JP2006208403A - Device for jamming coherent radar - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform effective jamming with respect to coherent radar, on a jamming device with respect the coherent radar which the jamming wave, transmitted to a radar, is controlled so as to become coherent. <P>SOLUTION: In the jamming device, the wave forms for each of radar pulses (1), (2) which are successively received are stored, and the stored wave forms are repeatedly and continuously regenerated for each of received radar pulse, a timing control function, in which the regeneration sum times Td<SB>11</SB>to Td<SB>16</SB>, Td<SB>21</SB>to Td<SB>26</SB>from the radar pulse input timing of each of the repeated regeneration jamming waves (1)-1 to 6, (2)-1 to 6 become constant over each of the received radar pulses (1), (2), ... is controlled in the device. That is, they are controlled such that: Td<SB>11</SB>=Td<SB>21</SB>=..., Td<SB>12</SB>=Td<SB>22</SB>=..., to Td<SB>16</SB>=Td<SB>26</SB>. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a coherent radar jamming apparatus that controls so that a jamming wave transmitted to a radar becomes coherent. A radio interference device that receives a radar pulse and returns the pulse wave needs to control and transmit the interference wave so that the interference wave to be returned is not suppressed by the signal processor on the radar side. The present invention relates to a coherent radar jamming apparatus that effectively transmits jamming waves without being suppressed by a signal processor.

  A conventional jamming device controls the frequency of an oscillator in the device so as to match the frequency of a received wave from a radar, and transmits a jammed wave having the same frequency as the received wave, thereby reflecting from the target. The wave was covered and the target detection interference (so-called power interference) to the radar was performed.

  However, it is difficult to completely match the oscillator frequency of the radio interference device with the frequency of the received wave from the radar, and a technique of transmitting an interference wave having a certain band has been generally used. Noise interference is an example of this type of technique that is often used.

  Conventional non-coherent radars cannot perform signal processing using signal coherency, and even if a non-coherent interference wave such as the above-described noise interference is transmitted, the signal processor on the radar side does not perform the signal processing. The jamming was not suppressed and effective jamming was possible.

  In recent years, coherent radars that suppress unnecessary waves by coherent signal processing have become mainstream, and coherent radars can suppress interference waves with a signal processor when the interference waves are not coherent signals. Has become impossible. Here, coherent means that phase continuity is maintained with respect to the waveform.

  Next, as a countermeasure, a jamming method that uses a stable oscillator, perfectly matches the frequency of the jamming wave generated with the radar frequency, and transmits the jamming wave with Doppler modulation was realized. When frequency hopping or chirp modulation is performed, it is difficult to accurately match the frequency of the disturbing wave with the radar frequency.

  Therefore, a radar pulse is received, the waveform is stored, and the stored waveform is repeatedly arranged and transmitted repeatedly, thereby generating a large number of pseudo target signals and making the target detection difficult (hereinafter, this method is called "Continuous regenerative wave interference") was devised. Japanese Patent Application No. 10-344980 “Modulator for jammer” by the present applicant is one example. However, even if this method is used, the interference wave does not always become coherent, so this point needs to be solved.

  Here, first, signal processing of the coherent radar targeted by the disturbing device of the present invention will be described. FIG. 11 is a schematic block diagram of a general coherent radar, and FIGS. 12 and 13 are explanatory diagrams of a transmission wave and a reception wave of the coherent radar. FIG. 12 shows a case where the reception wave is not Doppler modulated, that is, the target is FIG. 13 shows a case where the received wave is Doppler modulated, that is, a case where the target is moving in the radar installation direction. FIG. 14 is an explanatory diagram of target detection of the coherent radar.

  As shown in FIG. 11, the radar includes a transmission / reception system 11-10, a coherent signal processing system 11-20, and a data processing / display system 11-30. The transmission / reception system 11-10 includes a rotary joint 11-11, an up converter 11-12, a transmission waveform generation unit 11-13, a high stability oscillator 11-14, a down converter 11-15, a phase detector 11-16, and π / 2. And a phase shifter 11-17.

  The coherent signal processing system 11-20 includes a range Doppler processing unit 11-21 and a range Doppler CFAR processing unit 11-25, and the range Doppler processing unit 11-21 performs moving target detection (MTI) for each range bin. ) Unit 11-22, Doppler filter bank 11-23, and amplitude detection / maximum value detection unit 11-24.

  The moving target detection (MTI) unit 11-22 detects and outputs only the reflected wave that fluctuates from the moving target by calculating the difference between the delayed wave and the current received wave. The Doppler filter bank 11-23 has a narrow band filter bank such as FFT, and detects the Doppler frequency of the received wave.

  The range Doppler CFAR processing unit 11-25 sets a CFAR threshold in order to make a constant false alarm ratio (CFAR) due to noise / clutter and the like, and the presence of a target when the received wave exceeds the threshold Is detected. The data processing / display system 11-30 includes a display processing unit 11-31, a data processing unit 11-32, and a display 11-33, and displays a target detection result.

  The radar transmits a pulse wave obtained by pulse-modulating a signal obtained by up-converting a signal obtained by using the output of the high stability oscillator 11-14 from the transmission / reception system 11-10 (see (a) of FIG. 12 and FIG. 13) at a regular interval PRI (Pulse Repetition). (Interval)) (see (b) of FIGS. 12 and 13).

  The pulse wave transmitted from the radar is reflected by the target, and the reflected pulse wave is input as a received pulse train to the radar transmission / reception system 11-10 at every predetermined interval PRI (see FIGS. 12 and 13 (c)). . The received wave input to the radar is down-converted by the down-converter 11-15 using the high-stable oscillator 11-14 common to the transmission up-converter 11-12, and phase-detected by the phase detector 11-16. A phase detection value depending on the distance R to the target is obtained.

  In the case shown in FIG. 12 where the received wave is not Doppler modulated, the phase difference φ between the output of the highly stable oscillator and the received pulse is over the radar pulses of the first pulse, the second pulse, the third pulse,. Assuming that φ = π / 2 as shown in the figure, the detection output signals I and Q are cos π / 2 = 0 and sin π / 2 = 1 as shown in (e) and (f) of FIG. It is output as a considerable signal.

On the other hand, when the target moves and has a velocity component in the radar installation direction, the relative distance to the radar changes for each transmission pulse, so the phase detection value φ of the received wave has a constant frequency (Doppler) for each transmission pulse wave. It changes at the frequency f _d ). As shown in FIG. 13, in the example where the received wave is Doppler modulated (f _d = 13 / (16 PRI)), the phase detection value φ = 2π is obtained at f _d = 1 / RRI. As shown in FIG. 13C, the phase detection value φ sequentially changes by π / 2 → π / 8 → −π / 4 by 13π / 8, and the detection output signals I and Q are respectively shown in FIG. e), {cosπ / 2 = 0, sinπ / 2 = 1} → {cosπ / 8, sinπ / 8} → {cos (−π / 4), sin (−π / 4), as shown in FIGS. )} → {cos 13π / 8, sin 13π / 8} equivalent signal is output.

  The radar coherent signal processing system 11-20 pays attention to the change (Doppler frequency) of the phase detection output described above, clutter (reflected waves from obstacles such as the ground and clouds), noise, and the like unnecessary for target detection. The reflected wave from the moving target is identified using the difference in Doppler frequency, signal components such as clutter and noise are removed as much as possible, and only the reflected wave from the target is detected.

  For example, when a clutter signal (Doppler frequency = 0) and a target signal (with Doppler) are received as in the frequency characteristics of the radar reception signal shown in FIG. 14A, the moving target detection (MTI) unit 11 −22 extracts only the signal in the area covered by the broken line in FIG. 14B, so that the moving target detection (MTI) unit 11-22 reflects the reflected wave from the stationary object (Doppler frequency = 0). Remove. Thereby, most of the ground clutter (reflected wave from the ground) and the like appearing in the radar reception signal as shown in FIG.

  The output signal from the moving target detection (MTI) unit 11-22 is input to the Doppler filter bank 11-23, and the Doppler filter bank 11-23 has a pulse repetition frequency PRF (Pulse) as shown in FIG. (Repetition Frequency = 1 / PRI) is divided by a narrow-band filter bank to reduce the noise component entering one bank, thereby improving the S / N ratio and detecting the Doppler frequency component of the received wave.

  The output signal of the Doppler filter bank 11-23 is subjected to amplitude detection or maximum value detection by an amplitude detection / maximum value detection unit 11-24, and the output of the output signal has a constant false alarm probability fixed by a range Doppler CFAR processing unit 11-25. The presence of the target is detected by the received wave exceeding the CFAR threshold.

  With respect to the coherent radar described above, the generation of a continuous regenerative interference wave in which radar pulses are received and the waveform is stored, the stored waveforms are repeatedly arranged and transmitted, and the behavior of the radar due to the continuous regenerative interference wave are described below. explain.

  When a replica of a radar transmission wave pulse is repeatedly reproduced continuously as an interference wave, a single interference wave pulse is a signal similar to the original radar transmission wave pulse, so as a pseudo target for non-coherent radar Because it is recognized, it is possible to interfere by giving many pseudo targets to the radar.

  On the other hand, the coherent radar needs to be similar to the reflected wave from the target, including the periodicity of the phase change in the pulse train direction. However, in continuous regenerative wave interference, the waveform is stored independently for each input received wave pulse, and the stored waveform is continuously reproduced for each received wave pulse, so the phase change in the pulse train direction fluctuates irregularly. However, coherency may not be ensured.

  In that case, the frequency component of the jamming wave is diffused and the phase change in the pulse train direction of the jamming wave cannot be arbitrarily controlled. Therefore, avoid moving target detection (MTI) processing and Doppler filter bank processing of the jamming target radar. The frequency control required for effective interference cannot be performed on the interference wave. Therefore, for the coherent radar, the interference wave due to the continuous regenerative wave interference is suppressed by the signal processor on the radar side or removed without being recognized as a pseudo target, and an effective interference effect cannot be obtained.

  FIG. 15 shows an example in which coherency is ensured and not secured in continuous reproduction wave interference. In continuous regenerative wave interference, after receiving each received radar pulse independently for each received radar pulse input at a constant pulse repetition interval (PRI), the same waveform as the received wave is repeated after a delay time of Td. Play continuously.

  FIG. 15A shows an ideal case in which the detection pulse widths τ of the received radar pulses are all equal. In this case, the continuous reproduction interference wave is basically coherent. In the figure, A indicates a point after a certain time from the rise of each received radar pulse, but continuous reproduction disturbance at point A after a certain time over all the received radar pulses (1) to (3). It can be seen that the in-pulse phase of the wave is constant.

  FIG. 15B shows a case where the detection pulse widths τ of the received radar pulses are not equal, which is a very general case. Since the radar oscillates the transmission antenna beam, the reception level of the radar transmission wave in the jamming device varies greatly. When the rising / falling edge of the received radar pulse is lost, the pulse detection level at the jamming device is constant, and thus the detection pulse width is generally different according to the fluctuation of the reception level.

For this reason, the pulse width (τ, τ _max , τ _min ) of each continuously regenerative interference wave is different for each received radar pulse (4) to (6), and as in (a) of the figure, Assuming that a point after a certain time from the rise is A, and seeing the intra-pulse phase of the continuous regenerative interference wave at point A, it can be seen that all are different. In such a case, the interference wave becomes non-coherent, and the interference effect on the coherent radar is reduced.

There are the following documents as prior art documents related to the present invention.
Japanese Patent Laid-Open No. 9-73769 JP 11-295414 A JP-A-8-114670

  In this way, in continuous regenerative wave interference, since the waveform is stored independently for each input received pulse and repeatedly reproduced repeatedly, the phase change seen in the direction of the pulse train fluctuates irregularly and coherency is not ensured. There is a case.

  FIG. 16 and FIG. 17 are explanatory diagrams regarding the coherency of the continuous reproduction interference wave. 16 and 17, the pulse shown as the interference wave output indicates an arbitrary n-th repetition pulse of the continuous reproduction interference wave, and the other continuous reproduction repetition pulses are not shown.

  The radar device to be disturbed transmits a transmission pulse, which is pulse-modulated based on the output of the highly stable oscillator (see FIGS. 16 and 17A), at a repetitive period PRI period (see (b) in the figure). ). Since the jamming device is located at a distance R from the radar device, the transmission pulse is received after a time proportional to the distance R (= R / C C: speed of light) (see (c) in the figure).

  The interfering device stores the received pulse wave of the first pulse and, as shown in FIG. 4D, after a certain delay time Td from the rising of the received pulse wave, the radar device uses the amplified received pulse wave as an interfering wave. Is output. The radar apparatus receives the interference wave after a time proportional to the distance R as shown in (e) of the figure, detects the phase for each range bin shown in the figure (f), and (g) and (h) in the figure. The coherent signal processing is performed on the detection output shown in FIG.

  Here, attention is paid to the delay time Td until the received pulse waveform stored by the disturbing device is transmitted to the radar device. The example shown in FIG. 16 is a case where the output delay time Td regarding an arbitrary m-th repeated continuous regenerative disturbance pulse is always constant for each radar pulse input at the repetition period PRI. Further, the example shown in FIG. 17 is a case where the output delay time Td is not constant for each radar pulse.

  When compared with the example of the phase detection result in the radar device shown in FIGS. 16 and 17, in the case shown in FIG. 16, the phase detection waveform is constant as shown in FIG. In the case shown in FIG. 2, the phase detection waveform changes with the change in the output delay time Td as shown in FIG.

  Therefore, when the change time ΔTd of the output delay time Td for each transmission pulse varies irregularly, the phase detection waveform also varies irregularly, and the interference wave in this case is not coherent. The conventional continuous regenerative wave interference shown in FIG. 15B is equivalent to being transmitted in the state shown in FIG. 17, and the interference wave thus transmitted is not coherent.

  The present invention performs control focusing on the phase change of the continuous regenerative interference wave viewed in the pulse train direction, thereby ensuring coherency of the continuous regenerative interference wave and eliminating the interference wave by coherent signal processing in the coherent radar. An object of the present invention is to provide a coherent radio interference device that avoids and enables effective interference with a coherent radar.

  The coherent radar jamming apparatus of the present invention (1) stores the waveform of the received radar pulse, repeatedly reproduces the stored waveform, detects the input timing of the received radar pulse, and detects the detected timing signal. Receiving pulse input timing detection means for outputting to the control means, control means for performing storage timing control of the waveform storage reproduction means and repeated reproduction control of the storage waveform based on the detection timing signal, and each pulse of the received radar pulse A received radar pulse width detecting means for detecting the width and notifying each detected pulse width to the control means, and for each interfering wave repeatedly reproduced by the waveform storage / reproducing means, based on the Doppler modulation information, the Doppler frequency modulation is performed. Doppler modulation means for performing a plurality of radar pulses detected in advance. A time management function for controlling the waveform storage / reproduction means so that the difference between the reproduction delay times of the adjacent repeated reproduction interference waves from the input timing of each received radar pulse becomes a predetermined interval based on It is characterized by having.

  (2) The time management function has a means for detecting the maximum pulse width from the pulse widths of a plurality of radar pulses in advance, and reproduces the adjacent regenerative interference wave from adjacent received radar pulse input timings. The waveform storage / reproducing means is controlled so that the difference in delay time is the maximum pulse width interval.

  (3) The time management function has means for detecting a minimum pulse width from the pulse widths of a plurality of radar pulses in advance, and reproduces the adjacent regeneratively regenerated interference wave from each received radar pulse input timing. The waveform storage / reproducing means is controlled so that the difference in delay time becomes the interval of the minimum pulse width.

  Further, (4) the time management function has means for detecting the most frequent pulse width from the pulse widths of a plurality of radar pulses in advance, and the adjacent regenerative regenerative interference wave from each received radar pulse input timing. The waveform storage / reproducing means is controlled so that the difference in the reproduction delay time becomes the interval of the most frequent pulse width.

  Further, (5) the time management function includes a clipping control means for determining a cut-out reproduction width of the received radar pulse in advance, and a reproduction delay time from each received radar pulse input timing of the adjacent repetitive reproduced interference wave The waveform storage / reproducing means is controlled so that the difference between the two becomes the interval of the cut-out reproduction width.

  According to the present invention, when a continuous regenerative interference wave is transmitted every time a radar pulse is received, the transmission delay time of each continuous regenerative interference wave pulse is set to a constant transmission delay time for each received radar pulse. The regenerative interference wave is detected by the radar as a pseudo target without being removed by the moving target detection (MTI) process or the Doppler filter bank process because the coherency is ensured with respect to the partner radar apparatus. Can provide effective disturbance.

  Also, by setting the repetitive pulse width of the jamming wave as the maximum pulse width of the received radar pulse wave, the jamming wave is not continuously transmitted when the pulse width of the actually received radar wave is smaller than the jamming pulse width. However, the efficiency may be reduced due to the occurrence of missing parts, but since the stored waveform of the entire pulse width of the received radar pulse wave can be transmitted as an interference wave, the interference power detected by the radar is maximized and displayed. The brightness of the simulated target can be increased, and it is difficult to determine the true target in the radar.

  In addition, by setting the repetitive pulse width of the interference wave to the minimum pulse width of the received radar pulse wave, the part of the actually received radar wave is missing and the brightness of the pseudo target is lowered, but the interference wave detected by the radar The number of pulses becomes the maximum, and a large number of pseudo targets are displayed. This makes it difficult to determine the true target in the radar.

  Further, by setting the repetitive pulse width of the interference wave to the maximum pulse width of the received radar pulse, the luminance and the number of pseudo targets are displayed most efficiently. This makes it difficult to determine the true target in the radar.

  In addition, for the pulse compression radar, the luminance and the number of pseudo targets are displayed most efficiently by setting the repeated pulse width of the interference wave to the optimum cutout width. This makes it difficult to determine the true target in the radar.

  In order to make the interfering wave coherent with respect to the interference target radar device, from the detection of the received pulse from the radar device input to the interfering device to the output of an arbitrary m-th continuous repetitive interfering signal The delay time Td needs to be controlled so as to be always constant for each received pulse.

  The present invention applies an appropriate Doppler modulation on the basis of a coherent fundamental interference wave generated according to this principle, and passes through a moving target detection (MTI) filter of an interference target radar device to target an arbitrary Doppler filter bank. Generated and released.

  FIG. 1 is an explanatory diagram of a coherent continuous reproduction interference wave according to the present invention. This figure shows a case where the Doppler frequency is set to 0 for easy understanding. Waveforms (a) to (c) in the figure are the same as those in FIGS.

  (D) of FIG. 1 shows each repetitive pulse of the continuous regenerative interference wave, and each repetitive pulse (1) of the continuous regenerative interference wave with respect to the radar pulse (1) of the first pulse and the radar pulse (2) of the second pulse. ) -1 to 6 and (2) -1 to 6 are detected at the positions of the range bins # 5 to # 8, # 1 and # 2 in the radar device as shown in FIG. The phase detection value φ is 0, π / 2, π, 3π / 2, 0, π / 2 for the first radar pulse (1) and the second radar pulse (2), respectively. Therefore, the detection outputs (I, Q) are (1, 0), (0, 1), (-1, 0), (0, -1), as shown in (g) and (h) of the figure, respectively. (1, 0), (0, 1), and the phase shift is a constant value between the radar pulses (1), (2),.

If the set Doppler frequency is not 0 but f _dx , the phase detection value φ of each range bin is 2πPRI × f _dx between the radar pulses (1), (2),. Change. Since the radar apparatus performs processing for recognizing the Doppler frequency for each range bin, in the case of the example shown in FIG. 1, in each range bin (# 5 to # 8, # 1, # 2) to which an interference wave is input, the Doppler frequency Processing is performed as a zero pseudo target signal.

  FIG. 2 is an explanatory diagram of the first embodiment, which is the basic configuration of the present invention. (A) of the figure shows a functional block. The reception pulse input timing detection means 2-1 detects the input timing such as the rise / fall of the radar pulse to be disturbed, and the detection timing signal is controlled by the control means 2-. 2 is notified. The waveform storing / reproducing means 2-3 stores the radar pulse wave to be disturbed according to the control by the control means 2-2, and reproduces the stored radar pulse wave to be disturbed according to the control of the control means 2-2.

  The control means 2-2 controls the waveform storage / reproduction means 2-3 to store the radar pulse wave based on the detection timing signal from the reception pulse input timing detection means 2-1, and is the most suitable in the present invention. Outputs a timing signal when playing back an important memory waveform. The Doppler modulation means 2-4 performs Doppler modulation on the reproduction pulse waveform output from the waveform storage / reproduction means 2-3 based on a Doppler frequency control signal (Doppler modulation information) given from the outside.

Here, the timing at the time of reproducing the stored waveform is constant regardless of n with respect to the delay time Td _nm from the time when the nth radar pulse is detected until the mth repeated continuous disturbance wave is output. That is, each delay time Td _{11 to} Td from the time when each radar pulse of the 1st pulse, 2nd pulse,..., Nth pulse shown in FIG. _{n1, Td 12 ~Td n2, ...} , Td 1m ~Td nm, with respect to,
Td ₁₁ = Td ₂₁ =... = Td _n1 = Td ₁
Td ₁₂ = Td ₂₂ = ... = Td _n2 = Td ₂
Td _1m = Td _2m = ... = Td _nm = Td _m
And Here, the delay time _{Td 1, Td 2, ...,} Td m is any delay time corresponding to the generated order disturbance (false target signal), need not be constant.

  Each pulse wave of the continuous regenerative interference wave controlled in this way becomes a coherent wave, and when it is input to the radar device to be disturbed, the phase detection value changes according to the Doppler frequency set by the disturbing device. , It is pseudo-recognized as a target signal.

  FIG. 3 is an explanatory diagram of the effect of the interference wave according to the present invention, and shows how the generated interference wave is processed in the coherent signal processing system of the radar apparatus. For comparison, conventional processing for continuous reproduction wave interference is also shown. 3 (a-1) to (a-3) show conventional processing for continuous reproduction wave interference, and (b-1) to (b-3) show processing for continuous reproduction wave interference according to the present invention. Yes.

  Since the conventional continuous reproduction interference wave is non-coherent with respect to the interference wave subjected to PRF / 2 Doppler modulation, the frequency spreads as shown in FIG. On the other hand, since the continuous reproduction interference wave according to the present invention is coherent, there is no frequency spreading as shown in FIG.

  (A-2) and (b-2) in FIG. 3 show a state when the moving target detection (MTI) filter is passed, and (a-3) and (b-3) in FIG. The relationship between the filter bank and CFAR threshold and the detection level is shown. As shown in (a-3) of FIG. 3, since the conventional continuous reproduction interference wave is spread in frequency, the level at the Doppler bank 8 near the Doppler frequency of PRF / 2 is lowered and is not detected as an interference wave. On the other hand, the continuous regenerative interference wave according to the present invention exceeds the CFAR threshold level as a reception wave having a PRF / 2 Doppler frequency and is detected as a disturbance wave.

  As described above, since the interference wave of the present invention ensures coherency with respect to the counterpart radar apparatus, the spectrum of the interference wave that is a replica of the received radar pulse does not spread. Further, since it has the same spectrum as the target signal, it is Doppler shifted in the same manner as the target signal.

  Therefore, the interference wave is not removed by the moving target detection (MTI) process, and is input to the Doppler filter bank processing unit, where it is input to the same Doppler filter bank as the target signal. Is done.

  On the other hand, the interference wave in the continuous regenerative wave interference, which is a conventional interference technique, spreads the spectrum when it is input to the partner radar even though the single pulse waveform is a replica of the received pulse, so it is used for MTI processing and Doppler filter processing. The majority of the signal is removed and is not detected by the radar as a pseudo target.

Is In the embodiment shown in FIG. 1 is an embodiment to arbitrarily set a delay time Td ₁ ~Td _m until the output first ~m th repeated continuous disturbance of the embodiments described below in the respective delay time Td ₁ ~Td _m, what determines in conjunction with the received radar pulse width tau, focusing on differences between evaluating the interference effect on the display screen of the radar system, the radar pulse width tau the delay control time Td ₁ ~Td _m according to do.

  FIG. 4 is an explanatory diagram of the second embodiment of the present invention. (A) of the figure shows the structure of the functional block, and (b) of the figure shows the reproduction waveform. The operations of the reception pulse input timing detection unit 4-1, the waveform storage / reproduction unit 4-3, and the Doppler modulation unit 4-4 are the same as those in the first embodiment, but the reception pulse input timing detection unit 4 -1 also notifies the reception pulse width detection means 4-5 of the detection result.

  The reception pulse width detection unit 4-5 detects the pulse widths of the plurality of pulse waves received from the interference target radar, and notifies the control unit 4-2. When detecting the pulse width of a radar pulse wave, the detected pulse width is often not the same due to differences in radio wave propagation conditions or signal detection conditions on the jamming device side, even if the pulse width transmitted by the radar is the same. appear.

The maximum pulse detection means 4-6 in the control means 4-2 detects the maximum pulse width τ _{max based} on the pulse width information notified from the reception pulse width detection means 4-5. The control means 4-2 starts reproduction from the rise of the stored waveform, and regarding the delay time Td _nm from the time when the nth radar pulse is detected until the mth repeated continuous disturbance wave is output, Like the form, it is constant regardless of n.

Further, the waveform storing / reproducing means 4-3 is controlled so that the pulse width τ of the reproduced waveform becomes the previous maximum pulse width τ _max . That is, control is performed so that Td _m −Td _m−1 = τ _max for each delay time of adjacent continuous reproduction interference wave pulses.

With respect to the delay time Td _nm from the detection of the input of the nth received pulse from the interference target radar input to the jamming device to the output of the mth repeated jamming wave related to the nth input pulse, n Timing management is performed so as to be constant over each input pulse. At this time, the maximum pulse width τ _max of a predetermined number of received pulses is obtained in advance, and the output delay time Td of the mth repetitive pulse. for _m, performs timing control so that _{ΔTd = Td m -Td m-1} = τ max.

FIG. 4B shows a regenerative transmission waveform of a repetitive continuous interference wave when the received radar pulse width is smaller than the maximum pulse width τ _max . The reception pulse wave is reproduced from the rising to the falling within each period of the maximum pulse width τ _max and transmitted.

FIG. 5 is an explanatory diagram of the third embodiment of the present invention. (A) of the figure shows the structure of the functional block, and (b) of the figure shows the reproduction waveform. In the third embodiment, as shown in FIG. 5B, the nth received pulse is detected after detecting the input of the nth received pulse wave from the interference target radar input to the disturbing device. The timing management is performed so that the delay time Td _nm until the m-th repetitive interference wave related to the wave is output is always constant for each of the n received pulse waves. At that time, a predetermined number of received pulse waves minimum is previously obtained a pulse width tau _min, the m-th output delay time Td _m of repetitive disturbance pulse, performs timing control so that _{ΔTd = Td m -Td m-1} = τ min of It is.

The operations of the reception pulse input timing detection means 5-1, the waveform storage / reproduction means 5-3, the Doppler modulation means 5-4, and the reception pulse width detection means 5-5 are the same as those in the second embodiment. . The minimum pulse detection means 5-6 in the control means 5-2 detects the minimum pulse width τ _{min based} on the pulse width information notified from the reception pulse width detection means 5-5.

The control means 5-2 starts reproduction from the rise of the stored waveform, and controls the waveform arrangement / reproduction means 5-3 so that the pulse width τ of the reproduction waveform becomes the previous minimum pulse width τ _min . That is, control is performed so that Td _m −Td _m−1 = τ _min .

FIG. 6 is an explanatory diagram of the fourth embodiment of the present invention. (A) of the figure shows the structure of the functional block, and (b) of the figure shows the reproduction waveform. In the fourth embodiment, as shown in (b) of the figure, the nth received pulse is detected after detecting the input of the nth received pulse wave from the jamming target radar input to the jamming device. The timing management is performed so that the delay time Td _nm until the m-th repetitive interference wave related to the wave is output is always constant for each of the n received pulse waves. of obtained in advance the pulse width tau _mod received most frequently, the m-th output delay time Td _m of repetitive interference pulse, a timing control such that _{ΔTd = Td m -Td m-1} = τ mod Is to do.

The operations of the reception pulse input timing detection means 6-1, waveform storage / reproduction means 6-3, Doppler modulation means 6-4 and reception pulse width detection means 6-5 are the same as those in the second and third embodiments described above. It is the same. The mode pulse detection means 6-6 in the control means 6-2 detects the maximum frequency pulse width τ _mod from the pulse width information notified from the reception pulse width detection means 6-5.

The control means 6-2 starts the reproduction from the rise of the stored waveform, and controls the waveform storage / reproduction means 6-3 so that the pulse width τ of the reproduced waveform becomes the maximum frequency pulse width τ _mod . That is, control is performed so that Td _m −Td _m−1 = τ _mod .

FIG. 7 is an explanatory diagram of the fifth embodiment of the present invention. (A) of the figure shows the structure of the functional block, and (b) of the figure shows the reproduction waveform. In the fifth embodiment, as shown in FIG. 5B, the nth received pulse is detected after detecting the input of the nth received pulse wave from the interference target radar input to the disturbing device. Timing management is performed so that the delay time Td _nm until the m-th repetitive interference wave related to the wave is output is always constant for each of the n received pulse waves. rather than either, set in advance the cut-out pulse width tau _PULL, the m-th output delay time Td _m of repetitive interference pulse, a timing control such that _{ΔTd = Td m -Td m-1} = τ PULL Is what you do.

  The operations of the reception pulse input timing detection means 7-1, waveform storage / reproduction means 7-3, and Doppler modulation means 7-4 are the same as those in the second to fourth embodiments. The reception pulse width detection unit 7-5 detects the pulse widths of the received plurality of pulses of the interference target radar and notifies the control unit 7-2. When the interference target radar is a pulse compression radar, the radar pulse is a chirp wave (the frequency continuously changes in the pulse).

  The pulse cut-out control means 7-6 in the control means 7-2 determines which part of the received pulse wave is reproduced based on the pulse width information notified from the received pulse width detection means 7-5, and reproduces it. Determine the pulse width to be cut out.

As shown in FIG. 5B, the control means 7-2 starts reproduction from a stored waveform at a position where the reproduction waveform pulse is an arbitrary fixed time δ after the rising of the reception pulse, and the pulse width τ is first. The waveform storing / reproducing means 7-3 is controlled so as to be the cutout pulse width τ _PULL . That is, control is performed such that Td _m −Td _m−1 = τ _PULL .

  Here, the behavior of the interference wave in the coherent signal processing system of the radar described with reference to FIG. 3 is the same as the coherent interference wave of the first to fifth embodiments, and each of the first to fifth The difference in the disturbing action of the disturbing wave on the radar according to the embodiment appears in the data processing / display system.

  FIG. 8 shows an example of a radar display screen (B scope). As shown in the figure, on the radar screen, in addition to a true target surrounded by a circle, m pseudo targets based on m repeated regenerative disturbance pulses are displayed. The interval between the displayed pseudo targets depends on the transmission delay time Td of each repetitive continuous regenerative disturbance pulse.

  FIG. 9 is an explanatory diagram of an example corresponding to the above-described first embodiment. The received signal from the radar is A / D converted by the A / D converter 9-1 and is output from the semiconductor memory 9-2 in the waveform storing / reproducing means and the amplitude detector 9-7 in the received pulse input timing detecting means. Branch to both.

  When the reception signal capture period is reached, the control circuit 9-9 sends a write start pulse to the memory control counter 9-4 in the waveform storage / reproduction means to start signal writing to the semiconductor memory 9-2. At the same time, the operation of the memory control counter 9-4 in the waveform storing / reproducing means is simulated in the control circuit 9-9.

  The received signal is amplitude-detected by the amplitude detector 9-7, and its output is compared with the threshold value by the comparator 9-8. When the threshold value is exceeded, the detection timing signal is turned on to indicate that the received pulse has been detected. Notify the control circuit 9-9.

  The control circuit 9-9 calculates the waveform read start / end address based on the memory control counter value simulated therein at the change point of the detection timing signal. Further, in the output period of the interference wave, the transmission delay time Td starts to be counted down in synchronization with the rise of the detection timing signal.

  Next, the read start address and the read end address are set in the read start address latch 9-5 and the read end address latch 9-6 for the waveform storing / reproducing means, respectively, and after the countdown of the transmission delay time Td is completed, the reading is performed. Send a start pulse.

  Further, in synchronization with the transmission of the read start pulse, the countdown of the difference ΔTd from the transmission delay time of the next repetitive disturbing wave is repeated, and the read start pulse is sequentially transmitted after the countdown is completed. This operation is repeated until the next reception signal capture period. Here, the value of the difference ΔTd between the transmission delay time Td and the transmission delay time of the next repetitive interference wave is arbitrary. However, they are fixed values for each pulse repetition period PRI of the received signal.

  When the memory control counter 9-4 of the waveform storing / reproducing means receives the read start pulse, it generates an address or the like according to the read start / end address, and sequentially stores the waveform stored in synchronization with the read start pulse in the semiconductor memory 9- 2, the read waveform is D / A converted by a D / A converter 9-3, and then Doppler modulated by a mixer 9-10, a Doppler oscillator 9-11, and a Doppler control latch 9-12. The Doppler modulation is performed by the means and transmitted.

  FIG. 10 is an explanatory diagram of an example corresponding to the above-described second to fifth embodiments. The received signal from the radar is A / D converted by the A / D converter 10-1, and is output from the semiconductor memory 10-2 in the waveform storing / reproducing means and the amplitude detector 10-7 in the received pulse input timing detecting means. Branch to both.

  When the reception signal capture period is reached, the control circuit 10-9 sends a write start pulse to the memory control counter 10-4 in the waveform storing / reproducing means to start signal writing to the semiconductor memory 10-2. At the same time, the operation of the memory control counter 10-4 in the waveform storing / reproducing means is simulated in the control circuit 10-9.

  The received signal is amplitude-detected by the amplitude detector 10-7, and its output is compared with the threshold value by the comparator 10-8. When the threshold value is exceeded, the detection timing signal is turned on to indicate that the received pulse has been detected. In addition to notifying the control circuit 10-9, it is also branched and input to the pulse width counter 10-13 in the reception pulse width detection means.

  The pulse width counter 10-13 counts the ON time of the detection timing signal and sends detection pulse width data to the control circuit 10-9. The control circuit 10-9 calculates the waveform read start / end address based on the memory control counter value simulated therein at the change point of the detection timing signal.

  Further, the detection pulse width data is taken in, the maximum pulse width is calculated in the second embodiment, the minimum pulse width is calculated in the third embodiment, and the most frequent pulse width is calculated in the fourth embodiment. In the output period of the interference wave, the transmission delay time Td starts counting down in synchronization with the rise of the detection timing signal.

  Next, the read start address and the read end address are set in the read start address latch 10-5 and the read end address latch 10-6, respectively, for the waveform storing / reproducing means, and after the countdown of the transmission delay time Td is completed, the reading is performed. Send a start pulse. Here, in the case of the fifth embodiment, the read start address to be set is an address value obtained by adding a certain value, and the read end address is an address value obtained by further adding a certain pulse width to the read start address. .

  Further, in synchronization with the read start pulse transmission, the countdown of the difference ΔTd from the transmission delay time of the next repetitive disturbing wave is repeated, and after the countdown ends, the read start pulse is sequentially sent out. This operation is repeated until the next reception signal capture period. Here, the value of the transmission delay time Td is arbitrary. However, the value is fixed for each pulse repetition period PRI of the received signal. The difference ΔTd from the transmission delay time of the next repetitive interference wave is a constant value based on the pulse width calculated in each embodiment.

  When the memory control counter 10-4 of the waveform storing / reproducing means receives the read start pulse, it generates an address or the like according to the read start / end address, and sequentially stores the waveform stored in synchronization with the read start pulse in the semiconductor memory 10- 2, the read waveform is D / A converted by the D / A converter 10-3, and then Doppler modulated by the mixer 10-10, the Doppler oscillator 10-11, and the Doppler control latch 10-12. The Doppler modulation is performed by the means and transmitted.

It is explanatory drawing of the coherent continuous reproduction disturbance wave of this invention. It is explanatory drawing of 1st Embodiment which is a basic composition of this invention. It is explanatory drawing of the effect of the jamming wave by this invention. It is explanatory drawing of the 2nd Embodiment of this invention. It is explanatory drawing of the 3rd Embodiment of this invention. It is explanatory drawing of the 4th Embodiment of this invention. It is explanatory drawing of the 5th Embodiment of this invention. It is a figure which shows an example of a radar display screen (B scope). It is explanatory drawing of the Example corresponding to the 1st Embodiment of this invention. It is explanatory drawing of the Example corresponding to the 2nd thru | or 5th Embodiment of this invention. It is a schematic block diagram of a general coherent radar. It is explanatory drawing of the transmission wave and non-Doppler modulation reception wave of a coherent radar. It is explanatory drawing of the transmission wave and Doppler modulation reception wave of a coherent radar. It is explanatory drawing of the target detection of a coherent radar. It is explanatory drawing of coherency ensuring in continuous reproduction wave interference. It is explanatory drawing of the detection phase of a coherent continuous reproduction disturbance wave. It is explanatory drawing of the detection phase of a non-coherent continuous reproduction interference wave.

Explanation of symbols

(A) Interference target radar high-stable oscillator output (b) Interference target radar transmission pulse output (c) Jammer transmission pulse input (d) Jammer interference wave output (e) Interference target radar interference wave input (f) Interference target radar Range bin (g) Radar detection output (I)
(H) Radar detection output (Q)
(1) Transmission pulse output of the first pulse
(1) -1-6 Output 1st to 6th jamming wave for 1st transmission pulse
(2) Second transmission pulse output
(2) -1～6 1-6 th disturbance output Td ₁₁ ~Td ₁₆ 1~6 th disturbance transmission delay time Td ₂₁ ~Td ₂₆ 2 pulses for 1st pulse of the transmitted pulse relative to the second pulse of the transmitted pulse 1st to 6th interference wave transmission delay time for transmission pulses

Claims (5)

Waveform storage / reproducing means for storing the waveform of the received radar pulse and repeatedly reproducing the stored waveform;
Received pulse input timing detection means for detecting the input timing of the received radar pulse and outputting the detection timing signal to the control means;
Control means for performing storage timing control of the waveform storage and reproduction means and repeated reproduction control of the stored waveform based on the detection timing signal;
Receiving radar pulse width detecting means for detecting each pulse width of the received radar pulse, and notifying each detected pulse width to the control means;
Doppler modulation means for performing Doppler frequency modulation on the basis of Doppler modulation information for each interference wave repeatedly reproduced by the waveform storage reproduction means,
The control means, based on the pulse widths of a plurality of radar pulses detected in advance, makes a difference between the reproduction delay times of the adjacent repetitive reproduction interference waves from each received radar pulse input timing a predetermined interval. And a time management function for controlling the waveform storage / reproducing means.   The time management function includes means for detecting the maximum pulse width from the pulse widths of a plurality of radar pulses in advance, and the difference between the reproduction delay times of the adjacent repetitive reproduction interference waves from each received radar pulse input timing is 2. The coherent radar jamming apparatus according to claim 1, wherein the waveform storage / reproducing unit is controlled so as to have an interval of the maximum pulse width.   The time management function includes means for detecting a minimum pulse width from the pulse widths of a plurality of radar pulses in advance, and the difference between the reproduction delay times of the adjacent repetitive regenerative interference waves from each received radar pulse input timing is 2. The coherent radar jamming apparatus according to claim 1, wherein the waveform storage / reproducing means is controlled so as to be the interval of the minimum pulse width.   The time management function includes means for detecting the most frequent pulse width from the pulse widths of a plurality of radar pulses in advance, and the difference between the reproduction delay times of the adjacent repetitive reproduction interference waves from the respective received radar pulse input timings. 2. The coherent radar interference apparatus according to claim 1, wherein the waveform storage / reproducing unit is controlled so that the interval of the most frequent pulse width is set.   The time management function has a cutout control means for determining a cutout reproduction width of a received radar pulse in advance, and a difference between reproduction delay times of adjacent repeated reproduction interference waves from each received radar pulse input timing is 2. The coherent radar interference apparatus according to claim 1, wherein the waveform storage / reproducing unit is controlled so as to have an interval of a cut-out reproduction width.

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