CN1310552A - Method and device for inserting data to and extracting data from analog TV baseband signal - Google Patents
Method and device for inserting data to and extracting data from analog TV baseband signal Download PDFInfo
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- CN1310552A CN1310552A CN 00103050 CN00103050A CN1310552A CN 1310552 A CN1310552 A CN 1310552A CN 00103050 CN00103050 CN 00103050 CN 00103050 A CN00103050 A CN 00103050A CN 1310552 A CN1310552 A CN 1310552A
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Abstract
Modulated data are inserted into the vertical flyback blanking time interval or trace sych time interval of analog TV baseband signal. When the modulated data are inserted into the trace sych time interval, the data signal has frequency range in the gap between the horizontal sych signal spectrum and the color subcarrier signal spectrum. In the sending end, the signals of clock phase lock circuit and local vibrator phase lock circuit are phase-locked to synchronize with the color subcarrier signal; and in the receiving end, the signals of sampling clock generator and the local vibrator phase locking circuit are made to phase lock synchronize with the color subcarrier signal in color subcarrier phase lock circuit.
Description
The present invention relates to data send and receive in a kind of Television Broadcasting Network method and device thereof, particularly a kind of method and device thereof that in the simulated television baseband signal, inserts and extract data.
In the advance TV radio network, the realization bi-directional communication function is paid attention to day by day widely and is developed.In a lot of advanced Television Broadcasting Network, its headend equipment can both dynamically manage the set-top box that is positioned at user side in netting, as carries out online software upgrade, cipher control etc.The user also can obtain such as request program by this bi-directional communication function, and service such as surf the web.
Fig. 1 represents to have the schematic diagram of the television network of bi-directional communication function.In Fig. 1, programming server 2 is sent multi-channel analog or digital television program, through radio network interface 3 be transformed into be adapted at broadcasting in the transfer medium 5 signal that transmits after, deliver to the radio network interface 10 in the set-top box 7, can deliver to television set after sending into unit, machine top 8 again.Usually broadcasting transfer medium 5 can be cable television network, can also be wireless space.
When the two-way communication demand, interactive server 1 can pass through mutual network interface 4, and the mutual network interface 9 in mutual net 6 and the set-top box 7 carries out two-way communication with set-top box 7.Mutual net 6 can be a telephone network, and at this moment mutual network interface 4 and 9 is telephone modem.The problem of this mode is that message transmission rate is very low, can't satisfy the demand of growing high speed data communication services.
In order to improve downstream rate, the descending exchange channels 11 in the mutual net 6 can transmit by the medium the same with broadcasting transfer medium 5, and as in cable television network, it takies a channel transmission digital signal.Equally, uplink interaction passage 12 also can transmit by a frequency band in the cable television network, can realize high-speed bidirectional communication like this.
But the problem of this working method is that two high-speed digital receivers (in radio network interface 10, another is in mutual network interface 9) must be arranged in set-top box, thereby makes set-top box 7 costs very high.In order to reduce cost, the data of sending from interactive server can be sent into radio network interface 3, to carry out the time-division earlier compound with the digital television data stream that sends from programming server 2, in same channel, transmit again after the modulation, and receiving terminal set-top box 7 can be separated the TV programme after the demodulation with interactive data, thereby realizes with receiving digital television program and the service of acquisition high-speed down data simultaneously of single receiver.
But because historical reasons, analog television program also will exist for a long time, to in different channels, broadcast analog-and digital-TV simultaneously in the programming server 2, they will transmit in same broadcasting transfer medium 5 (as the cable in wired television network), like this when set-top box 7 is receiving analog television program, can't receive interactive data simultaneously, thereby seriously limit the application of single-receiver set-top box.
Purpose of the present invention make set-top box can also receive data simultaneously when receiving simulated television, and the data of inserting in analog signal will can not influence the work of common simulated television receiver exactly for addressing the above problem.
The method of inserting data in the simulated television baseband signal of the present invention is characterized in that, described data is inserted after ovennodulation in the capable time slot of vertical blanking of simulated television baseband signal, or is inserted in the synchronization slot of trace row; Or insert simultaneously in the capable time slot of baseband signal vertical blanking and trace row synchronization slot of simulated television.
When will be when the data of ovennodulation are inserted in the described synchronization slot, the frequency range of this modulated data signal be in the space between capable synchronous head signal frequency spectrum and the colour subcarrier signal frequency spectrum.
When the signal to noise ratio of described digital signal is big, are high-order orthogonal Modulation and Amplitude Modulation modes to the modulation system of described data; And when the signal to noise ratio of described digital signal hour, low order quadrature amplitude modulation mode is adopted in the modulation of described digital signal.
Identical to the described bandwidth that is inserted in the modulated data in the capable time slot of vertical blanking with the bandwidth of anolog TV signals.
When extracting described data, make it earlier by a band pass filter that is used for filtering row synchronous head and colour subcarrier signal.
The present invention also provides a kind of modulator that is used for data are inserted the transmitting terminal of simulated television baseband signal, comprise: bit also comprises: gain-controlled amplifier to sign changer, evolution raised cosine filter, 90-degree phase shifter, multiplier, adder and digital to analog converter; The clock phase lock circuitry that is connected to the sign reversing device with bit; The local oscillator phase lock circuitry that is connected with 90-degree phase shifter and multiplier; The colour subcarrier amplitude detection circuit that is connected with gain-controlled amplifier; Reach the colour subcarrier extraction circuit that is connected, receives tv baseband signal with clock phase lock circuitry, local oscillator phase lock circuitry, colour subcarrier amplitude detection circuit.
The present invention also provides a kind of demodulator that the data of inserting the simulated television baseband signal are carried out demodulation of being used for, comprise: gain controlled amplifier, D/A converting circuit, evolution raised cosine filter, 90-degree phase shifter, multiplier also comprise: the colour subcarrier amplitude detection circuit that is connected with gain controlled amplifier; The sampling clock generator that is connected with D/A converting circuit; The digital oscillator that is connected with 90-degree phase shifter and multiplier; With gain controlled amplifier, colour subcarrier amplitude detection circuit, sampling clock generator, the color subcarrier lock circuit that is connected with digital oscillator.
The signal of described clock phase lock circuitry and local oscillator phase lock circuitry is phase-locked synchronously with colour subcarrier signal respectively, and produces corresponding clock signals.
Described digital modulation signals level and colour subcarrier level are kept a fixed ratio.
The colour subcarrier signal that described sampling clock generator and color subcarrier lock circuit produce is phase-locked, clocking; The colour subcarrier signal that described digital oscillator and color subcarrier lock circuit produce is phase-locked, produces synchronous local oscillation signal.
The invention has the beneficial effects as follows, by adopting the method for in anolog TV signals, inserting data proposed by the invention, make simulated television when utilizing set-top box to receive anolog TV signals, also can receiving digital signals, and can not influence TV receiving effect.
The invention will be further described by the following examples and in conjunction with the accompanying drawings.
Fig. 1 represents to have the schematic diagram of the television network of bi-directional communication function.
Fig. 2 is the oscillogram that comprises the analog baseband signal of synchronization slot.
Fig. 3 is a spectrum diagram of modulated data signal being inserted anolog TV signals of the present invention.
Fig. 4 is the structure chart of data-modulated transmitting terminal and receiving terminal in the existing Television Broadcasting Network.
Fig. 5 (a) is the modulator that is used for inserting in the simulated television baseband signal data of the present invention, and Fig. 5 (b) is the demodulator that is used for inserting in the simulated television baseband signal data of the present invention.
The method of in the simulated television baseband signal, inserting data of the present invention, be to be inserted in the capable time slot of anolog TV signals baseband signal vertical blanking through the data after the modulation, also can be inserted in simultaneously the synchronization slot (described synchronization slot refers to that any row is from going the synchronous head starting point to the time slot between the picture signal starting point after reaching here) of trace row.In the capable time slot of vertical blanking, except the number row time slot that must keep by standard requirement, other every capable time slot all can insert the modulated signal that has with analog signal similar signal intensity except that synchronization slot.Because the signal to noise ratio of own modulated data signal can be higher than 40dB in these time slots, in order to improve data transmission efficiency, modulation system can adopt high-order modulating, as multilevel quadrature amplitude modulation (M-QAM) modulation system (wherein level progression M can be higher than 64), and the bandwidth of modulated signal can be similar with the anolog TV signals bandwidth.(such as being 6MHz to the TSC-system formula and being 8MHz) to Phase Alternation Line system.
Modulated signal after treatment also can insert in the synchronization slot of trace row.The waveform of the analog baseband signal of trace row in time domain as shown in Figure 2, wherein 13 for the row synchronous head, 14 is colour subcarrier, 15 is anolog TV signals.If data-signal directly inserts in the synchronization slot, it will form with row synchronous head and colour subcarrier signal and interfere with each other.So data-signal must can insert after treatment.Say from frequency domain characteristic, synchronizing signal 13 and 14 is only occupied the low side of whole anolog TV signals bandwidth and high-end, as shown in Figure 3, row synchronous head signal spectrum component mainly is in 0 to 1.5MHz scope, and colour subcarrier signal mainly is in 3.0MHz (to TSC-system) or more than the 3.5M (to Phase Alternation Line system), in general television set, there is a low pass filter only to leach capable synchronous head signal in the synchronizing signal restore circuit and in colored restore circuit, has a high pass (or band logical) filter only to leach colour subcarrier signal, so it just in time is in the space between capable synchronous head signal frequency spectrum and the colour subcarrier signal frequency spectrum, and it will can not cause interference to general television set.
And the data receiver end makes it earlier by a band pass filter when receiving this class modulated data, will go synchronous head and colour subcarrier signal filtering, only takes out modulated message signal, can prevent that anolog TV signals from disturbing digital signal.In order to eliminate the interference of modulated message signal to analogue synchronization signal as far as possible, the level of modulated message signal should be less than the anolog TV signals level.In this case, the signal to noise ratio of digital signal will reduce, thus must adopt the modulation system of lower-order, as 4QAM or 16QAM.The modulation system that sends signal in synchronization slot can be different with the modulation system of the signal that sends in vertical blanking is capable, but because of synchronous head is also arranged in vertical blanking is capable, in order to simplify circuit design, avoid too frequent modulation system to switch, in the capable synchronization slot of vertical blanking, can not transmit data.
In order to improve antijamming capability, all can adopt the forward error correction coding scheme in above-mentioned two kinds of slotting data modes, such as convolutional encoding mode and block encoding mode commonly used.Because signal is to send with burst mode, the block encoding mode is more suitable, as the RS coded system etc.In order to eliminate the influence that the formula that inspires is disturbed, generally all adopt interweaving encoding simultaneously.In order to make receiving terminal synchronous circuit energy operate as normal, scrambler also is a kind of mode of using always.A kind of transmitting terminal that combines above-mentioned various signal processing schemes and receiving terminal implementation are as shown in Figure 4.
The data that desire sends are elder generation's process forward error correction coding 17 before transmission, after handling, interweaving encoding 18 and scrambler 19 send into FIFO20, transmitting time controller 22 is subjected to the control of simulated television transmitting apparatus inner synchronousing signal, the operating time and the modulation system of (being synchronization slot and flyback blanking row time slot) control modulator 21 in suitable time slot.At receiving terminal, time of reception controller 24 is received synchronous circuit 28 controls (this reception synchronous circuit 28 is similar with the related circuit in the common simulation television set, no longer describes in detail), control 23 operating times of demodulator and mode of operation.Signal after the demodulation is through descrambling code 25, and export trellis decoded 26 and decoding FEC 27 backs.Each Digital Signal Processing partly is existing mature technology among the figure, no longer describes in detail.
In the ordinary course of things, synchronous demodulation is bigger with the signal difficulty that burst mode sends, generally need long preamble, make receiver end can carry out automatic gain control and various synchronous working (as frequency correction, phasing and clock recovery), because of this preamble does not contain the data that tendency to develop is sent,, reduce the user data transfer rate so can influence the channel utilance.
In order to address this problem, in the local oscillation signal source of transmitting terminal modulator 21 can with color subcarrier lock, modulated signal transmission level then be associated (promptly keeping a fixed amplitude ratio) with the colour subcarrier level.Can easily colour subcarrier be recovered out and as the reference frequency of demodulator circuit at one of receiving terminal and the similar circuit of the inner colour subcarrier restore circuit of general television set like this, and one with general television set in the similar circuit of gain control circuit also can finish gain control function.If modulated terminal make clock signal that control data sends into modulator also with color subcarrier lock, then the colour subcarrier that has recovered at receiving terminal also can be used as the clock signal of digital to analog converter, thereby finishes clock recovery work simultaneously.A kind of possible modulator and demodulator implementation as shown in Figure 5.
Shown in Fig. 5 (a), colour subcarrier extracts circuit 29 and extract colour subcarrier signal from tv baseband signal.Clock phase lock circuitry 30 and local oscillator phase lock circuitry 31 are phase-locked synchronously and produce corresponding clock signals and local oscillation signal with colour subcarrier signal respectively.Bit is obtained bit sequence and is become the two-way symbol under clock signal drives to code converter 32, they are respectively by entering multiplier 36 and 37 behind two evolution raised cosine filters 33 and 34, a road of local oscillation signal enters multiplier 36 behind 90-degree phase shifter 38, another road directly enters multiplier 37, output signal is after adder 39 additions, after sending into D/A converting circuit 54 earlier, send into gain controlled amplifier 40 again.Thereby colour subcarrier amplitude detection circuit 35 detects the multiplication factor of colour subcarrier amplitude and the controlled amplifier 40 of ride gain makes the amplitude of modulated digital signal and colour subcarrier amplitude that one fixing ratio be arranged.
Fig. 5 (b) is the receiving unit circuit.The base-band television signal that produces behind demodulation (wherein containing modulated digital signal) is sent into gain controlled amplifier 41 simultaneously, colour subcarrier range detector 42 and color subcarrier lock circuit 43.Colour subcarrier range detector 42 is measured the colour subcarrier amplitude, thereby by predetermined digital modulation signals and colour subcarrier amplitude ratio gain controlled Amplifier Gain is set.Sampling clock generator 54 and color subcarrier lock, clocking is supplied with D/A converting circuit 44, numeral oscillator 45 and color subcarrier lock, give by multiplier 46,47 and the demodulator circuit formed of 90-degree phase shifter 48 supply with synchronous local frequency, be frequency, phase place and clock and the complete synchronous baseband digital signal of transmitting terminal from the signals of multiplier 46 and 47 outputs like this, need not extra synchronous circuit.The two-way baseband signal is respectively by becoming numerical chracter behind evolution raised cosine filter 49,50 and the quantizer 51,52, output bit data flow behind sign bit converter 53.
As previously mentioned, the all fours of the related circuit in the equipment is sent in various relevant with colour subcarrier circuit that reaches described in the above-mentioned implementation and the transmitting-receiving of existing anolog TV signals, and remaining phase lock circuitry or signal generating circuit also be present full maturity openly and the technology of being used widely, with modulation, the relevant circuit of demodulation, as bit to the translation circuit between the symbol, the evolution raised cosine filter, multiplication, adder etc. also is the standard normal technology, so be not described in detail in this.
Multiple digital signal processing algorithm (as forward error correction encoding and decoding, modulation, filtering etc.) related in the above-mentioned various scheme can be realized with hardware chip, also can realize in the High Speed General dsp chip with software.Conversion between this class hardware and software algorithm has been open known technology, so no longer describe in detail.
By preceding as seen described, the method of inserting modulated signal in the synchronous head time slot of simulated television baseband signal and vertical blanking are capable that the present invention proposes also can be received high-speed digital signal when can make and receive anolog TV signals, and owing to send and receive the equal and color subcarrier lock of each signal, so whole receiving circuit can be realized very easily, avoided complicated multiple synchronous circuit, also avoid the use of preamble, thereby improved channel utilization greatly.
Claims (10)
1. a method of inserting data in the simulated television baseband signal is characterized in that, described data is inserted after ovennodulation in the capable time slot of vertical blanking of simulated television baseband signal, or is inserted in the synchronization slot of trace row; Or insert simultaneously in the capable time slot of baseband signal vertical blanking and trace row synchronization slot of simulated television.
2. the method for insertion data according to claim 1, it is characterized in that, when will be when the data of ovennodulation are inserted in the described synchronization slot, the frequency range of this modulated data signal be in the space between capable synchronous head signal frequency spectrum and the colour subcarrier signal frequency spectrum.
3. the method for insertion data according to claim 1 and 2 is characterized in that, when the signal to noise ratio of described digital signal is big, is high-order orthogonal Modulation and Amplitude Modulation modes to the modulation system of described data; And when the signal to noise ratio of described digital signal hour, low order quadrature amplitude modulation mode is adopted in the modulation of described digital signal.
4. the method for insertion data according to claim 1 is characterized in that, and is identical with the bandwidth of anolog TV signals to the described bandwidth that is inserted in the own modulating data in the capable time slot of vertical blanking.
5. method that the data of inserting the simulated television baseband signal are extracted, described data are inserted anolog TV signals with the described method of claim 1, it is characterized in that, when extracting described data, make it earlier by a band pass filter that is used for filtering row synchronous head and colour subcarrier signal.
6. modulator that is used for data are inserted the transmitting terminal of simulated television baseband signal, comprise: bit is to sign changer, evolution raised cosine filter, 90-degree phase shifter, multiplier, adder and digital to analog converter, it is characterized in that, also comprise: gain-controlled amplifier; The clock phase lock circuitry that is connected to the sign reversing device with bit; The local oscillator phase lock circuitry that is connected with 90-degree phase shifter and multiplier; The colour subcarrier amplitude detection circuit that is connected with gain-controlled amplifier; Reach the colour subcarrier extraction circuit that is connected, receives tv baseband signal with clock phase lock circuitry, local oscillator phase lock circuitry, colour subcarrier amplitude detection circuit.
7. one kind is used for demodulator that the data of inserting the simulated television baseband signal are carried out demodulation, comprise: gain controlled amplifier, D/A converting circuit, evolution raised cosine filter, 90-degree phase shifter, multiplier, it is characterized in that it also comprises: the colour subcarrier amplitude detection circuit that is connected with gain controlled amplifier; The sampling clock generator that is connected with D/A converting circuit; The digital oscillator that is connected with 90-degree phase shifter and multiplier; With gain controlled amplifier, colour subcarrier amplitude detection circuit, sampling clock generator, the color subcarrier lock circuit that is connected with digital oscillator.
8. modulator according to claim 6 is characterized in that, the signal of described clock phase lock circuitry and local oscillator phase lock circuitry is phase-locked synchronously with colour subcarrier signal respectively, and produces corresponding clock signals.
9. according to claim 6 or 8 described modulators, it is characterized in that described digital modulation signals level and colour subcarrier level are kept a fixed ratio.
10. demodulator according to claim 7 is characterized in that, the colour subcarrier signal that described sampling clock generator and color subcarrier lock circuit produce is phase-locked, clocking; The colour subcarrier signal that described digital oscillator and color subcarrier lock circuit produce is phase-locked, produces synchronous local oscillation signal.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB001030507A CN100384250C (en) | 2000-02-24 | 2000-02-24 | Method and device for inserting data to and extracting data from analog TV baseband signal |
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| Application Number | Priority Date | Filing Date | Title |
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| CNB001030507A CN100384250C (en) | 2000-02-24 | 2000-02-24 | Method and device for inserting data to and extracting data from analog TV baseband signal |
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| CN1310552A true CN1310552A (en) | 2001-08-29 |
| CN100384250C CN100384250C (en) | 2008-04-23 |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1322755C (en) * | 2001-12-18 | 2007-06-20 | 汤姆森许可公司 | Method and device for generating a graphic display for a setting menu of a networked device |
| CN105588609A (en) * | 2016-02-24 | 2016-05-18 | 叶志刚 | Device used for detecting mosquitoes |
| CN109150028A (en) * | 2018-10-11 | 2019-01-04 | 南京航空航天大学 | Three-level formula synchronous motor rotor position estimating system and estimation method |
| CN115529456A (en) * | 2022-09-28 | 2022-12-27 | 同致电子科技（厦门）有限公司 | Method for detecting color subcarrier frequency |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0250274B1 (en) * | 1987-03-19 | 1992-12-30 | France Telecom | Method and device for modulating television signals, especially those of the d2-mac-packet type |
| IL107825A (en) * | 1992-12-01 | 1997-08-14 | Scientific Atlanta | In-band/out-of-band data transmission method and apparatus for a television system |
| US5796440A (en) * | 1996-02-29 | 1998-08-18 | Rupinski; Frederick A. | Baseband video/audio/data transceiver |
-
2000
- 2000-02-24 CN CNB001030507A patent/CN100384250C/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1322755C (en) * | 2001-12-18 | 2007-06-20 | 汤姆森许可公司 | Method and device for generating a graphic display for a setting menu of a networked device |
| CN105588609A (en) * | 2016-02-24 | 2016-05-18 | 叶志刚 | Device used for detecting mosquitoes |
| CN109150028A (en) * | 2018-10-11 | 2019-01-04 | 南京航空航天大学 | Three-level formula synchronous motor rotor position estimating system and estimation method |
| CN109150028B (en) * | 2018-10-11 | 2020-04-07 | 南京航空航天大学 | Three-stage synchronous motor rotor position estimation system and estimation method |
| CN115529456A (en) * | 2022-09-28 | 2022-12-27 | 同致电子科技（厦门）有限公司 | Method for detecting color subcarrier frequency |
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| CN100384250C (en) | 2008-04-23 |
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