and the shorter delay in other common road interference detector of Figure 15.And the storage in second deferred mount 5263 provides the needs of realizing shorter delay second deferred mount 4263, second deferred mount 3263, second deferred mount 2263, second deferred mount 1263.)

When the NTSC frame of video of alternation of having removed filter A20 additional combinations, be created in to disturb and all be suppressed for all high-energy demodulation in the response of TV lock-out pulse, equalizing pulse and colored lock-out pulse.And the interference that originates from the picture material of immovable anolog TV signals between two frames is suppressed.When NTSC removal filter A20 is combined with the frame of video that replaces, NTSC removes the frame of video of these alternations of filter A100 difference ground combination, and removes the detector that filter A20 is provided for the change between the alternation frame of NTSC during the road disturbs altogether jointly together with NTSC.

Suppressing the demodulation at the frame-frame of certain pixel location that remaining problem that demodulation disturbs mainly relates to suppress to originate from the anolog TV signals grating disturbs.Filtering technique is restrained in the enough frames of these demodulation Recombinant Interferons.By relying on correction in the horizontal direction, NTSC removes filter B20 and B26 can be selected to be used to suppress remaining demodulation interference, and by relying on the correlation of vertical direction, this NTSC removes filter C20 and rearmounted coding comb filter C26 can be selected to suppress remaining demodulation interference.Consider the scheme of any these designs of realization.

If altogether the sound carrier of the anolog TV signals that disturb of road is not restrained in the SAW in IF amplifier chain 12 or the trapper, then NTSC removes filter B20 and rearmounted coding comb filter B26 circuit and preferably is chosen to the form that NTSC among Fig. 9 removes filter 120 and rearmounted coding comb filter 126.If altogether the sound carrier of the anolog TV signals that disturb of road is suppressed in the SAW in IF amplifier chain 12 or the trapper, then NTSC removes filter B20 and puts coding comb filter B26 circuit and preferably is chosen to the form that NTSC among Fig. 9 removes filter 220 and rearmounted coding comb filter 226.This is because the decorrelation that has only six symbol stationary phases to postpone between the video image composition normally is better than the correlation that postpones at a distance of 12 symbol stationary phases in the video image composition.

The optimal selection that NTSC removes filter C20 and rearmounted coding comb filter C26 circuit is not to be open-and-shut thing, because the selection of one must be done (consider field in the anolog TV signals that disturb alternately) another selection, whether be chosen in the comparatively close scan line of time in same, or the close scan line in the space in previous field, so that remove among the filter C20 combined with current scan line at NTSC.Be chosen in the close normally preferable selection of scan line of time in same, because the jump between the field just unlikely destroys the inhibition of the NTSC signal of being carried out by NTSC removal filter C20.Utilize this selection, this NTSC removal filter C20 and rearmounted coding comb filter C26 circuit can be that the NTSC in Figure 11 removes filter 320 and rearmounted coding comb filter 326.When NTSC has made up the scan line that replaces of vision signal with removing filter C20 addition, this NTSC removes filter C100 these scan lines that replace with difference ground combination video signal, and and C202 be provided for a detector together for the change between the scan line that replaces during the road disturbs altogether at NTSC.

In the situation of the selection that utilizes other, the circuit that NTSC removes filter C20 and rearmounted coding comb filter C26 is the situation that the NTSC shown in Figure 12 removes filter 420 and rearmounted coding comb filter 426.This NTSC removes filter C100 and squarer C102 provides a detector jointly, is used for detecting the change between the field of disturbing in the common road of NTSC.

The digital receiver of Figure 14 is improved another embodiment of the present invention, used additional parallel time amplitude limit operation, each operation all is to be realized by the level downlink connection of dividing other NTSC to remove filter, is subsequently to be connected to following other even number level time amplitude limiter of branch that divides other rearmounted coding comb filter.Though shown in Figure 14 is two additional data slicing operations in parallel, still can revise and use parallel data slicing operation, it can provide the ability that further becomes more meticulous for the symbol decoding best estimate as a result of proofreading and correct.

Can duplicate trellis decoder circuit 34, and in best estimate, be the judgement that quite successfully realizes various symbol decodings with respect to the symbol decoding result that refines.But this will be referred to the hardware designs of the numeral of suitable details.

In aforesaid some certain embodiments of the present invention, symbol decoding selects circuit 90 to comprise the symbolic coding voting circuit that poll provides from the postamble sulphur shape filter C26 of data amplitude limiter 22, first type postposition coding comb filter A26, second type postposition coding comb filter B26 and the third type.If the result of determination of four kinds of all symbols all occurs, then the decoded result that occurs simultaneously is sent to data assembler code device 30.If provide the symbol decoding result from data amplitude limiter 22, the postposition coding comb filter C26 of first type postposition coding comb filter A26, second type postposition coding comb filter B26 and the third type does not occur, and then carries out a simple voting process by voting circuit and selects the minimum decoded results that error may occur.

If connect a weighting circuit in the voting circuit back, then can obtain the decoding of more accurate symbol.The weighting that is used for deciding by vote can be corrected the variation of considering the various decoded results that may occur, if the decoded result of the majority of other symbol decoding circuit appearance apart is too far away, then reduces weighting according to the decoded results in the voting process.Use is similar to the circuit of Figure 15 B and the circuit that some is additional, the weighting that is used to decide by vote also can be to be determined for the inverse relation of energy measurement, and its energy measurement removes filter A100 by squarer 104, NTSC and squarer A102, NTSC remove filter B100 and squarer B102, NTSC remove filter C100 and squarer C102 determines.

By other the anolog TV signals of television standard that are different from NTSC, for example the common road that caused of PAL standard disturbs in the digital television system that may appear at the Digital Television that U.S.'s terrestrial broadcast uses, and the present invention is easy to revise and makes its design be suitable for this road altogether to disturb very much.

The technical staff who is familiar with digital communication receiver and aforesaid description of the invention and accompanying drawing can design the various corrections that are different from embodiments described herein.This will be interpreted as the scope of the claim that belongs to appended.Term in the claims " said " is to be used for reference to aforesaid content, and the use of " the " speech is the purpose of grammer rather than relates to appended content.

Claims (28)

1. A symbol decoding method for decoding a data stream of 2N-level symbols, each of which has a fixed phase delay of a specified time length, and the data stream of the 2N-level symbols is likely to be accompanied by co-channel interference analog TV signals Distortion (artifact), wherein N is a positive integer, said method produces the symbol decoding result of selection, and comprises the following steps: The step of comb filtering the data stream of said 2N level symbols to produce a comb filter response of precoded symbols having (4N-1) levels, thereby removing any analog of said co-channel interference The distortion of TV signal is suppressed, and the step of said comb filtering comprises several following sub-steps: delaying said 2N level symbol data stream by a prescribed number of said symbol fixed phase delays to produce a delayed 2N level symbol data stream; and Linearly combining said data stream of 2N-level symbols and said delayed data stream of 2N-level symbols according to one of addition and subtraction operations, so as to produce a data stream having (4N-1) precoded symbols as the result of a first linear combination of said comb filter responses; performing data clipping on said comb filter response for symbols having (4N-1) level precoded to produce precoded symbol decoded results; delaying the decoded result of said selected symbol by said predetermined number of symbols with a fixed phase delay to produce a delayed decoded result of the selected symbol; linearly combining said precoded symbol decoded result and said delayed selected symbol decoded result row to produce a second linearly combined result linearly combining said precoded symbol decoded result and Said step of linear combination of delay-selected symbol decoding results is carried out in accordance with said addition and addition of one of the steps of an addition or subtraction operation performed using sub-steps of linear combination to produce the first linear combination result It is realized by the opposite process of subtracting steps, and this operation is realized according to a modular algorithm; Determining when the symbol encoding description of the total synchronous data in said 2N level symbol data stream occurs; generating said synchronization data without error when a symbol-encoded description of said synchronization data occurs in a 2N-level symbol data stream; and generate the result of selected symbol decoding so as to respond to error-free sync data when said symbol description of sync data occurs in the 2N level symbol data stream, and at least for the time selected when it is not sync data The symbol times described correspond to the resulting responses of the second linear combination when they occur in said 2N level symbols. 2. The method for symbol decoding according to claim 1, comprising decoding said 2N level symbol data stream to produce the final symbol decoding result, the interference of the analog television signal of co-channel interference in the final decoding result Being automatically suppressed during symbol decoding, said method of producing a final symbol decoding result further comprises the following steps: performing data clipping on the data stream of said 2N level symbols, so as to generate an intermediate symbol acceptance result; determining whether said data stream of 2N level symbols is accompanied by co-channel interference analog television signal interference of a magnitude sufficient to cause substantial errors in the decoded results of said intermediate symbols; including said intermediate symbol decoding result in the response of said final symbol decoding result to determine that said 2N-level symbol data stream is not accompanied by sufficient strength to induce substantial errors in said intermediate symbol decoding result co-channel interference with analogue television signals; and Responsive to the determination that said 2N level symbol data stream is accompanied by co-channel interference simulated television signal interference of a magnitude sufficient to cause substantial errors in said intermediate symbol decoding results such that said final symbol The decoding result corresponds to said selected symbol decoding result. 3. A method for final symbol decoding results according to claim 2, wherein the response to said data stream of 2N level symbols is not accompanied by a co-channel of intensity sufficient to cause substantial error in said intermediate symbol decoding results In the case of determination of interference interfering with an analogue television signal, said intermediate symbol is present only at said selected time when a symbol encoding which is not the described synchronous data appears in the data stream of said 2N level symbols when the decoding result is included in said final symbol decoding result, said intermediate symbol decoding result is included in the best symbol decoding result; and comprising the further steps of: When the symbol encoding describing said synchronization data is present in said 2N level symbols, the result of decoding said final symbol corresponds to said error-free synchronization data. 4. The method for final symbol decoded results according to claim 3, wherein said data stream for determining said 2N level symbols is accompanied by sufficient to cause substantial error in said intermediate symbol decoded results In the step of the co-channel interference of the interference of the analog TV signal, the following sub-steps are included: differentially combining said intermediate symbol decoding result and said second linear combination result to produce a differential signal; determining the energy of said differential signal; and determining that said data stream of 2N level symbols is accompanied by co-channel interference analog television signals of sufficient magnitude to cause substantial errors in decoding results of said intermediate symbols upon detection of said differential signal exceeding a predetermined threshold value interference; and determining that said data stream of 2N level symbols is not accompanied by co-channeling of a magnitude sufficient to cause substantial errors in the decoded results of said intermediate symbols upon detecting that said differential signal does not exceed said predetermined gate value Interference that interferes with analog TV signals. 5. The method for producing the result of final symbol decoding according to claim 3, wherein said data stream for determining said 2N level symbols is accompanied by sufficient In the step of the interference of the co-channel interference of the error analog TV signal, include the following sub-steps: differentially combining said intermediate symbol decoding result and said second linear combination result to produce a differential signal; squaring said differential signal to produce a squared differential signal; producing the mean of said squared difference signal; determining that said data stream of 2N level symbols is accompanied by co-channel interference analog television signal interference of a magnitude sufficient to cause substantial errors in decoding results of said intermediate symbols upon detection of said mean value exceeding a predetermined threshold value ;and determining that said data stream of 2N level symbols is not accompanied by a data stream sufficient to cause substantial error in the decoding result of said intermediate symbols upon detecting that said rectified low-pass filter response does not exceed said predetermined threshold value The intensity of co-channel interference from analog TV signal interference. 6. The method for producing the final symbol decoding result according to claim 2, which adopts a digital television receiver to generate the data stream of said 2N level symbols by demodulating the amplified intermediate frequency signal, wherein the intermediate frequency signal is passed through Analogue television signals produced by frequency conversion of digital television signals in which said data stream for determining the 2N level symbols is accompanied by co-channel interference sufficient to cause actual errors in the decoding results of said intermediate symbols The step of interference includes the following sub-steps: Generate an intermediate frequency signal by converting the frequency of the digital TV signal; amplifying said intermediate frequency signal to provide an amplified intermediate frequency signal; synchronously detecting said amplified IF signal on the video carrier of said co-channel interfering analog television signal in a composite demodulation process to produce in-phase and quadrature-phase synchronized video detection responses; separating the video component of said co-channel interfering analog television signal from said in-phase and quadrature synchronous video detection responses; determining the energy of the separated video components of said co-channel interfering analogue television signal; detecting that the energy of said separated video component of said co-channel interference analog video signal exceeds a predetermined threshold, determining that said data stream of 2N level symbols is accompanied by sufficient Interference with co-channel interference analogue television signals of a magnitude that causes actual errors in the decoded results; and determining that said data stream of 2N level symbols is not accompanied by a data stream sufficient to cause substantial error in the decoding result of said intermediate symbols upon detecting that said rectified low-pass filter response does not exceed said predetermined threshold value The intensity of co-channel interference from analog TV signal interference. 7. The method for producing the final symbol decoding result according to claim 2, which adopts a digital television receiver to generate the shown data stream of 2N level symbols by demodulating the amplified intermediate frequency signal, wherein the intermediate frequency signal is passed to Generated by frequency conversion of a digital television signal in which the said data stream used to determine the 2N level symbols is accompanied by co-channel interference analog television signal interference sufficient to cause actual errors in the decoded results of said intermediate symbols The steps include the following sub-steps: Generate an intermediate frequency signal by converting the frequency of the digital TV signal; amplifying said intermediate frequency signal to provide an amplified intermediate frequency signal comprising modulated video and sound carriers of said co-channel interfering analog television signal; detecting an intermediate carrier sound signal responsive to heterodyning between the adjusted video and sound carriers of said co-channel interfering analog television signal included in said amplified intermediate frequency signal; determining the energy of said intermediate carrier sound signal; determining that the data stream of said 2N-level symbols is accompanied by co-channel interference of a magnitude sufficient to cause substantial errors in decoding results of said mid-symbols when detecting that the energy of said mid-carrier audio signal exceeds a predetermined threshold Interference with analog television signals; and When detecting that the energy of said intermediate carrier sound signal does not exceed said predetermined threshold value, determining that said data stream of 2N level symbols is not accompanied by enough energy to cause actual errors in said intermediate symbol decoding results The intensity of co-channel interference that interferes with an analog TV signal. 8. The method for symbol decoding according to claim 1, wherein said data stream of said 2N level symbol and said delayed data stream of said 2N level symbol in said comb filtering step The sub-step of performing linear combination is a subtractive process, and wherein said step of linearly combining the result of decoding said precoded symbol and said delayed selected symbol is a modulo 2N The process of arithmetic addition. 9. The method of symbol decoding according to claim 8, wherein said predetermined number of symbol fixed phase delays is twelve. 10. The method for symbol decoding according to claim 1, wherein said data stream of said 2N level symbol and said delayed data stream of said 2N level symbol in said comb filtering step The sub-step of performing linear combination is an additive process, and wherein said step of linearly combining the decoded results of said precoded symbols with the decoded results of said delayed selected symbols is a modulo 2N The process of arithmetic subtraction. 11. The method of symbol decoding according to claim 8, wherein said predetermined number of symbol fixed phase delays is six. 12. A method of symbol decoding according to claim 8, wherein said predetermined number of fixed phase delays of said symbols is substantially equal to the duration of 2 horizontal scan lines of said co-channel interference analog television signal. 13. A method of symbol decoding according to claim 8, wherein said predetermined number of fixed phase delays of said symbols is substantially equal to the duration of 262 horizontal scan lines of said co-channel interference analog television signal. 14. A method of symbol decoding according to claim 8, wherein said predetermined number of fixed phase delays of said symbols is substantially equal to the duration of two image frames of said co-channel interference analog television signal. 15. A combination comprising: The detection device of the digital TV signal is used to provide a data stream of 2N level symbols, each symbol has a fixed phase delay of a specified time length, and the data stream of the said 2N level symbols is susceptible to co-channel interference of analog TV signals interference; A first delay means, exhibiting a predetermined first number of delays of said symbol fixed phase delay, is connected to respond to the data stream of 2N level symbols having a first delay of the data stream of 2N level symbols, thereby producing the The first pair of differentially delayed data streams of said 2N level symbols; A first linear combiner for linearly combining a first pair of differentially delayed 2N-level symbol data streams, said first pair of differentially delayed data streams being received as the first and second linear combiners of the first linear combiner Two separate input signals, the data streams susceptible to interference from co-channel interfering analog television signals, to produce the output signal of the first linear combiner of (4N-1) level symbols, said (4N- 1) the first data stream of level symbols provides a first comb filter response in which said interference of said co-channel interfering analog television signal is suppressed; a first data slicer for decoding the first data stream of (4N-1) level symbols from the first linear combiner as separate output signals to generate decoding results of the first precoded symbols; A second linear combiner for linearly combining respectively received first and second input signals to provide respective output signals, said second linear combiner being connected to receive as respective first input signals the first a precoded symbol decoded result, one of said first and second linear combiners being an adder and the other being a subtractor; second delay means connected to delay the respective input signals by a first predetermined amount of said symbol fixed phase delay, thereby producing a second input signal to the second linear combiner; a data synchronization circuit for determining the time at which data for synchronization appearing in the 2N level symbol data stream; A circuit for producing an ideal symbol decoding result when a symbol used for data synchronization is determined to appear in a data stream of 2N level symbols; a plurality of input first multiplexers connected to provide respective output signals to second delay means as said second input signals for receiving said ideal symbol decoding results as input signals The first one, and the other one for receiving the output signal of the second linear combiner as its input signal, if and only if the symbol used for data synchronization occurs in the data stream of 2N level symbols, said first The multiplexer is adjusted to take as its output signal the first reproduction of its input signal, otherwise said first multiplexer is adjusted, at least at selected times, to combine said second linearly combined Said output signal of the converter is reproduced as the decoded result of the first postcoded symbols. 16. The combination according to claim 15, further comprising: a second data slicer, decoding said data stream of said 2N level symbols, for producing intermediate symbol decoding results sent to said first multiplexer as a second input signal, said Said output signal of the second linear combiner is sent to said first multiplexer as a third input signal; and NTSC co-channel interference detection circuit, used to determine whether the data stream of said 2N level symbol is accompanied by the interference of the analog TV signal of co-channel interference and whether it is in the middle of said second data limiter produced Uncorrectable error is caused in the symbol decoding result, when said NTSC co-channel interference detection circuit determines that the data stream of said 2N level symbol is not accompanied by the interference of the analog TV signal with co-channel interference and in said second data When uncorrectable errors are induced in the decoded results of said intermediate symbols produced by the slicer, said first multiplexer is connected to reproduce a second of its input signals, and when said NTSC co-channel interference is detected The circuit determines that said data stream of 2N level symbols is interference from an analog television signal with co-channel interference and induces uncorrectable errors in said intermediate symbol decoding results produced by said second data slicer , the first multiplexer is connected to regenerate its input signal to the third. 17. The combiner of claim 16, further comprising: A third delay means, exhibiting a predetermined second number of delays of said symbol fixed phase delay, is connected to respond to the data stream of 2N level symbols having a second delay of the data stream of 2N level symbols, thereby producing the The second pair of differentially delayed data streams of said 2N level symbols; A third linear combiner for linearly combining the second pair of differentially delayed 2N-level symbol data streams, said first pair of differentially delayed data streams being received as the first and second pairs of the third linear combiner Two separate input signals, which data streams are susceptible to interference from co-channel interfering analog television signals, to produce a second data stream of (4N-1) level symbols as the output of said third linear combiner signal, said second data stream of (4N-1) level symbols provides a second comb filter response wherein said interference of said co-channel interfering analog television signal is suppressed; a fourth linear combiner for linearly combining the received first and second input signals respectively to provide respective output signals to said first multiplexer as its further input signals, said third and one of the fourth linear combiners is an adder and the other is a subtractor; A third data slicer decodes the second data stream of (4N-1) level symbols from the third linear combiner as separate output signals to generate the decoded results of the second precoded symbols, which are added to the said fourth linear combiner as said respective first input signal; and Fourth delay means coupled to delay the output signal of said first multiplexer by a second predetermined amount of said symbol fixed phase delay to produce a second input signal of said fourth linear combiner. 18. The combination according to claim 15, wherein said first multiplexer is a two-terminal multiplexer which, when not conditioned to reproduce the first of its input signals as its said output signal, The multiplexer is adjusted to reproduce another of its input signals as said output signal, said combination also comprising: a second data slicer, decoding said data stream of said 2N level symbols, for producing intermediate symbol decoding results sent to said first multiplexer as a second input signal, said Said output signal of said second linear combiner is sent to said first multiplexer as a third input signal; NTSC co-channel interference detection circuit, used to determine whether the data stream of said 2N level symbol is accompanied by the interference of the analog TV signal of co-channel interference and whether it is in the middle of said second data limiter produced Uncorrectable errors are induced in symbol decoding results; a second multiplexer of a plurality of inputs connected to provide separate output signals to reproduce separate input signals as final symbol decoding results for receiving said intermediate symbol decoding results as first input signals, And for receiving said output signal of said first multiplexer as another input signal, if and only if said NTSC co-channel interference detection circuit determines that the data stream of said 2N level symbols is not accompanied by When the interference of the co-channel interfering analog television signal causes uncorrectable errors in the decoded results of the intermediate symbols, the multiplexer is adjusted to reproduce the first of its input signals, and when the NTSC When the co-channel interference detection circuit determines that the data stream of said 2N level symbol is the interference of the analog TV signal accompanied by co-channel interference and causes an uncorrectable error in the decoding result of the intermediate symbol, said multi-channel The converter is conditioned to regenerate another of its input signals. 19. The combination of claim 15, wherein said first linear combiner is a subtracter and said second linear combiner is an adder. 20. The combiner of claim 19, wherein said predetermined first number of said symbol fixed phase delays is twelve. 21. The combination of claim 15 wherein said first linear combiner is an adder and said second linear combiner is a modulo 2N subtractor. 22. The combination of claim 21, wherein said symbols are fixed by six of the predetermined first number of phase delays. 23. The combination of claim 19, wherein said predetermined first number of symbol fixed phase delays is substantially equal to the number of symbol fixed phase delays in two scan lines of said co-channel interfering analog television signal. 24. The combination of claim 19, wherein said predetermined first number of symbol fixed phase delays is 1368. 25. The combination according to claim 19, wherein said predetermined first number of symbol fixed phase delays is realized equal to the number of symbol fixed phase delays in 262 horizontal scan lines of said co-channel interference analog television signal . 26. The combination of claim 19, wherein said predetermined first number of symbol fixed phase delays is 179,208. 27. The combination of claim 19, wherein said predetermined first number of symbol fixed phase delays is substantially equal to the number of symbol fixed phase delays in two video frames of said co-channel interfering analog television signal. 28. The combination of claim 19, wherein said predetermined first number of fixed phase delays of symbols is 718,200.

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