Airborne radar waveform optimization method, apparatus and equipment based on PCFM

Abstract

This application relates to a method, apparatus, and device for optimizing airborne radar waveforms based on PCFM. The method involves performing instantaneous frequency analysis on the target template waveform and representing it using multi-code frequency modulation to obtain the initial waveform to be optimized. A simulated similarity function is constructed and used as a constraint. Simultaneously, with the detection performance of the transmitted signal as the optimization objective, a waveform optimization model is constructed. This model is then used to optimize the coded phase sequence of the initial waveform to be optimized, yielding preliminary optimization results. A joint optimization model for transmit and receive waveform processing is then constructed to further optimize the preliminary results. The optimized waveform is then used as the radar transmit waveform for radar detection. This method can improve target detection performance while avoiding identification.

Description

Technical Field

[0001] This application relates to the field of radar detection technology, and in particular to a method, apparatus and equipment for optimizing airborne radar waveforms based on PCFM. Background Technology

[0002] Radar systems are widely used in aviation, meteorological monitoring, traffic control, and many other fields, playing an indispensable role in ensuring the safe and efficient operation of various activities. As critical equipment, the radar signals of aircraft, if illegally acquired, could not only leak vital information such as the aircraft's location but also endanger passenger safety and hinder the successful execution of missions. In today's complex electromagnetic environment, filled with interference from various electronic devices, pulse descriptors of received signals are used to identify and locate potential radiation sources. Due to limitations of receiving equipment, traditional radar signal pulse descriptors include features such as angle of arrival, time of arrival, pulse width, pulse amplitude, and carrier frequency, some of which are particularly crucial for radiation source identification and matching.

[0003] With the development of electronic devices such as arbitrary waveform generators, radar signals can be modulated in richer and more detailed ways. By precisely controlling the intra-pulse characteristics of radar signal waveforms, the radar signal waveforms can achieve superior performance, simulating the characteristics and functions of other signals while maintaining the original radar performance, thus expanding the applications of airborne multi-functional radar. However, the overuse of complex waveforms can not only generate harmonic components or nonlinear intermodulation products, potentially wasting energy, but also pollute adjacent frequency bands, affecting other public electronic equipment such as navigation and broadcasting systems. Therefore, how to design radar waveforms that combine their own characteristics with those of other signals is an immediate problem that needs to be solved. Summary of the Invention

[0004] Therefore, it is necessary to provide a PCFM-based airborne radar waveform optimization method, apparatus, and equipment that can improve target detection performance while avoiding identification, in order to address the above-mentioned technical problems.

[0005] A method for optimizing airborne radar waveforms based on PCFM, the method comprising:

[0006] The target template waveform is obtained, and after instantaneous frequency analysis of the target template waveform, it is represented by a multi-code frequency modulation method to obtain the initial waveform to be optimized.

[0007] A simulated similarity function is constructed, which is used as a constraint. Simultaneously, the detection performance of the transmitted signal is used as the optimization objective. A waveform optimization model is constructed, and the encoded phase sequence of the initial waveform to be optimized is optimized using the waveform optimization model to obtain an optimized waveform similar to the target template waveform. The optimized waveform is then used as the preliminary optimization result.

[0008] A joint optimization model for waveforms in transmission and reception processing is constructed. Unmatched filter parameters are introduced. The preliminary optimization results are optimized by using the constructed autocorrelation template as a constraint and the signal-to-noise ratio as an optimization template, so as to obtain the waveform optimization result that is similar to the target template waveform and has the largest signal-to-noise ratio after processing at the receiving end.

[0009] The optimized waveform is used as the radar transmission waveform for radar detection.

[0010] In one embodiment, the target template waveform is a linear frequency modulated waveform.

[0011] In one embodiment, before optimizing the encoded phase sequence of the initial waveform to be optimized, a fractional Fourier transform is first performed on the initial waveform to be optimized.

[0012] In one embodiment, the simulated similarity function is expressed as:

[0013] ;

[0014] In the above formula, This represents a simulated similarity function. This indicates the number of coded symbols in the target template waveform. The width of the symbol is represented. This represents a phase perturbation sequence. This indicates the similarity index of disguises. Represents an imaginary number.

[0015] In one embodiment, the peak-to-sidelobe ratio is used as the detection performance, and the optimization objective is to minimize the peak-to-sidelobe ratio.

[0016] In one embodiment, when optimizing the encoded phase sequence of the initial waveform to be optimized using the waveform optimization model, the Ga solver in Matlab is used to solve the waveform optimization model.

[0017] In one embodiment, the unmatched filter parameters are obtained by solving a joint filter optimization problem, which is expressed as:

[0018] ;

[0019] In the above formula, and These represent the filter and the optimized waveform, respectively. The covariance matrix representing environmental noise. This represents the constant modulus constraint of the optimized waveform. This represents a parameter that measures the similarity to a reference waveform. This represents the coding parameters for multiple coded frequency modulation. Indicates a template sequence. express and The cross-correlation sequence.

[0020] This application also provides an airborne radar waveform optimization device based on PCFM, the device comprising:

[0021] The target template waveform acquisition module is used to acquire the target template waveform, perform instantaneous frequency analysis on the target template waveform, and represent it using a multi-code frequency modulation method to obtain the initial waveform to be optimized.

[0022] The waveform optimization module is used to construct a simulated similarity function, use the simulated similarity function as a constraint, and construct a waveform optimization model with the detection performance of the transmitted signal as the optimization target. The waveform optimization model is used to optimize the encoded phase sequence of the initial waveform to be optimized, so as to obtain an optimized waveform similar to the target template waveform, and the optimized waveform is used as the preliminary optimization result.

[0023] The joint optimization module is used to construct a joint optimization model for the waveform of transmission and reception processing. It introduces unmatched filter parameters, uses the constructed autocorrelation template as a constraint, and uses the signal-to-noise ratio as an optimization template to optimize the preliminary optimization results, so as to obtain the waveform optimization result that is similar to the target template waveform and has the largest signal-to-noise ratio after processing at the receiving end.

[0024] The radar waveform transmission module is used to use the optimized waveform as the radar transmission waveform for radar detection.

[0025] A computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program performing the following steps:

[0026] The target template waveform is obtained, and after instantaneous frequency analysis of the target template waveform, it is represented by a multi-code frequency modulation method to obtain the initial waveform to be optimized.

[0027] A simulated similarity function is constructed, which is used as a constraint. Simultaneously, the detection performance of the transmitted signal is used as the optimization objective. A waveform optimization model is constructed, and the encoded phase sequence of the initial waveform to be optimized is optimized using the waveform optimization model to obtain an optimized waveform similar to the target template waveform. The optimized waveform is then used as the preliminary optimization result.

[0028] A joint optimization model for waveforms in transmission and reception processing is constructed. Unmatched filter parameters are introduced. The preliminary optimization results are optimized by using the constructed autocorrelation template as a constraint and the signal-to-noise ratio as an optimization template, so as to obtain the waveform optimization result that is similar to the target template waveform and has the largest signal-to-noise ratio after processing at the receiving end.

[0029] The optimized waveform is used as the radar transmission waveform for radar detection.

[0030] A computer-readable storage medium having a computer program stored thereon, the computer program performing the following steps when executed by a processor:

[0031] The target template waveform is obtained, and after instantaneous frequency analysis of the target template waveform, it is represented by a multi-code frequency modulation method to obtain the initial waveform to be optimized.

[0032] A simulated similarity function is constructed, which is used as a constraint. Simultaneously, the detection performance of the transmitted signal is used as the optimization objective. A waveform optimization model is constructed, and the encoded phase sequence of the initial waveform to be optimized is optimized using the waveform optimization model to obtain an optimized waveform similar to the target template waveform. The optimized waveform is then used as the preliminary optimization result.

[0033] A joint optimization model for waveforms in transmission and reception processing is constructed. Unmatched filter parameters are introduced. The preliminary optimization results are optimized by using the constructed autocorrelation template as a constraint and the signal-to-noise ratio as an optimization template, so as to obtain the waveform optimization result that is similar to the target template waveform and has the largest signal-to-noise ratio after processing at the receiving end.

[0034] The optimized waveform is used as the radar transmission waveform for radar detection.

[0035] The aforementioned PCFM-based airborne radar waveform optimization method, apparatus, and equipment obtain the initial waveform to be optimized by performing instantaneous frequency analysis on the target template waveform and representing it using multi-code frequency modulation. A simulated similarity function is constructed and used as a constraint. Simultaneously, with the detection performance of the transmitted signal as the optimization objective, a waveform optimization model is constructed. This model is used to optimize the coded phase sequence of the initial waveform to be optimized, obtaining preliminary optimization results. Then, a joint optimization model for transmitted and received waveforms is constructed to further optimize the preliminary optimization results. The optimized waveform is used as the radar transmitted waveform for radar detection. This method can improve target detection performance while avoiding identification. Attached Figure Description

[0036] Figure 1 This is a flowchart illustrating an airborne radar waveform optimization method based on PCFM in one embodiment.

[0037] Figure 2 This is a schematic diagram illustrating the results of a simulation experiment involving PCFM optimized coding, where... Figure 2 (a) is a schematic diagram of the time-domain waveform of the optimized PCFM. Figure 2 (b) is a schematic diagram of the frequency domain waveform of the optimized PCFM. Figure 2 (c) is a schematic diagram comparing the autocorrelation function of the PCFM waveform before and after optimization;

[0038] Figure 3 This is a schematic diagram showing the SINR of a jointly designed filter and the SINR of a matched filter in a simulation experiment.

[0039] Figure 4 This is a structural block diagram of an airborne radar waveform optimization device based on PCFM in one embodiment;

[0040] Figure 5 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0042] Currently, radar signal intra-pulse modulation identification methods are mainly divided into two categories: traditional methods based on signal processing algorithms and intelligent methods based on time-frequency graph deep learning. In traditional methods, researchers determine the modulation type by extracting the time-frequency, phase, or statistical features of the signal. For example, identification methods based on decision theory, feature extraction, and cyclostationary analysis rely on instantaneous frequency analysis (such as the phase difference method) and time-frequency transformation (such as short-time Fourier transform (STFT) and Wigner-Ville distribution (WVD)) as core techniques. However, these methods have limited performance in complex electromagnetic environments, especially in scenarios with superimposed multi-component signals and low signal-to-noise ratio (SNR), where features are easily obscured by noise.

[0043] In recent years, deep learning-based intelligent methods have overcome the limitations of traditional algorithms through end-to-end feature learning. For example, the ML-Decoder framework inputs the Choi-Williams distribution (CWD) time-frequency map into a convolutional neural network and combines it with a decoder cross-attention mechanism to achieve multi-component signal recognition, achieving an average accuracy of 93.9%, significantly outperforming traditional machine learning intra-pulse recognition algorithms. Furthermore, existing research indicates that the CWD time-frequency map has become a mainstream input due to its high resolution and cross-term suppression capabilities; combined with improved residual networks (such as the Swin Transformer), it can maintain a recognition rate of over 97% even at an SNR of -8 dB.

[0044] Therefore, how to further improve the intra-pulse modulation performance while maintaining the original time-frequency characteristics in order to achieve high-resolution detection capability for weak targets is a noteworthy issue in the current radar waveform design field.

[0045] In response to the above problems, such as Figure 1 As shown, an airborne radar waveform optimization method based on PCFM is provided, including the following steps:

[0046] Step S100: Obtain the target template waveform. After performing instantaneous frequency analysis on the target template waveform, represent it using a multi-code frequency modulation method to obtain the initial waveform to be optimized.

[0047] Step S110: Construct a simulated similarity function, use the simulated similarity function as a constraint, and take the detection performance of the transmitted signal as the optimization target to construct a waveform optimization model. Use the waveform optimization model to optimize the encoded phase sequence of the initial waveform to be optimized, and obtain an optimized waveform similar to the target template waveform. Use the optimized waveform as the preliminary optimization result.

[0048] Step S120: Construct a joint optimization model for the waveforms of transmission and reception processing, introduce unmatched filter parameters, use the constructed autocorrelation template as a constraint, and use the signal-to-noise ratio as an optimization template to optimize the preliminary optimization results, and obtain the waveform optimization result that is similar to the target template waveform and has the largest signal-to-noise ratio after processing at the receiving end.

[0049] Step S130: Use the waveform optimization result as the radar transmission waveform for radar detection.

[0050] In this embodiment, a disguise design is implemented for the time-frequency diagram to prevent the algorithm from accurately identifying the intra-pulse modulation scheme of the radar waveform, which is an emerging deep learning-based intra-pulse feature recognition method. The Polyphase-Coded FM (PCFM) waveform used in this method was proposed in 2014. As a novel modulation method, it achieves continuous phase coding through smooth phase transitions, exhibiting significant advantages in spectral efficiency and physical feasibility. Compared to traditional continuous frequency modulation waveforms and phase-coded waveforms, PCFM not only alleviates signal distortion caused by transmitter bandwidth limitations, but its flexible coding space also provides more freedom for waveform optimization.

[0051] In step S100, the target template waveform is first acquired. The target template waveform is then simulated and used as a radar transmission waveform for detection. This causes other radar target identification systems to mistakenly identify the waveform as the target template waveform, thereby achieving the effect of evading identification.

[0052] It should be noted that this method is designed to optimize the radar transmission waveform carried on aircraft.

[0053] In this embodiment, the target template waveform is a linear frequency modulated (LFM) waveform.

[0054] In this embodiment, when simulating the target template waveform, it is first assumed that the PCFM waveform based on LFM encoding has N coded symbols, and its (N+1) phases can be represented as follows:

[0055] (1)

[0056] So at that moment t The corresponding PCFM waveform phase can be expressed as:

[0057] (2)

[0058] In formula (2), Indicates the duration of a single symbol. Indicates t pairs The remainder.

[0059] Specifically, the target template waveform for Linear Frequency Modulation (LFM) is represented as follows:

[0060] (3)

[0061] in, This represents the signal carrier frequency. Furthermore, substituting equation (8) from later text into equation (9), the signal expression and coding phase of the PCFM, i.e., the initial waveform to be optimized, are expressed as:

[0062] (4)

[0063] In formula (4), This represents the floor function. The m-th phase representation of the waveform encoding is defined in (1).

[0064] In step S110, before optimizing the encoded phase sequence of the initial waveform to be optimized, a fractional Fourier transform is performed on the initial waveform. Using the LFM waveform as the reference waveform, the rotation angle is... The fractional Fourier transform of the PCFM waveform can be expressed as:

[0065] (5)

[0066] This represents the fractional Fourier transform of the signal, where α represents the fractional rotation angle and u represents the independent variable in the fractional domain. The signal in this case is represented as: . yes The amplitude of the rotated signal is a constant that depends only on α. ​​By analyzing formula (5), the analog similarity function can be obtained. Specifically, it can be proven that when... For signals with a time interval of [-T / 2, T / 2], the magnitude of the fractional Fourier transform has a maximum value, which can be expressed as:

[0067] (6)

[0068] And when For signals with a time interval of [-T / 2, T / 2], the fractional Fourier transform can be expressed using Fresnel functions as follows:

[0069] (7)

[0070] In formula (7), .

[0071] And formula (7) When the value is at its maximum, at this time:

[0072] (8)

[0073] And only if in As N → ∞, the time-frequency spectrum reaches a large peak. Outside this interval, the Fresnel spectral values ​​are very small, and the function values ​​are negligible in comparison. The above derivation does not consider the effect of small phase fluctuations on the time-frequency distribution. In fact, when actual... With theory When a difference exists, the FRFT result will offset from the LFM result as follows:

[0074] (9)

[0075] In formula (9), For the first m One phase perturbation value. Note that the last term in formula (10) represents the influence of the PCFM signal structure on time-frequency analysis. Therefore, it is proposed that the difference between the PCFM waveform and the LFM signal lies in the fact that the former is modulated and affected by the phase structure and perturbation. Considering both formula (9) and formula (10), the simulation similarity index of PCFM to LFM waveform is proposed as follows:

[0076] (10)

[0077] The simulated similarity function can be defined by formula (10), and is expressed as:

[0078] (11)

[0079] In formula (11), This indicates the number of coded symbols in the target template waveform. The width of the symbol is represented. This represents the phase perturbation parameter. The spoofing similarity index is defined by equation (9).

[0080] In this embodiment, the peak-to-side-lobe ratio is also used as a detection performance indicator, and the minimum peak-to-side-lobe ratio is the optimization target.

[0081] Specifically, the peak-to-sidelobe ratio (PSL) is defined as the ratio of the peak value of the main lobe to the peak value of the sidelobes. It characterizes the autocorrelation sidelobe performance of a waveform and reflects the weak target detection capability of the radar waveform. Its calculation formula is as follows:

[0082] (12)

[0083] In formula (12), This represents the peak value of the main lobe of the autocorrelation function. It is the side lobe peak value. This indicates the maximum value. The larger the PSL value, the stronger the waveform's ability to detect weak targets.

[0084] Furthermore, targeting PSL, a detection performance improvement model based on LFM is established, introducing PCFM modulation to optimize detection performance while maintaining the original waveform characteristics. Thus, the waveform optimization model for the airborne radar waveform is obtained as follows:

[0085] (13)

[0086] In formula (13), It is a parameter that measures the similarity to a reference waveform.

[0087] In this embodiment, when optimizing the encoded phase sequence of the initial waveform to be optimized using the waveform optimization model, the Ga solver in Matlab is used to solve the waveform optimization model (i.e., formula (13)).

[0088] Specifically, the calling format for the Ga solver is:

[0089] (14)

[0090] In formula (14), The M-file function handle for calculating the fitness function, The number of variables in the fitness function. These are the constraint vectors for linear equations and linear inequalities, respectively. and These are the lower bounds of the variable's value. is a nonlinear constraint parameter. Among them, in formula (14) The value is determined by the cost function, namely the value determined by formula (11) above and formula (23) below.

[0091] Furthermore, based on the solution results, the continuous instantaneous frequencies are differentially divided and sliced ​​to obtain the phase sequence of the waveform, and continuous phase coding modulation is performed to obtain the optimized waveform.

[0092] like Figure 2 The figure shows the optimized waveform obtained using this method in a simulation experiment. The time-domain and frequency-domain waveforms of the optimized PCFM are illustrated in the figure below. Figure 2 (a) and Figure 2 As shown in (b), the autocorrelation function of the PCFM waveform before and after optimization is compared as follows: Figure 2 As shown in (c), the original PCFM waveform based on LFM encoding has a PSL of -13dB. However, after calculating the autocorrelation function of the optimized PCFM waveform, the optimized PSL level is -14.5dB, which is an improvement of about 1.5dB in PSL performance, thus improving the detection performance to a certain extent.

[0093] In step S120, the optimized waveform, which is similar to the target template waveform, is used as the radar transmission waveform for target detection. During the radar detection process, if the detection signal is received by other radar identification systems, it will be misjudged as a signal transmitted by other radars to avoid being identified.

[0094] To improve the target detection capability of the optimized waveform, a filter was further designed at the radar receiver to filter the echo signal obtained after radar detection using the optimized waveform as the radar transmission waveform, so as to achieve joint optimization of the waveform.

[0095] In this embodiment, assuming there is only one target in the scene, the SINR (Signal to Interference plus Noise Ratio) output by the filter at the actual target delay is expressed as:

[0096] (15)

[0097] In formula (15), and These represent the optimized waveform and filter, the complex sequence and the filter phase sequence, respectively. The covariance matrix representing environmental noise. Indicates environmental noise. Express your expectations.

[0098] Furthermore, when jointly optimizing the waveform, on the one hand, the sidelobe level of the correlation function should be considered. A lower level of sidelobe can prevent the weak target echo from being overwhelmed by the strong target echo. On the other hand, the main lobe width of the echo signal should be considered. A narrow main lobe width can improve the detection position and velocity resolution.

[0099] To facilitate the optimization and solution of formula (15), the optimized waveform is required. With filters The normalized cross-correlation function is lower than a template sequence Among them, the normalized cross-correlation function Represented as:

[0100] (16)

[0101] when k When = 0, the autocorrelation sequence XCS constraint is always equal to 1. For distance delays less than zero, XCS is expressed as... :

[0102] (17)

[0103] Specifically, in constructing template sequences At that time, its peak response should always be within k At point =0, and ensuring XCS has a suitable main lobe width and PSL. Considering the PCFM continuous phase coding constraint in waveform design, the optimization problem of the joint filter can be expressed as:

[0104] (18)

[0105] In formula (18), and These represent the filter and the optimized waveform, respectively. This represents the constant modulus constraint of the optimized waveform. This represents a parameter that measures the similarity to a reference waveform. This represents the coding parameters for multiple coded frequency modulation. Indicates a template sequence. express and The cross-correlation sequence.

[0106] In this embodiment, before solving formula (18), it is first analyzed. The filter is fixed in the matched filter, while the form in the joint design of the waveform filter is more flexible. Since the joint filter imposes more constraints on the waveform, the feasible region and optimal solution of the matched filter and the joint filter design are different. If we let If it is a globally optimal joint design, then it is obvious that:

[0107] (19)

[0108] However, this result does not mean that joint signal / filter design is better in all cases. This is because problem formula (19) must be solved numerically, and the optimization of the solution algorithm and the choice of initial values ​​also have a significant impact on the final result.

[0109] For the joint design problem of waveform filters, SINR is a function of the signal phase vector and the filter. Through derivation, the gradient of SINR with respect to the waveform phase and the filter phase can be obtained as follows:

[0110] (20)

[0111] In formula (20), This is the Hadamard product operation, which represents the element-wise multiplication of a matrix or vector. Describes the gradient of the variable and:

[0112] (twenty one)

[0113] The XCS matrix yields the Jacobian matrix for the waveform phase, expressed as:

[0114] (twenty two)

[0115] in, , denoted as convolution operation, and J represents the Jacobian matrix.

[0116] Then, the XCS matrix yields the Jacobian matrix of the filter vector, expressed as:

[0117] (twenty three)

[0118] like Figure 3 The diagram shows the SINR of the jointly designed filter and the SINR of the matched filter. It can be seen that the SINR based on the PCFM waveform and the filter has lower sidelobes (about 1 dB lower than the sidelobes of the matched filter) and narrower main lobe width (about 79% of the main lobe width of the matched filter), which can achieve better weak target detection capability and higher range resolution.

[0119] Among the aforementioned PCFM-based airborne radar waveform optimization methods, a PCFM-based waveform simulation optimization design method is proposed. By constructing a simulation similarity index, the peak-side lobe ratio (PSL) of the waveform is optimized while preserving the time-frequency distribution characteristics of the baseline waveform, thus improving the radar's detection capability against weak targets. This method combines a genetic search algorithm with a waveform / filter joint optimization model, achieving similar time-frequency characteristics of the camouflaged waveform to the low-threat waveform, a low probability of interception by reconnaissance systems, and better detection performance than the low-threat waveform. A waveform processing method is also provided. Simulation results show that, using a linear frequency modulated (LFM) waveform, the optimized PCFM waveform improves the PSL performance by approximately 1.5 dB compared to the baseline LFM, achieving a time-frequency domain camouflage similarity of 93.76%, providing a new approach for waveform design of airborne multi-functional radars in complex electromagnetic environments.

[0120] It should be understood that, although Figure 1 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 1 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0121] In one embodiment, such as Figure 4 As shown, an airborne radar waveform optimization device based on PCFM is provided, including: a target template waveform acquisition module 200, a waveform optimization module 210, a joint optimization module 220, and a radar waveform transmission module 230, wherein:

[0122] The target template waveform acquisition module 200 is used to acquire the target template waveform, perform instantaneous frequency analysis on the target template waveform, and represent it using a multi-code frequency modulation method to obtain the initial waveform to be optimized.

[0123] The waveform optimization module 210 is used to construct a simulated similarity function, use the simulated similarity function as a constraint, and take the detection performance of the transmitted signal as the optimization target to construct a waveform optimization model. The waveform optimization model is used to optimize the encoded phase sequence of the initial waveform to be optimized to obtain an optimized waveform similar to the target template waveform, and the optimized waveform is used as the preliminary optimization result.

[0124] The joint optimization module 220 is used to construct a joint optimization model for the waveform of transmission and reception processing. It introduces unmatched filter parameters, uses the constructed autocorrelation template as a constraint, and uses the signal-to-noise ratio as an optimization template to optimize the preliminary optimization results, thereby obtaining a waveform optimization result that is similar to the target template waveform and has the largest signal-to-noise ratio after processing at the receiving end.

[0125] The radar waveform transmission module 230 is used to use the waveform optimization result as the radar transmission waveform for radar detection.

[0126] Specific limitations regarding the PCFM-based airborne radar waveform optimization device can be found in the above description of the limitations of the PCFM-based airborne radar waveform optimization method, and will not be repeated here. Each module in the aforementioned PCFM-based airborne radar waveform optimization device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0127] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 5 As shown, the computer device includes a processor, memory, network interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The network interface is used to communicate with external terminals via a network connection. When the computer program is executed by the processor, it implements a PCFM-based airborne radar waveform optimization method. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0128] Those skilled in the art will understand that Figure 5 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0129] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0130] The target template waveform is obtained, and after instantaneous frequency analysis of the target template waveform, it is represented by a multi-code frequency modulation method to obtain the initial waveform to be optimized.

[0131] A simulated similarity function is constructed, which is used as a constraint. Simultaneously, the detection performance of the transmitted signal is used as the optimization objective. A waveform optimization model is constructed, and the encoded phase sequence of the initial waveform to be optimized is optimized using the waveform optimization model to obtain an optimized waveform similar to the target template waveform. The optimized waveform is then used as the preliminary optimization result.

[0132] A joint optimization model for waveforms in transmission and reception processing is constructed. Unmatched filter parameters are introduced. The preliminary optimization results are optimized by using the constructed autocorrelation template as a constraint and the signal-to-noise ratio as an optimization template, so as to obtain the waveform optimization result that is similar to the target template waveform and has the largest signal-to-noise ratio after processing at the receiving end.

[0133] The optimized waveform is used as the radar transmission waveform for radar detection.

[0134] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, the computer program performing the following steps when executed by a processor:

[0135] The target template waveform is obtained, and after instantaneous frequency analysis of the target template waveform, it is represented by a multi-code frequency modulation method to obtain the initial waveform to be optimized.

[0136] A simulated similarity function is constructed, which is used as a constraint. Simultaneously, the detection performance of the transmitted signal is used as the optimization objective. A waveform optimization model is constructed, and the encoded phase sequence of the initial waveform to be optimized is optimized using the waveform optimization model to obtain an optimized waveform similar to the target template waveform. The optimized waveform is then used as the preliminary optimization result.

[0137] A joint optimization model for waveforms in transmission and reception processing is constructed. Unmatched filter parameters are introduced. The preliminary optimization results are optimized by using the constructed autocorrelation template as a constraint and the signal-to-noise ratio as an optimization template, so as to obtain the waveform optimization result that is similar to the target template waveform and has the largest signal-to-noise ratio after processing at the receiving end.

[0138] The optimized waveform is used as the radar transmission waveform for radar detection.

[0139] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0140] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0141] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A PCFM-based airborne radar waveform optimization method, characterized in that, include: The target template waveform is obtained, and after instantaneous frequency analysis of the target template waveform, it is represented by a multi-code frequency modulation method to obtain the initial waveform to be optimized. The target template waveform is a linear frequency modulation waveform. A simulated similarity function is constructed, which serves as a constraint. Simultaneously, the detection performance of the transmitted signal is used as the optimization objective. A waveform optimization model is then constructed, and this model is applied to optimize the encoded phase sequence of the initial waveform to be optimized, resulting in an optimized waveform similar to the target template waveform. This optimized waveform is then used as the preliminary optimization result. Before optimizing the encoded phase sequence of the initial waveform to be optimized, a fractional Fourier transform is performed on it. The simulated similarity function is expressed as follows: In the above formula, denotes an analog similarity function, denotes the number of coded symbols in the target template waveform, denotes a symbol time width, denotes a phase perturbation sequence, denotes a camouflage similarity index, denotes an imaginary number; A joint optimization model for waveforms in transmission and reception processing is constructed. Unmatched filter parameters are introduced. The preliminary optimization results are optimized using the constructed autocorrelation template as a constraint and the signal-to-noise ratio as an optimization template. The optimized waveform is obtained that is similar to the target template waveform and has the largest signal-to-noise ratio after processing at the receiving end. The peak sidelobe ratio is used as the detection performance, and the minimum peak sidelobe ratio is the optimization target. The optimized waveform is used as the radar transmission waveform for radar detection.

2. The airborne radar waveform optimization method based on PCFM according to claim 1, characterized in that, When optimizing the encoded phase sequence of the initial waveform to be optimized using the waveform optimization model, the Ga solver in Matlab is used to solve the waveform optimization model.

3. The airborne radar waveform optimization method based on PCFM according to claim 2, characterized in that, The unmatched filter parameters are obtained by solving a joint filter optimization problem, which is expressed as: In the above formula, and These represent the filter and the optimized waveform, respectively. The covariance matrix representing environmental noise. This represents the constant modulus constraint of the optimized waveform. This represents a parameter related to waveform similarity. This represents the coding parameters for multiple coded frequency modulation. Indicates a template sequence. express and The cross-correlation sequence.

4. An airborne radar waveform optimization device based on PCFM, characterized in that, The airborne radar waveform optimization method based on PCFM as described in any one of claims 1-3 includes: The target template waveform acquisition module is used to acquire the target template waveform, perform instantaneous frequency analysis on the target template waveform, and represent it using a multi-code frequency modulation method to obtain the initial waveform to be optimized. The waveform optimization module is used to construct a simulated similarity function, use the simulated similarity function as a constraint, and construct a waveform optimization model with the detection performance of the transmitted signal as the optimization target. The waveform optimization model is used to optimize the encoded phase sequence of the initial waveform to be optimized, so as to obtain an optimized waveform similar to the target template waveform, and the optimized waveform is used as the preliminary optimization result. The joint optimization module is used to construct a joint optimization model for the waveform of transmission and reception processing. It introduces unmatched filter parameters, uses the constructed autocorrelation template as a constraint, and uses the signal-to-noise ratio as an optimization template to optimize the preliminary optimization results, so as to obtain the waveform optimization result that is similar to the target template waveform and has the largest signal-to-noise ratio after processing at the receiving end. The radar waveform transmission module is used to use the optimized waveform as the radar transmission waveform for radar detection.

5. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 3.

Images