Method for detecting impact of diverting interference on automatic range tracking system of pulse-doppler radar station

Abstract

FIELD: radars.SUBSTANCE: invention can be used in pulse-Doppler radar stations to detect the impact of diverting interference on their automatic range tracking (ART) systems before the useful signal leaves the working area of the time discriminator of the ART system. The claimed method involves detecting received radio pulses, then limiting them, integrating them within the duration of the burst, and comparing the level of accumulated pulses with the threshold. For detection, a synchronous phase detector is used, to the control input of which a copy of the probing signal is fed, which is in phase with the received echo signal of the target and coincides with it in frequency and time delay. The detected signal is fed to two identical channels, in one of which the signal is limited in amplitude from above relative to the zero level, inverted and accumulated, and in the other, the signal is limited in amplitude from below relative to the zero level and accumulated. The signals accumulated in each channel are compared with the detection threshold set by noise and corresponding to a given false alarm level. If the detection threshold is exceeded by signals in both channels, a decision is made about the influence of range-diverting interference; if the detection threshold is exceeded by a signal in only one channel, a decision is made about stable automatic target tracking in range; if the threshold is not exceeded in both channels, a decision is made about the absence of a target and interference.EFFECT: increasing the immunity of a pulse-Doppler radar from the effects of range-diverting interference.1 cl, 10 dwg

Description

[0001] The proposed invention relates to the field of radar and radio countermeasures and can be used to protect pulse-Doppler radar stations (RLS) from the effects of range-diverting pulse interference.

[0002] Pulse escaping interference is a sequence of response pulses delayed relative to the signal by an amount monotonically varying from zero to a specified value, t3. When the jammer is turned on, the jamming signal delay time, t3, is 0. As a result, two superimposed pulses—a signal and an interference—are simultaneously received by the automatic range tracking system (ARS). If the amplitude of the interference pulse is greater than the signal amplitude, then, as the delay increases, the range strobe will begin to follow the more powerful interference signal. When t3 exceeds the aperture of the time discriminator characteristic, the ARS system will "lose" the target and switch to tracking the interference. However, even though the automatic range finder will track the false target simulated by the interference signal, the radar will still receive information about the target's angular position.The automatic direction tracking (ADT) channel functions normally, since the jamming signal carries information about the angular coordinates of the target on which the jamming source is located. To introduce jamming disturbances into the ADT channel, after the end of the jamming pulse series, the jamming transmitter is switched off, and the ADT system enters search mode. During the search period, no signal is received at the ADT channel input, and information about the target's angular coordinates is lost. After the ADT system acquires the target, a new deflection cycle begins. Thus, the deflection jammer causes errors in range measurements (and consequently, speed) and leads to interruptions in information in the angle-measuring channel [1, pp. 77-78].

[0003] Therefore, the damage caused to radar by the impact of such evasive interference, expressed in the time spent on re-searching and capturing the target for tracking, emphasizes the relevance of protection against them.

[0004] The above analysis allows us to conclude that in order to effectively protect against pulse interference that leads in range, it is necessary to reveal the fact of its impact on the ASD system as early as possible.

[0005] Currently, there are a sufficient number of ways to expose the impact of range-diverting interference on the ASD system.

[0006] A universal method for detecting the effects of interference is one in which the radar range tracking strobe is protected from escaping interference by using guard strobes. The latter are located at fixed points on either side of the main radar strobe. These strobes are not additional tracking strobes; they provide signal detection before or after the main radar strobe. When the interference signal diverts the main strobe, the target signal appears in one of the guard strobes, which allows one to conclude that interference is present [2, pp. 110-111]. A disadvantage of this method is the relatively late discovery of the fact of interference, which can complicate the reacquisition of the target signal after its detection in the guard strobe.

[0007] A more sophisticated method of jamming detection involves protecting the radar's range strobes from escaping interference and other sources using additional (auxiliary) strobe circuits. These additional strobes are located near the primary strobe and, when the radar is exposed to interference, can move in any direction relative to the primary strobe [2, p. 111]. A disadvantage of this method is the significant complication of the ASD system hardware due to the introduction of additional tracking systems.

[0008] There is a method for detecting the presence of repeater pulses using narrow watchdog strobes. This method consists of subtracting the output signals of the leading and lagging watchdog strobes and comparing them with a reference voltage to determine the presence of repeater pulses on the target. The watchdog strobes are set so that one captures the leading edge, the other - the slope of the pulse signal. Since there is a time delay in any pulse repetition system, the leading edge of the repeater pulse will appear later than the actually reflected pulse signal. If the signal detected by the lagging watchdog strobe is greater than the signal detected by the leading watchdog strobe by the value of the set threshold, then a decision is made about the presence of a repeated pulse. [2, p. 113]. The disadvantage of this method is that the procedure in question must be used before the ASD system is turned on, otherwise the range tracking system will nullify the described effect.

[0009] The general disadvantage of the methods discussed above is that the effect of the diverting interference is revealed either when the ASD system is turned off, that is, in the target detection mode, or when the useful signal leaves the working area of ​​the time discriminator (TD) of the ASD system in the target automatic tracking mode, which leads to time costs for repeated search and target acquisition for tracking.

[0010] Analysis of information sources - patent and scientific and technical literature showed that the closest in type and sequence of operations to the declared one (prototype) is a method for protecting radar from asynchronous impulse interference, based on the use of a video signal integrator for suppressing random video pulses [3, pp. 201-202], which consists in the fact that radio pulses from the receiver output are detected and limited to a level only slightly exceeding the average noise level, then they are accumulated in the video signal integrator during the time of moving the antenna by an angle equal to the beam width [3, Fig. 6.11 p. 202], the output signal of the integrator is fed to a threshold circuit, the bias level in which is set in such a way that in order to obtain the output voltage supplied to the indicator, several pulses must be superimposed.With this processing, a pulse sequence that is not synchronized with the radar pulse repetition rate (asynchronous pulse interference) will be distributed across various elements of the range sweep, and none of them will exceed the threshold circuit offset level. The disadvantage of this method is that it is designed to protect against asynchronous pulse interference and cannot detect the impact of escaping pulse interference on the ADA system without making a number of modifications.

[0011] The technical result of the present invention is the development of a method for detecting the impact of escaping interference on the ASD system of a pulse-Doppler radar, ensuring the disclosure of the impact of interference before the target echo signal leaves the working area of ​​the system's VD by taking into account the change in the law of amplitude-phase manipulation of the signal-interference mixture when the interference and signal are mismatched in time by an amount not exceeding the duration of the signal.

[0012] The technical result is achieved in that in the method for detecting the impact of escaping interference on the automatic range tracking system of a pulse-Doppler radar station, which consists in detecting received radio pulses with their subsequent limitation, integration (accumulation) within the duration of the packet and comparison of the level of the accumulated pulses with the threshold, according to the invention, a synchronous phase detector is used for detection, to the control input of which a copy of the probing signal is fed, in phase with the received echo signal of the target and coinciding with it in frequency and time delay, the detected signal is fed to two identical channels in one of which the signal is limited in amplitude from above relative to the zero level, inverted and accumulated, and in the other channel - limited in amplitude from below relative to the zero level and accumulated, the signals accumulated in each channel are compared with the detection threshold,set by noise and corresponding to the specified false alarm level, when the detection threshold is exceeded by signals in both channels, a decision is made about the influence of interference that leads to range deviation; when the detection threshold is exceeded by a signal in only one channel, a decision is made about stable automatic target tracking in range; if the threshold is not exceeded in both channels, a decision is made about the absence of a target and interference.

[0013] The physical essence of the proposed method is as follows.

[0014] At one interval of unambiguous measurement of the range of a pulse-Doppler radar for a radio pulse reflected from a target, described by the expression:

[0015]

[0016] where U c and ϕ с - amplitude and initial phase of the radio pulse reflected from the target;

[0017] ƒ0 - carrier frequency of the probing radio pulse;

[0018] F дс - Doppler frequency addition in the reflected signal;

[0019] τ и - pulse duration,

[0020] The evasive imitation interference will look like:

[0021]

[0022] Since the interference is signal-like, it will differ from the signal only in the parameters that ensure the displacement of the VD tracking strobes (amplitude U п and the initial phase ϕ п and Doppler frequency addition F дп ). If we do not take into account the delay of the target echo signal relative to the probing one and accept F дс = F дп = 0, then at the initial moment of impact (the interference is aligned in time with the target echo signal) at the input of the ASD system there will be an additive signal-interference mixture of the form:

[0023]

[0024] To calculate the amplitude values ​​of U ∑ and the initial phase ϕ ∑ the resulting signal y(t) uses the expressions [4, p. 167]:

[0025]

[0026]

[0027] Analysis of expression (4) shows that the amplitude U ∑ depends both on the values ​​of the signal and noise amplitudes and on the difference in their initial phases Δϕ = ϕ п - ϕ с and varies within the range of |U с -U п | to |U с +U п |. This circumstance imposes certain requirements on the power of the simulating interference to ensure reliable coverage of the signal at the initial moment of diversion.

[0028] During the process of shifting the VD strobes, the simulating interference is shifted in time relative to the target echo signal by a value of τ. The type of additive signal-interference mixture at the input of the ASD system at τ < τ и can be described by the expression:

[0029] According to (6), the resulting signal y(t) at τ < τ иwill have amplitude and phase manipulation (Fig. 1), which can be used to reveal the fact of the impact of diverting interference on the ASD system.

[0030] As is well known, the phase detector (PD) is a sensitive element that allows us to detect phase jumps. If we apply an additive signal-noise mixture (6) to the PD input, and use a harmonic oscillation of the following type as the reference signal:

[0031]

[0032] with an amplitude U0 significantly exceeding the amplitude of the input signal, and an initial phase ϕ0, then the video signal at its output will look like:

[0033]

[0034] where K is the FD transfer coefficient.

[0035] Consequently, the PD output signal will be an amplitude-modulated signal consisting of three interconnected video pulses of varying amplitudes. Moreover, depending on the phase relationship of the PD input and reference signals, the output signal can be either unipolar (Fig. 2) or bipolar (Fig. 3), which can be used to detect the onset of interference.

[0036] In phase detection, the issue of matching the initial phases of the received and reference signals becomes relevant, since if their phases differ by π / 2, the detector output signal will be zero. The phase detector is not so critical to the initial phase of the interference, since during the rejection process, the phase difference between the reference signal and the simulating interference will change in the range of 0 ÷ 2 π. To eliminate this drawback and suppress the out-of-phase noise component, a synchronous phase detector is used, described in [5, p. 216], in which the initial phase ϕ0 of the reference signal coincides with the initial phase ϕ сtarget echo signal.

[0037] In real-world conditions, the error signal voltage at the VD output of a pulse-Doppler radar's ASD system is generated by processing the entire received pulse train, rather than individual pulses. This is primarily due to the low pulse energy of the train. Therefore, for small signal-to-noise ratios, processing individual output video pulses from the FD is unlikely to reveal differences in the depth and sign of amplitude manipulation due to time mismatches between the echo signal pulses and the simulated interference at the ASD system input.

[0038] When a packet of radio pulses is fed to the FD input, which is a mixture of the target echo signal and evasive interference with Doppler frequency additions F дс = F дп ≠ 0, and the reference signal (7) signal at its output can be represented in the form [6, p. 47]:

[0039]

[0040] where T is the pulse repetition period;

[0041] n = 1,2…, N is the repetition period number.

[0042] According to (9), amplitude modulation of the video pulses of the burst occurs at the PD output according to a harmonic law, caused by the presence of a Doppler frequency additive, in addition to the unipolarity (Fig. 4) or bipolarity (Fig. 5) of each pulse due to the time mismatch between the signal and interference pulses. The results presented in Figures 4 and 5 indicate the possibility of selecting a signal for the onset of VD strobe drift (amplitude bipolarity within a pulse), while at the same time confirming the difficulty of its detection due to the amplitude modulation of the pulses of the burst caused by the Doppler frequency additive.

[0043] At F д = 0 expression (9) will take the form:

[0044]

[0045] Therefore, if we compensate for the Doppler frequency addition in the input signal of the FD, then, in accordance with (8) and (10), the signal at its output, depending on the nature of the effect of the interference leading along the range, will represent an unmodulated sequence of unipolar (Fig. 6) or bipolar video pulses (Fig. 7).

[0046] Doppler compensation can be achieved by using a harmonic oscillation of the following type as the reference signal of the FD:

[0047]

[0048] where - an estimate of the Doppler frequency of the target echo signal, obtained from the results of measuring the radial velocity of the target by the automatic velocity tracking system (AVTS) of a pulse-Doppler radar.

[0049] If the signal is z фд (t) (Fig. 7) apply to the inputs of two parallel-connected limiters with the following characteristics:

[0050]

[0051] then their output signals will be sequences of positive video pulses corresponding to the positive for the limiter with characteristic g1 and the negative for the limiter with characteristic g2 components of the signal z фд (t). The resulting sequences of video pulses are accumulated in integrators. Before accumulation, negative video pulses are inverted.

[0052] To eliminate the possibility of noise accumulation during the absence of a signal in the intervals between pulses, it is proposed in [7, pp. 117-118] to perform preliminary gating of the input signal with a sequence of pulses, the temporal position of which corresponds to the expected arrival time of the target echo signal. In the proposed method, such gating can be implemented by using a copy of the probing signal, in-phase with the received target echo signal and matching it in frequency and time delay, as the reference oscillation of the PD. In this case, the reference oscillation of the PD will take the form:

[0053]

[0054] where τ3 is the estimate of the target echo signal delay time obtained from the results of measuring the range to the target by the ASD pulse-Doppler radar system.

[0055] To prevent false decisions based on accumulated noise residues, the output signals of the integrators of both channels are compared in threshold devices with threshold levels C, set for noise according to the Neyman-Pearson criterion. Upon exceeding the threshold levels in both channels, a decision is made to begin diverting the time strobes with a simulated interference before the target echo signal leaves the active range of the ASD system's VD.

[0056] If the signal z is applied to the inputs of the limiters фд(t) (Fig. 6), then after accumulation in the integrator, only the output signal of the limiter with characteristic g1 will exceed the threshold level. When a sequence of negative unipolar video pulses is fed to the limiters from the FD output, only the output signal of the limiter with characteristic g2 will exceed the threshold level after accumulation in the integrator. In these cases (the signal exceeding the threshold level in only one channel), a decision is made on stable target tracking.

[0057] Thus, the stated technical result is achieved.

[0058] The claimed method is explained by graphic drawings, which show:

[0059] Fig. 1 - additive signal-noise mixture at the input of the ASD system at τ = 0.5τ и ;

[0060] Fig. 2 - unipolar signal at the PD output at τ = 0.2 τ и ;

[0061] Fig. 3 - bipolar signal at the PD output at τ = 0.5 τ и ;

[0062] Fig. 4 - a packet of unipolar video pulses at the FD output at F дс = F дп ≠ 0;

[0063] Fig. 5 - a packet of bipolar video pulses at the FD output at F дс = F дп ≠ 0;

[0064] Fig. 6 - a packet of unipolar video pulses at the PD output with compensated Doppler frequency addition in the signal at the detector input;

[0065] Fig. 7 - a packet of bipolar video pulses at the PD output with compensated Doppler frequency addition in the signal at the detector input;

[0066] Fig. 8 - block diagram of the device for detecting the impact of evasive interference on the ASD system of a pulse-Doppler radar.

[0067] In Fig. 8 the following designations are used:

[0068] 8.1 - synchronous FD;

[0069] 8.2 - FD reference signal generator;

[0070] 8.3 1 - signal limiter by amplitude from below relative to the zero level;

[0071] 8.3 2- signal limiter by amplitude above the zero level;

[0072] 8.4 - inverter;

[0073] 8.5 1 , 8.5 2 - integrators (accumulators);

[0074] 8.6 1 , 8.6 2 - comparison units with detection threshold (threshold devices);

[0075] 8.7 - logical element "AND";

[0076] 8.8 - exclusive OR logical element;

[0077] 8.9 - decision making block;

[0078] Fig. 9 - time diagrams of the signal passage through the elements of the block diagram of the detector of the effect of the leading interference on the ASD system at τ = 0;

[0079] Fig. 10 - timing diagrams of the signal passage through the elements of the block diagram of the detector of the effect of radiating interference on the ASD system at τ = 0.5 τ и .

[0080] The proposed method can be implemented using the block diagram of the device shown in Fig. 8.

[0081] The device for detecting the effect of escaping interference on the ASD system of a pulse-Doppler radar (Fig. 8) contains a synchronous FD 8.1, one of the inputs of which is connected to the output of the reference signal generator FD 8.2, and the second input is the input of the device for detecting the effect of escaping interference on the ASD system, the output of FD 8.1 is connected in parallel with the inputs of the signal limiters by amplitude relative to the zero level from below 8.3 1 and on top 8.3 2 , the output of the limiter from below is 8.3 1 connected to the input of integrator 8.5 1 , and the limiter output from above is 8.3 2 connected to the input of inverter 8.4, which is connected in series with the second integrator 8.5 2 , integrator output 8.5 1 connected to the input of the comparison unit with a detection threshold of 8.6 1 , and the integrator output is 8.6 2 connected to the input of the comparison unit with a detection threshold of 8.6 2 , control inputs of comparison blocks with a detection threshold of 8.61 and 8.6 2 are connected to each other and a voltage corresponding to the threshold level is applied to them, the output of the comparison unit with a detection threshold of 8.6 1 connected in parallel with the first inputs of the logical elements “AND” 8.7 and “exclusive OR” 8.8, and the output of the comparison block with the detection threshold 8.6 2 connected in parallel with their second inputs, the output of the AND logical element 8.7 is connected to the first input of the decision-making unit 8.9, and the output of the exclusive OR logical element 8.8 is connected to the second input of the decision-making unit 8.9, the output of the decision-making unit 8.9 is the output of the device for detecting the impact of the leading interference on the ASD system.

[0082] The device for detecting the impact of evasive interference on the ASD system of a pulse-Doppler radar operates as follows.

[0083] Since the device is designed to detect the impact of diverting interference on the ASD system, signals are sent to its input only during automatic target tracking by range.

[0084] When tracking a target by the ASD system, a signal y(t) will be present at the input of the synchronous FD 8.1, which is an additive mixture of noise and a packet of radio pulses reflected from the target, or a mixture of noise, a packet of radio pulses reflected from the target, and diverting interference, which is the same packet of radio pulses as the signal reflected from the target, but has a larger amplitude and is shifted in time relative to the target signal by τ < τ и . The case of accompanying only interference (τ > τ и) we do not consider. Voltage s(t), which is a copy of the probing signal, in phase with the received echo signal of the target and coinciding with it in frequency and time delay (13), is fed to the second input of FD 8.1 from the reference signal generator 8.2. The reference signal generator FD 8.2 is tuned to the frequency of the echo signal of the target, taking into account but information received from the ACS system. The delay of the generator signal 8.2 relative to the radar probing signal is equal to the estimated delay time of the target echo signal obtained from the results of measuring the range to the target by the ASD system.

[0085] If the additive mixture y(t) at the input of FD 8.1 contains only noise and the target echo signal or noise, the target echo signal and the deflecting interference coinciding in time with the useful signal at the initial moment of deflection (τ = 0), then a sequence of unipolar positive video pulses z will be generated at the output of FD 8.1. фд(t) (Fig. 6), which is fed to the inputs of the amplitude signal limiters 8.31 and 8.3 2 In accordance with the limiter operating algorithm, this sequence of video pulses will be sent to the output of limiter 8.3 1 , at the output of the limiter 8.3 2 a zero-level voltage z2(t) will be generated, which, after passing through inverter 8.4 and accumulation in integrator 8.5 2 (z H2 (t)) will not exceed the threshold level C of the threshold device 8.6 2 , set according to noise. As a result, the output of the threshold device is 8.6 2 a logical 0 signal will be generated. The one present at the output of the limiter 8.3 1 sequence of video pulses z1(t) after accumulation in the integrator 8.5 1 (zн1(t)) will exceed the threshold level C of threshold device 8.b 1 . As a result, the output of the threshold device is 8.6 1A logical 1 signal will be generated. Consequently, a logical 1 signal will be present at the first inputs of the AND 8.7 and XOR 8.8 logic elements, and a logical 0 signal will be present at the second inputs. This, in accordance with their operating logic, will generate a logical 0 signal at the first input of the decision block 8.9 and a logical 1 signal at its second input. Based on this combination of input signals, the decision block 8.9 will generate a decision on stable automatic target tracking in range.

[0086] If a sequence of unipolar negative video pulses z is formed at the output of FD 8.1. фд (t), then it will pass through limiter 8.3 2 and after inversion in inverter 8.4 and accumulation in integrator 8.5 2 (z H2 (t)) will exceed the threshold level C of the threshold device 8.6 2 . As a result, the output of the threshold device is 8.6 2 a logical 1 signal will be generated. At the output of the limiter 8.3 1a zero-level voltage z1(t) will be generated, which after accumulation in the integrator 8.5 1 (z Hl (t)) will not exceed the threshold level C of the threshold device 8.6 1 . As a result, the output of the threshold device is 8.6 1 a logical 0 signal will be generated. This combination of signals at the inputs of the logical elements “AND” 8.7 and “exclusive OR” 8.8 will generate a logical 0 signal at the first input of the decision-making block 8.9 and a logical 1 signal at its second input, which corresponds to the generation by block 8.9 of a decision on stable automatic target tracking in range.

[0087] If the additive mixture y(t) at the input of FD 8.1 contains noise, a target echo signal and a leading interference, misaligned in time with the useful signal during the leading process within the location of the target echo signal in the working area of ​​the VD (0.5τ и ≤ τ < τ и ), then at the output of FD 8.1 a sequence of bipolar video pulses z will be generated фд(t) (Fig. 7), which is fed to the inputs of the signal amplitude limiters 8.3 1 and 8.3 2 . In accordance with the algorithm of operation of the limiters at the output of limiter 8.3 1 a sequence of positive video pulses z1(t) will be formed, extracted from the bipolar sequence z фд (t), and at the output of the limiter 8.3 2 - a sequence of negative video pulses z2(t). Sequences of positive video pulses z1(t) after accumulation in the integrator 8.5 1 (z H1 (t)) and negative video pulses z2(t) after passing through inverter 8.4 and accumulation in integrator 8.5 2 (z H2 (t)) will exceed threshold levels of threshold devices 8.6 1 and 8.6 2 . As a result, at the outputs of the threshold devices 8.6 1 and 8.6 2signals of logical 1 will be generated and fed to both inputs of the logical elements “AND” 8.7 and “exclusive OR” 8.8. Such a combination of signals at the inputs of logical elements 8.7 and 8.8 will form a logical 1 signal at the first input of the decision-making block 8.9 and a logical 0 signal at its second input, which corresponds to the generation by block 8.9 of a decision on the impact of the diverting interference.

[0088] If the signal y(t) at the input of FD 8.1 contains only noise, then at the output of FD 8.1, sequences of both bipolar and unipolar video pulses z can be formed фд (t), which will arrive at the inputs of the signal amplitude limiters 8.3 1 and 8.3 2 . In case of presence of a sequence of bipolar video pulses at the input of the limiter, at the output of the limiter 8.3 1 a sequence of positive video pulses z1(t) will be formed, and at the output of limiter 8.3 2- a sequence of negative video pulses z2(t). But a sequence of positive video pulses z1(t) after accumulation in the integrator 8.5 1 (z н1 (t)) and negative video pulses z2(t) after passing through inverter 8.4 and accumulation in integrator 8.5 2 (z н2 (t)) will not exceed threshold levels C of threshold devices 8.6 1 and 8.6 2 .

[0089] If there are limiters at the input 8.3 1 and 8.3 2 sequences of unipolar video pulses, with their positive polarity at the output of limiter 8.3 1 a sequence of positive video pulses z1(t) will be formed, and at the output of the limiter 8.3 2 a zero-level voltage z2(t) will be generated. With a negative polarity of the video pulse sequence z фд (t) at the output of the limiter 8.3 2 a sequence of negative video pulses z2(t) will be formed, and at the output of the limiter 8.31 a zero-level voltage z1(t) will be generated. But the sequence of positive video pulses z1(t) after accumulation in the integrator 8.5 1 (z н1 (t)) or negative video pulses z2(t) after passing through inverter 8.4 and accumulation in integrator 8.5 2 (z н2 (t)) will not exceed the threshold level C of the threshold device 8.6 1 or 8.6 2 . Zero-level voltages after accumulation in the integrator 8.5 1 or after passing through inverter 8.4 and accumulation in integrator 8.5 2 threshold levels C threshold devices 8.6 1 or 8.6 2 will also not be exceeded. If the output signals of the integrators are not exceeded at the same time, 8.5 1 and 8.5 2 threshold levels C at the outputs of threshold devices 8.6 1 and 8.6 2signals of logical 0 will be generated and fed to both inputs of the logical elements “AND” 8.7 and “exclusive OR” 8.8. Such a combination of signals at the inputs of logical elements 8.7 and 8.8 will generate signals of logical 0 at both inputs of decision block 8.9, which corresponds to the generation by block 8.9 of a decision on the absence of a target and interference.

[0090] The declared technical result is confirmed by the results obtained by the simulation modeling method in the MATLAB application package.

[0091] The simulation was carried out with the following initial data: an additive mixture y(t) containing white noise (target echo signal) and diverting interference with a signal-to-noise ratio of 10 dB and an interference level exceeding the signal level by 1.5 times was fed to the input of the device (Fig. 8); the useful signal and interference were identical packets of 14 radio pulses with a duty cycle of 10, differing only in amplitude and time mismatch (at τ = 0 and τ = 0.5τ и); a normal random process with a mathematical expectation equal to 0 and unit variance was taken as noise; a copy of the target echo signal was used as the reference voltage s(t) of FD 8.1; threshold levels C of threshold devices 8.6 1 and 8.6 2 were set based on the results of a statistical experiment at the level of accumulated noise in integrators 8.5 1 and 8.5 2 for a false alarm probability of 10 -4 when feeding only noise to the 8.1 FD input.

[0092] The simulation results for the time mismatch between the target echo signal and the diverting interference τ = 0 are shown in Fig. 9, and for τ = 0.5τ и - in Fig. 10. The obtained results, namely the formation of unipolar video pulses z фд (t) at the output of FD 8.1, the presence of a non-zero signal z1(t) only at the output of limiter 8.3 1 exceeding the threshold level with only the output voltage z н1 (t) integrator 8.5 1at τ = 0 (Fig. 9), as well as the formation of bipolar video pulses z фд (t) at the output of FD 8.1, the presence of non-zero signals z1(t) and z2(t) at the outputs of limiters 8.3 1 and 8.3 2 , exceeding the threshold level with output voltages z н1 (t) and z н2 (t) integrators 8.5 1 and 8.5 2 in both channels at τ = 0.5τ и (Fig. 10) confirm the efficiency of the method.

[0093] Thus, the discovery, during the process of diverting the ASD system by interference, of the fact of phase manipulation in the resulting signal containing the target echo signal and the diverting interference, by means of its synchronous phase detection followed by two-channel processing, including a limitation on the amplitude from below relative to the zero level, accumulation and comparison with the threshold in one channel and a limitation on the amplitude from above relative to the zero level, inversion, accumulation and comparison with the threshold in another channel, as well as the subsequent analysis of the results of comparing the threshold exceedances in the channels makes it possible to detect the impact of the diverting interference on the ASD system of a pulse-Doppler radar before the useful signal leaves the working area of ​​the VD, thereby achieving the declared technical result.

[0094] Bibliography

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[0101] 7. Theory and technology of processing radar information against a background of interference / Ya.D. Shirman, V.N. Manzhos. - M .: Radio and Communications, 1981, 416 p: ill. - Text: direct.

Claims

A method for detecting the impact of escaping interference on the automatic range tracking system of a pulse-Doppler radar station, which consists of detecting received radio pulses with their subsequent limiting, integrating (accumulating) within the duration of a burst and comparing the level of the accumulated pulses with a threshold, characterized in that a synchronous phase detector is used for detection, to the control input of which a copy of the probing signal is fed, in phase with the received echo signal of the target and coinciding with it in frequency and time delay, the detected signal is fed to two identical channels, in one of which the signal is limited in amplitude from above relative to the zero level, inverted and accumulated, and in the other channel it is limited in amplitude from below relative to the zero level and accumulated, the signals accumulated in each channel are compared with the detection threshold set for noise and corresponding to a specified false alarm level,when the detection threshold is exceeded by signals in both channels, a decision is made about the influence of range-diverting interference; when the detection threshold is exceeded by a signal in only one channel, a decision is made about stable automatic target tracking in range; if the threshold is not exceeded in both channels, a decision is made about the absence of a target and interference.

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