Anti-slicing reconstruction interference method and system based on frequency modulation slope polarity alternation and timing agility

Abstract

This invention discloses a method and system for resisting slice reconstruction interference based on alternating frequency modulation slope polarity and time-series agility. It mainly addresses the problems of high complexity, poor real-time performance, and high dependence on prior information and training data in existing technologies. The scheme is as follows: At the transmitting end, a joint agile transmission signal is established based on the number of sub-pulses, sub-pulse duration, sub-pulse interval, sub-pulse bandwidth, and sub-pulse frequency modulation slope; at the receiving end, the received signal is segmented according to the recorded sub-pulse timing to obtain each segment signal, and pulse compression and delay compensation for both matched and mismatched channels are performed simultaneously; dynamic weights are generated based on the energy of the two compensated channels; an anomaly suppression factor is constructed based on the energy of the matched channels of each segment, and the output of each segment's matched channels is weighted and accumulated using this factor and the dynamic weights to obtain a one-dimensional range profile result. This invention does not require a large amount of training data or estimation of interference parameters, has low computational complexity, can suppress false targets generated by slice reconstruction interference while maintaining the energy of the real target, and can be used for target detection.

Description

Technical Field

[0001] This invention belongs to the field of radar signal processing and electronic countermeasures technology. It further describes a method and system for resisting slice reconstruction interference, which can be used to randomly alternate the slope polarity of intra-pulse linear frequency modulated signals and combine them with inter-pulse timing agility design to effectively suppress slice-based relay interference signals, thereby correctly detecting real targets. Background Technology

[0002] Linear frequency modulated (LFM) signals are widely used in modern radar systems due to their advantages such as large bandwidth and high range resolution. However, with the continuous development of electronic warfare technology, slice-reconstruction (C&I) jamming, as a typical coherent and agile jamming technique, poses a serious threat to LFM radars. Jammers generate coherent false targets that are highly similar to the time-frequency structure of the real echo by periodically sampling and repeatedly delaying the radar's transmitted signal. Because such jamming signals have a highly correlated modulation structure with the transmitted signal, traditional threshold detection and Doppler filtering methods are difficult to effectively distinguish them. After pulse compression, dense clusters of false targets easily form in the radar echo, severely interfering with the reliable detection and tracking of real targets.

[0003] Currently, the main measures to suppress slice reconstruction interference include time-frequency domain filtering, mismatch filtering, coding or agile waveform design, and data-driven methods, among which:

[0004] Time-frequency domain or transform-domain filtering methods utilize techniques such as Short-Time Fourier Transform (STFT) or Fractional Fourier Transform (FrFT) to identify and suppress interference in the transform domain. However, these methods typically involve high-dimensional matrix operations, resulting in significant computational overhead. This makes it difficult to meet the real-time processing requirements of radar systems for highly dynamic targets, and their effectiveness is not stable enough when interference parameters are unknown or change rapidly.

[0005] Mismatch filtering or non-match processing reduces the peak value of false targets by designing specific mismatch filters. However, such methods usually require accurate prior information about the interference (such as slice period, duty cycle, etc.) or a complex parameter tuning process, and have limited robustness in real-world complex electromagnetic environments.

[0006] Encoding or agile waveform design reduces the peak pulse compression of interference by altering the modulation parameters of sub-pulses within a pulse train (such as phase coding, frequency modulation slope, carrier frequency, etc.), creating a modulation mismatch between the signal slice forwarded by the jammer and the matched filter reference function of the current pulse. However, existing methods of this kind mostly focus on optimizing the waveform structure at the transmitter, while the receiver still uses a traditional processing architecture with a single filter matching the parameters of the current pulse and full-segment equal-weight accumulation. Under this asymmetrical transmission and reception processing condition, the signal slice intercepted and periodically forwarded by the jammer may contain components with the same modulation parameters as adjacent sub-pulses. These components can still generate high correlation peaks after matched filtering and are synchronously amplified during subsequent equal-weight accumulation, thus limiting the interference suppression effect.

[0007] Data-driven methods use neural networks to classify and suppress interference features, but these methods are highly dependent on the completeness of training samples and are difficult to deploy in the underlying hardware, such as field-programmable gate arrays (FPGAs) and digital signal processors (DSPs).

[0008] Patent document with application number CN202511189485.8 discloses a radar target detection and parameter estimation method for low signal-to-noise ratio conditions. It uses a CNN-LSTM architecture to construct a detection network, takes the range Doppler image of the echo signal as input, extracts local spatial features through convolution and captures the temporal sequence of pulses by LSTM to realize the detection of weak targets, and further designs a CNN-LSTM parameter estimation network to output the target's range and velocity estimates. This method has three main shortcomings: First, the training of deep learning models relies on a large number of labeled samples, while radar echo data in actual jamming scenarios is difficult to obtain sufficiently, resulting in limited generalization ability of the model to jamming patterns outside the training set. Second, the inference computation of the CNN-LSTM architecture is large, making it difficult to meet the stringent latency requirements of airborne or missile-borne radar platforms for real-time processing. Third, this scheme essentially performs post-processing identification on the jammed signal at the receiving end, without actively building anti-jamming capabilities at the transmitted waveform level. When the adversary uses slice reconstruction jamming, the jammer intercepts and forwards modulated radar pulse segments, which can generate false targets with features similar to the real target on the range Doppler map. The detection network cannot effectively remove them based solely on the information from the receiving end, and the detection and estimation performance will deteriorate significantly.

[0009] In summary, existing anti-jamming technologies still have shortcomings in terms of algorithm complexity, real-time performance, robustness, and dependence on prior information. Therefore, designing a radar waveform with low temporal predictability, strong anti-jamming capability, and low computational complexity, and achieving robust suppression of slice reconstruction interference under unknown interference parameters and low signal-to-noise ratio environments, is a pressing technical problem to be solved in the field of radar anti-jamming. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the existing technology and propose a method and system for resisting slice reconstruction interference based on alternating frequency modulation slope polarity and time-series agility, so as to reduce the computational complexity of interference suppression processing, get rid of the dependence on a large number of training samples and interference prior information, and realize real-time suppression of slice reconstruction interference.

[0011] The technical approach to achieve the above objectives is as follows: At the transmitting end, by designing a transmit waveform with jointly agile frequency modulation slope polarity and timing, it is difficult for slice reconstruction interference to form a stable match with the reference template of the currently processed sub-segment, thereby reducing its ability to form false target peaks after pulse compression; at the receiving end, the received signal is segmented and pulse compression is performed on the matched channel and mismatched channel respectively. A self-consistency index is constructed based on the difference between the outputs of the two channels and dynamic weights are generated, providing effective discrimination information for interference suppression without relying on a large number of training samples; in the post-processing stage, through inter-segment delay compensation, cross-segment anomaly suppression, and weighted coherent accumulation, effective suppression of slice reconstruction interference is achieved under conditions of low computational complexity.

[0012] Based on the above ideas, the technical solution of the present invention includes:

[0013] 1. A method for resisting slice reconstruction interference based on alternating frequency modulation slope polarity and time-series agility, characterized in that it includes:

[0014] (1) The radar is based on the number of sub-pulses Sub-pulse duration Sub-pulse gap Sub-pulse bandwidth and subpulse frequency modulation slope Establish joint agile transmission signal Record sub-pulse timing With frequency modulation slope And launch;

[0015] (2) The radar receives signals that include target echoes, slice reconstruction interference, and noise. Perform segmentation processing to obtain Sub-segment signal ;

[0016] (3) Pair pulse signal Perform pulse compression on the matched channel and the mismatched channel separately to obtain the output of the matched channel. and mismatched channel output ,in The sub-pulse number. For delay units;

[0017] (4) Output the matching channel and mismatched channel output Perform time delay compensation to obtain the compensated matching channel output. and mismatched channel output ;

[0018] (5) Calculate the energy output of the compensated matching channel. Energy output from mismatched channels A self-consistency index is constructed based on these two types of energy. And generate corresponding dynamic weights. ;

[0019] (6) For fixed delay units A median benchmark is constructed based on the matching channel energy of each segment. And based on this, abnormal inhibitory factors are generated. Combined with this abnormal inhibitory factor and dynamic weights The outputs of each segment's matching channel after time delay compensation are weighted and accumulated to obtain a one-dimensional distance image result. .

[0020] Furthermore, in (3) the pair of sub-pulse signals Perform pulse compression on the matched channel and pulse compression on the mismatched channel separately, including:

[0021] 3a) Matched channel pulse compression:

[0022] 3a1) Let For the first Sub-segment signal The corresponding matching channel reference signal, its form is based on the recorded first... Subpulse frequency modulation slope Sure:

[0023] like for The matching channel reference signal is: ,

[0024] like for The matching channel reference signal is: ;

[0025] 3a2) Using the matched channel reference signal sub-segment signals Perform matched filtering to obtain the matched channel output: ,in, for Conjugate time reversal;

[0026] 3b) Mismatched channel pulse compression:

[0027] 3b1) Let For the first Sub-segment signal The corresponding mismatched channel reference signal, its form is based on the recorded first... Subpulse frequency modulation slope Sure:

[0028] like for The mismatch channel reference signal is: ,

[0029] like for The mismatch channel reference signal is: ;

[0030] 3b2) Using the mismatched channel reference signal sub-segment signals Perform matched filtering to obtain the output of the mismatched channel: ,in, for The conjugate time reversal.

[0031] 2. A slice reconstruction interference-resistant system based on alternating frequency modulation slope polarity and timing agility, characterized in that it includes:

[0032] The waveform generation module is used to generate waveforms based on the number of sub-pulses. Sub-pulse duration Sub-pulse gap Sub-pulse bandwidth and subpulse frequency modulation slope Establish joint agile transmission signal Record sub-pulse timing With frequency modulation slope And launch;

[0033] The segmentation processing module is used to process the received signal, which includes target echo, slice reconstruction interference, and noise. Perform segmentation processing to obtain Sub-segment signal ;

[0034] Dual-channel pulse compression module for processing sub-pulse signals Perform pulse compression on the matched channel and the mismatched channel separately to obtain the output of the matched channel. and mismatched channel output ;

[0035] The delay compensation module is used to adjust the output of the matching channel. and mismatched channel output Perform time delay compensation to obtain the compensated matching channel output. and mismatched channel output ;

[0036] The self-consistency index construction and dynamic weight generation module is used to calculate the energy of the compensated matching channel output. Energy output from mismatched channels A self-consistency index is constructed based on these two types of energy. And generate corresponding dynamic weights. ;

[0037] Anomaly suppression and accumulation module, used for fixed delay units A median benchmark is constructed based on the matching channel energy of each segment. And based on this, abnormal inhibitory factors are generated. Combined with this abnormal inhibitory factor and dynamic weights The outputs of each segment's matching channel after time delay compensation are weighted and accumulated to obtain a one-dimensional distance image result. .

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] Firstly, since this invention only employs core operations such as segmented pulse compression, point-by-point energy comparison, and scalar weight mapping, it avoids high-dimensional matrix operations and complex transform domain searches, thereby reducing overall computational complexity, saving computational overhead, and improving the real-time performance of echo signal processing.

[0040] Secondly, by employing an alternating design of the frequency modulation slope of adjacent sub-pulses and inserting random gaps between sub-pulses, this invention can cause a polarity mismatch between the interference slice and the current reference signal when the interference slice falls into the processing interval of adjacent sub-pulses. At the same time, it breaks the strict timing periodicity between sub-pulses, reduces the probability of the jammer accurately intercepting and predicting the transmission timing, thereby weakening the false target focusing effect after the interference meridian accumulates across sub-segments.

[0041] Third, since the present invention judges interference solely based on the energy difference between the received signal in the matched and mismatched channels, it does not require precise estimation of prior parameters such as the jammer's slice period and duty cycle, nor does it require a large amount of training data, thus achieving adaptive suppression of slice reconstruction interference. Attached Figure Description

[0042] Figure 1 This is a flowchart of the anti-slice reconstruction interference method based on alternating frequency modulation slope polarity and timing agility of the present invention;

[0043] Figure 2 This is a schematic diagram of the transmitted signal in the method of the present invention;

[0044] Figure 3 This is a schematic diagram of the received signal composition and segmentation processing results in the method of the present invention;

[0045] Figure 4 This is a schematic diagram of the pulse compression response mechanism under the conditions of frequency modulation slope polarity matching and mismatch in the method of the present invention;

[0046] Figure 5 This is a block diagram of the anti-slice reconstruction interference system based on alternating frequency modulation slope polarity and timing agility of the present invention;

[0047] Figure 6 This is a comparison of one-dimensional distance images under slice reconstruction interference conditions using the conventional LFM pulse compression method and the method of this invention. Detailed Implementation

[0048] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative effort should all fall within the protection scope of the present invention.

[0049] It should be noted that the step numbers in the specification and claims of this invention are only for the purpose of clearly describing the embodiments of this invention and facilitating understanding, and their order is not limited.

[0050] Example 1: A method for resisting slice reconstruction interference based on alternating frequency modulation slope polarity and timing agility.

[0051] Reference Figure 1 The implementation steps of the instance include:

[0052] Step 1: Construct the joint agile transmission signal and transmit it.

[0053] 1.1) Assume the transmitted signal from the transmitter is... It consists of 1 sub-pulses, each sub-pulse being a linear frequency modulated signal, with a sub-pulse duration of 1. bandwidth is The amplitude of the frequency modulation slope is The combined agile transmission signal is generated as follows:

[0054] 1.1.1) For the first Sub-pulse, Set its frequency modulation slope to satisfy That is, the polarity of the frequency modulation slope of adjacent sub-pulses changes alternately;

[0055] 1.1.2) Generate sub-pulse signals according to the set frequency modulation slope polarity. :

[0056] When setting the number When the frequency modulation slope of each sub-pulse is positive, then ,

[0057] When setting the number When the frequency modulation slope of each sub-pulse is negative, then ;

[0058] 1.1.3) Insert sub-pulse gaps of random duration between adjacent sub-pulses. Let the start time of the first sub-pulse be... , No. The start time of each sub-pulse is: , ,

[0059] in For the first The sub-pulse and the first The duration of random intervals between sub-pulses This is the lower limit of the random interval duration. Its upper limit, in this embodiment , ;

[0060] 1.1.4) The sub-pulse signals are spliced ​​together according to their start times to obtain the combined agile transmission signal. :

[0061] .

[0062] In this example, the number of sub-pulses The sub-pulse duration is Sub-pulse bandwidth Frequency modulation slope amplitude Received the transmission signal from the Joint Aerobot. The waveform in the time domain is as follows Figure 2 As shown.

[0063] 1.2) Record the timing of sub-pulses With frequency modulation slope , for the joint agile transmission signal Launch.

[0064] Step 2: Segmentation of the received signal.

[0065] 2.1) Acquiring the received signal:

[0066] The transmitted signal will be intercepted by a jammer during its propagation through space. The jammer will then generate slices based on the intercepted signal to reconstruct the jamming signal. The steps for generating slice reconstruction interference are as follows:

[0067] 2.1.1) The jammer utilizes a sampling pulse train The intercepted radar transmission signals are periodically sampled to obtain sliced ​​signals. :

[0068] ,

[0069] in, , For sampling pulse width, The sampling period is In this embodiment, the sampling pulse width of the jammer is a rectangular function. Sampling period .

[0070] 2.1.2) Interference with the slice signal conduct Secondary delayed forwarding and superposition generate slice reconstruction interference. :

[0071] ,

[0072] In this embodiment, the number of forwardings .

[0073] 2.1.3) The jammer transmits the jamming signal to the radar, and the radar receiver receives the signal. Composed of the target echo, sliced ​​reconstructed interference signal, and noise, it is represented as follows:

[0074] ,

[0075] in, The target echo amplitude coefficient, For target latency, The amplitude coefficient of the interference signal is determined by the interference-to-signal ratio. Sure, To interfere with delay, It is additive white Gaussian noise, and its magnitude is determined by the signal-to-noise ratio. Confirmed, in this embodiment, it is set , , Interference delay Delay compared to target Lag The time-frequency diagram of the received signal, such as Figure 3As shown in (a).

[0076] Since the slice reconstruction interference in the received signal may fall into the processing interval corresponding to adjacent sub-segments or sub-pulse gaps after delayed forwarding, when processing the received signal, only the effective signal within the time interval corresponding to each sub-pulse needs to be extracted. The time interval corresponding to the sub-pulse gap is not included in the subsequent calculation. Therefore, based on the sub-pulse timing recorded in step 1... The received signal is segmented as follows:

[0077] 2.2) The receiving end follows the sub-pulse timing sequence recorded in step 1. With frequency modulation slope , build Each corresponding processing interval:

[0078] ,

[0079] in, For the first The processing interval corresponding to each sub-pulse;

[0080] 2.3) In the processing interval Internal extraction of received data to form the first Sub-segment signal :

[0081] ,

[0082] ,

[0083] in, For processing intervals Indicator functions.

[0084] After segmentation processing, the effective signal intervals corresponding to each sub-pulse are extracted, providing input for subsequent dual-channel pulse compression. Furthermore, the random gaps between the transmitted signal sub-pulses disrupt the strict timing periodicity between them, reducing the probability of the jammer accurately intercepting and predicting the transmission timing. Through segmentation processing of the received signal, the effect of slice reconstruction jamming on the radar producing false targets is initially weakened. The time-frequency diagram of the received signal after segmentation processing is shown below. Figure 3 As shown in (b).

[0085] Step 3, dual-channel pulse compression.

[0086] After the segmentation process in step 2, each sub-segment signal, in addition to containing the target echo with the same frequency modulation slope polarity as the current sub-segment, may also contain interference slices overflowing from adjacent sub-pulses due to interference forwarding delay. Since the frequency modulation slope polarities of adjacent sub-pulses are opposite, these interference slices are inconsistent with the desired polarity of the current sub-segment. To obtain the pulse compression response of each delay unit under reference signals of two polarities, it is necessary to process each sub-segment signal... Simultaneous compression of the matching and mismatched pulse channels is implemented, including:

[0087] 3.1) Matching channel pulse compression:

[0088] 3.1.1) Based on the number recorded in step 1 Frequency modulation slope of each sub-pulse Determine the first The reference signal of the matching channel corresponding to each sub-segment signal :

[0089] like ,but ,

[0090] like ,but ;

[0091] 3.1.2) Using the matched channel reference signal sub-segment signals Perform matched filtering to obtain the matched channel output. :

[0092] ,

[0093] in, for Conjugate time reversal;

[0094] 3.2) Mismatched channel pulse compression:

[0095] 3.2.1) According to the number recorded in step 1 Frequency modulation slope of each sub-pulse Determine the first The reference signal for the mismatched channel corresponding to each segment signal :

[0096] like ,but ,

[0097] like ,but ;

[0098] 3.2.2) Using the mismatched channel reference signal sub-segment signals Perform matched filtering to obtain the output of the mismatched channel. :

[0099] ,

[0100] in, for The conjugate time reversal.

[0101] After the segment signal is simultaneously compressed by the matched channel pulse compression and the mismatched channel pulse compression, the focusing effect of the pulse compression output of the two channels depends on the matching relationship between the frequency modulation slope polarity of the input signal and the polarity of their respective reference signals:

[0102] If the frequency modulation slope polarity of the input sub-segment signal is consistent with the polarity of the reference signal of the matching channel, the output of the matching channel will form a strong focus, while the output of the mismatched channel will have a poor focusing effect.

[0103] Conversely, the mismatched channel output has stronger focus, while the matched channel output has poorer performance. A comparison of the effects of matched and mismatched pulse pressure outputs is shown below. Figure 4 As shown.

[0104] Step 4, delay compensation.

[0105] Due to the start time of each sub-pulse Unlike step 3, the pulse compression results of each sub-segment output have a relative offset on the time delay axis. If cross-segment accumulation is performed directly, the responses of the same target in each sub-segment cannot be aligned and superimposed. To align the pulse compression outputs of each sub-segment under the same time delay coordinate, it is necessary to perform reverse time delay shift compensation on the matched channel output and mismatched channel output of each sub-segment according to the sub-pulse timing parameters recorded in step 1. The implementation includes:

[0106] 4.1) Regarding the first Matching channel output of each segment Translate it along the positive direction of the time delay axis The output of the matching channel after delay compensation is obtained:

[0107] ,

[0108] 4.2) For the first Mismatched channel output of each segment The same compensation method is used to obtain the time-delay compensated output of the mismatched channel:

[0109] ,

[0110] in, For the first The start time of each sub-pulse This is a time delay variable.

[0111] After the above compensation, the responses in each segment pulse compression output located at the same target time delay will be aligned on the time delay axis, providing a unified time delay reference benchmark for the construction of self-consistency index and dynamic weight generation in step 5, as well as the anomaly suppression and weighted accumulation in step 6.

[0112] Step 5: Construct self-consistent indices and generate dynamic weights.

[0113] After delay compensation in step 4, the outputs of the matched and mismatched channels of each sub-segment are aligned under the same delay coordinates. Since the target echo with polarity matching produces strong focusing in the matched channel but decreases in focusing ability in the mismatched channel, while the interference slice overflowing across the window exhibits the opposite characteristics, the energy difference between the two channels at the same delay unit can be used to measure the consistency between the signal component at that point and the polarity of the expected frequency modulation slope of the current sub-segment, and dynamic weights can be generated for each delay unit of each sub-segment accordingly.

[0114] 5.1) Output based on the matched channel after time delay compensation Output with mismatched channels The energy of the matching channel is calculated. Energy of mismatched channels :

[0115] ,

[0116] ,

[0117] 5.2) Construct a self-consistency index based on the matched channel energy and the mismatched channel energy. :

[0118] ,

[0119] in, As a numerically stable term, in this embodiment, we take... , for the Each delay unit of each sub-segment Calculate the self-consistency index Its value is determined by the polarity of the frequency modulation slope of the signal at that delay unit and the frequency modulation slope set for the current sub-segment. The matching relationship determines:

[0120] If the polarities of the two channels are the same, the energy of the matched channel is dominant over that of the mismatched channel. Approaching 1; if the point contains an interference slice of opposite polarity overflowing from an adjacent sub-pulse, the mismatched channel energy is enhanced. Decrease.

[0121] 5.3) Based on the self-consistency index Generate dynamic weights :

[0122] like This indicates that the point is relatively consistent with the expected polarity of the current sub-pulse, and is therefore given a larger weight.

[0123] like This indicates a significant polarity mismatch at this point, and therefore a smaller weight is assigned to it.

[0124] Its formula is expressed as follows:

[0125] ,

[0126] in, As the lower limit of the weight, The threshold for self-consistency decisions. The selection can be based on simulation or experimental statistical results; in this embodiment... , .

[0127] Step 6, anomaly suppression and weighted accumulation.

[0128] The dynamic weights generated in step 5 While polarity mismatch components in each delay unit can be suppressed, in some delay units, certain segments may not be identified by the dynamic weights because the interference slice happens to have the same polarity as the current segment. This results in an abnormal energy spike in that segment that is much higher than other segments in that delay unit. To further eliminate such local anomalies, it is necessary to utilize the stability of the energy distribution among segments within the same delay unit, using the median as a benchmark to detect abnormal segments, and then combine this with dynamic weights for weighted coherent accumulation. The implementation includes:

[0129] 6.1) The output energy of each segment's matching channel in the time delay unit The size of the output energy median :

[0130] ,

[0131] 6.2) Let The threshold for abnormal energy multiples. As the lower limit of the weight, based on the energy of the matching channel. and The size relationship generates abnormal inhibitory factors. :

[0132] If its matching channel energy If so, the segment is determined to have an abnormal peak value in the delay unit and is assigned the minimum weight;

[0133] If its matching channel energy If the segment does not have an abnormal peak value in the delay unit, it is determined that the segment does not have an abnormal peak value and is given a larger weight.

[0134] Its formula is expressed as follows:

[0135] ,

[0136] In this embodiment , The value is the same as in step 5.

[0137] 6.3) Dynamic weights With abnormal inhibitory factors Matching channel output after point-by-point multiplication with delay compensation Then, cross-segment coherent accumulation is performed to obtain the one-dimensional distance image result:

[0138] ,

[0139] Pick This serves as a one-dimensional distance profile, which can be used for subsequent object detection. During the aforementioned accumulation process, dynamic weights... and abnormal inhibitory factors The effect is applied point-by-point to each time delay unit in each sub-segment. For the time delay unit where the real target is located, due to its frequency modulation slope polarity being different from that of the current sub-segment... Consistent and with stable energy between segments, both weights are close to 1, the target energy is... The accumulation of individual segments effectively enhances the signal; however, if the delay unit containing the interference is affected by polarity mismatch... Suppress it; if the polarities are exactly the same but the energy is abnormally high, then This further suppresses the impact. The two mechanisms complement each other, significantly reducing the cumulative contribution of interference and suppressing the false target peak in the one-dimensional range profile.

[0140] Example 2: Anti-slice reconstruction interference system based on alternating frequency modulation slope polarity and timing agility.

[0141] Reference Figure 5 This example includes: waveform generation module 1, segmentation processing module 2, dual-channel pulse compression module 3, time delay compensation module 4, self-consistency index construction and dynamic weight generation module 5, and anomaly suppression and accumulation module 6. Among them, the dual-channel pulse compression module 3 includes a matched channel pulse compression submodule 31 and a mismatched channel pulse compression submodule 32.

[0142] The functions of each module are as follows:

[0143] The waveform generation module 1 is used to generate waveforms based on the number of sub-pulses. Sub-pulse duration Sub-pulse gap Sub-pulse bandwidth and subpulse frequency modulation slope Establish joint agile transmission signal Record sub-pulse timing With frequency modulation slope And launch;

[0144] The segmentation processing module 2 is used to process the received signal, which includes the echo, slice reconstruction interference, and noise of the signal emitted by the waveform generation module 1. The system receives and segments the data to obtain the desired results. Sub-segment signal The obtained sub-segment signal is then transmitted to the dual-channel pulse compression module 3;

[0145] The dual-channel pulse compression module 3 is used to process the pulses obtained from the segmentation processing module 2. Sub-pulse signal Perform pulse compression on the matched channel and the mismatched channel separately to obtain the output of the matched channel. and mismatched channel output The dual-channel output is then passed to the delay compensation module 4.

[0146] The dual-channel pulse compression module 3 is used to process the pulses obtained from the segmentation processing module 2. Sub-pulse signal Perform pulse compression on the matched channel and the mismatched channel separately to obtain the output of the matched channel. and mismatched channel output Among them, the matching channel pulse compression submodule 31 is used to use the first The matching channel reference signal corresponding to each segment For sub-segment signals Perform matched filtering to obtain the matched channel output. ; Mismatched channel pulse compression submodule 32, used for use with the first The mismatched channel reference signal corresponding to each segment The sub-segment signals obtained from segment processing module 2 Perform matched filtering to obtain the output of the mismatched channel. The outputs of these two sub-modules are both passed to the delay compensation module 4;

[0147] The time delay compensation module 4 is used to adjust the output of the matching channel obtained from the dual-channel pulse compression module 3. and mismatched channel output Perform time delay compensation to obtain the compensated matching channel output. and mismatched channel output Then, the compensated output is passed to the self-consistency index construction and dynamic weight generation module 5;

[0148] The self-consistency index construction and dynamic weight generation module 5 calculates the energy of the matching channel output based on the compensated dual-channel output output by the delay compensation module 4. Energy output from mismatched channels Constructing a self-consistent index Generate corresponding dynamic weights The matching channel output energy and dynamic weight are transmitted to the anomaly suppression and accumulation module 6.

[0149] The anomaly suppression and accumulation module 6 is used to calculate the matching channel output energy based on the self-consistency index construction and dynamic weight generation module 5. Constructing the median benchmark And based on this, abnormal inhibitory factors are generated. Combined with this abnormal inhibitory factor and the dynamic weights obtained from the self-consistency index construction and dynamic weight generation module 5 The outputs of each segment's matching channel after time delay compensation are weighted and accumulated to obtain a one-dimensional distance image result. .

[0150] It should be noted that the above functional modules can be implemented, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, they can be implemented, in whole or in part, as program instruction products. A program instruction product includes one or a set of program instructions. When the program instructions are loaded and executed on a computer, the described process or function is generated, in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The program instructions can be stored in a computer-readable and writable storage medium, or transferred from one computer's readable and writable storage medium to another.

[0151] The direct coupling or communication connections between the modules shown or discussed in this embodiment can be achieved through indirect coupling or communication connections via interfaces, devices, or modules. The functional modules and sub-modules in this embodiment can dynamically reside within a single processing unit, or each module can exist physically independently, or two or more modules can dynamically reside within a single processing unit. When these dynamic components are implemented as software functional modules and sold or used as independent products, they can also be stored in a computer-readable and writable storage medium. This storage medium can be a memory, disk, or optical disc, etc.

[0152] The effects of this invention can be further illustrated by the following simulation experiments:

[0153] I. Simulation Conditions

[0154] The hardware environment is as follows: CPU is Intel(R) Core(TM) i9-10900 with a clock speed of 2.80 GHz, memory is 16.0GB, and operating system is 64-bit; software environment is Microsoft Windows 10 Professional and MATLAB 2019 simulation software.

[0155] Assuming the interference type is slice reconstruction interference, its sampling pulse width is... Sampling period Number of reposts Interference delay Delay compared to target Lag Dry letter ratio Signal-to-noise ratio .

[0156] Let the intra-pulse frequency modulation slope polarity and the timing-coupled agile waveform bandwidth of this invention be respectively... The sub-pulse duration is The number of sub-pulses is The duration of the sub-pulse interval is Randomly select values ​​within the range; assume the waveform bandwidth of the conventional LFM pulse compression method is... Pulse duration .

[0157] II. Simulation Content

[0158] Under the above conditions, pulses were emitted using both the present invention and the conventional LFM pulse compression method under slice reconstruction interference conditions. After receiving the echo signals, the received signals were processed to obtain a one-dimensional range image, and the results are as follows. Figure 6 ,in Figure 6 (a) The result is the output using the conventional LFM pulse compression method. Figure 6 (b) is the result output using the method of the present invention.

[0159] from Figure 6 (a) It can be seen that the pulse compression output of the conventional LFM pulse compression method under the condition of slice reconstruction interference contains multiple dense false target peaks, and the amplitude of the false target peaks is higher than that of the real target main peak, making it difficult to effectively distinguish between the two.

[0160] from Figure 6(b) As can be seen, the true target peak remains clearly distinguishable in the output results of this invention, while the false target peak is significantly suppressed. This is because: the alternating polarity of the frequency modulation slope causes a mismatch between the interference slice overflowing across the window and the expected reference signal of the current sub-pulse segment, resulting in a decrease in its pulse compression focusing capability; the random sub-pulse gap disrupts the periodic structure of the interference, reducing the consistency of the false target across each sub-segment; the receiver adaptively adjusts the dynamic weight of the interfered range unit by constructing a self-consistency index and generating dynamic weights, and can further combine the cross-sub-segment anomaly suppression mechanism to weaken local abnormal peaks.

[0161] The comparative results show that, under the same interference conditions, the method of the present invention can better suppress false targets generated by slice reconstruction interference and maintain the detectability of real targets.

Claims

1. A method for resisting slice reconstruction interference based on alternating frequency modulation slope polarity and time-series agility, characterized in that, include: (1) The radar is based on the number of sub-pulses Sub-pulse duration Sub-pulse gap Sub-pulse bandwidth and subpulse frequency modulation slope Establish joint agile transmission signal Record sub-pulse timing With frequency modulation slope And launch; (2) The radar receives signals that include target echoes, slice reconstruction interference, and noise. Perform segmentation processing to obtain Sub-segment signal ; (3) Pair pulse signal Perform pulse compression on the matched channel and the mismatched channel separately to obtain the output of the matched channel. and mismatched channel output ,in The sub-pulse number. For delay units; (4) Output the matching channel and mismatched channel output Perform time delay compensation to obtain the compensated matching channel output. and mismatched channel output ; (5) Calculate the energy output of the compensated matching channel. Energy output from mismatched channels A self-consistency index is constructed based on these two types of energy. And generate corresponding dynamic weights. ; (6) For fixed delay units A median benchmark is constructed based on the matching channel energy of each segment. And based on this, abnormal inhibitory factors are generated. Combined with this abnormal inhibitory factor and dynamic weights The outputs of each segment's matching channel after time delay compensation are weighted and accumulated to obtain a one-dimensional distance image result. .

2. The method according to claim 1, characterized in that, The establishment of a joint agile transmission signal in (1) ,include: 1a) For the first Subpulse ( ), and set its frequency modulation slope to satisfy ,in That is, the polarity of the frequency modulation slope of adjacent sub-pulses changes alternately; 1b) Generate sub-pulse signals according to the set frequency modulation slope polarity. : When setting the number When the frequency modulation slope of each sub-pulse is positive, its sub-pulse signal is: ； When setting the number When the frequency modulation slope of each sub-pulse is negative, its sub-pulse signal is: ； 1c) Let the first... The start time of each sub-pulse is , No. The start time of each sub-pulse is , ,in For the first The sub-pulse and the first The duration of random intervals between sub-pulses This is the lower limit of the random interval duration. Its upper limit; 1d) The sub-pulse signals are spliced ​​together according to their start times to obtain the combined agile transmission signal. : 。 3. The method according to claim 1, characterized in that, In (2), the radar receives signals that include target echoes, slice reconstruction interference, and noise. Segmentation processing is performed, including: 2a) Based on the recorded sub-pulse timing , build Each corresponding processing interval : ， in, This serves as a reference delay parameter for reception processing. 2b) In each processing interval Internally, the received signal is extracted based on the indication function. ,get Sub-segment signal : ， ， in, For processing intervals Indicator functions.

4. The method according to claim 1, characterized in that, The sub-pulse signal in (3) Perform pulse compression on the matched channel and pulse compression on the mismatched channel separately, including: 3a) Matched channel pulse compression: 3a1) Let For the first Sub-segment signal The corresponding matching channel reference signal, its form is based on the recorded first... Subpulse frequency modulation slope Sure: like for The matching channel reference signal is: , like for The matching channel reference signal is: ; 3a2) Using the matched channel reference signal sub-segment signals Perform matched filtering to obtain the matched channel output. : ， in, for Conjugate time reversal; 3b) Mismatched channel pulse compression: 3b1) Let For the first Sub-segment signal The corresponding mismatched channel reference signal, its form is based on the recorded first... Subpulse frequency modulation slope Sure: like for The mismatch channel reference signal is: , like for The mismatch channel reference signal is: ; 3b2) Using the mismatched channel reference signal sub-segment signals Perform matched filtering to obtain the output of the mismatched channel. : ， in, for The conjugate time reversal.

5. The method according to claim 1, characterized in that, The matching channel output in (4) and mismatched channel output Time delay compensation is performed based on the start time of each sub-pulse relative to the first sub-pulse. The matched channel output and the mismatched channel output are respectively compensated by reverse time delay shift to obtain the aligned matched channel output. and mismatched channel output : ， ， in, This is a time delay variable.

6. The method according to claim 1, characterized in that, The calculated compensated matching channel output energy in (5) Energy output from mismatched channels It is output based on the aligned matching channels. and mismatched channel output The calculated formulas are as follows: ， 。 7. The method according to claim 1, characterized in that, The energy based on channel output in (5) Energy output from mismatched channels Constructing a self-consistent index And generate corresponding dynamic weights. The formulas are as follows: ， ， in, For numerically stable terms, The threshold for self-consistency decisions. This is the lower limit of the weight.

8. The method according to claim 1, characterized in that: The median benchmark is constructed in (6). And based on this, abnormal inhibitory factors are generated. ,include: 6a) For each delay unit Extract its in Median energy in the output of each segment matching channel : ， 6b) Let For the abnormal energy multiple threshold, the first Each sub-segment, based on the matching channel energy Identify abnormal inhibitory factors : ， in, This is the lower limit of the weight; The abnormal inhibitory factor in (6) and dynamic weights Weighted accumulation of the outputs of each segment matching channel is to apply dynamic weights. With abnormal inhibitory factors Matching channel output after point-by-point multiplication with delay compensation And perform cross-segment coherent accumulation to obtain one-dimensional distance image results. : 。 9. A system for resisting slice reconstruction interference based on alternating frequency modulation slope polarity and timing agility, characterized in that, include: The waveform generation module is used to generate waveforms based on the number of sub-pulses. Sub-pulse duration Sub-pulse gap Sub-pulse bandwidth and subpulse frequency modulation slope Establish joint agile transmission signal Record sub-pulse timing With frequency modulation slope And launch; The segmentation processing module is used to process the received signal, which includes target echo, slice reconstruction interference, and noise. Perform segmentation processing to obtain Sub-segment signal ; Dual-channel pulse compression module for processing sub-pulse signals Perform pulse compression on the matched channel and the mismatched channel separately to obtain the output of the matched channel. and mismatched channel output ; The delay compensation module is used to adjust the output of the matching channel. and mismatched channel output Perform time delay compensation to obtain the compensated matching channel output. and mismatched channel output ; The self-consistency index construction and dynamic weight generation module is used to calculate the energy of the compensated matching channel output. Energy output from mismatched channels A self-consistency index is constructed based on these two types of energy. And generate corresponding dynamic weights. ; Anomaly suppression and accumulation module, used for fixed delay units A median benchmark is constructed based on the matching channel energy of each segment. And based on this, abnormal inhibitory factors are generated. Combined with this abnormal inhibitory factor and dynamic weights The outputs of each segment's matching channel after time delay compensation are weighted and accumulated to obtain a one-dimensional distance image result. .

10. The system according to claim 9, characterized in that, The dual-channel pulse compression module includes: Matching channel pulse compression submodule, used for using the first The matching channel reference signal corresponding to each segment sub-segment signals Perform matched filtering to obtain the matched channel output. ,in The form is determined by the sub-pulse frequency modulation slope Sure; Mismatched channel pulse compression submodule, used for use with the first The mismatched channel reference signal corresponding to each segment sub-segment signals Perform matched filtering to obtain the output of the mismatched channel. ,in The form is determined by the sub-pulse frequency modulation slope Sure.

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