CN104199001A - Velocity-deception-jamming-resistant phase encoding method for cognitive radar - Google Patents

Abstract

The invention discloses a velocity-deception-jamming-resistant phase encoding method for a cognitive radar, belongs to the technical field of radar jamming resistance, and particularly relates to a radar jamming-resistant waveform design technology. According to the method, relevant parameters of a target and jamming are extracted from prior information acquired by the cognitive radar, a stop band is arranged close to each real target Doppler according to a real target Doppler estimated value, a stop band is arranged at the same position as a constant-mode encoding sequence configured in advanced, and an optimal pulse-to-pulse phase encoding transmission waveform is designed according to the criterion that the spectrum energy of a coded signal in the stop band, thereby effectively inhibiting velocity deception jamming in a multi-target and multi-jamming scene, increasing the signal-to-jamming ratio of each real target, and realizing the effect of correct detection of a plurality of real targets.

Description

A kind of phase encoding method that cognitive Radar Anti velocity gate deception disturbs

Technical field

The invention belongs to Anti-jamming Technology for Radar field, particularly Radar Anti interference waveform designing technique.

Background technology

Along with the appearance of the modern Cheat Jamming Technique based on digital radiofrequency memory (DRFM), gate stealing is stepped into the coherent interference epoch.Jammer copies the also Doppler parameter of modulation signal to it after intercepting and capturing radar signal, then undesired signal is forwarded back to radar receiver and forms velocity gate deception interference.This class is disturbed can affect the detection of radar to real goal Doppler, makes radar speed ripple door losing lock, disturbs the normal detection of radar to target, has also greatly consumed radar resource simultaneously.Therefore,, for guaranteeing that radar is disturbing the correct detection and tracking to target under bad border, the ability that improves the interference of Radar Anti velocity gate deception has important theory value and practical significance.

Waveform Design is effective measures of antagonism radar speed cheating interference.Zhang Jingdong has proposed a kind of anti-velocity gate deception interference waveform method for designing, it utilizes hyperchannel to process estimation interfere information, and the coding waveforms designing adaptively based on initial phase suppresses velocity gate deception interference, see [Jindong Zhang, Daiyin Zhu, Gong Zhang, New Antivelocity Deception Jamming Technique using Pulses with Adaptive Initial Phases.IEEE Transactions on Aerospace and Electronic Systems, 49 (2): 1290-1300,2013].The method can effectively suppress strong jamming in single real goal scene, but disturbs scene for multiple goal more, the interference free performance degradation of the method, and some real goal may not correctly be detected by radar.From the document of publishing at present, for the anti-velocity gate deception interference waveform design of multiple goal scene, also there is not research.

Summary of the invention

The object of the invention is the deficiency for background technology, design a kind of phase encoding method that cognitive Radar Anti velocity gate deception disturbs, the prior imformation that the cognitive radar of the method utilization obtains, therefrom extract the correlation parameter of target and interference, according to coded signal spectrum energy minimum criteria in stopband, phase encoding transmitted waveform between the arteries and veins of devise optimum, thereby reach in multiple goal and disturb effectively inhibition velocity gate deception interference in scene more, improve the signal interference ratio at each real goal place, realize the object of the correct detection of a plurality of real goals.

The invention provides a kind of phase encoding method that cognitive Radar Anti velocity gate deception disturbs, it comprises the following steps:

Step 1: the constantly outside transponder pulse string signal of cognitive radar, while receiving target echoed signal, echoed signal is carried out to initial analysis, if cognitive radar has detected velocity gate deception, disturb, in the relevant processing of next one interval, launching one group of initial phase is 0 simple train of impulses; If cognitive radar has identified velocity gate deception and disturbed, forward step 2 to;

Step 2: cognitive radar carries out real-time analysis to echoed signal, and constantly update target and interfere information, simultaneously by the correlation parameter of parameter estimation algorithm estimating target and interference: pulse repetition time number i, the number P of false target jamming profile of Doppler's estimated value of real goal, interference hysteresis radar are, the amplitude of each false target jamming profile and Doppler;

Step 3: adopt the correlation parameter of target that step 2 estimates and interference as prior imformation, construct the cost function J (x, α) of anti-interference coding waveform=|| x-B α || ²,

Wherein, || i|| representing matrix 2 norms, α is auxiliary variable, B is a matrix that characterizes stopband collection spectrum energy;

Step 4, cyclic iterative are asked the optimum code sequence that makes cost function minimum:

Step 4.1: first during iteration, the permanent mode sequence x of random initializtion, x is for needing the coded sequence of design;

Step 4.2: increase iterations, first fix permanent mode sequence x for cost function, to its differentiate and make derivative equal 0, calculate the auxiliary variable α=B that makes cost function minimum ^hx; Fixing auxiliary variable α again, calculates the permanent mode sequence of the cost function minimum of sening as an envoy to $\tilde{x}=e^{j\arg \left(\mathrm{B\α}\right)};$

E wherein ⁽ⁱ⁾represent exponential function, j represents imaginary unit, and it is a matrix that characterizes stopband collection spectrum energy that arg (i) represents to ask phase angle function, B;

Step 4.3: calculate the 2 poor norms of permanent mode sequence that adjacent twice iteration obtains, judge whether stopping iteration: if its value is less than the convergency value of setting, stop iteration, the permanent mode sequence that last iteration obtains is optimum code sequence; If its value is greater than the convergency value of setting, order repeating step 4.2-4.3, until satisfy condition;

Step 5: according to the optimum code sequence of trying to achieve in step 4, calculate successively the next relevant all exomonental initial phases in interval of processing:

Wherein, N is a relevant overall pulse number of processing in interval, φ _nfor the next one is relevant, process n exomonental encoding phase in interval, φ _1-i, φ _2-i..., φ ₀for the initial phase of a front i pulse, for the phase place of n element in the optimum code sequence of trying to achieve in step 4, for the phase angle of a (n), be component relevant with interference in n pulse repetition time, P is interference number, with be respectively p amplitude and the Doppler frequency of disturbing, Tr is the radar pulse repetition period, e ⁽ⁱ⁾represent exponential function, Σ is summation symbol.

The concrete steps of described step 3 are:

Step 3.1: construct permanent mould coded sequence x;

Near step 3.2 a: stopband is set each real goal Doppler according to Doppler's estimated value of real goal, and resistance band is determined according to the accuracy rating of real goal estimated value, a stopband collection of union formation of a plurality of stopbands;

Step 3.3: to stopband being set on the permanent mould coded sequence x of step 3.1 structure, the position of stopband is set and in step 3.2, Doppler's estimated value of real goal to be arranged to the position of stopband corresponding one by one, thereby forms the stopband collection of permanent mould coded sequence x;

Step 3.4: make discrete time Fourier transform to being provided with the permanent mould coded sequence x of stopband, calculate the spectrum energy in each stopband, the spectrum energy in each stopband is done to weighting and process, calculate the total frequency spectrum energy in stopband collection;

Step 3.5: the cost function according to the total frequency spectrum energy structure calculating about coded sequence: J (x, α)=|| x-B α || ², for making the spectrum energy of coded sequence in stopband collection minimum, need to minimize cost function.

Innovative point of the present invention: a kind of anti-velocity gate deception interference waveform method for designing is provided, can realizes the correct detection of a plurality of real goals more in the multiple goal scenes of disturbing.

The present invention proposes a kind of phase encoding method that cognitive Radar Anti velocity gate deception disturbs, the method takes full advantage of the priori of cognitive radar, adopt coded signal spectrum energy minimum criteria in stopband to carry out Waveform Design, regulate the weight of each stopband, thereby have in multiple goal, disturb in scene more and can effectively suppress to disturb, improve the signal interference ratio at each real goal place, realize the effect of the correct detection of a plurality of real goals.

Accompanying drawing explanation

Fig. 1 is overview flow chart of the present invention;

When Fig. 2 is i=2, transponder pulse and the schematic diagram disturbing in a CPI;

Fig. 3 is that cyclic iterative solves cost function optimum solution process flow diagram;

The transponder pulse of Fig. 4 for adopting fixed transmission pulse and adopting this method to design, the simulation result comparison diagram of radar return Doppler frequency spectrum;

The Doppler frequency spectrum of radar return when Fig. 4-1 adopts fixed transmission pulse in Fig. 4; The Doppler frequency spectrum of radar return when Fig. 4-2 adopt the transponder pulse of this method design.

Embodiment

Specific embodiment of the invention step is as follows:

Step 1: the constantly outside transponder pulse string signal of cognitive radar, while receiving target echoed signal, echoed signal is carried out to initial analysis, if cognitive radar has detected velocity gate deception, disturb, in the relevant processing of next one interval, launching one group of initial phase is 0 simple train of impulses; If cognitive radar has identified velocity gate deception and disturbed, forward step 2 to;

Step 2: cognitive radar carries out real-time analysis to echoed signal, and constantly update target and interfere information, simultaneously by the correlation parameter of parameter estimation algorithm estimating target and interference: pulse repetition time number i, the number P of false target jamming profile of Doppler's estimated value of real goal, interference hysteresis radar are, the amplitude of each false target jamming profile and Doppler;

Step 3: adopt the correlation parameter of target that step 2 estimates and interference as prior imformation, construct the cost function J (x, α) of anti-interference coding waveform=|| x-B α || ²,

Wherein, || i|| representing matrix 2 norms, α is auxiliary variable, B is a matrix that characterizes stopband collection spectrum energy;

Step 3.1: construct permanent mould coded sequence wherein x is the coded sequence that needs design, [i] ^tthe transposition of representing matrix, e ⁽ⁱ⁾represent exponential function, θ _n(n=1,2 ..., N) being the phase place of n element in coded sequence, N is a relevant overall pulse number of processing in interval;

Near step 3.2 a: stopband is set each real goal Doppler according to Doppler's estimated value of real goal, and resistance band is determined according to the accuracy rating of real goal estimated value, a stopband collection of union formation of a plurality of stopbands

N wherein _sfor stopband number, f _k1, f _k2be respectively the bound of k stopband, symbol ∪ represents a plurality of union of sets collection;

Step 3.3: to stopband being set on the permanent mould coded sequence x of step 3.1 structure, the position of stopband is set and in step 3.2, Doppler's estimated value of real goal to be arranged to the position of stopband corresponding one by one, thereby forms the stopband collection of permanent mould coded sequence x;

Step 3.4: make discrete time Fourier transform to being provided with the permanent mould coded sequence x of stopband, calculate the spectrum energy in each stopband, the spectrum energy in each stopband is done to weighting and process, calculate the total frequency spectrum energy J=x in stopband collection ^hrx;

Wherein, x is the sequence that needs design, and R is a matrix that characterizes stopband collection spectrum energy, and the element that the capable n of its m lists is

$R_{\mathrm{mn}}=\underset{k=1}{\overset{N_s}{\mathrm{\Σ}}}{\mathrm{\ω}}_k\left\{\begin{array}{cc}\frac{e^{j2\mathrm{\π}{f}_{k2}{T}_r(m-n)}-e^{j2\mathrm{\π}{f}_{k1}{T}_r(m-n)}}{j2\mathrm{\π}(m-n)},& m\≠n\\ (f_{k2}-f_{k1})T_r,& m=n\end{array}\right.;$

Wherein, j represents imaginary unit, e ⁽ⁱ⁾represent exponential function, N _sfor the stopband number arranging, ω _k(ω _k>=0) be the weights of k stopband, f _k1, f _k2be respectively lower limit and the upper limit of k stopband, T _rfor radar transmitted pulse recurrence interval.

Step 3.5: the cost function according to the total frequency spectrum energy structure calculating about coded sequence: J (x, α)=|| x-B α || ²,

Wherein, B is R matrix 0 eigenwert characteristic of correspondence vector matrix; For making the spectrum energy of coded sequence in stopband collection minimum, need to minimize cost function;

Step 4, cyclic iterative are asked the optimum code sequence that makes cost function minimum:

4.1: first during iteration, the permanent mode sequence x of random initializtion, x is for needing the coded sequence of design;

4.2: increase iterations, for cost function, first fix permanent mode sequence x, to its differentiate and make derivative equal 0, calculate the auxiliary variable α=B that makes cost function minimum ^hx; Fixing auxiliary variable α again, calculates the permanent mode sequence of the cost function minimum of sening as an envoy to $\tilde{x}=e^{j\arg \left(\mathrm{B\α}\right)};$

E wherein ⁽ⁱ⁾represent exponential function, j represents imaginary unit, and it is a matrix that characterizes stopband collection spectrum energy that arg (i) represents to ask phase angle function, B;

4.3: calculate poor matrix 2 norms of permanent mode sequence that adjacent twice iteration obtains, to whether stopping iteration, judge: if (convergency value of ε for setting), stops iteration, the permanent mode sequence that last iteration obtains it is optimum code sequence; If order repeating step 4.2-4.3, until satisfy condition;

Step 5: according to the optimum code sequence of trying to achieve in step 4, calculate successively the next relevant all exomonental initial phases in interval of processing:

Wherein, N is a relevant overall pulse number of processing in interval, φ _nfor the next one is relevant, process n exomonental encoding phase in interval, φ _1-i, φ _2-i..., φ ₀for the initial phase of a front i pulse, for the phase place of n element in the optimum code sequence of trying to achieve in step 4, for the phase angle of a (n), be component relevant with interference in n pulse repetition time, P is interference number, be respectively p amplitude and the Doppler frequency of disturbing, T _rfor radar pulse repetition period, e ⁽ⁱ⁾represent exponential function, Σ is summation symbol.

Effect of the present invention further illustrates by following simulation comparison test:

Simulating scenes: have 2 real goals in radar main lobe, each real goal all carries a deception jammer, jammer is implemented velocity gate deception to radar and is disturbed, and undesired signal and real goal echoed signal are at same range unit.Each real goal echo signal amplitude is 1, and its Doppler's estimated value is respectively 5kHz and 15kHz; Disturb hysteresis 1 pulse repetition time of radar; Jammer discharges 4 false target jamming profile signals simultaneously, and interference magnitude is respectively 1.5,3.2,2.5 and 1.7, and the Doppler of the undesired signal that jammer produces is respectively 4.5kHz, 5.4kHz, 14.8kHz and 15.6kHz; A relevant umber of pulse of processing in interval (CPI) is 512; The exomonental pulse repetition time is 25 μ s; The transponder pulse initial phase in the 0th moment is φ ₀=0.

In above-mentioned emulation, adopt fixed transmission pulse and adopt the transponder pulse of this method design, through Monte Carlo simulation 100 times, the simulation result of radar return Doppler frequency spectrum is as shown in Figure 4.From Fig. 4-1, while adopting fixed transmission pulse, on the doppler spectral of radar return, there are a plurality of decoys, because decoy energy is higher than real goal, disturb the detection that can affect real goal.By Fig. 4-2, can be found out, adopt this method design transponder pulse, form two stopbands near the real goal of the doppler spectral of radar return, disturb suppressedly, the signal interference ratio at real goal Doppler place can reach 22dB, and radar can correctly detect target.

By specific embodiment of the invention, can find out, in multiple goal, disturb in scene more, by waveform design method provided by the invention, can suppress greatly velocity gate deception and disturb, improve near the signal interference ratio of real goal, realize the correct detection of radar to a plurality of real goals.

Claims (2)

1. the phase encoding method that cognitive Radar Anti velocity gate deception disturbs, the method comprises:

Step 1: the constantly outside transponder pulse string signal of cognitive radar, while receiving target echoed signal, echoed signal is carried out to initial analysis, if cognitive radar has detected velocity gate deception, disturb, in the relevant processing of next one interval, launching one group of initial phase is 0 simple train of impulses; If cognitive radar has identified velocity gate deception and disturbed, forward step 2 to;

Step 2: cognitive radar carries out real-time analysis to echoed signal, and constantly update target and interfere information, simultaneously by the correlation parameter of parameter estimation algorithm estimating target and interference: pulse repetition time number i, the number P of false target jamming profile of Doppler's estimated value of real goal, interference hysteresis radar are, the amplitude of each false target jamming profile and Doppler;

Step 3: adopt the correlation parameter of target that step 2 estimates and interference as prior imformation, construct the cost function J (x, α) of anti-interference coding waveform=|| x-B α || ²,

Wherein, || i|| representing matrix 2 norms, α is auxiliary variable, B is a matrix that characterizes stopband collection spectrum energy;

Step 4, cyclic iterative are asked the optimum code sequence that makes cost function minimum:

Step 4.1: first during iteration, the permanent mode sequence x of random initializtion, x is for needing the coded sequence of design;

Step 4.2: increase iterations, first fix permanent mode sequence x for cost function, to its differentiate and make derivative equal 0, calculate the auxiliary variable α=B that makes cost function minimum ^hx; Fixing auxiliary variable α again, calculates the permanent mode sequence of the cost function minimum of sening as an envoy to $\tilde{x}=e^{j\arg \left(\mathrm{B\α}\right)};$

E wherein ⁽ⁱ⁾represent exponential function, j represents imaginary unit, and it is a matrix that characterizes stopband collection spectrum energy that arg (i) represents to ask phase angle function, B;

Step 4.3: calculate the 2 poor norms of permanent mode sequence that adjacent twice iteration obtains, judge whether stopping iteration: if its value is less than the convergency value of setting, stop iteration, the permanent mode sequence that last iteration obtains is optimum code sequence; If its value is greater than the convergency value of setting, order repeating step 4.2-4.3, until satisfy condition;

Step 5: according to the optimum code sequence of trying to achieve in step 4, calculate successively the next relevant all exomonental initial phases in interval of processing:

Wherein, N is a relevant overall pulse number of processing in interval, φ _nfor the next one is relevant, process n exomonental encoding phase in interval, φ _1-i, φ _2-i..., φ ₀for the initial phase of a front i pulse, for the phase place of n element in the optimum code sequence of trying to achieve in step 4, phase angle, be component relevant with interference in n pulse repetition time, P is interference number, with be respectively p amplitude and the Doppler frequency of disturbing, T _rfor radar pulse repetition period, e ⁽ⁱ⁾represent exponential function, Σ is summation symbol.

2. the phase encoding method that a kind of cognitive Radar Anti velocity gate deception as claimed in claim 1 disturbs, the concrete steps of its feature extraction step 3 are:

Step 3.1: construct permanent mould coded sequence x;

Near step 3.2 a: stopband is set each real goal Doppler according to Doppler's estimated value of real goal, and resistance band is determined according to the accuracy rating of real goal estimated value, a stopband collection of union formation of a plurality of stopbands;

Step 3.3: to stopband being set on the permanent mould coded sequence x of step 3.1 structure, the position of stopband is set and in step 3.2, Doppler's estimated value of real goal to be arranged to the position of stopband corresponding one by one, thereby forms the stopband collection of permanent mould coded sequence x;

Step 3.4: make discrete time Fourier transform to being provided with the permanent mould coded sequence x of stopband, calculate the spectrum energy in each stopband, the spectrum energy in each stopband is done to weighting and process, calculate the total frequency spectrum energy in stopband collection;

Step 3.5: the cost function according to the total frequency spectrum energy structure calculating about coded sequence: J (x, α)=|| x-B α || ², for making the spectrum energy of coded sequence in stopband collection minimum, need to minimize cost function.