A detection and interference integrated waveform generation method based on intermittent sampling

Abstract

The present invention proposes a detection and interference integrated waveform generation method based on intermittent sampling, which uses the combined minimization criterion of the sidelobe peak ratio of the Doppler fuzzy function of the integrated signal and the ratio of the standard deviation of the amplitude after pulse compression to the mean to optimize and construct the corresponding objective function; the objective function is solved by a genetic algorithm to obtain the optimal amplitude coding method. The fuzzy function is an effective tool for analyzing the detection performance of radar signals. The linear frequency modulation signal is insensitive to the Doppler frequency and has a high sidelobe peak. The process of integrated signal optimization design is to find the maximum value by changing the pulse amplitude coding sequence, while the genetic algorithm takes the coding of the decision variable as the operation object, the objective function value as the search information, and the fitness function to measure the individual's excellence. It has good global search performance, so the genetic algorithm is used to solve the objective function. The integrated waveform signal generated by the present invention has a certain detection function while interfering with the opponent's signal.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated waveform optimization design of radar detection, linear frequency modulation and pulse amplitude coding modulation, and in particular relates to a detection and interference integrated waveform generation method based on intermittent sampling. Background Art

[0002] In modern electronic warfare, electronic reconnaissance and jamming both play a crucial role. Effectively attacking an enemy's electronic systems is as important as effectively protecting one's own. Radars and jammers are functionally distinct and, in most cases, designed separately. However, they share structural similarities. For example, jammers also have a transmitting function and can utilize this signal for detection. Therefore, combining radar detection and jamming functions to reduce the number of equipment required for combat is being considered. This would not only reduce costs but also improve operational performance, opening up new possibilities for system miniaturization and integration.

[0003] To improve radar range and resolution, modern radars commonly use pulse compression radar, with linear frequency modulation (LFM) being the most common signal. Intermittent sampling and forwarding is an effective jamming technique for signals with large time-bandwidth products. Intermittent sampling and forwarding of LFM signals can also be expressed in the time domain as pulse amplitude modulation (PAM). The resulting jamming signal, compressed by intermittent sampling and forwarding, can generate a certain number of false targets. However, uniform intermittent sampling and forwarding produces a limited number of false targets, making the jamming effect less pronounced. Summary of the Invention

[0004] In response to the above-mentioned needs and shortcomings of the prior art, the present invention proposes a method for generating an integrated detection and interference waveform based on intermittent sampling. This method uses the combined minimization criteria of the sidelobe peak ratio of the integrated signal Doppler ambiguity function and the ratio of the standard deviation to the mean of the pulse compression amplitude to establish an optimization model and construct a corresponding objective function. A genetic algorithm is used to solve the objective function and obtain the optimal amplitude encoding method. The ambiguity function can reflect measurement accuracy as well as distance and velocity resolution, and is an effective tool for analyzing radar signal detection performance. Linear frequency modulation signals are insensitive to Doppler frequency and have high sidelobe peaks. The integrated signal optimization design process involves finding the optimal value by changing the pulse amplitude coding sequence. The genetic algorithm uses the encoding of the decision variable as the operation object, the objective function value as the search information, and the fitness function to measure the quality of the individual. It has good global search performance, so a genetic algorithm is used to solve the objective function. The integrated waveform signal generated by the present invention not only interferes with the opponent's signal but also has a certain detection function.

[0005] The specific implementation contents of the present invention are as follows:

[0006] The present invention proposes a detection and interference integrated waveform generation method based on intermittent sampling, which specifically includes the following steps:

[0007] Step 1: First, calculate the sidelobe peak ratio r1(t) and the ratio of the standard deviation of the pulse amplitude to the mean r2(t) of the Doppler ambiguity function; then, construct the objective function R(t) based on the sidelobe peak ratio r1(t) and the ratio of the standard deviation of the pulse amplitude to the mean r2(t) of the Doppler ambiguity function and the minimization criterion;

[0008] Step 2: Use the sampling genetic algorithm to solve the objective function R(t) and obtain the optimal amplitude coding method; finally, use the optimal amplitude coding method to generate an integrated waveform for detecting interference.

[0009] In order to better implement the present invention, further, the step 1 specifically includes the following steps:

[0010] Step 1.1: Construct the detection performance evaluation criteria: calculate the sidelobe peak ratio r1(t) of the Doppler ambiguity function;

[0011] Step 1.2: Construct the interference performance evaluation standard: calculate the ratio of the standard deviation of the pulse amplitude to the mean r2(t);

[0012] Step 1.3: Based on the sidelobe peak ratio r1(t) of the Doppler ambiguity function and the ratio of the standard deviation to the mean of the pulse amplitude r2(t), construct the objective function R(t) according to the minimization criterion.

[0013] In order to better implement the present invention, further, the specific operations of step 1.1 are:

[0014] Step 1.1.1: Define the fuzzy function χ of the integrated signal y(t) y (τ,ξ), the specific calculation formula is as follows:

[0015]

[0016] Where t is the time variable, is the conjugate operation of the signal y(t) after the time delay τ, e j2πζt is the Doppler frequency shift.

[0017] Step 1.1.2: For the fuzzy function χ y (τ,ξ) is transformed to obtain the Doppler ambiguity function χ of the integrated signal y (0,ξ), the specific formula is:

[0018]

[0019] Where, is the conjugate operation of the signal y(t).

[0020] Step 1.1.3: Calculate the sidelobe peak ratio r1(t) of the Doppler ambiguity function. The specific formula is:

[0021]

[0022] Where, ξ d The Doppler frequency corresponding to the sidelobe peak value;

[0023] The sidelobe peak ratio r1(t) is inversely correlated with the detection performance of the detection-interference integrated waveform, that is, the smaller the sidelobe peak ratio r1(t), the better the detection performance.

[0024] In order to better implement the present invention, further, the step 1.2 specifically includes the following steps:

[0025] Step 1.2.1: After the intermittent sampling and forwarding of the linear frequency modulation signal pulse compression, a certain number of false targets are generated. The system function h(t) of the matched filter of the integrated signal y(t) is set to:

[0026]

[0027] Where t0 is the constant that makes the system function h(t) a causal realizable system, and “-” represents conjugate calculation;

[0028] Therefore h(t) can be expressed as:

[0029]

[0030] s(t) is a linear frequency modulation signal, and the expression of s(t) is:

[0031]

[0032] Where, f c is the carrier frequency; is the frequency modulation slope; B is the signal bandwidth; T is the radar signal length; For a rectangular signal, the expression is:

[0033]

[0034] Step 1.2.2: Modulate the linear frequency modulation signal s(t) to obtain the integrated signal y(t). The expression of the integrated signal y(t) is:

[0035]

[0036] Where c(t) is the modulation signal, For the modulation operation:

[0037] Substitute the above integrated signal y(t) and system function h(t) into the integrated signal pulse pressure formula to calculate the calculated signal x(t), and we get:

[0038]

[0039] Where * is the convolution operation; μ is the amount of calculation introduced by the convolution formula;

[0040] Step 1.2.3: Calculate the ratio of the standard deviation of the amplitude of the integrated signal y(t) to the mean after pulse compression, r2(t), to measure the interference effect. The formula for calculating the ratio of the standard deviation of the amplitude of the integrated signal y(t) to the mean after pulse compression, r2(t), is as follows:

[0041]

[0042] Where, σ 2 (·) is the variance operation, E(·) is the mean operation, and r2(t) is inversely correlated with the interference performance, that is, the smaller r2(t), the better the interference performance.

[0043] In order to better implement the present invention, further, the specific operations of step 1.3 are:

[0044] Construct the objective function R(t). The specific construction formula is as follows:

[0045]

[0046] Wherein, α1 and α2 are weighting coefficients, α1+α2=1.

[0047] In order to better implement the present invention, further, the step 2 specifically includes the following steps:

[0048] Step 2.1: Initialize the integrated waveform set;

[0049] Step 2.2: Use genetic algorithm to solve the objective function R(t) and obtain the optimal waveform individual;

[0050] Step 2.3: Select, cross, mutate, and update each individual in the population;

[0051] Step 2.4: Set the number of iterations and repeat steps 2.2 to 2.3. When the individuals in the population output by the nth iteration and the n-1th iteration are the same, find the optimal integrated waveform and exit the loop.

[0052] Step 2.5: Generate the optimal integrated waveform obtained by solution.

[0053] In order to better implement the present invention, further, the step 2.1 specifically includes the following steps:

[0054] Step 2.1.1: Define the integrated waveform set y n There are N individuals in total, and the number of code elements of the individual amplitude coding of each waveform is P, then the waveform individual of the nth amplitude coding modulation is expressed as:

[0055] y n =[y n (1),y n (2),...,y n (p),...,y n (P)];

[0056] Among them, 1≤n≤N, y n (p) is the short pulse corresponding to the p-th symbol of the integrated signal;

[0057] Step 2.1.2: Represent the binary amplitude-coded signal c(t) with a random sequence as follows:

[0058]

[0059] Where P represents the length of the random sequence, g(t) is the rectangular pulse signal, and the expression is: c k represents a random sequence, with a value of {0,1}; k is the kth code element of the random sequence; is a rectangular signal, T c represents the symbol period;

[0060] Step 2.1.3: In the binary sequence, I represents the number of consecutive 0s in each segment, and J represents the number of consecutive 1s in each segment. For the short pulse y corresponding to the pth code element of the nth individual in step 2.1.1, n (p) is expressed as:

[0061]

[0062] c ip represents the pth binary sequence, which is located in the i-th sequence of the zero string I, i∈[1,2,...,I]; c jp represents the pth binary sequence, which is located in the jth of a string J, j∈[1,2,...,J]; s p (t) is the linear frequency modulation signal corresponding to the pth code element, and the formula is:

[0063] s p (t) = s(t)c(p);

[0064] The expression of s(t) is:

[0065]

[0066] Where, f c is the carrier frequency; is the frequency modulation slope; B is the signal bandwidth; T is the radar signal length; For a rectangular signal, the expression is:

[0067]

[0068] c(p)=c p g(t-pT c ),T c represents the symbol period, c p represents the pth code element, which has a value of 1; g(t) is a rectangular pulse signal, which is expressed as

[0069] In order to better implement the present invention, further, the specific operations of step 2.2 are as follows:

[0070] Step 2.2.1: Set the integrated waveform set y in step 2.1 n The N coded modulated waveforms in the GA are used as the initial population;

[0071] Step 2.2.2: Calculate the fitness function of each population Fitness function The calculation formula is:

[0072]

[0073] In order to better implement the present invention, further, the integrated waveform is obtained by modulating the LFM signal with a set of binary amplitude coded signals, which is manifested in the time domain as intermittent sampling and forwarding interference of the LFM signal;

[0074] Code 0 indicates sampling, and code 1 indicates forwarding. Follow the steps below to perform forwarding:

[0075] First, the minimum sampling time unit is fixed as τ;

[0076] Next, the first bit of the fixed binary sequence is coded 0, and the number of consecutive coded 1s is greater than or equal to the number of consecutive coded 0s;

[0077] Finally, forwarding is performed in a forwarding manner in which the sampling unit closest to the current moment forwards first.

[0078] In order to better implement the present invention, further, if code 1 still appears after all the sampled signals are forwarded, repeated forwarding is performed.

[0079] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0080] 1) The integrated signal designed by the present invention not only has interference performance but also detection performance, which makes it possible for the system to develop towards miniaturization and integration;

[0081] 2) The present invention uses intermittent sampling and forwarding technology to realize amplitude coding modulation, divides the received large-time-width pulse compression signal into several short pulses with irregular pulse widths for transmission, hides the detection signal in the interference signal, misleads the other party into judging the detection signal as an interference signal, thereby reducing the interception probability and making it less likely to be detected. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 A schematic flow chart of the method of the present invention is provided;

[0083] Figure 2 It is the intermittent sampling and forwarding interference mechanism corresponding to pulse amplitude modulation;

[0084] Figure 3 is the R value of the initial and final populations after using the genetic algorithm;

[0085] Figure 4 is the fitness function curve of the genetic algorithm;

[0086] Figure 5 It is the optimal integrated waveform;

[0087] Figure 6 Doppler ambiguity function diagram for the integrated signal and the uniform intermittent sampling forwarding interference signal;

[0088] Figure 7 This is the time domain diagram of the integrated signal and the uniform intermittent sampling forwarding interference signal pulse compression. DETAILED DESCRIPTION

[0089] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. It should be understood that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, and therefore should not be regarded as limiting the scope of protection. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technical personnel in this field without making creative work are within the scope of protection of the present invention.

[0090] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0091] Example 1:

[0092] This embodiment proposes a detection and interference integrated waveform generation method based on intermittent sampling, which specifically includes the following steps:

[0093] Step 1: First, calculate the sidelobe peak ratio r1(t) and the ratio of the standard deviation of the pulse amplitude to the mean r2(t) of the Doppler ambiguity function; then, construct the objective function R(t) based on the sidelobe peak ratio r1(t) and the ratio of the standard deviation of the pulse amplitude to the mean r2(t) of the Doppler ambiguity function and the minimization criterion;

[0094] Step 2: Use the sampling genetic algorithm to solve the objective function R(t) and obtain the optimal amplitude coding method; finally, use the optimal amplitude coding method to generate an integrated waveform for detecting interference.

[0095] Working principle: The optimization model is established by combining the minimization criteria of the sidelobe peak ratio of the integrated signal Doppler ambiguity function and the ratio of the standard deviation of the amplitude after pulse compression to the mean, and the corresponding objective function is constructed; the objective function is solved by the genetic algorithm to obtain the optimal amplitude coding method. The ambiguity function can reflect the measurement accuracy as well as the distance and speed resolution, and is an effective tool for analyzing the detection performance of radar signals. The linear frequency modulation signal is insensitive to the Doppler frequency and has a high sidelobe peak. The process of integrated signal optimization design is to find the maximum value by changing the pulse amplitude coding sequence, while the genetic algorithm uses the coding of the decision variable as the operation object, the objective function value as the search information, and the fitness function to measure the individual's excellence. It has good global search performance, so the genetic algorithm is used to solve the objective function. The integrated waveform signal generated by the present invention has a certain detection function while interfering with the opponent's signal.

[0096] Example 2:

[0097] This embodiment is based on the above embodiment 1, and in order to better implement the present invention, further, as shown in FIG. Figure 1 As shown, the step 1 specifically includes the following steps:

[0098] Step 1.1: Construct the detection performance evaluation criteria: calculate the sidelobe peak ratio r1(t) of the Doppler ambiguity function;

[0099] Step 1.2: Construct the interference performance evaluation standard: calculate the ratio of the standard deviation of the pulse amplitude to the mean r2(t);

[0100] Step 1.3: Based on the sidelobe peak ratio r1(t) of the Doppler ambiguity function and the ratio of the standard deviation to the mean of the pulse amplitude r2(t), construct the objective function R(t) according to the minimization criterion.

[0101] In order to better implement the present invention, further, the specific operations of step 1.1 are:

[0102] Step 1.1.1: Define the fuzzy function χ of the integrated signal y(t) y (τ,ξ), the specific calculation formula is as follows:

[0103]

[0104] Where: τ is the time delay, ξ is the Doppler frequency, t is the time variable, is the conjugate operation of the signal y(t) after the time delay τ, e j2πζt is the Doppler frequency shift;

[0105] Step 1.1.2: For the fuzzy function χ y (τ,ξ) is transformed to obtain the Doppler ambiguity function χ of the integrated signal y (0,ξ), the specific formula is:

[0106]

[0107] Where, Conjugate operation of signal y(t);

[0108] Step 1.1.3: Calculate the sidelobe peak ratio r1(t) of the Doppler ambiguity function. The specific formula is:

[0109]

[0110] Where, ξ d The Doppler frequency corresponding to the sidelobe peak value;

[0111] The sidelobe peak ratio r1(t) is inversely correlated with the detection performance of the detection-interference integrated waveform, that is, the smaller the sidelobe peak ratio r1(t), the better the detection performance.

[0112] In order to better implement the present invention, further, the step 1.2 specifically includes the following steps:

[0113] Step 1.2.1: After the intermittent sampling and forwarding of the linear frequency modulation signal pulse compression, a certain number of false targets are generated. The system function h(t) of the matched filter of the integrated signal y(t) is set to:

[0114]

[0115] Where t0 is the constant that makes the system function h(t) a causal realizable system, and “-” represents conjugate calculation, so h(t) can be expressed as:

[0116]

[0117] s(t) is a linear frequency modulation signal, and the expression of s(t) is:

[0118]

[0119] Where, f c is the carrier frequency; is the frequency modulation slope; B is the signal bandwidth; T is the radar signal length; For a rectangular signal, the expression is:

[0120]

[0121] Step 1.2.2: Modulate the linear frequency modulation signal s(t) to obtain the integrated signal y(t). The expression of the integrated signal y(t) is:

[0122]

[0123] Where c(t) is the modulation signal, For the modulation operation:

[0124] Substitute the above integrated signal y(t) and system function h(t) into the integrated signal pulse pressure formula to calculate the calculated signal x(t), and we get:

[0125]

[0126] Where * is the convolution operation; μ is the amount of calculation introduced by the convolution formula;

[0127] Step 1.2.3: Calculate the ratio of the standard deviation of the amplitude of the integrated signal y(t) to the mean after pulse compression, r2(t), to measure the interference effect. The formula for calculating the ratio of the standard deviation of the amplitude of the integrated signal y(t) to the mean after pulse compression, r2(t), is as follows:

[0128]

[0129] Where, σ 2(·) is the variance operation, E(·) is the mean operation, and r2(t) is inversely correlated with the interference performance, that is, the smaller r2(t), the better the interference performance.

[0130] In order to better implement the present invention, further, the specific operations of step 1.3 are:

[0131] Construct the objective function R(t). The specific construction formula is as follows:

[0132]

[0133] Wherein, α1 and α2 are weighting coefficients, α1+α2=1.

[0134] In order to better implement the present invention, further, the step 2 specifically includes the following steps:

[0135] Step 2.1: Initialize the integrated waveform set;

[0136] Step 2.2: Use genetic algorithm to solve the objective function R(t) and obtain the optimal waveform individual;

[0137] Step 2.3: Select, cross, mutate, and update each individual in the population;

[0138] Step 2.4: Set the number of iterations and repeat steps 2.2 to 2.3. When the individuals in the population output by the nth iteration and the n-1th iteration are the same, find the optimal integrated waveform and exit the loop.

[0139] Step 2.5: Generate the optimal integrated waveform obtained by solution.

[0140] In order to better implement the present invention, further, the step 2.1 specifically includes the following steps:

[0141] Step 2.1.1: Define the integrated waveform set y n There are N individuals in total, and the number of code elements of the individual amplitude coding of each waveform is P, then the waveform individual of the nth amplitude coding modulation is expressed as:

[0142] y n =[y n (1),y n (2),...,y n (p),...,y n (P)];

[0143] Among them, 1≤n≤N, y n (p) is the short pulse corresponding to the p-th symbol of the integrated signal;

[0144] Step 2.1.2: Represent the binary amplitude-coded signal c(t) with a random sequence as follows:

[0145]

[0146] Where P represents the length of the random sequence, g(t) is the rectangular pulse signal, and the expression is: c k represents a random sequence, with a value of {0,1}; k is the kth code element of the random sequence; is a rectangular signal, T c represents the symbol period;

[0147] Step 2.1.3: In the binary sequence, I represents the number of consecutive 0s in each segment, and J represents the number of consecutive 1s in each segment. For the short pulse y corresponding to the pth code element of the nth individual in step 2.1.1, n (p), expressed as:

[0148]

[0149] c ip represents the pth binary sequence, which is located in the i-th sequence of the zero string I, i∈[1,2,...,I]; c jp represents the pth binary sequence, which is located in the jth of a string J, j∈[1,2,...,J]; s p (t) is the linear frequency modulation signal corresponding to the pth code element, and the formula is:

[0150] s p (t) = s(t)c(p);

[0151] The expression of s(t) is:

[0152]

[0153] Where, f c is the carrier frequency; is the frequency modulation slope; B is the signal bandwidth; T is the radar signal length; For a rectangular signal, the expression is:

[0154]

[0155] c(p)=c p g(t-pT c ),T c represents the symbol period, c p represents the pth code element, which has a value of 1; g(t) is a rectangular pulse signal, which is expressed as

[0156] In order to better implement the present invention, further, the specific operations of step 2.2 are as follows:

[0157] Step 2.2.1: Set the integrated waveform set y in step 2.1 n The N coded modulated waveforms in the GA are used as the initial population;

[0158] Step 2.2.2: Calculate the fitness function of each population Fitness function The calculation formula is:

[0159]

[0160] The rest of this embodiment is the same as that of the above-mentioned embodiment 1, and therefore will not be described in detail.

[0161] Example 3:

[0162] This embodiment is based on any one of the above embodiments 1-2, and in order to better implement the present invention, further, as follows Figure 2 As shown, the integrated waveform is obtained by modulating the LFM signal with a set of binary amplitude coded signals, which is manifested in the time domain as intermittent sampling and forwarding interference of the LFM signal;

[0163] Code 0 indicates sampling, and code 1 indicates forwarding. Follow the steps below to perform forwarding:

[0164] First, the minimum sampling time unit is fixed as τ;

[0165] Next, the first bit of the fixed binary sequence is coded 0, and the number of consecutive coded 1s is greater than or equal to the number of consecutive coded 0s;

[0166] Finally, forwarding is performed in a forwarding manner in which the sampling unit closest to the current moment forwards first.

[0167] In order to better implement the present invention, further, if code 1 still appears after all the sampled signals are forwarded, repeated forwarding is performed.

[0168] The rest of this embodiment is the same as any of the above embodiments 1-2, so it will not be repeated here.

[0169] Example 4:

[0170] This embodiment, based on any one of the above embodiments 1-3, provides an integrated waveform optimization method based on intermittent sampling, and the specific implementation steps are as follows:

[0171] Step 1.1: Construct detection performance evaluation criteria

[0172] The ambiguity function is an important tool for analyzing radar detection performance. The ambiguity function χ of the integrated signal y(t) is y (τ,ξ) can be defined as:

[0173]

[0174] In formula (1), τ is the time delay, ξ is the Doppler frequency; “-” is the conjugate operation, is the conjugate operation of the signal y(t) after the time delay τ, e j2πζt is the Doppler frequency shift.

[0175] The linear frequency modulation signal is not sensitive to Doppler frequency shift after pulse compression, and the sidelobe peak is high. It is advisable to take the Doppler sidelobe peak ratio as the part to be optimized and use it to measure the detection performance of the integrated signal. According to formula (1), the Doppler ambiguity function χ of the integrated signal can be obtained y (0,ξ) is:

[0176]

[0177] Therefore, the sidelobe peak ratio r1(t) of the Doppler ambiguity function is:

[0178]

[0179] In formula (3), ξ d is the Doppler frequency corresponding to the sidelobe peak, where the smaller r1(t) is, the better the detection performance is.

[0180] Simulation parameter settings: delay is 0, Doppler frequency ξ range is -2.5~2.5MHz, main lobe peak is χ y The maximum value of (0,ξ), the sidelobe peak χ y (0,ξ d ) is to first find all the maximum points χ except the main lobe peak y (0,ξ i ), the maximum point satisfies χ y (0,ξ i -Δ)<χ y (0,ξ i )<χ y (0,ξ i +Δ), Δ is infinitesimal, and then the maximum value is found from all the maximum values, which is the sidelobe peak value χ y (0,ξ d ).

[0181] Step 1.2: Construct interference performance evaluation criteria

[0182] After intermittent sampling and forwarding, the linear frequency modulation signal pulse compression will produce a certain number of false targets. The system function of the integrated signal y(t) matched filter is:

[0183]

[0184] t0 is a constant that makes it a causal realizable system, which can be set to t0 = 0. “-” represents conjugate calculation, and s(t) is a linear frequency modulation signal. The expression is:

[0185]

[0186] In formula (5), is a rectangular signal, and the expression is f c is the carrier frequency; is the frequency modulation slope; B is the signal bandwidth; T is the radar signal length.

[0187] The simulation parameters are set as follows: radar signal length 20 μs, carrier frequency 0, signal bandwidth 10 MHz, sampling frequency 40 MHz, frequency modulation slope 5×10 11 Hz / s.

[0188] Therefore, the expression of h(t) is:

[0189]

[0190] The integrated signal y(t) is converted into pulsed output x(t):

[0191]

[0192] Where c(t) is the modulation signal, For modulation operation

[0193] The more false targets there are and the higher the amplitude is, the better the jamming effect is. Therefore, the ratio of the standard deviation of the signal amplitude to the mean after integrated signal pulse compression, r2(t), is used to measure the jamming effect. r2(t) is calculated as follows:

[0194]

[0195] In formula (8), σ 2 (·) is the variance operation, E(·) is the mean operation, and the smaller r2(t), the better the interference performance.

[0196] Step 3: Constructing the performance evaluation standard for integrated detection and interference signal

[0197] In order to achieve both detection and jamming performance, according to steps one and two, the smaller r1(t) and r2(t) are, the better. Therefore, the objective function R(t) is constructed as follows:

[0198]

[0199] Among them, α1 and α2 are weighting coefficients, and α1+α2=1.

[0200] Simulation parameter setting: After multiple calculations, we can get r2(t) is about 5 times of r1(t).

[0201] The rest of this embodiment is the same as any of the above embodiments 1-3, so it will not be repeated here.

[0202] Example 5:

[0203] This embodiment is based on any one of the above embodiments 1-4, and for the integrated waveform design method, the specific implementation steps are as follows:

[0204] Step 2.1: Initialize the integrated waveform set

[0205] There are N individuals in the integrated waveform set, and the number of code elements of amplitude coding of each waveform individual is P. Then the waveform individual of amplitude coding modulation of the nth waveform can be expressed as:

[0206] y n =[y n (1),y n (2),...,y n (p),...,y n (P)] (10)

[0207] In formula (10), 1≤n≤N, where y n (p) is the short pulse corresponding to the pth code element of the integrated signal. Among them, the binary amplitude coded signal can be expressed as a random sequence:

[0208]

[0209] In formula (11), P represents the length of the random sequence, T c Represents the code element period, g(t) is a rectangular pulse signal, and the expression is c k Represents a random sequence with a value of {0,1}.

[0210] In the binary sequence, I represents the number of consecutive 0s in each segment, and J represents the number of consecutive 1s in each segment. Figure 2 As shown, therefore, in formula (10), the short pulse y corresponding to the p-th code element of the n-th individual n (p) can be expressed as:

[0211]

[0212] In formula (12), c ip represents the pth binary sequence, which is located in the i-th sequence of the zero string I, i∈[1,2,...,I]; c jp represents the pth binary sequence, which is located in the jth position in a string J, j∈[1,2,...,J]. p (t) is the linear frequency modulation signal corresponding to the pth code element, and the formula is:

[0213] s p (t)=s(t)c(p) (13)

[0214] In formula (13), the linear frequency modulation signal s(t) is the same as formula (5), c(p) = c p g(t-pT c ),T c Represents the code element period, g(t) is a rectangular pulse signal, and the expression is c p Represents the pth code element and its value is 1.

[0215] Simulation parameter settings: sequence length P is 40, symbol period T c The minimum sampling time unit τ is 500 ns, and the other parameter settings are the same as step 2 in the integrated waveform optimization method.

[0216] Step 2.2: Use the genetic algorithm to find the optimal waveform individual. The steps are as follows:

[0217] Step 2.2.1: Use the N coded modulated waveform individuals in the set in step 1 as the initial population in the genetic algorithm, and set the population size N to 40;

[0218] Step 2.2.2: Calculate the fitness function of each population. The fitness function calculation formula is:

[0219]

[0220] That is, the smaller the objective function R(t), the larger the fitness function.

[0221] Step 2.3: Select, crossover, mutate, and update each individual in the population. The roulette wheel algorithm is used for selection, with the selection probability set to 0.5, the crossover rate to 0.8, and the mutation rate to 0.001.

[0222] Step 2.4: Set the number of iterations and repeat steps 22 to 23. When the individuals in the population output by the nth iteration and the n-1th iteration are the same, it means that the optimal integrated waveform has been solved and the loop is exited.

[0223] The rest of this embodiment is the same as any of the above embodiments 1-4, so it will not be repeated here.

[0224] Example 6:

[0225] This example verifies the effectiveness of the method of the present invention based on any one of the above examples 1-5 as follows:

[0226] Figure 3 The values ​​of the objective function R(t) of the 40 initial populations, that is, the integrated waveform, are shown. It can be seen that the final integrated waveform objective function reaches the minimum value.

[0227] Figure 4 It shows that the final fitness function converges, that is, the optimal solution is found.

[0228] Figure 5 Schematic diagram of the optimal integrated waveform.

[0229] Figure 6 This is a comparison diagram of the Doppler ambiguity function between the optimized integrated waveform and the uniform intermittent sampling forwarding interference. It can be seen that the sidelobe peak of the optimized integrated signal is significantly reduced and the detection performance is improved.

[0230] Figure 7 This is the time domain diagram of the optimized integrated signal and the uniform intermittent sampling signal after pulse compression. It can be seen that the number of false targets increases and the amplitude increases after the integrated signal pulse compression, and the interference performance is improved.

[0231] Working Principle: In summary, the method described in this invention first establishes an optimization model based on the combined minimization criteria of the sidelobe peak ratio of the Doppler ambiguity function of the integrated signal and the ratio of the standard deviation to the mean of the pulse compression amplitude, constructing the corresponding objective function. A genetic algorithm is then used to solve the objective function and obtain the optimal amplitude coding scheme. This method designs an integrated signal that combines interference performance with detection performance, saving system local oscillators and opening up new possibilities for system miniaturization and integrated development.

[0232] The rest of this embodiment is the same as any of the above embodiments 1-5, so it will not be repeated here.

[0233] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A detection and interference integrated waveform generation method based on intermittent sampling, characterized in that: The specific steps include: Step 1: First, calculate the sidelobe peak ratio r1(t) and the ratio of the standard deviation of the amplitude after pulse compression to the mean r2(t) of the Doppler ambiguity function; then, construct the objective function R(t) based on the sidelobe peak ratio r1(t) and the ratio of the standard deviation of the amplitude after pulse compression to the mean r2(t) of the Doppler ambiguity function and the minimization criterion; Step 2: The sampling genetic algorithm is used to solve the objective function R(t) and obtain the optimal amplitude coding method; finally, the optimal amplitude coding method is used to generate an integrated waveform for detecting interference.

2. The method for generating an integrated detection and interference waveform based on intermittent sampling according to claim 1, characterized in that: The step 1 specifically comprises the following steps: Step 1.1: Construct the detection performance evaluation criteria: calculate the sidelobe peak ratio r1(t) of the Doppler ambiguity function; Step 1.2: Construct the interference performance evaluation standard: calculate the ratio of the standard deviation of the pulse pressure amplitude to the mean value r2(t); Step 1.3: Based on the sidelobe peak ratio r1(t) of the Doppler ambiguity function and the ratio of the standard deviation to the mean of the pulse amplitude after compression r2(t), the objective function R(t) is constructed according to the minimization criterion.

3. The method for generating an integrated detection and interference waveform based on intermittent sampling according to claim 2, characterized in that: The specific operations of step 1.1 are: Step 1.1.1: Define the fuzzy function χ of the integrated signal y(t) y (τ,ξ), the specific calculation formula is as follows: Where: τ is the time delay, ξ is the Doppler frequency, t is the time variable, is the conjugate operation of the signal y(t) after the delay τ, e j2πζt is the Doppler frequency shift; Step 1.1.2: For the fuzzy function χ y (τ,ξ) is transformed to obtain the Doppler ambiguity function χ of the integrated signal y (0,ξ), the specific formula is: In the formula, Conjugate operation of signal y(t); Step 1.1.3: Calculate the sidelobe peak ratio r1(t) of the Doppler ambiguity function. The specific formula is: In the formula, ξ d The Doppler frequency corresponding to the peak value of the side lobe; The sidelobe peak ratio r1(t) is inversely correlated with the detection performance of the detection-interference integrated waveform, that is, the smaller the sidelobe peak ratio r1(t), the better the detection performance.

4. The method for generating an integrated detection and interference waveform based on intermittent sampling according to claim 2, characterized in that: The step 1.2 specifically includes the following steps: Step 1.2.1: After the intermittent sampling and forwarding of the linear frequency modulation signal pulse compression, a certain number of false targets are generated, and the system function h(t) of the integrated signal y(t) matching filter is set to: Where t0 is a constant that makes the system function h(t) a causal realizable system, and the superscript "-" represents conjugate calculation, so the system function h(t) is also expressed as: s(t) is a linear frequency modulation signal, and the expression of s(t) is: In the formula, f c is the carrier frequency; is the frequency modulation slope; B is the signal bandwidth; T is the radar signal length; For a rectangular signal, the expression is: Step 1.2.2: Modulate the linear frequency modulation signal s(t) to obtain the integrated signal y(t). The expression of the integrated signal y(t) is: Where c(t) is the modulation signal, For the modulation operation: Substitute the above integrated signal y(t) and system function h(t) into the integrated signal pulse pressure formula to calculate the calculated signal x(t), and we get: In the formula, * is the convolution operation; Step 1.2.3: Calculate the ratio of the standard deviation of the amplitude of the integrated signal y(t) after pulse compression to the mean r2(t) to measure the interference effect. The calculation formula of the ratio of the standard deviation of the amplitude after pulse compression to the mean r2(t) is as follows: In the formula, σ 2 (·) is the variance operation, E(·) is the mean operation, r2(t) is inversely correlated with the interference performance, that is, the smaller r2(t) is, the better the interference performance is.

5. A detection and interference integrated waveform generation method based on intermittent sampling as described in claim 2, 3 or 4, characterized in that: The specific operation of step 1.3 is: Construct the objective function R(t), the specific construction formula is as follows: In the formula, α1 and α2 are weighting coefficients, α1+α2=1.

6. The method for generating an integrated detection and interference waveform based on intermittent sampling according to claim 1, characterized in that: The step 2 specifically includes the following steps: Step 2.1: Initialize the integrated waveform set; Step 2.2: Use genetic algorithm to solve the objective function R(t) and obtain the optimal waveform individual; Step 2.3: Select, crossover, mutate, and update each individual in the population; Step 2.4: Set the number of iterations, and execute steps 2.2 to 2.3 in a loop. When the individuals in the population output by the nth iteration and the n-1th iteration are the same, find the optimal integrated waveform and exit the loop. Step 2.5: Generate the optimal integrated waveform obtained by solution.

7. The method for generating an integrated detection and interference waveform based on intermittent sampling according to claim 6, characterized in that: The step 2.1 specifically includes the following steps: Step 2.1.1: Define the integrated waveform set y n There are N individuals in total, and the number of code elements of the individual amplitude coding of each waveform is P, then the waveform individual of the nth amplitude coded modulation is expressed as: and n =[and n (1),and n (2),...,and n (p),...,and n (P)]; Among them, 1≤n≤N, y n (p) is the short pulse corresponding to the pth code element of the integrated signal; Step 2.1.2: Represent the binary amplitude coded signal c(t) with a random sequence as follows: In the formula, P represents the length of the random sequence, g(t) is the rectangular pulse signal, and the expression is c k represents a random sequence, with a value of {0,1}; k is the kth code element in the random sequence; is a rectangular signal, T c represents the symbol period; Step 2.1.3: In the binary sequence, I represents the number of consecutive 0s in each short segment, and J represents the number of consecutive 1s in each short segment. For the short pulse y corresponding to the pth code element of the nth individual in step 2.1.1, n (p), expressed as: c ip represents the pth binary sequence, which is located in the i-th sequence of the continuous zero string I, i∈[1,2,...,I]; c jp represents the p-th binary sequence, which is located in the j-th sequence of 1 string J, j∈[1,2,...,J]; s p (t) is the linear frequency modulation signal corresponding to the pth code element, and the formula is: s p (t)=s(t)c(p); The expression of s(t) is: In the formula, f c is the carrier frequency; is the frequency modulation slope; B is the signal bandwidth; T is the radar signal length; For a rectangular signal, the expression is: c(p)=c p g(t-pT c ),T c represents the symbol period, c p represents the pth code element, and its value is 1; g(t) is a rectangular pulse signal, and its expression is 8. The method for generating an integrated detection and interference waveform based on intermittent sampling according to claim 7, characterized in that: The specific operations of step 2.2 are: Step 2.2.1: Set the integrated waveform set y in step 2.1 n The N coded modulated waveforms in the GA are used as the initial population; Step 2.2.2: Calculate the fitness function of each population Fitness function The calculation formula is:

9. The method for generating an integrated detection and interference waveform based on intermittent sampling according to claim 7, characterized in that: The integrated waveform is obtained by modulating the LFM signal with a set of binary amplitude coded signals, and in the time domain, it is manifested as intermittent sampling and forwarding interference of the LFM signal; Code 0 indicates sampling, and code 1 indicates forwarding; Follow the steps below to forward: First, the minimum sampling time unit is fixed as τ; Next, the first bit of the fixed binary sequence is coded 0, and the number of consecutive coded 1s is greater than or equal to the number of consecutive coded 0s; Finally, forwarding is performed in a forwarding manner in which the sampling unit closest to the current moment forwards first.

10. The method for generating an integrated detection and interference waveform based on intermittent sampling according to claim 9, characterized in that: If code 1 still appears after all sampled signals have been forwarded, repeat the forwarding.

Images