A joint optimization radar waveform design method based on double mutual information

Abstract

The application discloses a kind of based on double mutual information's joint optimization radar waveform design method, comprising: radar signal is transmitted to detection environment, and receive the radar echo signal reflected by detection environment;Radar echo signal includes: pure clutter data and target plus clutter data;According to pure clutter data and target plus clutter data respectively determine the average power spectrum of clutter and the power spectrum of target;According to the preset distribution of the power spectrum of color noise, the preset frequency point quantity, the preset total energy, the radar system operating bandwidth, the average power spectrum of clutter and the power spectrum of target, respectively determine the maximum signal-to-clutter-noise ratio criterion under radar's transmission waveform energy spectrum and the maximum signal-to-clutter-noise ratio criterion under radar's transmission waveform energy spectrum;By preset weighted fusion value, the maximum signal-to-clutter-noise ratio criterion under radar's transmission waveform energy spectrum and the maximum signal-to-clutter-noise ratio criterion under radar's transmission waveform energy spectrum are weighted and fused, and the maximum signal-to-clutter-noise ratio criterion under radar's transmission waveform energy spectrum is obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of radars, and particularly relates to a joint optimization radar waveform design method based on double mutual information. BACKGROUND

[0002] With the complication of today's electromagnetic environment, only the adaptive processing of the receiving end of the radar system has gradually reached the performance bottleneck of the radar, and how to reasonably utilize the transmitting end of the radar system to design the transmitting waveform and improve the adaptability of the system to the external environment has gradually become a research hotspot of modern intelligent radars. Compared with the traditional radar, the closed-loop processing capability of the cognitive radar can adaptively design the transmitting waveform matched with the target and the environment according to the information, so as to realize the improvement of the radar system performance. When the radar is in the traditional working mode, the transmitting waveform and the transmitting-receiving mode of the radar system are relatively constant, and at this time, the radar system is in the open-loop working mode, lacks the cognitive ability to the environment, and is difficult to utilize the freedom of the transmitting end to realize the improvement of the working performance of the radar system. The acquisition of the environmental information has a great influence on the detection performance of the adaptive radar system, and we can reduce the influence on the radar system when facing different working environments through the waveform design of the radar transmitting end, so as to improve the output signal-to-clutter-and-noise ratio and the mutual information of the radar system and realize the improvement of the working performance of the radar system.

[0003] In recent years, the radar transmitting waveform energy spectrum design method in the clutter background is usually to acquire the target and environmental information, and then adopt the corresponding waveform optimization design criterion to optimize the transmitting waveform of the transmitting end. How to design the transmitting waveform matched with the environment is the core of the waveform design of the cognitive radar system. The traditional maximum signal-to-clutter-and-noise ratio criterion and the maximum mutual information criterion can only optimize from the dimensions of improving the system output signal-to-clutter-and-noise ratio or improving the target information mutual information in the received echo. At this time, the optimization mode and index are relatively single, so in recent years, many scholars and researchers have composed the traditional joint optimization criterion according to the two optimization criteria of the signal-to-clutter-and-noise ratio and the mutual information to realize the waveform optimization demand of the radar system when performing different tasks.

[0004] However, from the perspective of the demand of the multi-functional radar system performing different working tasks, the traditional radar waveform joint optimization criterion is determined according to the maximum signal-to-clutter-and-noise ratio criterion and the maximum mutual information criterion, but when the radar system performs the target detection task, the output signal-to-clutter-and-noise ratio of the transmitting waveform designed by the traditional joint optimization criterion still has the space for improvement, and at this time, the performance of the radar system in performing the target detection task is poor, and there is the problem of low target detection probability. SUMMARY

[0005] In order to solve the above problems existing in the related art, the present application provides a joint optimization radar waveform design method based on double mutual information.

[0006] The present application provides a joint optimization radar waveform design method based on double mutual information, comprising:

[0007] The radar signal is transmitted to the detection environment, and the radar echo signal reflected by the detection environment is received; the radar echo signal comprises pure clutter data and target plus clutter data;

[0008] The average power spectrum of the clutter and the power spectrum of the target are determined according to the pure clutter data and the target plus clutter data, respectively;

[0009] The transmit waveform energy spectrum of the radar under the maximum signal-to-clutter ratio criterion and the transmit waveform energy spectrum of the radar under the double mutual information criterion are determined according to the preset distribution of the power spectrum of the color noise, the preset frequency point number, the preset total energy, the radar system operating bandwidth, the average power spectrum of the clutter and the power spectrum of the target, respectively;

[0010] The transmit waveform energy spectrum of the radar under the maximum signal-to-clutter ratio criterion and the transmit waveform energy spectrum of the radar under the double mutual information criterion are fused by a preset weighting fusion value to obtain the transmit waveform energy spectrum of the radar optimized by the double mutual information; the preset weighting fusion value is used to adjust the transmit waveform of the radar to the transmit waveform under a specific radar task.

[0011] In some embodiments, the determination of the transmit waveform energy spectrum of the radar under the maximum signal-to-clutter ratio criterion and the transmit waveform energy spectrum of the radar under the double mutual information criterion according to the preset distribution of the power spectrum of the color noise, the preset frequency point number, the preset total energy, the average power spectrum of the clutter and the power spectrum of the target comprises:

[0012] The transmit waveform energy spectrum of the radar under the maximum signal-to-clutter ratio criterion at each frequency point is solved by a maximum edge distribution algorithm according to the preset distribution of the power spectrum of the color noise, the preset frequency point number, the preset total energy, the radar system operating bandwidth, the average power spectrum of the clutter, the power spectrum of the target, a first optimization target function and a preset operation number;

[0013] The transmit waveform energy spectrum of the radar under the double mutual information criterion at each frequency point is solved by a maximum edge distribution algorithm according to the preset distribution of the power spectrum of the color noise, the preset frequency point number, the preset total energy, the radar system operating bandwidth, the average power spectrum of the clutter, the power spectrum of the target, a second optimization target function and a preset operation number.

[0014] In some embodiments, the first optimization target function is:

[0015] Where K is the number of frequency points, k = 1, 2, ..., K, |H(f k )| 2 Let P be the power spectrum at the k-th frequency point in the power spectrum of the target. c (f k P represents the power spectrum at the k-th frequency point in the average power spectrum of the clutter. n (f k Let be the power spectrum at the k-th frequency point in the preset distribution of the power spectrum of the colored noise. B is the operating bandwidth of the radar system. E s Let u1(k) be the preset total energy, and u1(k) be the energy spectrum of the radar's transmitted waveform at the k-th frequency point under the maximum signal-to-clutter-to-noise ratio criterion.

[0016] In some embodiments, the second optimization objective function is:

[0017] Where K is the number of frequency points, k = 1, 2, ..., K, |H(f k )| 2 Let P be the power spectrum at the k-th frequency point in the power spectrum of the target. c (f k P represents the power spectrum at the k-th frequency point in the average power spectrum of the clutter. n (f k Let be the power spectrum at the k-th frequency point in the preset distribution of the power spectrum of the colored noise. B is the operating bandwidth of the radar system. E s Let u2(k) be the preset total energy, u2(k) be the energy spectrum of the radar's transmitted waveform at the k-th frequency point under the dual mutual information criterion, and ln(.) be the logarithmic function with base e.

[0018] In some embodiments, the step of weightedly fusing the transmitted waveform energy spectrum of the radar under the maximum signal-to-clutter-noise ratio criterion and the transmitted waveform energy spectrum of the radar under the dual mutual information criterion with a preset weighted fusion value to obtain the transmitted waveform energy spectrum of the radar jointly optimized by dual mutual information includes:

[0019] The product value between the preset weighted fusion value and the energy spectrum of the radar's transmitted waveform under the maximum signal-to-clutter-to-noise ratio criterion is determined to obtain the first product value;

[0020] The absolute value of the difference between the preset weighted fusion value and 1 is determined, and the product value between the absolute value of the difference and the energy spectrum of the radar's transmitted waveform under the dual mutual information criterion is determined to obtain the second product value.

[0021] The sum of the first product value and the second product value is used as the transmission waveform energy spectrum of the double mutual information jointly optimized radar.

[0022] In some embodiments, the expression of the transmission waveform energy spectrum of the kth frequency point in the transmission waveform energy spectrum of the double mutual information jointly optimized radar is:

[0023] U(k) = ηu1(k) + (1-η)u2(k);

[0024] wherein k = 1, 2,..., K, K is the number of frequency points, U(k) is the transmission waveform energy spectrum amplitude of the kth frequency point in the transmission waveform energy spectrum of the double mutual information jointly optimized radar, η is the preset weighted fusion value, u1(k) is the transmission waveform energy spectrum of the radar at the kth frequency point under the maximum signal-to-clutter ratio criterion, and u2(k) is the transmission waveform energy spectrum of the radar at the kth frequency point under the double mutual information criterion.

[0025] In some embodiments, the average power spectrum of the clutter and the power spectrum of the target are determined according to the pure clutter data and the target plus clutter data, respectively, including:

[0026] performing short-time Fourier transform on the pure clutter data to obtain the average power spectrum of the clutter;

[0027] performing short-time Fourier transform on the target plus clutter data to obtain the power spectrum of the target.

[0028] The present application has the following beneficial technical effects:

[0029] The present application uses the pulse response of the target to construct the mutual information criterion, and also uses the obtained clutter information to construct the double mutual information criterion, and performs weighted fusion on the maximum signal-to-clutter ratio criterion and the double mutual information criterion, thereby solving the problem of single optimization mode of the conventional waveform design criterion based on the signal-to-clutter ratio and the mutual information, and the demand for waveform optimization design of the radar system when performing different working tasks can be realized by adjusting the weighted factor (preset weighted fusion value) of the double mutual information criterion and the signal-to-clutter ratio criterion, and the output signal-to-clutter ratio of the radar system is further optimized, thereby improving the target detection performance of the radar system.

[0030] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 a flowchart of the double mutual information based joint optimization radar waveform design method provided by the embodiments of the present application;

[0032] Figure 2An exemplary radar transmit-receive schematic diagram provided by the embodiment of the present application in the case of extending the target model and considering clutter and color noise;

[0033] Figure 3A An exemplary average power spectrum of the simulated clutter, power spectrum of the target and color noise power spectrum provided by the embodiment of the present application;

[0034] Figure 3B An exemplary energy spectrum comparison schematic diagram of the joint optimization radar waveform design method based on the double mutual information of the present application and the traditional joint optimization criterion and the mutual information criterion;

[0035] Figure 3C An exemplary signal-to-clutter-and-noise ratio change with the transmission power schematic diagram of the joint optimization radar waveform design method based on the double mutual information of the present application and the traditional joint optimization criterion and the mutual information criterion;

[0036] Figure 3D An exemplary signal-to-clutter-and-noise ratio change with the clutter intensity schematic diagram of the joint optimization radar waveform design method based on the double mutual information of the present application and the traditional joint optimization criterion and the mutual information criterion;

[0037] Figure 4A An exemplary physical diagram of the corner reflector target provided by the embodiment of the present application;

[0038] Figure 4B An exemplary measured echo data schematic diagram of the corner reflector provided by the embodiment of the present application;

[0039] Figure 4C An exemplary average power spectrum of the clutter schematic diagram provided by the embodiment of the present application;

[0040] Figure 4D An exemplary power spectrum schematic diagram of the corner reflector provided by the embodiment of the present application;

[0041] Figure 5A An exemplary energy spectrum comparison schematic diagram of the joint optimization radar waveform design method based on the double mutual information of the present application and the traditional joint optimization criterion and the linear frequency modulation signal;

[0042] Figure 5B An exemplary signal-to-clutter-and-noise ratio change with the transmission power schematic diagram of the joint optimization radar waveform design method based on the double mutual information of the present application and the traditional joint optimization criterion and the linear frequency modulation signal;

[0043] Figure 6A An exemplary physical diagram of the radar vehicle target provided by the embodiment of the present application;

[0044] Figure 6B A measured echo data diagram of an exemplary radar vehicle provided for an embodiment of the present application;

[0045] Figure 6C Another diagram of an exemplary average power spectrum of clutter provided for an embodiment of the present application;

[0046] Figure 6D A power spectrum diagram of an exemplary radar vehicle provided for an embodiment of the present application;

[0047] Figure 7A Another comparative diagram of an exemplary joint optimization radar waveform design method based on dual mutual information provided for an embodiment of the present application and a conventional joint optimization criterion and an energy spectrum of a linear frequency modulation signal;

[0048] Figure 7B Another diagram of an exemplary change of a signal-to-clutter-plus-noise ratio with respect to a transmission power of a joint optimization radar waveform design method based on dual mutual information provided for an embodiment of the present application and a conventional joint optimization criterion and a linear frequency modulation signal. DETAILED DESCRIPTION

[0049] The present application will be further described below in connection with specific embodiments, but the embodiments of the present application are not limited thereto.

[0050] In the description of the present application, the terms "first", "second", "third", etc. are used only to describe various features, and are not to be construed as indicating or implying relative importance or a specific order of the features indicated. Thus, features limited to "first", "second" or "third" can explicitly or implicitly include one or more of the features. In the description of the present application, the term "a plurality of" means two or more, unless otherwise specifically limited.

[0051] In the description of the present application, the description referring to the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the description of the present application, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, a person skilled in the art can combine and integrate different embodiments or examples described in the present specification.

[0052] Although the application has been described in connection with various embodiments thereof, modifications and / or additions, which are within the scope of the application may occur to those skilled in the art. For example, features of the disclosed embodiments can be combined in an alternate manner, except where mutually exclusive. Where the disclosure is consistent with the prior art except for an explicitly different teaching, the present application is not to be construed as providing an industrial applicable disclosure. Terms such as "comprising", "including", "containing", etc. do not exclude the presence of elements or steps other than those listed in a claim. Individual features of the application may be created and provided by an individual device, unit, apparatus, machine, etc. depending on the particular usage. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to an advantage.

[0053] Figure 1 is a flow chart of a joint optimization radar waveform design method based on double mutual information provided by an embodiment of the application, as shown in Figure 1 , the method comprises the following steps:

[0054] S101, transmitting a radar signal to a detection environment, and receiving a radar echo signal reflected by the detection environment; the radar echo signal comprises pure clutter data and target plus clutter data.

[0055] Here, the radar transmitter can be used to transmit signals to the detection environment, and the radar receiver can be used to receive echo data reflected by the detection environment, obtain radar echo data, and the radar echo data is divided into pure clutter data and echo data containing targets (i.e. target plus clutter data), wherein the pure clutter data mainly includes ground clutter data.

[0056] S102, determining the average power spectrum of the clutter and the power spectrum of the target according to the pure clutter data and the target plus clutter data respectively.

[0057] Here, the pure clutter data can be subjected to short-time Fourier transform to obtain the average power spectrum P c (f) of the clutter, and the target plus clutter data can be subjected to short-time Fourier transform to obtain the power spectrum |H(f k )| 2 .

[0058] S103, determining the transmit waveform energy spectrum of the radar under the maximum signal-to-clutter ratio criterion and the transmit waveform energy spectrum of the radar under the double mutual information criterion according to the preset distribution of the power spectrum of the colored noise, the preset number of frequency points, the preset total energy, the average power spectrum of the clutter and the power spectrum of the target.

[0059] Here, the preset distribution of the power spectrum P n (f) of the colored noise, the preset number of frequency points K, the preset total energy E s , the working bandwidth B of the radar system, the average power spectrum P c (f) of the clutter and the power spectrum |H(fk 2 , the first optimization objective function and a preset operation number M, a transmit waveform energy spectrum u1(k) of the radar at each frequency point under a maximum signal-to-clutter-noise ratio criterion is solved by a maximum edge allocation algorithm; and according to a preset distribution of a power spectrum of the color noise, the preset frequency point number K, a preset total energy E s , the radar system operating bandwidth B, an average power spectrum P c (f) of the clutter k 2 , the second optimization objective function and a preset operation number M, a transmit waveform energy spectrum u2(k) of the radar at each frequency point under a double mutual information criterion is solved by the maximum edge allocation algorithm.

[0060] Specifically, the preset distribution to which the power spectrum of the color noise conforms can be a Gaussian distribution or other distributions, and no limitation is made in this regard.

[0061] Specifically, the first optimization objective function is: wherein k = 1, 2, …, K, |H(f k 2 is a power spectrum at the kth frequency point in the power spectrum of the target, P c (f k ) is a power spectrum at the kth frequency point in the average power spectrum of the clutter, P n (f k ) is a power spectrum at the kth frequency point in the preset distribution of the power spectrum of the color noise, u1(k) is a transmit waveform energy spectrum of the radar at the kth frequency point under the maximum signal-to-clutter-noise ratio criterion.

[0062] Here, |H(f k 2 , P n (f k ), P c (f k ) and E s can be substituted into the first optimization objective function, after which the maximum edge allocation algorithm is adopted to solve u1(k), and the solving problem is actually a process of maximizing under the constraint that the total energy E is constant, when solving u1(k), u max is discretized and divided into M parts, MΔ = u max , Δ is a unit energy of energy allocation, the value set of u1(k) is {0, Δ, 2Δ, …, MΔ}, and u1(k) is finally solved to obtain.

[0063] Specifically, the second optimization objective function is: ​​​​Wherein, u2(k) is the transmit waveform energy spectrum of the radar under the double mutual information criterion at the kth frequency point, and ln(.) is a logarithmic function with e as the base.

[0064] Here, |H(f k )| 2 , P n (f k ), P c (f k ) and E s can also be substituted into the second optimization objective function, after which the maximum edge allocation algorithm is used to solve u2(k), and in solving u2(k), u2(k) is discretized and divided into M parts, MΔ=u2(k), Δ being the unit energy of energy allocation, and the value set of u2(k) being {0, Δ, 2Δ,..., MΔ}. Finally, u2(k) is obtained by solving.

[0065] S104, the transmit waveform energy spectrum of the radar under the maximum signal-to-clutter-noise ratio criterion and the transmit waveform energy spectrum of the radar under the double mutual information criterion are weighted and fused by a preset weighted fusion value to obtain the transmit waveform energy spectrum of the radar under the double mutual information joint optimization; the preset weighted fusion value is used to adjust the transmit waveform of the radar to the transmit waveform under a specific radar task.

[0066] Here, the product value between the preset weighted fusion value and the transmit waveform energy spectrum of the radar under the maximum signal-to-clutter-noise ratio criterion can be determined to obtain a first product value; the absolute value of the difference between the preset weighted fusion value and 1 is determined, and the product value between the absolute value of the difference and the transmit waveform energy spectrum of the radar under the double mutual information criterion is determined to obtain a second product value; the sum of the first product value and the second product value is taken as the transmit waveform energy spectrum of the radar under the double mutual information joint optimization.

[0067] Specifically, the expression of the transmit waveform energy spectrum of the kth frequency point in the transmit waveform energy spectrum of the radar under the double mutual information joint optimization is: U(k)=ηu1(k)+(1-η)u2(k); U(k) is the amplitude of the transmit waveform energy spectrum of the kth frequency point in the transmit waveform energy spectrum of the radar under the double mutual information joint optimization, η is the preset weighted fusion value, u1(k) is the transmit waveform energy spectrum of the radar under the maximum signal-to-clutter-noise ratio criterion at the kth frequency point, and u2(k) is the transmit waveform energy spectrum of the radar under the double mutual information criterion at the kth frequency point.

[0068] The derivation process of the above first optimization objective function and second optimization objective function is described as follows:

[0069] 1. Constructing the signal-to-clutter-noise ratio criterion

[0070] When the radar resolution is high enough, the target can be modeled as an extended target model, and when there are targets with power spectrum density Pn The colored noise and power spectral density of (f) are P c (f) In the case of clutter, the radar transmit-receive schematic diagram is as follows: Figure 2 As shown. Figure 2 In this diagram, s(t) represents the radar's transmitted signal, x(t) represents the received echo signal before passing through the matched filter r(t), c(t) represents the system impulse response to clutter, and n(t) represents the system's colored noise. h (t) is s(t)*h(t), x c (t) represents s(t)*c(t), r(t) represents the matched filter, y(t) represents the received radar echo signal, and h(t) represents the target's system impulse response. From the perspective of the scattering centers, the target's impulse response is the set of transfer functions of each scattering center. These scattering centers are distributed along the range dimension. Taking the target impulse response as an example, assuming the phase and target response amplitude are known, h(t) can be expressed as: L is the number of possible target scattering centers in the set of scattering centers, and t i and a i Let represent the time delay and amplitude of the i-th target scattering center, respectively, and δ(·) represent the impulse function. Then, after passing through the matched filter at the radar receiver, the relationship between the radar transmitted waveform and the output signal-to-clutter ratio is: Where, |S(f)| 2 This represents the frequency domain form of s(t) after Fourier transform, thus the expression for the maximum signal-to-noise ratio criterion can be obtained as follows:

[0071] 2. Constructing a mutual information criterion

[0072] Depend on Figure 2 It can be seen that the received echo signal before passing through the matched filter r(t) can be expressed as: x(t) = s(t)*h(t) + s(t)*c(t) + n(t). It is known that the received echo signal at this point contains both target information related terms s(t)*h(t) and clutter information related terms s(t)*c(t). To improve the detection performance of the radar system, this can be achieved by increasing the system's output signal-to-clutter ratio (SNR). Ideally, the received echo signal should contain sufficient target information while minimizing clutter information, thereby improving the radar system's target detection performance. Therefore, the mutual information between the received echo signal and the target can be maximized while minimizing the mutual information between the received echo signal and clutter. The optimization criterion is: This expression can be equivalent to: In the formula, I H(·) represents the mutual information between the received echo signal and the target impulse response, I C (·) represents the mutual information between the received echo signal and the clutter impulse response. At this time, the information entropy of the echo Y is where, represents the variance of x h (t), represents the variance of the clutter signal, represents the variance of the color noise; at the same time, the conditional entropy H(Y|C) can be represented as: where C represents the information amount when the clutter signal is known, so there is the expression: I(Y;C) represents the information amount of the target obtained by real-time detection. In the current case, the mutual information between the received echo and the clutter signal of the radar system is: In addition, Therefore, the waveform optimization expression of the double mutual information criterion is:

[0073] 3. Linearly weighted fusion of the double mutual information criterion and the signal-to-clutter ratio criterion

[0074] In order to improve the output signal-to-clutter ratio and mutual information of the radar system, the method combines the maximum signal-to-clutter ratio criterion and the double mutual information criterion, and adjusts the optimal waveform transmitted by the radar system by adjusting the weight, so as to improve the performance of the radar system.

[0075] We let η be the weighted fusion parameter, and according to the maximum signal-to-clutter ratio and double mutual information criterion expression, the optimization objective function of the joint signal-to-clutter ratio criterion and double mutual information criterion can be listed as:

[0076]

[0077] At this time, when maximizing the weighted joint optimization criterion based on the double mutual information criterion, by adjusting the weighted fusion weight η, the signal-to-clutter ratio and the double mutual information can be maximized, or a certain index can be maximized. The double mutual information criterion is mainly used to improve the detection performance of the radar system, so the optimization criterion of the joint double mutual information and the maximum signal-to-clutter ratio can be used to maximize the output signal-to-clutter ratio of the receiving end while ensuring the mutual information amount of the received echo signal according to the situation of the radar detection environment and the demand of the radar transmitted waveform. The weight of the joint optimization criterion is controlled to maximize the output signal-to-clutter ratio of the receiving end. Compared with the single maximum signal-to-clutter ratio criterion, the joint optimization criterion has the advantage of more mutual information, and compared with the traditional joint optimization criterion, it also has a higher signal-to-clutter ratio, thereby obtaining more performance improvement of the radar system. Considering the energy constraint, the optimization model at this time is modeled as:

[0078] 4. Solving the waveform energy spectrum by the maximum edge allocation algorithm

[0079] Considering the complexity of solving the optimal waveform energy spectrum using the Lagrange multiplier method, and the need for extensive multiplier searches leading to tedious calculations and excessive computation, this paper proposes a maximum edge allocation algorithm to address this issue. First, the objective function is discretized, resulting in the following expression: At this point, the energy constraint is discretized into st and, u(k)=|S(f k )| 2 , The optimization problem can then be expressed as: At this point, the waveform optimization design problem transforms into... Under constraints, find the process of maximizing ∑L(u1(k),u2(k),k), where, This formula means that, under the current criterion, u is allocated at the k-th frequency point. j (k) In terms of energy, according to the currently used criteria, the specific amount of performance improvement. For u max Discretize it into M parts, then MΔ = u max Δ represents the unit energy allocated to energy, u j The set of values ​​for (k) is {0,Δ,2Δ,...,MΔ}, and the final solution obtained is the optimal radar transmit waveform energy spectrum.

[0080] Compared with the joint optimization criterion of signal-to-clutter ratio (SCR) and mutual information weighting, the optimized transmit waveform of this invention has a higher output SCR. Compared with single SCR and mutual information criteria, this invention meets the need for waveform optimization when the radar system performs different tasks for specific radar missions. This invention solves the optimal waveform by using the maximum edge allocation algorithm, avoiding the problem of excessive computation caused by the Lagrange multiplier method in searching for the optimal multiplier, and improving the efficiency of solving the waveform energy spectrum.

[0081] The technical effects of the embodiments of the present invention will be further illustrated below using simulation experimental data.

[0082] Simulation Example 1: Using simulation data to compare the performance of the radar transmission waveform design results.

[0083] exist Figure 3A Under the same simulation data, the joint optimization radar waveform design method based on dual mutual information of this invention ( Figure 3B The performance comparison results of the dual mutual information fusion criterion in the model with the traditional joint optimization criterion and the mutual information criterion are as follows: Figures 3B-3D As shown. Figure 3BThe energy spectrum comparison diagram of the joint optimization radar waveform design method based on double mutual information of the application and the traditional joint optimization criterion and the mutual information criterion; Figure 3C The signal-to-clutter ratio change diagram with the transmission power of the joint optimization radar waveform design method based on double mutual information of the application and the traditional joint optimization criterion and the mutual information criterion; Figure 3D The signal-to-clutter ratio change diagram with the clutter intensity of the joint optimization radar waveform design method based on double mutual information of the application and the traditional joint optimization criterion and the mutual information criterion.

[0084] Simulation example two, the performance comparison of the radar transmission waveform design result is carried out by using the measured angle reflection data.

[0085] In the same measured angle reflection data as shown in Figures 4A-4D The performance comparison result of the joint optimization radar waveform design method based on double mutual information of the application and the traditional joint optimization criterion and the linear frequency modulation signal is as shown in Figures 5A-5B . Figure 4A It is a physical map of the angle reflection target; Figure 4B It is a measured echo data diagram of the angle reflection; Figure 4C It is an average power spectrum diagram of the clutter; Figure 4D It is a power spectrum diagram of the angle reflection. Figure 5A The energy spectrum comparison diagram of the joint optimization radar waveform design method based on double mutual information of the application and the traditional joint optimization criterion and the linear frequency modulation signal; Figure 5B The signal-to-clutter ratio change diagram with the transmission power of the joint optimization radar waveform design method based on double mutual information of the application and the traditional joint optimization criterion and the linear frequency modulation signal.

[0086] Simulation example three, the performance comparison of the radar transmission waveform design result is carried out by using the measured radar vehicle data.

[0087] In the same measured radar vehicle data as shown in Figures 6A-6D The performance comparison result of the joint optimization radar waveform design method based on double mutual information of the application and the traditional joint optimization criterion and the linear frequency modulation signal is as shown in Figures 7A-7B . Figure 6A It is a physical map of the radar vehicle target; Figure 6B It is a measured echo data diagram of the radar vehicle; Figure 6C It is an average power spectrum diagram of the clutter; Figure 6D It is a power spectrum diagram of the radar vehicle. Figure 7A The energy spectrum comparison diagram of the joint optimization radar waveform design method based on double mutual information of the application and the traditional joint optimization criterion and the linear frequency modulation signal; Figure 7BThe schematic diagram of the signal-to-clutter ratio of the traditional joint optimization criterion and the linear frequency modulation signal changing with the transmission power is shown in the method for designing the radar waveform based on the double mutual information of the application.

[0088] According to the above simulation, the application can achieve better technical effects compared with the prior art.

[0089] The above is a further detailed description of the application in combination with specific preferred embodiments, and the specific implementation of the application cannot be limited to these descriptions. For ordinary skilled persons in the technical field to which the application belongs, a number of simple deductions or substitutions can be made without departing from the concept of the application, and all of them should be considered as falling within the protection scope of the application.

Claims

1. A joint optimization radar waveform design method based on mutual information, characterized in that, include: It transmits radar signals to the detection environment and receives radar echo signals reflected from the detection environment; The radar echo signal includes: pure clutter data and target-added clutter data; The average power spectrum of the clutter and the power spectrum of the target are determined based on the pure clutter data and the target-added clutter data, respectively. Based on the preset distribution of the power spectrum of the colored noise, the preset number of frequency points, the preset total energy, the radar system operating bandwidth, the average power spectrum of the clutter and the power spectrum of the target, the transmitted waveform energy spectrum of the radar under the maximum signal-to-clutter-to-noise ratio criterion and the transmitted waveform energy spectrum of the radar under the dual mutual information criterion are determined respectively. By using a preset weighted fusion value, the transmitted waveform energy spectrum of the radar under the maximum signal-to-clutter-to-noise ratio criterion and the transmitted waveform energy spectrum of the radar under the dual mutual information criterion are weighted and fused to obtain the transmitted waveform energy spectrum of the radar jointly optimized by dual mutual information; the preset weighted fusion value is used to adjust the transmitted waveform of the radar to the transmitted waveform under a specific radar mission. The step of weightedly fusing the transmitted waveform energy spectrum of the radar under the maximum signal-to-clutter-to-noise ratio criterion and the transmitted waveform energy spectrum of the radar under the dual mutual information criterion by using a preset weighted fusion value to obtain the transmitted waveform energy spectrum of the radar jointly optimized by dual mutual information includes: The product value between the preset weighted fusion value and the energy spectrum of the radar's transmitted waveform under the maximum signal-to-clutter-to-noise ratio criterion is determined to obtain the first product value; The absolute value of the difference between the preset weighted fusion value and 1 is determined, and the product value between the absolute value of the difference and the energy spectrum of the radar's transmitted waveform under the dual mutual information criterion is determined to obtain the second product value. The sum of the first product value and the second product value is used as the transmitted waveform energy spectrum of the radar jointly optimized by the dual mutual information.

2. The joint optimization radar waveform design method based on mutual information as described in claim 1, characterized in that, The step of determining the radar's transmitted waveform energy spectrum under the maximum signal-to-clutter ratio criterion and the radar's transmitted waveform energy spectrum under the dual mutual information criterion, based on the preset distribution of the power spectrum of the colored noise, the preset number of frequency points, the preset total energy, the radar system's operating bandwidth, the average power spectrum of the clutter, and the power spectrum of the target, respectively, includes: Based on the preset distribution of the power spectrum of the colored noise, the preset number of frequency points, the preset total energy, the working bandwidth of the radar system, the average power spectrum of the clutter, the power spectrum of the target, the first optimization objective function, and the preset number of operations, the maximum edge allocation algorithm is used to solve the energy spectrum of the radar's transmitted waveform at each frequency point under the maximum signal-to-clutter-to-noise ratio criterion. Based on the preset distribution of the power spectrum of the colored noise, the preset number of frequency points, the preset total energy, the radar system operating bandwidth, the average power spectrum of the clutter, the power spectrum of the target, the second optimization objective function, and the preset number of operations, the energy spectrum of the radar's transmitted waveform at each frequency point under the dual mutual information criterion is solved by the maximum edge allocation algorithm.

3. The joint optimization radar waveform design method based on mutual information as described in claim 2, characterized in that, The first optimization objective function is: ;in, The number of frequency points, , The power spectrum of the target is the first Power spectrum at each frequency point The first in the average power spectrum of the clutter Power spectrum at each frequency point The first element in the preset distribution of the power spectrum of the colored noise Power spectrum at each frequency point , The operating bandwidth of the radar system. , The preset total energy, For the radar under the maximum signal-to-clutter-to-noise ratio criterion, in the first... The energy spectrum of the transmitted waveform at each frequency point.

4. The joint optimization radar waveform design method based on mutual information as described in claim 2, characterized in that, The second optimization objective function is: ;in, The number of frequency points, , The power spectrum of the target is the first Power spectrum at each frequency point The first in the average power spectrum of the clutter Power spectrum at each frequency point The first element in the preset distribution of the power spectrum of the colored noise Power spectrum at each frequency point , The operating bandwidth of the radar system. , The preset total energy, For radar under the dual mutual information criterion in the first... The energy spectrum of the transmitted waveform at each frequency point It is a logarithmic function with base e.

5. The joint optimization radar waveform design method based on mutual information as described in claim 1, characterized in that, The transmitted waveform energy spectrum of the radar jointly optimized by dual mutual information is as follows: The expression for the energy spectrum of the transmitted waveform at each frequency point is: ； in, , The number of frequency points, The energy spectrum of the transmitted waveform of the radar jointly optimized by mutual information is the first... The amplitude of the transmitted waveform energy spectrum at each frequency point The preset weighted fusion value, For the radar under the maximum signal-to-clutter-to-noise ratio criterion, in the first... The energy spectrum of the transmitted waveform at each frequency point For radar under the dual mutual information criterion in the first... The energy spectrum of the transmitted waveform at each frequency point.

6. The joint optimization radar waveform design method based on mutual information as described in claim 1, characterized in that, The step of determining the average power spectrum of the clutter and the power spectrum of the target based on the pure clutter data and the target-added clutter data respectively includes: The average power spectrum of the clutter is obtained by performing a short-time Fourier transform on the pure clutter data. The power spectrum of the target is obtained by performing a short-time Fourier transform on the cluttered data.

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