Anti-Intermittent Sampling Repeater Jamming and Target Detection Method Based on Time-Domain Waveform Features

Abstract

The present invention proposes an anti-intermittent sampling and forwarding interference and target detection method based on time-domain waveform features, including: eliminating interference by using the amplitude characteristics of strong interference signals in the time domain, so as to obtain interference-free radar echo signals. For the obtained interference-free radar echo signals, a secondary CFAR strategy combining signal smoothing and variable parameter CFAR detection is used to eliminate the problem of target peak dispersion caused by the cutting of target echoes, so as to achieve target detection. The interference signal elimination of the present invention is carried out in the time domain, without the need for complex transform domain calculations, only involving amplitude value judgment and interval judgment, with high operation efficiency, strong real-time performance and stability, and is easy to be realized in engineering; a secondary CFAR strategy of performing CFAR detection after signal smoothing is adopted to solve the problem of target peak splitting caused by time-domain interference elimination.

Description

Technical Field

[0001] The invention belongs to the technical field of radar signal processing, and in particular to a method for resisting intermittent sampling and forwarding interference and detecting a target based on time domain waveform characteristics. Background Art

[0002] In modern electronic warfare scenarios, radar plays an irreplaceable role in battlefield perception. With the rapid development of various active jamming technologies, the battlefield electromagnetic environment has become increasingly complex, and the interference threats faced by radar have become increasingly serious.

[0003] Interrupted-Sampling Repeater Jamming (ISRJ) based on Digital Radio Frequency Memory (DRFM) equipment generates interference signals that are highly coherent with the transmitted pulses and have a low delay by repeatedly sampling and forwarding the radar transmit pulses, thereby generating a large number of electronic false targets to drown out the real targets, and can raise the echo noise floor through smart noise modulation to achieve the suppression interference effect. Therefore, interrupted sampling repeater jamming has become a main lobe jamming style widely used in modern electronic warfare with its superior jamming performance and flexible jamming methods.

[0004] At present, research on main lobe intermittent sampling forwarding interference suppression or intermittent sampling forwarding interference electronic false target elimination is constantly advancing. Most algorithms rely on the estimation of intermittent sampling forwarding interference working parameters, or require calculations in complex transform domains such as time-frequency domain. Some adaptive algorithms implemented using neural networks rely on high-speed computing equipment, which is difficult to apply. Therefore, it is necessary to study an intermittent sampling forwarding interference suppression algorithm that is simple and effective in implementation. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention proposes a method for resisting intermittent sampling forwarding interference and target detection based on time domain waveform characteristics for pulse radar, so as to solve the problem that the main lobe intermittent forwarding interference affects the radar target detection performance.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] On the one hand, the present invention provides a method for resisting intermittent sampling forwarding interference based on time domain waveform characteristics, comprising:

[0008] Obtain radar echo signals, and preliminarily determine areas with interference signals and areas without interference signals based on the radar echo signals and the set energy threshold;

[0009] Consider the echo amplitude fluctuation generated within one pulse time, determine the duration of the region preliminarily judged as the interference-free signal region, and identify the interference signal region and the final interference-free signal region within the region preliminarily judged as the interference-free signal region;

[0010] Reconstruct Gaussian white noise based on the prior noise energy, and replace both the region preliminarily judged as the interference signal region and the interference signal region within the region preliminarily judged as the interference-free signal region with Gaussian white noise, thereby obtaining an interference-free radar echo signal.

[0011] In a second aspect, the present invention provides a target detection method, which adopts an anti-intermittent sampling and forwarding interference method based on time-domain waveform features to obtain an interference-free radar echo signal, and then performs target detection based on the interference-free radar echo signal.

[0012] Preferably, the target detection method includes:

[0013] Adopt an anti-intermittent sampling and forwarding interference method based on time-domain waveform features to obtain an interference-free radar echo signal, and output the average length of all intervals judged as the interference signal region and the interval between adjacent interference signal regions;

[0014] Perform matched filtering on the radar echo signal to obtain a one-dimensional range image;

[0015] Use the transmit signal pulse width, interference slice width, and slice forwarding times to estimate the peak distribution on the one-dimensional range image, and obtain the peak interval parameter;

[0016] Set the signal smoothing window length and the second-order constant false alarm rate detection parameter according to the peak interval parameter;

[0017] Perform signal smoothing on the one-dimensional range image based on the signal smoothing window length;

[0018] Perform second-order constant false alarm rate detection on the smoothed signal, and perform continuous interval judgment on the detection result. Map each continuous interval to the one-dimensional range image, and take the position of the maximum value point on the one-dimensional range image within each continuous interval as the target detection result.

[0019] On the other hand, the present invention provides a computer device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements the steps of the above-mentioned anti-intermittent sampling and forwarding interference method based on time-domain waveform features.

[0020] On the other hand, the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the steps of the above-mentioned anti-intermittent sampling and forwarding interference method based on time-domain waveform features.

[0021] On the other hand, the present invention provides a computer program product stored on a computer-readable storage medium and including computer instructions which, when run by a processor, cause a computer device to implement the steps of the above anti-intermittent sampling and forwarding interference method based on time-domain waveform features.

[0022] On the other hand, the present invention provides a computer device comprising a memory and a processor, the memory storing a computer program, and the processor implementing the steps of the above target detection method when executing the computer program.

[0023] On the other hand, the present invention provides a computer-readable storage medium having a computer program stored thereon, and the computer program implementing the steps of the above target detection method when executed by a processor.

[0024] On the other hand, the present invention provides a computer program product stored on a computer-readable storage medium and including computer instructions which, when run by a processor, cause a computer device to implement the steps of the above target detection method.

[0025] The present invention sets an interference determination amplitude threshold based on prior environmental noise energy estimation, and preliminarily distinguishes the area with interference signals from the area without interference signals through simple threshold judgment; considering the amplitude fluctuation of the received signal within one pulse time, it judges the duration of the area without interference signals, refines the distinction between the area with and without interference signals, and reduces the interval determination error caused by signal amplitude fluctuation; estimates the interference slice width and the slice forwarding times based on the length and interval of the divided interference area; reconstructs Gaussian white noise based on the prior noise energy, replaces the area with interference signals with noise, so as to obtain an interference-free echo. Next, it also includes a secondary constant false alarm rate detection for detecting the target echo signal cut into multiple segments. Compared with the prior art, the technical effects of the present invention are as follows:

[0026] The present invention provides an anti-intermittent sampling and forwarding interference method based on time-domain waveform features, which uses the amplitude characteristics of strong interference signals in the time domain to eliminate interference, so as to obtain an interference-free radar echo signal.

[0027] Based on the above anti-intermittent sampling and forwarding interference method based on time-domain waveform features, the present invention further provides a target detection method. For the obtained interference-free radar echo signal, it further excludes the problem of target peak dispersion caused by the cutting of the target echo through a secondary CFAR strategy combining signal smoothing and variable parameter CFAR detection, so as to achieve target detection.

[0028] The interference signal rejection of the present invention is carried out in the time domain, without the need for complex transform domain calculations, only involving amplitude value judgment and interval judgment, with high operation efficiency, strong real-time performance and stability, and is easy to be implemented in engineering.

[0029] The present invention adopts a secondary CFAR strategy of performing CFAR detection after signal smoothing to solve the problem of target peak splitting caused by interference rejection in the time domain. The present invention only affects the time domain echo received by the radar and the range one-dimensional image, and can further improve the target signal-to-noise ratio in combination with the data accumulation algorithm, and has good practical application ability. Brief Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0031] Figure 1 It is a flowchart of an anti-intermittent sampling and forwarding interference method based on time domain waveform characteristics provided in an embodiment;

[0032] Figure 2 It is a schematic diagram of the time domain echo amplitude of the outfield measured data in an embodiment;

[0033] Figure 3 For Figure 2 a schematic diagram of a partial enlargement of the interference signal area in the disturbed echo in;

[0034] Figure 4 It is a schematic diagram of the generated interference rejection window;

[0035] Figure 5 For Figure 4 a result diagram of a partial enlargement of the generated interference rejection window in;

[0036] Figure 6 For Figure 2 a schematic diagram of the time domain amplitude of the echo after interference signal rejection based on time domain waveform characteristics;

[0037] Figure 7 It is a comparison diagram of the range one-dimensional images obtained after the radar echo signals before and after anti-interference of the measured data in an embodiment are matched filtered;

[0038] Figure 8 It is a diagram of the splitting situation of the target peak point after anti-interference;

[0039] Figure 9 It is an overall process framework diagram of a target detection method provided in an embodiment;

[0040] Figure 10 Schematic diagram for comparing the range one-dimensional image after anti-interference, the signal smoothing result of the secondary CFAR, and the CFAR detection threshold;

[0041] Figure 11 For Simulation 1 Comparison chart of the range one-dimensional image after anti-interference, the signal smoothing result of the secondary CFAR, the CFAR detection threshold, and the single CFAR detection result under the slice interference scenario. Specific implementation manners

[0042] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0043] In one embodiment, an anti-intermittent sampling and forwarding interference method based on time-domain waveform features is provided. The interference signal is removed based on time-domain waveform features. Specifically, the intermittent sampling and forwarding interference signal is removed through two threshold judgments of an energy threshold and an interval length, including:

[0044] Obtain the radar echo signal,

[0045] Based on the radar echo signal and the set energy threshold, preliminarily judge the area with interference signals and the area without interference signals;

[0046] Considering the echo amplitude fluctuation generated within one pulse time, judge the duration of the area preliminarily judged as the area without interference signals to determine the area with interference signals and the final area without interference signals in the area preliminarily judged as the area without interference signals;

[0047] Reconstruct Gaussian white noise based on the prior noise energy, and replace both the area preliminarily judged as having interference signals and the area with interference signals in the area preliminarily judged as the area without interference signals with Gaussian white noise, so as to obtain an interference-free radar echo signal.

[0048] In an actual application scenario, the target echo energy is usually submerged in the noise floor, while the intermittent sampling and forwarding interference signal has a strong signal energy due to only passing through one-way propagation. There is a difference in amplitude between the two in the time domain. The target echo is the signal after the complete transmitted pulse is scattered by the target, while the intermittent sampling and forwarding interference signal is a discontinuous storage and forwarding signal of the radar transmitted waveform, which is manifested as short pulses with a fixed interval in the time domain. Therefore, by generating a window function based on the time-domain waveform features of the received radar echo signal, the intermittent sampling and forwarding interference signal can be removed. The specific removal method is described as follows:

[0049] Assume that the transmitted waveform of the radar satisfies the constant modulus constraint, then t At any time, the pulse waveform transmitted by the radar can be expressed by the following formula:

[0050] (1)

[0051] where is the pulse width of the radar transmitted waveform, is the function of the radar transmitted waveform varying with time.

[0052] Assume that the intermittent sampling and repeater jammer samples the radar pulse times after receiving it, obtaining sliced signals, and the time width of each slice is . After times of repeating, the ISRJ signal generated by the jammer can be written as:

[0053] (2)

[0054] where represents the total time required for sampling and repeating the first sliced signals. The signal sampled by the intermittent sampling and repeater jammer is:

[0055] (3)

[0056] The ISRJ signal repeated by the intermittent sampling and repeater jammer is:

[0057] (4)

[0058] Assume that the radar illuminates targets, and the time delays of the echo scattered by each target are ( represents the th target) The scattering coefficients of the targets are respectively . Among them, the time delay of the echo scattered by the target carrying the ISRJ jammer is , and the complex amplitude of the ISRJ jamming signal is

[0059] where is the prior environmental noise, usually referring to Gaussian white noise.

[0060] In the radar echo signal processing flow, analog-to-digital conversion is usually required to obtain discrete digital signals. Then, for the case of discrete-time digital echoes, based on the sampling rate the number of sampling points of the radar echo signal is obtained , the received radar echo signal .

[0061] In an actual scenario, the energy n of the radar echo signal corresponding to the th sampling point received is usually lower than the energy of the prior environmental noise , while the energy of the ISRJ signal is usually higher than the energy of the prior environmental noise . Therefore, an energy threshold is set based on a certain multiple of the energy of the prior environmental noise , and the regions with interference signals and without interference signals are preliminarily judged from the formula (6) - formula (7) to obtain the regions exceeding the threshold;

[0062] Among them, is a function to find the index of the value satisfying the condition in the array, is a function to calculate the signal amplitude, is the index of the points in the region exceeding the energy threshold (i.e., the region preliminarily judged to have interference signals), is the index of the points in the region not exceeding the energy threshold, that is, the region preliminarily judged to have no interference signals.

[0063] Figure 2 is a schematic diagram of the time-domain echo amplitude of the measured data in the field in an embodiment. Specifically, it is the time-domain amplitude of the radar echo signal after being interfered by 2 intermittent sampling and forwarding interference signals. The receiver sampling rate is 10 , the pulse width of the transmitted signal is 60 , the echo contains two intermittent sampling and forwarding interference signals, and the slice width of both is 10 , and it is forwarded once. Figure 3 is Figure 2 a schematic diagram of the partial enlargement of the interference signal region in the interfered echo in Figure 3 . As shown, the energy of the interference signal is much higher than that of the target echo, and the interference signal with a higher amplitude is subjected to smart noise modulation, which can achieve a suppression effect. In this data, the average energy of the noise is about 318096, and the amplitude is about 564. The set threshold multiple , then . ​

[0064] In the actually received radar echo signal, affected by the complex electromagnetic environment and propagation path, the echo amplitude will fluctuate. Therefore, not all points in the region that has not passed the energy threshold belong to the interference-free echo. There are interference signal points that are missed due to random amplitude fluctuations and need to be additionally judged for the interval length. Therefore, the present invention further proposes to consider the echo amplitude fluctuation generated within one pulse time and judge the duration of the region initially judged as the interference-free signal region to determine the interference signal region and the final interference-free signal region in the region initially judged as the interference-free signal region.

[0065] First, obtain The index of the value greater than 1 in the difference array is the start and end points of the continuous intervals in, so as to obtain the length of each continuous interval in the region that has not passed the energy threshold. Specifically, it can be obtained from formulas (8)-(11);

[0066]

[0067] Among them, is the difference function, is the start point of the interval, is the end point of the interval, is the array length, is the array length function, .

[0068] Formula (8) obtains the index values of all discontinuous points in through difference calculation. It is easy to know that each element value in is the end point of each continuous interval in, and the termination position of the last continuous interval must be the end of, so adding the element at the back end of the array can obtain the start position index array of all continuous intervals, as shown in formula (10). Since the condition for judging that the interval is discontinuous is the difference between adjacent elements in is greater than 1, each element in plus the increment "1" is the start position of the interval starting from the second continuous interval, and the start position of the first continuous interval must be 1. Therefore, adding the element 1 at the front end can obtain the start position index array of all continuous intervals, as shown in formula (9). Formula (11) calculates the difference between the end position and the start position of each continuous interval to obtain the length array of each interval, , represents the The length of consecutive intervals. Considering that there may be anomalies where there are multiple consecutive isolated points exceeding the threshold, eliminate the elements with a value of 0 in

[0069] According to the sampling rate of the radar echo signal receiving system and the interference slice width set the time threshold ;

[0070] Based on the time threshold, judge the length of each consecutive interval in the region that has not exceeded the energy threshold to obtain the final interference-free signal region.

[0071] The time threshold needs to be set according to the sampling rate of the receiving system and the interference slice width and is obtained by formula (12) in the known case; in the unknown case, let be its minimum value, and , is set to the minimum value calculated by formula (13). Considering that the output signal of the jammer may have a trailing phenomenon, the magnification factor is set to to avoid the signal amplitude of the trailing section from affecting the interval judgment;

[0072] where is the rounding function.

[0073] Based on the time threshold judge the length of each consecutive interval in the region that has not exceeded the energy threshold. The judgment method is as follows: for any consecutive interval length in the region that has not exceeded the energy threshold, if the consecutive interval length is greater than or equal to the time threshold, it is an interference-free signal region; if the consecutive interval length is less than the time threshold, it is a region with interference signals in the region preliminarily judged as an interference-free signal region, as shown in formula (14):

[0074]

[0075] After the above calculations, determine the region with interference signals in the region preliminarily judged as an interference-free signal region and the final interference-free signal region. The region preliminarily judged as having interference signals and the region with interference signals in the region preliminarily judged as an interference-free signal region are used as the final region with interference signals.

[0076] Reconstruct Gaussian white noise based on the prior noise energy, replace all areas with interfering signals with Gaussian white noise to obtain a radar echo signal without interference. Perform target detection based on the obtained radar echo signal without interference. The specific target detection method is not limited, and existing methods can be used to achieve target detection.

[0077] Based on Equation (13), in the measured data (assuming the parameters of the jammer are unknown by default), Figure 4 is a schematic diagram of the generated interference rejection window, Figure 5 is for Figure 4 the result diagram after locally magnifying the generated interference rejection window in Figure 6 is for Figure 2 the schematic diagram of the time-domain amplitude of the echo after removing the interference signal based on the time-domain waveform characteristics, and the time-domain echo after interference rejection is obtained.

[0078] In one embodiment, a target detection method is proposed. The intermittent sampling and forwarding interference signal is removed by two threshold judgments of the energy threshold and the interval length, and then the range one-dimensional image without interference is obtained through matched filtering. After smoothing the range one-dimensional image, CFAR detection is performed, and the target detection result is obtained by judging the position of the maximum value in the interval on the original one-dimensional image. Specifically, the steps include:

[0079] Adopt the anti-intermittent sampling and forwarding interference method based on the time-domain waveform characteristics provided in the above embodiment to obtain a radar echo signal without interference, and output the average length of all intervals determined to have interference signal areas and the interval between adjacent interference signal areas;

[0080] Perform matched filtering on the radar echo signal to obtain the range one-dimensional image;

[0081] Use the pulse width of the transmitted signal, the width of the interference slice, and the number of slice forwarding times to estimate the peak distribution on the range one-dimensional image to obtain the peak interval parameter;

[0082] Set the signal smoothing window length and the secondary constant false alarm rate detection parameter according to the peak interval parameter;

[0083] Perform signal smoothing on the range one-dimensional image based on the signal smoothing window length;

[0084] Perform secondary constant false alarm rate detection on the smoothed signal, and perform continuous interval judgment on the detection result. Map each continuous interval to the range one-dimensional image, and take the position of the maximum value point on the range one-dimensional image within each continuous interval as the target detection result, so as to achieve the purpose of removing the influence of target side lobes.

[0085] Among them, the anti-intermittent sampling and forwarding interference method based on the time-domain waveform characteristics to obtain a radar echo signal without interference has been described in detail in the foregoing embodiment and will not be elaborated here.

[0086] In the radar receiving echo, the target echo is usually interfered by various noises, clutters, etc. In order to suppress the above interference to achieve target detection, a filter is needed for frequency selection. In addition, in order to solve the contradiction between the detection range and spatial resolution of the radar, it is necessary to perform pulse compression processing on the radar receiving echo, that is, the radar transmits a waveform with a relatively wide width so that the transmitted signal has a sufficiently high energy to ensure the detection range of the radar. When receiving the target echo, the radar echo is pulse compressed, thereby compressing the wide pulse into an extremely narrow pulse with a high peak value, thereby improving the radar's distance resolution. Therefore, it is necessary to perform matched filtering on the radar receiving echo.

[0087] The matched filter at the receiving end of the pulse radar is usually based on a signal constructed based on the emission parameters of the radiation source, which is called the reference signal. . The matched filter convolves the received echo with the conjugate of the reference signal in the time domain, and transforms it to the frequency domain by multiplying the two. Discrete Fourier Transform (DFT) and Inverse Discrete Fourier Transform (IDFT) are shown in formula (15) and formula (16). In practical applications, their fast algorithms are usually used, namely Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT).

[0088] The Fourier transform of the received wave and the reference signal is performed according to formula (15) and formula (16) to obtain the spectrum of the two. and , then the one-dimensional image of the distance after matched filtering is as follows:

[0089]

[0090] Figure 7 The one-dimensional image of the distance is obtained after matched filtering of the echo before and after the measured data anti-interference in an embodiment, wherein the anti-interference method is the anti-interruption sampling forwarding interference method based on the time domain waveform characteristics provided in the above embodiment. It can be clearly seen that after the time domain interference removal process, there is basically no interference signal energy remaining on the one-dimensional image of the distance.

[0091] After the time domain interference signal is removed, the target echo signal is truncated into a form similar to the ISRJ signal, and there is a split from the target peak point on the one-dimensional image. In order to avoid the influence of the secondary peak on the target detection, it is necessary to set the CFAR detection threshold based on the split peak distribution law.

[0092] Estimate the peak distribution on the one-dimensional range image using the transmitted signal pulse width, interference slice width, and slice forwarding times to obtain the peak interval parameter, i.e., the main and side peak intervals. Specifically, the target peak points on the one-dimensional range image are split, and the interval between the split peaks depends on the number of slice signals segmented from the target echo. In the scenario of a single intermittent sampling and forwarding interference signal, if the transmitted signal pulse width is known , the interference slice width and the slice forwarding times , based on the receiver sampling rate the known number of samples for the pulse width and the number of samples for the slice signal , then the number of slice signals segmented from the target echo signal can be calculated by the following formula:

[0093]

[0094] where, is the floor function, is the remainder function of.

[0095] Based on the number of slice signals segmented from the target echo signal , the main and side peak intervals are obtained as follows:

[0096] In the scenario of two intermittent sampling and forwarding interference signals, if the interference slice widths are the same, it does not affect the calculation of the main and side peak intervals, and the calculation method of the main and side peak intervals is the same as that in the scenario of only a single intermittent sampling and forwarding interference signal. If the interference slice widths of the two intermittent sampling and forwarding interference signals are different, it is equivalent to further slicing each wider interference slice based on the smaller interference slice width. For the smaller interference slices, the signal pulse width used to calculate the number of interference slices is the slice width of the larger interference slice, and its is calculated based on formula (18), and then multiplied by the number of slice signals of the larger interference slice which is the final . In the scenario of more intermittent sampling and forwarding interference signals, it can be deduced by analogy.

[0097] In the actual application scenario, the detailed working parameters of the jammer are unknown. When applying the present invention, it is usually regarded as a single interference, and the interval between adjacent interference regions is equivalent to the interference slice width , and the ratio between the average interval length of the interference signal region and after rounding is equivalent to the slice forwarding times , then calculate the main and secondary peak intervals based on Equation (18) and Equation (19).

[0098] Figure 5 To Figure 4 Figure of the result after locally magnifying the interference rejection window generated in 、the forwarding times is 2. It can be known from Equation (18) and Equation (19) that the peak interval is 6. Figure 8 Figure of the splitting situation of the target peak point after anti-interference, which conforms to the calculation result.

[0099] The present invention uses a secondary CFAR strategy for target detection. First, set the signal smoothing window length and secondary constant false alarm rate detection parameters according to the main and secondary peak intervals to smooth the range profile, and smooth the split peaks into a curve; then perform secondary constant false alarm rate detection on the smoothed curve, and make a continuous interval judgment on the detection result, map each continuous interval to the range profile, and take the position of the maximum value point on the range profile within each continuous interval as the target detection result.

[0100] The signal smoothing window length and secondary constant false alarm rate detection parameters need to be set in segments according to the value of the main and secondary peak intervals . The main influencing parameter is the signal smoothing window length and the protection window length (one-sided) of the CFAR detection. The training window length of the CFAR detection can be set to a fixed value. According to the main and secondary peak intervals, the main distinguishing scenarios are divided into 、 and . When the main and secondary peak intervals are very large, in order to avoid excessive signal smoothing, the signal smoothing window length cannot exceed . At this time, the energy of the secondary peak is relatively low, and usually only the first and second secondary peaks have a greater impact on the CFAR detection. Therefore, the protection window length needs to cover the second secondary peak; and when is at an intermediate value, the main and secondary peaks are relatively closely distributed. The signal smoothing window length needs to cover the first secondary peak, and the CFAR detection protection window length needs to cover the third secondary peak; when is further reduced, the main and secondary peaks are relatively closely distributed. The signal smoothing window length needs to cover the second secondary peak, and the CFAR detection protection window length needs to cover the fifth secondary peak. The specific settings are as follows:

[0101] In order to avoid the split secondary peaks from being detected and affecting the detection of the main peak, first, based on the signal smoothing window length perform on the range profile Perform signal smoothing as shown in formula (22):

[0102]

[0103] Wherein, is the minimum value function, is the maximum value function, is the number of pulse sampling points of the radar echo signal.

[0104] For the smoothed signal perform CFAR detection and set the constant false alarm rate , the detection threshold at the -th range cell is as follows:

[0105]

[0106] Wherein, is the position index of the training cell interval on the left side of the target point , is the position index of the training cell interval on the right side of the target point .

[0107] For perform threshold judgment to obtain the over-threshold point index array :

[0108] Wherein, is the function to find the element indices where the corresponding elements in two arrays of the same length meet the conditions.

[0109] Similar to formulas (8) to (10), perform continuous interval judgment on the over-threshold point index array . To avoid the influence of possible adjacent peaks, when performing the start and end point judgment of the interval based on formula (8), change the threshold "1" in formula (8) to a larger number , > 1, and finally obtain the continuous interval:

[0110]

[0111] Find the maximum value index in each continuous interval on the range one-dimensional image , which is the target point range cell:

[0112] So far, the final target detection result is obtained, achieving the purpose of eliminating the influence of the target side peak. Refer to Figure 9 which is the overall process framework diagram of the target detection method provided in the above embodiment.

[0113] Figure 10 Schematic diagram for comparing the one-dimensional range profile after anti-interference, the signal smoothing result of the secondary CFAR, and the CFAR detection threshold. Since the target peak intervals in the measured data are too small to clearly observe the difference between the secondary CFAR strategy and the single CFAR strategy, the simulation is affected by analyzing the data with slice interference, as Figure 11 shown. Figure 11 For Simulation 1 In the slice interference scenario, the comparison diagram of the one-dimensional range profile after anti-interference, the signal smoothing result of the secondary CFAR, and the CFAR detection threshold with the single CFAR detection result. It can be easily seen that through the above secondary CFAR strategy, the influence of the target split peak can be effectively suppressed.

[0114] On the other hand, the present invention provides a computer device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the steps of the anti-intermittent sampling and forwarding interference method based on time-domain waveform features provided in any of the above embodiments are implemented. This computer device can be a server. This computer device includes a processor, a memory, a network interface, and a database connected through a system bus. Among them, the processor of this computer device is used to provide computing and control capabilities. The memory of this computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of this computer device is used to store sample data. The network interface of this computer device is used to communicate with an external terminal through a network connection.

[0115] On the other hand, the present invention provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the anti-intermittent sampling and forwarding interference method based on time-domain waveform features provided in any of the above embodiments are implemented.

[0116] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, storage, database, or other medium used in the various embodiments provided in the present application can include non-volatile and / or volatile memories. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or an external cache. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and Rambus dynamic RAM (RDRAM), etc.

[0117] Matters not described in the present invention are well-known technologies.

[0118] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, 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, it should be considered as the scope described in this specification.

[0119] The above-described embodiments only represent several implementation manners of the present application. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

[0120] The above is only the preferred embodiment of the present invention and is not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An anti-intermittent sampling and repeater jamming method based on time-domain waveform characteristics, characterized in that Including: Obtain radar echo signals. Based on the radar echo signals and a set energy threshold, preliminarily determine the interference signal area and the non-interference signal area, where the energy threshold is set based on a certain multiple of the prior environmental noise energy. Considering the echo amplitude fluctuation generated within one pulse time, judge the duration of the area preliminarily determined as the non-interference signal area to determine the interference signal area in the area preliminarily determined as the non-interference signal area. The area preliminarily determined as the interference signal area and the interference signal area in the area preliminarily determined as the non-interference signal area are used as the final interference signal area. Reconstruct Gaussian white noise based on the prior noise energy, and replace both the area preliminarily determined as the interference signal area and the interference signal area in the area preliminarily determined as the non-interference signal area with Gaussian white noise, so as to obtain an interference-free radar echo signal.

2. The anti-intermittent sampling and repeater jamming method based on time-domain waveform features according to claim 1, wherein Based on a certain multiple of the prior environmental noise energy Set an energy threshold , where represents the prior environmental noise energy.

3. The anti-intermittent sampling and forwarding jamming method based on time-domain waveform features according to claim 2, characterized in that Preliminarily determine the interference signal area and the non-interference signal area. The method is as follows: Among them is a function to find the index of the value that meets the condition in the array; is a function to calculate the signal amplitude; is the n radar echo signal corresponding to the index of the point passing through the energy threshold region, that is, the region initially judged to have interference signals; is the index of the point not passing through the energy threshold region, that is, the region initially judged to have no interference signals.

4. The anti-intermittent sampling and forwarding jamming method based on time-domain waveform features according to claim 3, characterized in that Determine the interference signal area in the area preliminarily determined as the non-interference signal area and the final non-interference signal area, including: Obtain The index of the value greater than 1 in the difference array is the start and end points of the continuous interval in, so as to obtain the length of each continuous interval in the area where the energy threshold is not exceeded; Set a time threshold according to the sampling rate of the radar echo signal receiving system and the interference slice width. Based on the time threshold, judge the length of each continuous interval in the area that has not passed the energy threshold to obtain the final non-interference signal area.

5. The anti-intermittent sampling and forwarding interference method based on time-domain waveform characteristics according to claim 4, wherein According to the sampling rate of the radar echo signal receiving system and the interference slice width Set a time threshold, and the method includes: Width of interference slice If known, time threshold ; Width of the interference slice If it is unknown, let be its minimum value, , time threshold ; Among them, is a rounding function.

6. The anti-intermittent sampling and repeater jamming method based on time-domain waveform features according to claim 4, characterized in that Based on the time threshold, judge the length of each continuous interval in the area that has not passed the energy threshold. The method is as follows: For any continuous interval length in the area that has not passed the energy threshold, if the continuous interval length is greater than or equal to the time threshold, it is a non-interference signal area; if the continuous interval length is less than the time threshold, it is an interference signal area in the area preliminarily determined as the non-interference signal area.

7. A target detection method, characterized in that, Including: Adopt the anti-intermittent sampling and repeater jamming method based on time-domain waveform features as described in any one of claims 1 to 6 to obtain an interference-free radar echo signal, and output the average interval length of all areas judged as interference signal areas and the interval between adjacent interference signal areas. Perform matched filtering on the radar echo signal to obtain a range one-dimensional image. Use the transmit signal pulse width, interference slice width, and slice repeater times to estimate the peak distribution on the range one-dimensional image to obtain peak interval parameters. Set a signal smoothing window length and a secondary constant false alarm rate detection parameter according to the peak interval parameters. Perform signal smoothing on the range one-dimensional image based on the signal smoothing window length. Perform secondary constant false alarm rate detection on the smoothed signal, and perform continuous interval judgment on the detection results. Map each continuous interval to the range one-dimensional image, and take the position of the maximum value point on the range one-dimensional image within each continuous interval as the target detection result.

8. The object detection method according to claim 7, wherein Use the transmit signal pulse width, interference slice width, and slice repeater times to estimate the peak distribution on the range one-dimensional image to obtain peak interval parameters, including: Equivalent the interval between adjacent interference regions to the interference slice width , take the integer part of the ratio between the interval average length of the interference signal region and as the equivalent slice forwarding times ; Known transmit signal pulse width , interference slice width and slice forwarding times , based on the receiver sampling rate Number of sampling points for known pulse width and number of sampling points for slice signal , the number of slice signals segmented from the target echo signal is calculated by the following formula: wherein, is the floor function, is the remainder function of The number of slice signals segmented from the target echo signal , the main and secondary peak intervals are obtained as follows: Main and secondary peak interval That is, the required peak interval parameter.

9. The object detection method according to claim 8, wherein Set a signal smoothing window length and a secondary constant false alarm rate detection parameter according to the peak interval parameters, where the signal smoothing window length and the protection window length of the CFAR detection are set as follows: Among them is the signal smoothing window length, is the protection window length for CFAR detection.

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