Intermittent sampling forwarding interference resisting method based on multistage threshold processing

Abstract

The invention relates to a method for resisting intermittent sampling forwarding interference based on multistage threshold processing. The method comprises the following steps: acquiring a sum path orthogonal baseband signal and an auxiliary branch orthogonal baseband signal; determining a target echo signal range, and calculating a signal matrix of a sum path level based on the target echo signal range and the sum path orthogonal baseband signal; determining a first-level interference elimination threshold according to the signal matrix, and performing first-level interference elimination processing on the signal matrix and the sum path orthogonal baseband signal based on the first-level interference elimination threshold; according to the pulse sampling point number and the zero setting point number of the first-stage interference elimination processing, interference judgment is carried out on the sum path orthogonal baseband signal after the first-stage interference elimination processing; and when interference exists, determining a second-level interference elimination threshold according to the signal matrix after the first-level interference elimination processing, and performing multi-level interference elimination processing on the sum path orthogonal baseband signal after the first-level interference elimination processing based on the second-level interference elimination threshold to obtain a target signal. According to the invention, confrontation to intermittent sampling forwarding interference is realized.

Description

Technical Field

[0001] The present disclosure relates to the field of radar countermeasure technology, and in particular to a method for counteracting intermittent sampling forwarding interference based on multi-level threshold processing. Background Art

[0002] With the use of active jammers, the electromagnetic combat environment faced by ground radars is becoming increasingly complex. Digital frequency storage and forwarding jamming is a common working mode in active jammers. On the one hand, it can generate an interference waveform with strong coherence with the radar transmission waveform. On the other hand, because it can quickly and accurately recognize the radar transmission waveform, it can cover the radar operating frequency.

[0003] In the prior art, in some typical working scenarios such as missile-borne jammers, intermittent sampling and forwarding jammers have been widely used as a typical digital frequency storage and forwarding jammer to generate intra-pulse interference to ground radars. However, since the recognition time of radar waveform mode and frequency by intermittent sampling and forwarding jammers has reached the microsecond level, conventional waveform agility or frequency agility methods can no longer counter intermittent sampling and forwarding jammers.

[0004] Therefore, it is necessary to provide a new technical solution to improve one or more problems existing in the above solutions.

[0005] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0006] The purpose of the embodiments of the present disclosure is to provide a method for counteracting intermittent sampling and forwarding interference based on multi-level threshold processing, so as to counteract intermittent sampling and forwarding interference, so that the interference is effectively suppressed and the target signal can be detected normally.

[0007] According to an embodiment of the present disclosure, a method for counteracting intermittent sampling forwarding interference based on multi-stage threshold processing is provided, comprising:

[0008] Obtaining the sum-branch orthogonal baseband signal and the auxiliary branch orthogonal baseband signal;

[0009] Determine a target echo signal range, and calculate a signal matrix based on the target echo signal range and the orthogonal baseband signal;

[0010] Determine a primary interference removal threshold according to the signal matrix, and perform primary interference removal processing on the signal matrix and the summed orthogonal baseband signal based on the primary interference removal threshold;

[0011] Perform interference judgment on the sum-path orthogonal baseband signal after the first-level interference elimination processing according to the number of pulse sampling points and the number of zeroing points of the first-level interference elimination processing;

[0012] When interference exists, a secondary interference removal threshold is determined according to the signal matrix after the primary interference removal processing, and multi-stage interference removal processing is performed on the orthogonal baseband signal after the primary interference removal processing based on the secondary interference removal threshold to obtain the target signal.

[0013] In an exemplary embodiment of the present disclosure, the target echo signal range is determined by formula (1):

[0014]

[0015] Among them, j start Indicates the starting point of the target echo signal, j end Indicates the target echo signal cutoff point, t q Indicates the time from the front edge of the signal to the front edge of the gate, F s represents the sampling frequency, and τ represents the pulse width of the transmitted signal.

[0016] In an exemplary embodiment of the present disclosure, the calculating of the signal matrix based on the target echo signal range and the sum of the orthogonal baseband signals includes:

[0017] Performing modulus processing on the summing-path orthogonal baseband signal and the auxiliary branch orthogonal baseband signal to obtain a modulus matrix of the summing-path orthogonal baseband signal and a modulus matrix of the auxiliary branch orthogonal baseband signal;

[0018] Based on the target echo signal range, the module value matrix of the summed orthogonal baseband signals is selected and processed to obtain the signal matrix.

[0019] In an exemplary embodiment of the present disclosure, determining the primary interference rejection threshold according to the signal matrix includes:

[0020] The signal matrix is ​​averaged to obtain a first-level time domain threshold;

[0021] Based on the primary time domain threshold and spatial domain threshold, the signal matrix is ​​subjected to threshold processing by formula (2) to obtain a first sequence:

[0022]

[0023] Among them, A3 ik Indicates the first sequence, A2' ik represents the pulse signal in the signal matrix that satisfies the first sequence, |A2 ij | represents the modulus of each pulse signal in the signal matrix, avg1 iRepresents the first-level time domain threshold, P coef represents the airspace threshold, |A1 Fij | represents the modulus value of each pulse signal of the auxiliary branch orthogonal baseband signal, && represents the "and" relationship;

[0024] Performing non-zero value selection processing on the first sequence to obtain a second sequence;

[0025] The second sequence is averaged to obtain the first-level interference removal threshold.

[0026] In an exemplary embodiment of the present disclosure, the performing of a first-level interference removal process on the signal matrix and the sum of orthogonal baseband signals based on the first-level interference removal threshold includes:

[0027] Based on the primary interference rejection threshold, the signal matrix is ​​subjected to primary interference zeroing processing by formula (3), and the sum of the orthogonal baseband signals is subjected to primary interference zeroing processing by formula (4):

[0028]

[0029] Among them, A2 ik represents the signal matrix after the first-level interference zeroing process, |A2 ij | represents the modulus value of each pulse signal in the signal matrix, gate1 i represents the first-level interference rejection threshold, K1 represents the first threshold coefficient, k represents the target echo signal range, and the value range of k is [j start ,j end ];

[0030]

[0031] Among them, A ik represents the sum of the orthogonal baseband signals after the first-level interference zeroing process, |A ij | represents the modulus of each pulse signal of the orthogonal baseband signal, gate1 i represents the first-level interference rejection threshold, K1 represents the first threshold coefficient, k represents the target echo signal range, and the value range of k is [j start ,j end ].

[0032] In an exemplary embodiment of the present disclosure, the interference judgment is performed on the sum-path orthogonal baseband signal after the first-level interference elimination processing according to the number of pulse sampling points and the number of zeroing points of the first-level interference elimination processing, including:

[0033] Based on the sum of the orthogonal baseband signals after the first-level interference elimination process, the fluctuation factor is calculated by formula (5):

[0034]

[0035] Among them, Ra i represents the fluctuation factor, X 1i It represents the pulse zeroing signal vector of the orthogonal baseband signal in the first-level interference zeroing process, X 2i It represents the signal vector of each pulse not set to zero when the orthogonal baseband signal is processed in the first-level interference zeroing process, abs(X 1i ) indicates that X 1i Take the absolute value, abs(X 2i ) indicates that X 2i Take the absolute value, mean(abs(X 1i )) indicates abs(X 1i ) takes the mean, mean(abs(X 2i )) indicates abs(X 2i ) take the mean;

[0036] Based on the sum of the orthogonal baseband signals after the first-level interference removal process, the number of first-level interference zeroing points is obtained;

[0037] The first-level interference zeroing points and the fluctuation factor are compared to obtain a first comparison result, and an interference judgment result is obtained according to the first comparison result.

[0038] In an exemplary embodiment of the present disclosure, the comparing the number of the first-level interference zeroing points with the fluctuation factor to obtain a first comparison result, and obtaining an interference judgment result according to the first comparison result includes:

[0039] The comparison is performed using formula (6):

[0040] Q i <0.3K&&Ra i >Coeff1(6)

[0041] Among them, Q i represents the number of zeroing points for primary interference, K represents the number of pulse sampling points, Ra i represents the fluctuation factor, Coeff1 represents the first noise level coefficient;

[0042] When formula (6) is satisfied, there is no interference in the sum-path orthogonal baseband signal after the first-level interference elimination process; otherwise, there is interference.

[0043] In an exemplary embodiment of the present disclosure, when interference exists, determining a secondary interference removal threshold according to a signal matrix after primary interference removal processing includes:

[0044] The signal matrix after the first-level interference elimination process is processed by selecting non-zero values ​​to obtain a third sequence;

[0045] Performing averaging processing on the third sequence to obtain a first multi-level time domain threshold;

[0046] Based on the first multi-level time domain threshold, performing threshold processing on the third sequence to obtain a fourth sequence;

[0047] Performing non-zero value selection processing on the fourth sequence to obtain a fifth sequence, and performing averaging processing on the fifth sequence to obtain a second multi-level time domain threshold;

[0048] The first multi-level time domain threshold and the second multi-level time domain threshold are processed by formula (7) to obtain the secondary interference rejection threshold:

[0049]

[0050] Among them, gate2 i Indicates the secondary interference rejection threshold, avg4 i Indicates the second multi-level time domain threshold, avg3 i represents the first multi-level time domain threshold, and K2 represents the second threshold coefficient.

[0051] In an exemplary embodiment of the present disclosure, the performing multi-stage interference removal processing on the sum-path orthogonal baseband signal after the first-stage interference removal processing based on the second-stage interference removal threshold includes:

[0052] Based on the secondary interference rejection threshold and the spatial domain threshold, interference zeroing processing is performed on the sum-path orthogonal baseband signal after the primary interference rejection processing by formula (8):

[0053]

[0054] Among them, A7 ij represents the orthogonal baseband signal after multi-stage interference removal, |A ij | represents the orthogonal baseband signal after the first-level interference elimination process, K3 represents the third threshold coefficient, gate2 i represents the secondary interference rejection threshold, P coef represents the airspace threshold, which is determined by the antenna gain of the radar's auxiliary branch and the antenna gain of the sum path. Fij | represents the modulus value of each pulse signal of the auxiliary branch orthogonal baseband signal, && represents the "and" relationship, A ik Represents the sum-and-quadrature baseband signal without zeroing.

[0055] In an exemplary embodiment of the present disclosure, after performing multi-stage interference removal processing on the sum of orthogonal baseband signals after the first-stage interference removal processing based on the second-stage interference removal threshold, the method further includes:

[0056] Based on the sum-path orthogonal baseband signal after multi-stage interference elimination processing, the number of multi-stage interference zeroing points is obtained;

[0057] Determine a zeroing threshold according to the length of the summed orthogonal baseband signal, compare the number of multi-level interference zeroing points with the zeroing threshold, and obtain a second comparison result;

[0058] According to the second comparison result, one of the sum-path orthogonal baseband signals after the first-stage interference elimination processing and the sum-path orthogonal baseband signals after the multi-stage interference elimination processing is selected as the target signal.

[0059] The technical solution provided by the present disclosure may have the following beneficial effects:

[0060] In the embodiments of the present disclosure, according to the time domain characteristics of intermittent sampling forwarding interference, the signal matrix of the S-path level is determined based on the target echo signal range and the S-path orthogonal baseband signal, which can remove the interference transition band introduced by the transient effect of the filter, and maximize the guarantee that the signal matrix of the S-path level is not affected by interference, thereby enhancing the accuracy of the target echo noise level processing; further, according to the first-level interference rejection threshold determined by the signal matrix, the first-level interference rejection processing is performed on the signal matrix and the S-path orthogonal baseband signal, and according to the number of pulse sampling points and the number of zeroing points of the first-level interference rejection processing, the S-path orthogonal baseband signal after the first-level interference rejection processing is subjected to interference judgment; when interference exists, the second-level interference rejection threshold is determined according to the signal matrix after the first-level interference rejection processing, and based on the second-level interference rejection threshold, multi-level interference rejection processing is performed on the S-path orthogonal baseband signal after the first-level interference rejection processing, so as to realize the countermeasure against intermittent sampling forwarding interference, so that the interference is effectively suppressed and the target signal can be detected normally.

[0061] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0063] Figure 1 A flowchart showing the steps of a method for counteracting intermittent sampling forwarding interference based on multi-stage threshold processing in an exemplary embodiment of the present disclosure;

[0064] Figure 2A schematic diagram showing the real part of the sum of the orthogonal baseband signals of a certain target tracking wave position under the intermittent sampling forwarding interference state in an exemplary embodiment of the present disclosure;

[0065] Figure 3 A schematic diagram showing a mode of a summed orthogonal baseband signal after multi-stage interference rejection processing in an exemplary embodiment of the present disclosure;

[0066] Figure 4 A schematic diagram showing a sum-path orthogonal baseband signal that has not been processed for interference removal and a target signal that has been processed for multi-stage interference removal in an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0067] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the disclosure will be more comprehensive and complete and to fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0068] In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0069] In this example implementation, a method for counteracting intermittent sampling forwarding interference based on multi-level threshold processing is first provided. Figure 1 As shown in , the method may include the following steps:

[0070] Step S101: Acquire the sum branch orthogonal baseband signal and the auxiliary branch orthogonal baseband signal;

[0071] Step S102: determining the target echo signal range, and calculating the signal matrix of the sum level based on the target echo signal range and the sum orthogonal baseband signal;

[0072] Step S103: determining a primary interference rejection threshold according to the signal matrix, and performing primary interference rejection processing on the signal matrix and the orthogonal baseband signal based on the primary interference rejection threshold;

[0073] Step S104: performing interference judgment on the sum-path orthogonal baseband signal after the first-level interference elimination process according to the number of pulse sampling points and the number of zeroing points of the first-level interference elimination process;

[0074] Step S105: When interference exists, a secondary interference removal threshold is determined according to the signal matrix after the primary interference removal processing, and multi-stage interference removal processing is performed on the orthogonal baseband signal after the primary interference removal processing based on the secondary interference removal threshold to obtain the target signal.

[0075] It should be noted that, in step S104, if it is determined that there is no interference, the summed orthogonal baseband signal after the first-level interference elimination process is directly used as the target signal.

[0076] In the embodiments of the present disclosure, according to the time domain characteristics of intermittent sampling forwarding interference, the signal matrix of the S-path level is determined based on the target echo signal range and the S-path orthogonal baseband signal, which can remove the interference transition band introduced by the transient effect of the filter and maximize the guarantee that the signal matrix of the S-path level is not affected by interference; further, according to the first-level interference rejection threshold determined by the signal matrix, the signal matrix and the S-path orthogonal baseband signal are subjected to first-level interference rejection processing, and according to the number of pulse sampling points and the number of zeroing points of the first-level interference rejection processing, interference judgment is performed on the S-path orthogonal baseband signal after the first-level interference rejection processing; when interference exists, the second-level interference rejection threshold is determined according to the signal matrix after the first-level interference rejection processing, and based on the second-level interference rejection threshold, multi-level interference rejection processing is performed on the S-path orthogonal baseband signal after the first-level interference rejection processing, so as to achieve the countermeasure against intermittent sampling forwarding interference, so that the interference is effectively suppressed and the target signal can be detected normally.

[0077] Below, each step of the above method in this example implementation will be described in more detail.

[0078] Specifically, in step S101, obtaining the sum-branch orthogonal baseband signal and the auxiliary branch orthogonal baseband signal is achieved by the following method: Assume that a coherent processing cycle of the ground pulse radar is T CPI , the number of pulses contained in a coherent processing cycle is N, and the pulse repetition period is T r , the gate width is T bm , the sampling frequency is F s , then the length of the orthogonal baseband signal M = F s T bm , the sum of the orthogonal baseband signals within a coherent processing cycle can be expressed as:

[0079]

[0080] Among them, A Σ Represents the amplitude matrix of the orthogonal baseband signal, Aij represents the amplitude of the sum-path orthogonal baseband signal of the j-th distance unit in the i-th pulse repetition period within the coherent processing period, the value range of i is [1, N], and the value range of j is [1, M];

[0081] The auxiliary branch orthogonal baseband signal within a coherent processing cycle can be expressed as:

[0082]

[0083] Among them, A F Represents the amplitude matrix of the auxiliary branch orthogonal baseband signal, AF ij It represents the amplitude of the auxiliary branch orthogonal baseband signal of the jth range unit in the i-th pulse repetition period within the coherent processing period. The value range of i is [1, N] and the value range of j is [1, M].

[0084] Specifically, in step S102, the target echo signal range is determined by formula (1):

[0085]

[0086] Among them, j start Indicates the starting point of the target echo signal, j end Indicates the target echo signal cutoff point, t q Indicates the time from the front edge of the signal to the front edge of the gate, F s represents the sampling frequency, and τ represents the pulse width of the transmitted signal.

[0087] When the target echo signal range is determined by formula (1) above, it is in tracking mode, using the relative relationship between the gate and the echo signal, so that the range of the target echo signal can be selected to the maximum extent, and the accuracy of the target echo noise level processing can be enhanced, thereby achieving the maximum guarantee that the signal matrix of the harmonic level is not affected by interference.

[0088] Further, in step S102, calculating a signal matrix based on the target echo signal range and the orthogonal baseband signal may include the following sub-steps:

[0089] Step S1021: performing modulus processing on the summed orthogonal baseband signal and the auxiliary branch orthogonal baseband signal to obtain a modulus value matrix of the summed orthogonal baseband signal and a modulus value matrix of the auxiliary branch orthogonal baseband signal, wherein the modulus value matrix of the summed orthogonal baseband signal can be expressed as:

[0090]

[0091] Among them, A1 Σ represents the module value matrix of the orthogonal baseband signal, |A ij| represents the modulus value of the sum-path orthogonal baseband signal of the jth distance unit in the i-th pulse repetition period within the coherent processing period, the value range of i is [1, N], and the value range of j is [1, M];

[0092] The modulus matrix of the auxiliary branch orthogonal baseband signal can be expressed as:

[0093]

[0094] Among them, A1 F represents the modulus matrix of the auxiliary branch orthogonal baseband signal, |AF ij | represents the modulus value of the auxiliary branch orthogonal baseband signal of the jth range unit in the i-th pulse repetition period within the coherent processing period, the value range of i is [1, N], and the value range of j is [1, M];

[0095] Step S1022: Based on the target echo signal range determined by formula (1), the module value matrix of the sum of the orthogonal baseband signals is selected and processed to obtain a signal matrix:

[0096]

[0097] Among them, A2 represents the signal matrix, k represents the target echo signal range, and the value range of k is [j start ,j end ],j start Indicates the starting point of the target echo signal, j end Indicates the target echo signal cutoff point, |A ik | represents the modulus value of the orthogonal baseband signal within the target echo signal range.

[0098] For example, the step S103 is described by taking the ith pulse of the signal matrix as an example. In step S103, determining the first-level interference rejection threshold according to the signal matrix may include the following steps:

[0099] Step S1031: The signal matrix is ​​averaged to obtain a first-level time domain threshold, where the i-th pulse signal in the signal matrix is For example, A2 can be specifically calculated by the following formula (14): i To perform averaging:

[0100]

[0101] Among them, avg1 i represents the first-level time domain threshold, K represents the number of pulse sampling points, |A ik | represents the modulus of the orthogonal baseband signal within the target echo signal range, k represents the target echo signal range, and the value range of k is [j start ,jend ],j start Indicates the starting point of the target echo signal, j end Indicates the target echo signal cutoff point;

[0102] Step S1032: Based on the primary time domain threshold and the spatial domain threshold, the i-th pulse signal of the signal matrix is ​​subjected to threshold processing by formula (2) to obtain a first sequence:

[0103]

[0104] Among them, A3 ik Indicates the first sequence, A2' ik represents the pulse signal in the signal matrix that satisfies the first sequence, |A2 ij | represents the modulus of each pulse signal in the signal matrix, avg1 i Represents the first-level time domain threshold, P coef represents the airspace threshold, which is determined by the antenna gain of the radar's auxiliary branch and the antenna gain of the sum path. Fij | represents the modulus value of each pulse signal of the auxiliary branch orthogonal baseband signal, && represents the "and" relationship;

[0105] Step S1033: Perform non-zero value selection processing on the first sequence to obtain a second sequence, wherein the second sequence is a set of elements in the first sequence that are not 0, and the second sequence can be expressed as A4 i =[A4 i1 ,…,A4 i2 ,…,A4 iP ], P is the number of non-zero elements in the first sequence, which is also the number of elements in the second sequence;

[0106] Step S1034: perform averaging processing on the second sequence to obtain the first-level interference removal threshold:

[0107]

[0108] Among them, gate1 i represents the first-level interference rejection threshold, P represents the number of elements in the second sequence, p represents the sequence number of the element in the second sequence, |A4 ip | represents an element in the second sequence.

[0109] When the i-th pulse signal of the signal matrix is ​​subjected to threshold processing, the spatial relative relationship between the sum path and the auxiliary branch is taken into consideration. At the same time, the first-level interference rejection threshold selected and determined in combination with the above method is conducive to achieving the countermeasure against intermittent sampling forwarding interference, especially when the interference pulse period and duty cycle vary in a relatively large range, a better interference countermeasure effect can be achieved.

[0110] For example, the i-th pulse of the signal matrix is ​​taken as an example to further illustrate step S103. In step S103, the first-level interference removal process is performed on each pulse signal of the signal matrix and each pulse signal of the orthogonal baseband signal based on the first-level interference removal threshold, including:

[0111] Step S1035: Based on the primary interference rejection threshold, the signal matrix is ​​subjected to primary interference zeroing processing by formula (3), and the sum-path orthogonal baseband signal is subjected to primary interference zeroing processing by formula (4):

[0112]

[0113] Among them, A2 ik represents the signal matrix after the first-level interference zeroing process, |A2 ij | represents the modulus value of each pulse signal in the signal matrix, gate1 i represents the first-level interference rejection threshold, K1 represents the first threshold coefficient, k represents the target echo signal range, and the value range of k is [j start ,j end ];

[0114]

[0115] Among them, A ik represents the sum of the orthogonal baseband signals after the first-level interference zeroing process, |A ij | represents the modulus of each pulse signal of the orthogonal baseband signal, gate1 i represents the first-level interference rejection threshold, K1 represents the first threshold coefficient, k represents the target echo signal range, and the value range of k is [j start ,j end ].

[0116] The signal matrix and the orthogonal baseband signal of the sum path are set to zero through step S1035, so as to perform a first-level interference removal process on each pulse signal of the signal matrix and each pulse signal of the orthogonal baseband signal of the sum path, so as to counteract the intermittent sampling forwarding interference.

[0117] It should be noted that, in the process of performing the primary interference zeroing process on each pulse signal of the orthogonal baseband signal through step S1035, the number of primary interference zeroing points H of each pulse signal is recorded. i , record and path orthogonal baseband signal in the first level interference zeroing process each pulse zeroing signal vector X 1i , record and path orthogonal baseband signal in the first level interference zeroing process each pulse is not zeroed signal vector X 2i. So as to be used in the subsequent step S104 to perform interference judgment on the sum-path orthogonal baseband signal after the first-level interference elimination processing.

[0118] For example, in step S104, according to the number of pulse sampling points and the number of zeroing points of the first-level interference elimination processing, interference judgment is performed on the sum-path orthogonal baseband signal after the first-level interference elimination processing obtained in step S1035, which may include the following steps:

[0119] Step S1041: Based on the sum of the orthogonal baseband signals after the first-level interference elimination process, obtain the pulse zeroing signal vector X of the sum of the orthogonal baseband signals during the first-level interference zeroing process. 1i The signal vector X of each pulse not set to zero when the orthogonal baseband signal is processed in the first-level interference zeroing process 2i , the fluctuation factor is calculated by formula (5):

[0120]

[0121] Among them, Ra i represents the fluctuation factor, X 1i It represents the pulse zeroing signal vector of the orthogonal baseband signal in the first-level interference zeroing process, X 2i It represents the signal vector of each pulse not set to zero when the orthogonal baseband signal is processed in the first-level interference zeroing process, abs(X 1i ) indicates that X 1i Take the absolute value, abs(X 2i ) indicates that X 2i Take the absolute value, mean(abs(X 1i )) indicates abs(X 1i ) takes the mean, mean(abs(X 2i )) indicates abs(X 2i ) take the mean;

[0122] Step S1042: Based on the sum of the orthogonal baseband signals after the first-level interference elimination process, obtain the first-level interference zeroing point number H i , wherein the number of zero-setting points for the first-level interference is recorded as the number of zero-setting points for the first-level interference elimination process mentioned above;

[0123] Step S1043: Set the first-level interference to zero point H i and fluctuation factor Ra i Perform a comparison process to obtain a first comparison result, and obtain an interference judgment result based on the first comparison result.

[0124] Specifically, in step S1043, the number of first-level interference zero points H i and fluctuation factor Ra iPerforming a comparison process to obtain a first comparison result, and obtaining an interference determination result according to the first comparison result, including:

[0125] The comparison is performed using formula (6):

[0126] H i <0.3K&&Ra i >Coeff1(6)

[0127] Among them, H i represents the number of zeroing points for primary interference, K represents the number of pulse sampling points, Ra i represents the fluctuation factor, Coeff1 represents the first noise level coefficient;

[0128] When formula (6) is satisfied, there is no interference in the sum-path orthogonal baseband signal after the first-level interference elimination process; otherwise, there is interference.

[0129] Interference judgment is performed on the orthogonal baseband signal after the first-level interference elimination processing through step S104 to determine whether the orthogonal baseband signal after the first-level interference elimination processing needs to be subjected to multi-level interference elimination processing to further combat intermittent sampling forwarding interference and ensure that the target signal finally obtained can be effectively detected.

[0130] Specifically, in step S105, when there is interference in the sum of the orthogonal baseband signals after the first-level interference elimination process, determining the second-level interference elimination threshold according to the signal matrix after the first-level interference elimination process may include the following steps:

[0131] Step S1051: Perform non-zero value selection processing on the signal matrix after the first-level interference elimination processing to obtain a third sequence. The third sequence is a set of non-zero elements in the signal matrix after the first-level interference elimination processing. For the i-th pulse signal of the signal matrix after the first-level interference elimination processing, the third sequence can be expressed as A5 i , the number of non-zero elements in the signal matrix after the first-level interference elimination process is Q, which is the third sequence A5 i The number of elements in ;

[0132] Step S1052: perform averaging processing on the third sequence to obtain a first multi-level time domain threshold:

[0133]

[0134] Among them, avg3 i represents the first multi-level time domain threshold, Q represents the number of elements in the third sequence, q represents the sequence number of the element in the third sequence, |A5 iq | represents the modulus value of the elements in the third sequence;

[0135] Step S1053: Based on the first multi-level time domain threshold avg3 i , perform threshold processing on the third sequence to obtain the fourth sequence:

[0136]

[0137] Among them, A6 iq Indicates the fourth sequence, A5 iq Represents the modulus value of the elements in the third sequence, |A5 iq Indicates A5 iq The modulus of avg3 i represents the first multi-level time domain threshold;

[0138] Step S1054: Perform non-zero value selection processing on the fourth sequence to obtain a fifth sequence, that is, the fifth sequence is a set of non-zero elements in the fourth sequence, and perform averaging processing on the fifth sequence to obtain a second multi-level time domain threshold avg4 i ;

[0139] Step S1055: The first multi-level time domain threshold avg3 is calculated by formula (7). i and the second multi-level time domain threshold avg4 i After processing, the secondary interference rejection threshold is obtained:

[0140]

[0141] Among them, gate2 i Indicates the secondary interference rejection threshold, avg4 i Represents the second multi-level time domain threshold, avg3 i represents the first multi-level time domain threshold, and K2 represents the second threshold coefficient.

[0142] Further, in step S105, multi-stage interference removal processing is performed on the sum-path orthogonal baseband signal after the first-stage interference removal processing based on the second-stage interference removal threshold, including:

[0143] Step S1056: Based on the secondary interference rejection threshold and the spatial domain threshold, interference zeroing processing is performed on the sum-path orthogonal baseband signal after the primary interference rejection processing by formula (8):

[0144]

[0145] Among them, A7 ij represents the orthogonal baseband signal after multi-stage interference removal, |A ij | represents the orthogonal baseband signal after the first-level interference elimination process, K3 represents the third threshold coefficient, gate2 i represents the secondary interference rejection threshold, P coefrepresents the airspace threshold, which is determined by the antenna gain of the radar's auxiliary branch and the antenna gain of the sum path. Fij | represents the modulus value of each pulse signal of the auxiliary branch orthogonal baseband signal, && represents the "and" relationship, A ik Represents the sum-and-quadrature baseband signal without zeroing.

[0146] The above steps determine the secondary interference rejection threshold by comparing and comprehensively logically judging the first multi-level time domain threshold and the second multi-level time domain threshold. Subsequently, each pulse signal within a coherent processing cycle is set to zero according to the obtained secondary interference rejection threshold, thereby counteracting intermittent sampling forwarding interference.

[0147] Optionally, in step S105, after performing multi-stage interference removal processing on the sum of orthogonal baseband signals after the primary interference removal processing based on the secondary interference removal threshold, the method further includes:

[0148] Step S1057: Based on the sum of the orthogonal baseband signals after multi-level interference elimination, obtain the number of multi-level interference zeroing points, recorded as num t ;

[0149] According to the length M of the orthogonal baseband signal, the zeroing threshold 0.7M is determined, and the number of multi-level interference zeroing points num is set. t Compare with the zero-setting threshold 0.7M to obtain a second comparison result;

[0150] Step S1058: According to the second comparison result, one of the sum-path orthogonal baseband signals after the first-stage interference elimination process and the sum-path orthogonal baseband signals after the multi-stage interference elimination process is selected as the target signal, specifically:

[0151] When the multi-level interference is set to zero, the number of points num t When it is greater than the zero threshold of 0.7M, the sum-path orthogonal baseband signal after the first-level interference elimination process is selected as the target signal and output;

[0152] When the multi-level interference is set to zero, the number of points num t When it is less than or equal to the zero threshold of 0.7M, the sum-path orthogonal baseband signal after multi-stage interference elimination is selected as the target signal and output.

[0153] It should be noted that in num t >0.7M, if the orthogonal baseband signal after multi-stage interference elimination is selected as the target signal, there will be an unexpected situation where too many points are eliminated. Therefore, the above-mentioned settings of step S1057 and step S1058 in this embodiment can avoid the situation where too many points are eliminated. It should also be noted that, under normal circumstances, the duty cycle will not be too large, that is, num tThe situation of >0.7M is extremely unlikely to occur. Therefore, when it is determined that interference exists in step three, most of the time, the orthogonal baseband signal after multi-level interference elimination processing will be selected as the target signal to counter the intermittent sampling forwarding interference.

[0154] Optionally, in step S105, before the target signal is output, pulse compression, coherent integration, constant false alarm detection and sum-difference normalization processing need to be performed on the target signal to obtain the target signal to be finally output.

[0155] In the embodiment of the present application, in order to further verify the effect of the method for countering intermittent sampling forwarding interference based on multi-level threshold processing proposed in the present application on countering intermittent sampling forwarding interference, a simulation experiment was carried out, and the coherent processing period of the pulse radar was set to 10ms, and the pulse repetition period T r is 1ms, a coherent processing cycle T CPI The number of transmitted pulses is N = 10, the pulse width tau = 128 μs, and the gate width is T bm =165μs, sampling frequency F s =20MHz. Then the length of the baseband signal sampling points in one pulse repetition period is M=3300, and the length used to calculate the signal level is 2800 points, which is the target echo signal range mentioned above.

[0156] The simulation data and simulation results in this simulation experiment are referenced Figures 2 to 4 As shown:

[0157] Specifically, Figure 2 The figure shows the real part of the sum of the orthogonal baseband signals of a target tracking position under the intermittent sampling forwarding interference state. Figure 3 A schematic diagram showing the mode of the orthogonal baseband signal after multi-stage interference removal processing is shown. Figure 4 The figure shows a schematic diagram of the orthogonal baseband signal without interference removal and the target signal obtained after multi-stage interference removal. Figure 4 It can be seen that when the interference is not set to zero, the target signal is submerged in the intermittent sampling forwarding interference and cannot be detected. After using the method proposed in the present disclosure to perform multi-level interference elimination processing, the interference is effectively suppressed and the target signal can be detected normally.

[0158] Regarding the system in the above embodiment, the specific manner in which each unit performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0159] It should be noted that although several units of the system for action execution are mentioned in the above detailed description, this division is not mandatory. In fact, according to the embodiment of the present disclosure, the features and functions of two or more units described above can be concretized in one unit. Conversely, the features and functions of a unit described above can be further divided into multiple units for concretization. Some or all of the units can be selected according to actual needs to achieve the purpose of the disclosed solution. Those of ordinary skill in the art can understand and implement it without paying creative work.

[0160] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

Claims

1. A method for counteracting intermittent sampling forwarding interference based on multi-level threshold processing, characterized in that: include: Obtaining the sum-branch orthogonal baseband signal and the auxiliary branch orthogonal baseband signal; Determine a target echo signal range, and calculate a signal matrix based on the target echo signal range and the orthogonal baseband signal; Determine a primary interference removal threshold according to the signal matrix, and perform primary interference removal processing on the signal matrix and the summed orthogonal baseband signal based on the primary interference removal threshold; Perform interference judgment on the sum-path orthogonal baseband signal after the first-level interference elimination processing according to the number of pulse sampling points and the number of zeroing points of the first-level interference elimination processing; When interference exists, a secondary interference removal threshold is determined according to the signal matrix after the primary interference removal processing, and multi-stage interference removal processing is performed on the orthogonal baseband signal after the primary interference removal processing based on the secondary interference removal threshold to obtain the target signal.

2. The method for counteracting intermittent sampling forwarding interference based on multi-level threshold processing according to claim 1 is characterized in that: The target echo signal range is determined by formula (1): Among them, j start Indicates the starting point of the target echo signal, j end Indicates the target echo signal cutoff point, t q Indicates the time from the front edge of the signal to the front edge of the gate, F s represents the sampling frequency, and τ represents the pulse width of the transmitted signal.

3. The method for counteracting intermittent sampling forwarding interference based on multi-level threshold processing according to claim 1 is characterized in that: The calculating of the signal matrix based on the target echo signal range and the summed orthogonal baseband signal comprises: Performing modulus processing on the summing-path orthogonal baseband signal and the auxiliary branch orthogonal baseband signal to obtain a modulus matrix of the summing-path orthogonal baseband signal and a modulus matrix of the auxiliary branch orthogonal baseband signal; Based on the target echo signal range, the module value matrix of the summed orthogonal baseband signals is selected and processed to obtain the signal matrix.

4. The method for counteracting intermittent sampling forwarding interference based on multi-level threshold processing according to claim 2 is characterized in that: The step of determining the primary interference rejection threshold according to the signal matrix includes: Performing mean processing on the signal matrix to obtain a first-level time domain threshold; Based on the primary time domain threshold and spatial domain threshold, the signal matrix is ​​subjected to threshold processing by formula (2) to obtain a first sequence: Among them, A3 ik Indicates the first sequence, A2' ik represents the pulse signal in the signal matrix that satisfies the first sequence, |A2 ij | represents the modulus of each pulse signal in the signal matrix, avg1 i Represents the first-level time domain threshold, P coef represents the airspace threshold, |A1 Fij | represents the modulus value of each pulse signal of the auxiliary branch orthogonal baseband signal, && represents the relationship of "and"; Performing non-zero value selection processing on the first sequence to obtain a second sequence; The second sequence is averaged to obtain the first-level interference removal threshold.

5. The method for combating intermittent sampling forwarding interference based on multi-level threshold processing according to claim 4 is characterized in that: The performing a first-level interference removal process on the signal matrix and the summed orthogonal baseband signal based on the first-level interference removal threshold comprises: Based on the primary interference rejection threshold, the signal matrix is ​​subjected to primary interference zeroing processing by formula (3), and the sum of the orthogonal baseband signals is subjected to primary interference zeroing processing by formula (4): Among them, A2 ik represents the signal matrix after the first-level interference zeroing process, |A2 ij | represents the modulus value of each pulse signal in the signal matrix, gate1 i represents the first-level interference rejection threshold, K1 represents the first threshold coefficient, k represents the target echo signal range, and the value range of k is [j start ,j end ]; Among them, A ik represents the sum of the orthogonal baseband signals after the first-level interference zeroing process, |A ij | represents the modulus of each pulse signal of the orthogonal baseband signal, gate1 i represents the first-level interference rejection threshold, K1 represents the first threshold coefficient, k represents the target echo signal range, and the value range of k is [j start ,j end ].

6. The method for combating intermittent sampling and forwarding interference based on multi-level threshold processing according to claim 1, characterized in that: The interference determination is performed on the sum-path orthogonal baseband signal after the first-level interference elimination process according to the number of pulse sampling points and the number of zeroing points in the first-level interference elimination process, including: Based on the sum of the orthogonal baseband signals after the first-level interference elimination process, the fluctuation factor is calculated by formula (5): Among them, Ra i represents the fluctuation factor, X 1i It represents the pulse zeroing signal vector of the orthogonal baseband signal in the first-level interference zeroing process, X 2i It represents the signal vector of each pulse not set to zero when the orthogonal baseband signal is processed in the first-level interference zeroing process, abs(X 1i ) indicates that X 1i Take the absolute value, abs(X 2i ) indicates that X 2i Take the absolute value, mean(abs(X 1i )) indicates abs(X 1i ) takes the mean, mean(abs(X 2i )) indicates abs(X 2i ) take the mean; Based on the sum of the orthogonal baseband signals after the first-level interference removal process, the number of first-level interference zeroing points is obtained; The first-level interference zeroing points and the fluctuation factor are compared to obtain a first comparison result, and an interference judgment result is obtained according to the first comparison result.

7. The method for combating intermittent sampling forwarding interference based on multi-level threshold processing according to claim 6 is characterized in that: The comparing the number of the first-level interference zeroing points with the fluctuation factor to obtain a first comparison result, and obtaining an interference judgment result according to the first comparison result, includes: The comparison is performed using formula (6): Q i <0.3K&&Ra i >Coeff1(6) Among them, Q i represents the number of zeroing points for primary interference, K represents the number of pulse sampling points, Ra i represents the fluctuation factor, Coeff1 represents the first noise level coefficient; When formula (6) is satisfied, there is no interference in the sum-path orthogonal baseband signal after the first-level interference elimination process; otherwise, there is interference.

8. The method for combating intermittent sampling and forwarding interference based on multi-level threshold processing according to claim 1, characterized in that: When interference exists, determining the secondary interference removal threshold according to the signal matrix after the primary interference removal process includes: The signal matrix after the first-level interference elimination process is processed by selecting non-zero values ​​to obtain a third sequence; Performing averaging processing on the third sequence to obtain a first multi-level time domain threshold; Based on the first multi-level time domain threshold, performing threshold processing on the third sequence to obtain a fourth sequence; Performing non-zero value selection processing on the fourth sequence to obtain a fifth sequence, and performing averaging processing on the fifth sequence to obtain a second multi-level time domain threshold; The first multi-level time domain threshold and the second multi-level time domain threshold are processed by formula (7) to obtain the secondary interference rejection threshold: Among them, gate2 i Indicates the secondary interference rejection threshold, avg4 i Represents the second multi-level time domain threshold, avg3 i represents the first multi-level time domain threshold, and K2 represents the second threshold coefficient.

9. The method for combating intermittent sampling and forwarding interference based on multi-level threshold processing according to claim 8, characterized in that: The performing multi-stage interference removal processing on the sum-path orthogonal baseband signal after the first-stage interference removal processing based on the second-stage interference removal threshold comprises: Based on the secondary interference rejection threshold and the spatial domain threshold, interference zeroing processing is performed on the sum-path orthogonal baseband signal after the primary interference rejection processing by formula (8): Among them, A7 ij represents the orthogonal baseband signal after multi-stage interference removal, |A ij | represents the orthogonal baseband signal after the first-level interference elimination process, K3 represents the third threshold coefficient, gate2 i represents the secondary interference rejection threshold, P coef represents the airspace threshold, which is determined by the antenna gain of the radar's auxiliary branch and the antenna gain of the sum path. Fij | represents the modulus of each pulse signal of the auxiliary branch orthogonal baseband signal, && represents the "and" relationship, A ik Represents the sum-and-quadrature baseband signal without zeroing.

10. The method for combating intermittent sampling forwarding interference based on multi-level threshold processing according to claim 9, characterized in that: After performing multi-stage interference elimination processing on the sum of orthogonal baseband signals after the first-stage interference elimination processing based on the second-stage interference elimination threshold, the method further includes: Based on the sum-path orthogonal baseband signal after multi-stage interference elimination processing, the number of multi-stage interference zeroing points is obtained; Determine a zeroing threshold according to the length of the summed orthogonal baseband signal, compare the number of multi-level interference zeroing points with the zeroing threshold, and obtain a second comparison result; According to the second comparison result, one of the sum-path orthogonal baseband signals after the first-stage interference elimination processing and the sum-path orthogonal baseband signals after the multi-stage interference elimination processing is selected as the target signal.

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