DE1211697B - Radar device with varying transmission pulse repetition frequency and fixed-character suppression - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

GOIs

German class: 21 a4- 48/63

Number: 1211697

File number: M 45546 IX d / 21 a4

Filing date: June 4, 1960

Opening day: March 3, 1966

The invention relates to a transmission pulse train with a varying frequency and fixed-character suppression radar.

As is known, a pulse radar device is often used, in particular, with a preferably statistical one distributed varying transmission pulse repetition frequency operated to a possible opponent an effective To make disturbance of the radar device by means of a jammer largely more difficult; because such a jammer must be built up much more complex than it is then necessary if only with him a radar device with constant, periodic pulse repetition frequency is to be disturbed. Usually becomes a statistically distributed varying transmission pulse repetition frequency for a radar device from a Noise generator derived.

A radar device with a varying transmission pulse rate can - although it is often desirable would be - but not without further ado with one in radar devices with a periodic transmission pulse repetition frequency usual arrangement of this type for fixed-character expression be equipped with the received and preferably in an intermediate frequency band transposed signals are routed over two parallel signal piades, which are different Delay it. have ngszehen, whereby the delay times from each other by the pulse train period or ώ an integral multiple of this Distinguish period. To these two signal paths is there a coincidence stage or a similar one with this usual arrangement? Circuit connected that does not issue an ÄLigangssignsI if both of its inputs signals are fed in at the same time. Since in such an arrangement for the suppression of characters; Fesi aims in both signal paths at the same time S: o.n; '.! C generate and do moving targets not Un. gives each output signal the coincidence point in the display in the radar display only one Display of moving targets while fixed targets are not displayed due to this character suppression will.

At a.! are berxnnlen pulse radar device with Festzcichenuntcrdrückung of the type described in terms of substantial reduction of the number you to Anzeigeraisfällen leading so-called tape speeds in both the mutual Impiilsabiuii'de the transmit pulse repetition frequency and the Ver; ögcrungsztiien the above-mentioned Signalpfacie the arrangement for clutter suppression equally periodically and sprangariij; meander :, ννο :: Ί several different delay lines having delay lines Radar device with varying transmission pulse repetition frequency and fixed-character suppression

Applicant:

The Marconi Company Limited, London

Representative:

Dr.-Ing. B. Joliannesson, patent attorney,

Hanover, Göttinger Chaussee 76

Named as inventor:

Ernst Friedrich Scherisch, Great Baddow, Essex

(Great Britain)

Claimed priority:
Great Britain from June 8, 1959,

dated November 3, 1959 (19 514)

are provided in various combinations by means of a switching device as a function of the respective mutual transmission pulse intervals can be switched into the signal paths.

Apparently the difference in delays between the signals should be in the two Signal paths of the arrangement for marking terminal

yes, if the pulse train frequency is an in
given limits is arbitrary, preferably statistically varying frequency, can also be varied accordingly, which is at least a very complicated and impractical structure of the arrangement for

; -, would require peg suppression if

'O' OC

this arrangement should work on the principle of that in the known radar device mentioned with periodic and abrupt change of the Siiidehüpttlsfoljsirequeiiz and the delay <c time use is made.

The invention is based on the object of circumventing these difficulties and a satisfactory one Specify radar device with fixed-character suppression, dns works with a varying pulse repetition frequency.

The invention thus relates to a mi; varying, preferably statistically fluctuating Transmission pulse rate and fixed character suppression working radar device in which a counter-switching of the echo pulses of two pulse trains in a circuit arrangement with two signals -:?. the. takes place, one of which is a delay eos 510 153

3 4

line contains. In one of the two, the invention consists independently of two different cathode rays like radar device essentially in that means can be scanned, namely from a write to Conversion of the received echo signals to beam that is connected to one another by the broken line 14 Intermediate frequency and means of storage is interpreted, and of a reading beam passing through the the intermediate-frequency signals is symbolized in a broken line 15. The cathode Known memory in the rhythm of the varying and the deflection means for the writing beam are through Transmission pulse repetition frequency are provided that the means symbolizes the block 16. The electron beam 14 to read the memory with an essentially is modulated by signals from the receiver 7 constant frequency are provided, which of their and the deflection means by a sawtooth wave The size is controlled by a sawtooth generator 17 for a single fixed delay. This annoyance measured delay line tuned and rator is geihrer via a delay circuit 18 Phase after in a fixed relationship to the intermediate triggers or otherwise from the pulse generator 3 frequency is held, and that means for feeding controlled, wherein the delay circuit a Verder read signals on the two-path sound delay, which as far as possible of the sum processing arrangement are provided. 15 of the delay times of elements 4, 6 and 7 are the same

The radar device according to the invention points opposite, so that the deflection of the beam 14 with the

over the known prior art the very occurrence of the transmitted pulses is synchronized.

significant advantage that, despite its varying, the beam 14 accordingly scans the electrode 13 in

Transmission pulse repetition frequency, which preferably has a statistical distribution irregular, but in

tistically distributed varying transmission pulse repetition frequency 20 synchronism with the likewise in statistical

is, its arrangement for fixed-character suppression division of irregularly transmitted pulses, with which-

is known per se and only one for a phase like that all received echo signals

only fixed delay measured delay can be written into the memory,

line contains. "As can be seen, the

On the basis of the drawing, the following are shown and those taken from the reading beam

particularly advantageous embodiments of the Er signals intermediate frequency and no video frequency;

Finding described in detail. This still shows that the transmitter 4 with the oscillator

Fig. 1 is a block diagram of an embodiment of the receiver 7 is connected, coherence with respect to

example of the invention and borrowed the intermediate frequency in the transmit-receive

F i g. 2 is a block diagram of a further Aus 30 system. On the reading side, the reading beam 15 is

exemplary embodiment of the invention. Fig. 2 shows only controlled in such a way that it co-

those parts that are inherent to understanding the difference. Zv / ar is the pulse repetition rate of the

the arrangement according to FIG. 2 compared to the statistical data based on the sender within certain limits.

F i g. 1 are necessary. Splits; However, the impulses are transmitted through on the receiving side

The same reference numerals denote the same parts 35 the operation of the memory a smooth impulse two figures. In Fig. 2 parts not shown given repetition frequency.

are the same as those shown in FIG. 1 are shown. They are signals stored on the shield electrode 13

are also read together in the same way with one another by the reading beam 15, which with

switched. substantially constant speed at a

According to Fig. 1, the output of a noise 40 repetition frequency is deflected, which z. B. an-

generator 1 to an amplitude known per se equal to the mean repetition frequency of the in

sieve and gate circuit 2 connected, the peak statistical distribution sent out irregularly

values of the noise voltage, which is a given pulse. The cathode and deflection system for

Exceed amplitude, then lets through when the reading beam 15 is symbolized by the block 19

it is in the open state. The Aus 45 siert, and the deflection of the reading beam is through

output signals of stage 2 are generated to trigger a sawtooth wave, which is released from the

Pulse generator 3 used, the pulses of which the decaying sawtooth generator 20 comes from, which

Transmission of the high-frequency pulses from a transmitter 4 is followed by an amplifier 21.

check which one known per se read from the reading beam 15 from the memory

Antenna system 5 via the transmit / receive 50 signals are connected in parallel to the inputs

Soft 6 feeds. supplied by two signal paths 22, 23, of which

Echo signals that are received by the antenna system 5, the former is a direct path and the latter from will catch, a fixed delay line 24 exists over the transmit-receive, which Switch6 to a receiver? given, which usually has a delay that the Obtaining a 55 nominal period of the scanning of the reading beam 15 that can be taken from its output Intermediate frequency connected to an oscillator 8 is the same, although - as can be seen - it is also possible. The output voltage of the oscillator 8 is borrowed, the delay of the delay line 24 also given to a mixer 9, which is twice or another multiple of the second input to a quartz-stabilized sampling period of the reading beam 15 to equalize. Intermediate frequency generator 10 is located. The output signals 60 The output signals of the paths 22, 23 become one The voltage of the mixer 9 is fed via a suitable coincidence detector or a similar counter-filter the transmitter 4, in which an arrangement 25 combining high-level signals therefrom to frequency is generated from which the transmission pulses are derived. As can be seen, the parts 22 to 25 represent stand. essentially an arrangement known per se

The intermediate-frequency output voltage of the 65 for fixed-character suppression. The output receiver 7 is used to control the intensity of the signal of the arrangement 25 is known per se Write beam of a cathode ray storage tube 12 given evaluation and display means by the used, which has a storage electrode 13, which block 26 are symbolized.

5 6

The tube 12 has an additional electrode 27, known memory can be used, for example magnetic

which is arranged to store at the end of each.

Deflection of the beam 15 is hit by this. Of course, the memory is in the arrangement die Output signals from the additional electrode 27 according to FIG. 1 can always be deleted. The extinguishing agents are used as an input signal of a frequency 5, however, are not shown because of the invention vergicichsstufe 28 supplied, on whose other one-radar device there is the possibility at this point gear the output signal of the coincidence detector 25 to use different erasure methods; given as an example will. The stage 28 is known per se and could wise after a so-called destructive results in a control signal on the output side, if the reading method is being used, the reading method is an additional one Electrode 27 on with the output io beam when reading deletes the stored values, signal of the arrangement 25 synchronous and from this or it could not use a storage tube suppressed output signal is emitted. the one in which the reading beam is not erased the stage 28 may be of the coincidence type, but in which there may be separate suppression detectors. devices are provided.

The output signal of the stage 28 is used for the 15 Another possibility is the use

Frequency control of the generator 20 used to be a memory device in which the signals

act that the reading beam 15 is not too fast or integrated and the distractions of the writing

distracted too slowly. and reading beams are chosen such that between

A second frequency control of the sawtooth two consecutive read processes of a generator 20 is carried out by one of the phase 20 plurality of write processes. This possibility comparison stage 29 causes a derived signal, whereby an additional circuit would of course make the phase comparison stage 29 required in the output signal, which is known per se and not contained in the tube 12 intermediate frequency phase itself is the subject of the invention and which is safe with the intermediate frequency from the quartz - Would have to provide that the write beam compares to such a generator 10. In this way, controls the ₂₅ times and with each such speed comparison stage 29, the frequency of the generator 20 is deflected speed that each point on the such that the reading beam 15 with the desired storage screen is deflected by the write beam with the same speed and that the same intermediate frequency phase as in the previous intermediate frequency in the output signal of the tube 12 going writing process is met. This is how it occurs elsewhere. 30 can be used between consecutive reads

If the repetition frequency of the reading beam cannot be stored several times without the is desired, the electrode 27 is made possible by the intermediate frequency one-reading beam met in periods of time that are lost from the stored information; then delay period in unit 24 differ. Accordingly, it can be adapted to the output of the memory the two signals at the input of the 35 closed array become the fixed-character sub-coincidence detector 25 - one from path 22, pressing work properly. One in connection the other from path 23, 24 - not deleted; this would have to be a suitable device, for example rather, a signal at the output of the coincidence will cause the generator 17, which is the detector 25 generated. Then, stage 28 generates two steering waveforms for the write beam, ab signals - one of 25 and the other 40 given signals depending on the phase of the of 27 - and thus result at the output of the stage of the mixer 9 are signals emitted while 28 a signal which is sent to the sawtooth generator 20 as the deflection speed of the write beam in FIG Correction voltage is supplied to keep the Ab- itself constant in a known manner at each deflection steering of the reading beam must be kept at the desired frequency. adapt. 45 From the foregoing it should be apparent that it

The deflection frequency of the reading beam 15 must therefore not be absolutely necessary that the reading half in a fixed, predetermined relationship to the intermediate frequency, approximately equal to the mean transmission pulse frequency stand so that there is coherence in the intermediate repetition frequency, for example could - as already frequency range stored and read im- indicated above - the corresponding device so pulse exists, without which the counter circuit can be designed so that the write beam between each successive fixed characters in the coincidence detector successive reading process several times the Ein-25 not to the complete desired suppression storage with corresponding multiple discharges would. The problem of coherence in making fixed grooves.

Character suppression in impulse radars with F i g. 2 shows magnetron transmitters insofar as it is necessary for understanding is known per se and is at 55 Hch, a further refinement and improvement these known radar devices by the arrangement of Fig. 1. From the above-mentioned, It is advantageous to use one of the reasons known per se to oscillate at the intermediate frequency Coherence oscillator solved. to ensure that the leading edge of each transmitted

The output signals of the additional electrode 27 pulse always have a predetermined phase relationship (Fig. 1) are simultaneously a gate pulse 60 to the intermediate-frequency output signal of the empgenerator 30 supplied, which has triggered catcher as a result. F i g. 2 shows an arrangement which and a pulse of a predetermined length each - this requirement is automatically met. The main one then emits when the reading beam 15 the electrical difference of the arrangement according to FIG. 1 trode 27 hits. The gate pulses of the generator 30 and 2 are in the arrangement according to FIG. 2 in the open the gate in the amplitude filter and gate 65 insertion of a bistable circuit within the circuit 2nd dash-dotted block 31 between the amplitude

Instead of the in the arrangement according to FIG. 1 sieve and gate circuit 2 and the pulse generator 3.

memory types shown are also different per se. The bistable circuit, which consists of two per se

consists of tubes connected to one another in a known manner, acts between units 2 and 3 as an automatic delay arrangement and thus provides sure that the pulses fed to stage 3 only occur when the intermediate frequency Wave from the crystal oscillator 10 is in a predetermined phase, preferably when they are through the Zero line goes. In the arrangement according to FIG. 2 is the output signal of stage 10 except - as already shown - the stages 9 and 29 simultaneously - via line 32 - the control grid of the second tube of the bistable circuit 31 supplied. The bistable circuit 31 oscillates freely at a frequency which somewhat smaller than the smallest of the impulse repetition frequency which occurs irregularly in statistical distribution which comes from level 2. These vibrations are the pulse generator 3 as negative Pulses supplied when the left tube becomes conductive. The right tube is advanced through stage 2 ahead of time their free oscillation, and the delay for triggering stage 3 is triggered by this vibrating multivibrator causes. The left tube of the multivibrator is switched to the conductive state by a trigger signal via line 32, also shortly before this would occur as a result of their free swinging.

With the arrangement according to FIG. 2 pulses are therefore only transmitted if all three of the following Conditions are met:

a) a noise peak at the output of unit 1 exceeds a predetermined amplitude,

b) the noise peaks occur in a predetermined period which corresponds to the impingement of the reading beam 15 follows on electrode 27,

c) the intermediate frequency at the output of the oscillator 10 has a predetermined phase.

Claims (5)

Patent claims: 1. Working with varying transmission pulse repetition frequency and fixed-character suppression Radar device, with a counter-circuit of the echo pulses of two pulse trains in a circuit arrangement takes place with two signal paths, one of which contains a delay line, characterized in that means for converting the received echo signals to a Intermediate frequency and means for storing the intermediate frequency signals in a known per se Memory in the rhythm of the varying transmission pulse repetition frequency are provided that Means are provided for reading the memory at a substantially constant frequency which are sized on the delay line sized for a single fixed delay tuned and kept in a fixed relationship to the intermediate frequency according to their phase is, and that means for feeding the read signals to the two-path circuit arrangement are provided. 2. Radar device according to claim 1-, characterized in that the memory is a cathode ray storage tube contains the two cathode rays of which, i. H. whose write and read beams can be deflected independently of one another. 3. Radar device according to claim 2, characterized in that a sawtooth generator controlled by the transmission pulses and a self-oscillating sawtooth generator connected to an automatic frequency control device are provided for deflecting the write beam, the frequency control device being supplied with the output signals of the means for suppressing bookmarks and signals which occur at a predetermined point when the memory is scanned once per scanning period. 4. Radar device according to claim 3, characterized in that a phase comparison circuit for phase comparison of the phase of the intermediate frequency of the receiver with the phase of the Intermediate frequency, which is present in the signals extracted from the memory, for the additional Frequency control of the self-oscillating sawtooth generator is provided. 5. Radar device according to claim 3 or 4, characterized in that for generating the Signals that occur at a given point when the memory is scanned once per scanning period occur, an additional electrode is arranged in the cathode ray storage tube in this way is that the read beam hits it once in each sampling period. Considered publications:
German Auslegeschrift No. 1 033 281;
U.S. Patent No. 2,426,216;
Telecommunications, 6 (1956), 4 (April), pp. J 80 and 181. 1 sheet of drawings 609 510/163 2. 66 © Bundesdruckerei Berlin