CN115453477A - Cancellation method for multipath clutter in monitoring channel signals of external radiation source radar - Google Patents
Cancellation method for multipath clutter in monitoring channel signals of external radiation source radar Download PDFInfo
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
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Abstract
The invention discloses a cancellation method of multipath clutter in an external radiation source radar monitoring channel signal, which comprises the following steps: respectively obtaining a reference signal and a monitoring signal by using a reference channel and a monitoring channel of an external radiation source radar; performing down-conversion processing on the reference signal and the monitoring signal to obtain a baseband reference signal and a baseband monitoring signal after down-conversion; estimating the number of multipath clutter signals in a monitoring channel by using the baseband reference signal and the baseband monitoring signal; according to the number of the estimated multipath clutter signals, sparse matching cancellation is carried out on the multipath clutter signals by using an orthogonal matching tracking method to obtain a multipath clutter sparse coefficient; and performing sparse matching cancellation on the multipath clutter by using the multipath clutter sparse coefficient to obtain a signal after multipath clutter cancellation. The dimension of the clutter filtering matrix of the invention is only related to the number of multipath clutter contained in the monitoring channel signal, thus greatly reducing the complexity of solving the sparse matching coefficient and improving the calculation efficiency.
Description
Technical Field
The invention belongs to the technical field of radar signal processing, and particularly relates to a cancellation method of multipath clutter in signals of a monitoring channel of an external radiation source radar, which is used for accurately realizing cancellation of the multipath clutter in the monitoring channel of an external radiation source radar system.
Background
The radar of external radiation source is a radar of new system which uses electromagnetic signal of third party (such as digital broadcast television signal, communication or navigation satellite signal, global mobile communication system, etc.) to detect target. External radiation source radars are usually equipped with a reference antenna for receiving radiation source signals and a monitoring antenna for receiving target echo signals, the signals received by the reference antenna and the monitoring antenna being referred to as reference signals and monitoring signals, respectively. Ideally, the reference signal is a pure radiation source signal, the monitoring signal only includes a radiation source signal (i.e., a target echo signal) reflected twice by the target, and coherent accumulation is performed on the reference signal and the monitoring signal to obtain the time delay and the doppler frequency of the echo signal relative to the reference signal. Based on the method, a plurality of applications such as detection, positioning, tracking and the like of the target can be realized. However, the actually received monitoring signals contain strong multipath clutter and direct waves, and a large number of false targets are generated during coherent accumulation of the signals, so that difficulty is brought to target detection of the external radiation source radar.
At present, the multi-path clutter cancellation methods widely applied include time domain Adaptive filtering methods, such as Least Mean Square (LMS), normalized Least Mean Square (NLMS), gradient Adaptive Grid (GAL), recursive Least Square (RLS), and the like; and time domain projection methods such as extended phase Cancellation (ECA), ECA-B (ECA-Batch), ECA-S (ECA-slicing), ECA-C (ECA-Carrier), and the like. The self-adaptive filtering method is low in convergence speed, and parameter values depend on historical experience; the time domain projection method has no convergence problem, but has large calculation amount for matrix inversion and slow solving speed.
Disclosure of Invention
In order to solve the above problems in the prior art, the present invention provides a method for canceling multipath clutter in an external radiation source radar monitoring channel signal. The technical problem to be solved by the invention is realized by the following technical scheme:
one aspect of the present invention provides a method for canceling multipath clutter in a radar monitoring channel signal of an external radiation source, comprising:
s1: respectively obtaining a reference signal and a monitoring signal by using a reference channel and a monitoring channel of an external radiation source radar, wherein the monitoring signal is a signal which is reflected by a target and then received by the monitoring channel;
s2: performing down-conversion processing on the reference signal and the monitoring signal to obtain a baseband reference signal and a baseband monitoring signal after down-conversion;
s3: estimating the number of multipath clutter signals in a monitoring channel by using the baseband reference signal and the baseband monitoring signal;
s4: according to the number of the estimated multipath clutter signals, sparse matching cancellation is carried out on the multipath clutter signals by using an orthogonal matching tracking method to obtain a multipath clutter sparse coefficient;
s5: and performing sparse matching cancellation on the multipath clutter by using the multipath clutter sparse coefficient to obtain a signal after multipath clutter cancellation.
In one embodiment of the present invention, the S1 includes:
s1a: setting the sampling frequency f of an external radiation source radar receiver s Direction of beam reception
Receiving bandwidth B and detection threshold T h ；
S1b: setting the minimum value d of the time delay unit of the multipath clutter signal according to the double-base detection range of different scenes min And maximum value d max ；
S1c: and receiving a reference signal by using a reference channel of the external radiation source radar, and receiving a monitoring signal by using a monitoring channel of the external radiation source radar.
In one embodiment of the present invention, the S2 includes:
carrying out digital down-conversion on the received reference signal and the monitoring signal to obtain a baseband reference signal s after down-conversion ref (t) and a baseband monitor signal s surv (t)：
s surv (t)＝s echo (t)+s m (t)+w(t)
Wherein f is 0 Is the center frequency, s, of the baseband signal echo (t) represents a target echo signal received by the monitoring channel, s m (t) represents multipath clutter signals received by a monitoring channel, w (t) is white Gaussian noise, and the target echo signal s echo (t) is expressed as:
wherein A is the complex amplitude of the target echo signal, u (t) is the complex envelope of the reference signal, τ is the time delay of the target echo signal relative to the reference signal, f d Is the doppler frequency of the target echo signal.
In one embodiment of the present invention, the S3 includes:
s3a: calculating a cross-correlation function of the baseband reference signal and the baseband monitoring signal:
χ 0 (n)＝IFFT{FFT[s ref (n),2N]·FFT * [s surv (n),2N]}
where n is a discrete point in time, s ref (n) is a base band reference signal s ref (t) discretization of the representation, s surv (n) is a baseband monitor signal s surv (t), N is the length of the baseband reference signal and the baseband monitoring signal, and FFT (-) represents a Fourier representationThe interior transform, IFFT (-) represents the inverse fourier transform;
s3b: recording the cross-correlation function χ 0 (n) in a time delay unit [ d ] min ,d max ]Inner correlation result exceeds the detection threshold T h Average of the fractions:
A ve ＝mean(χ 0 (n)＞T h )；
s3c: will be Chi 0 (n) in time delay units [ d ] min ,d max ]Inner correlation results exceed gamma. A ve The parts of (A) form a new array x 1 Wherein γ is a constant factor;
s3d: counting the new array χ 1 The number of maximum values cnt is estimated, and the number of multipath clutter signals is M 0 And = η · cnt, where η is a constant factor.
In one embodiment of the present invention, the S4 includes:
s4a: from a discretized baseband reference signal s ref (n) generating a multipath clutter word space matrix D:
wherein K = d max -d min N represents discrete time, N represents signal length, f s S representing the sampling frequency of the radar receiver of the external source, first column in matrix D ref (1) Front portion has d min 0, s of the last column ref (1) Front total K + d min +1 and 0;
s4b: and performing unit representation on each column of the multipath clutter word space matrix D:
D＝[a 1 ,a 2 ,…,a K ]，
wherein, a i Representing the unitized multipath clutter signal, i = 1.., K;
s4c: residual signal r after initialization cancellation 0 ＝s surv And initializing a multipath clutter matrix index set Lambda and iteration times m:
m＝1；
s4d: calculating a position index lambda of the current multipath clutter signal in the multipath clutter word space matrix D m ：
Wherein m represents the number of iterative cycles;
s4e: indexing the obtained position by lambda m Adding multipath clutter matrix index set
Λ m ＝Λ m-1 ∪{λ m }；
S4f: updating a residual signal with the multipath clutter matrix index set:
wherein, the first and the second end of the pipe are connected with each other,
is part of the multipath clutter word space matrix D,
is composed of index set Λ m A new spatial matrix composed of corresponding column signals;
s4g: let M = M +1, repeat steps S4d-S4g, when the iteration exit condition M = M is satisfied 0 The loop is exited to obtain the multi-path clutter word space matrix after the iterative update
Wherein M is 0 The number of the multipath clutter signals estimated.
S4h: using iteratively updated multipath clutter word space matrix
Calculate moreDiameter clutter sparse coefficient:
wherein s is surv Representing a baseband supervisory signal.
In one embodiment of the present invention, the S5 includes:
and performing sparse matching cancellation on the multipath clutter by using the multipath clutter sparse coefficient to obtain a signal after multipath clutter cancellation:
another aspect of the present invention provides a storage medium having stored thereon a computer program for executing the steps of the method for canceling multipath clutter in a surveillance channel signal of an external radiation source radar according to any one of the above embodiments.
A further aspect of the invention provides an electronic device comprising a memory having stored therein a computer program and a processor which, when invoked on the computer program in the memory, carries out the steps of a method of cancellation of multipath clutter in a surveillance channel signal of an external radiation source radar as described in any one of the above embodiments.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the multipath clutter cancellation method based on orthogonal matching pursuit, the dimension of the clutter filter matrix is only related to the number of the multipath clutter contained in the monitoring channel signal, so that the complexity of solving a sparse matching coefficient can be greatly reduced, and the calculation efficiency is improved.
2. The multipath clutter cancellation method of orthogonal matching pursuit adopted by the invention has no special requirement on the correlation of the column vector of the multipath clutter filter matrix, thus being suitable for more practical application scenes.
The present invention will be described in further detail with reference to the accompanying drawings and examples.
Drawings
Fig. 1 is a flowchart of a method for canceling multipath clutter in a radar monitoring channel signal of an external radiation source according to an embodiment of the present invention;
fig. 2 is a schematic processing procedure of a method for canceling multipath clutter in a monitoring channel signal of an external radiation source radar according to an embodiment of the present invention;
FIG. 3 is a slice diagram of a zero-frequency mutual ambiguity function before clutter cancellation using the cancellation method of the embodiment of the present invention;
FIG. 4 is a diagram illustrating cross-correlation results exceeding a detection threshold in a time delay unit;
fig. 5 is a cross-ambiguity function slice diagram after clutter cancellation by using the cancellation method according to the embodiment of the present invention.
Detailed Description
To further illustrate the technical means and effects of the present invention adopted to achieve the predetermined object, the following detailed description is provided for the cancellation method of multipath clutter in a radar monitoring channel signal of an external radiation source according to the present invention with reference to the accompanying drawings and the detailed description.
The foregoing and other technical matters, features and effects of the present invention will be apparent from the following detailed description of the embodiments, which is to be read in connection with the accompanying drawings. While the present invention has been described in connection with the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or device that comprises a list of elements does not include only those elements but may include other elements not expressly listed. Without further limitation, an element defined by the phrase "comprising a … …" does not exclude the presence of additional like elements in an article or apparatus that comprises the element.
The embodiment of the invention provides a cancellation method of multipath clutter in an external radiation source radar monitoring channel signal, please refer to fig. 1 and fig. 2, the cancellation method of the multipath clutter comprises the following steps:
s1: and respectively obtaining a reference signal and a monitoring signal by using a reference channel and a monitoring channel of the external radiation source radar.
Specifically, step S1 of this embodiment includes the following sub-steps:
s1a: setting the sampling frequency f of an external radiation source radar receiver s Direction of beam reception
Receiving bandwidth B and detection threshold T h And the like.
S1b: setting the relevant parameters of the multipath clutter signals. Double-base detection range [ R ] according to different scenes min ,R max ]Setting minimum value d of time delay unit for multipath clutter signal min And maximum value d max I.e. by
Where c is the speed of light and floor (·) denotes rounding down.
S1c: and receiving a reference signal by using a reference channel of the external radiation source radar, and receiving a monitoring signal by using a monitoring channel of the external radiation source radar, wherein the monitoring signal is a signal which is reflected by a target and then received by the monitoring channel.
As described above, an external radiation source radar is generally provided with a reference antenna that receives a radiation source signal and a monitoring antenna that receives a target echo signal, and signals received by the reference antenna and the monitoring antenna are referred to as a reference signal and a monitoring signal, respectively. Ideally, the reference signal is a clean radiation source signal, and the monitor signal only includes a radiation source signal after the target has secondarily reflected (i.e., a target echo signal). In practical cases, the received reference signal may be expressed as:
where u (t) is the complex envelope of the reference signal, f c Is the carrier frequency of the transmitted signal,
is the initial phase of the transmitted signal and t represents time.
S2: and performing down-conversion processing on the reference signal and the monitoring signal to obtain a baseband reference signal and a baseband monitoring signal after down-conversion.
Specifically, digital down-conversion is performed on the received high-frequency reference signal and the monitoring signal to obtain a down-converted baseband reference signal s ref (t) and a baseband monitor signal s surv (t) are each represented by
s surv (t)＝s echo (t)+s m (t)+w(t)
Wherein f is 0 Is the center frequency, s, of the baseband signal echo (t) target echo signals received by the monitoring channel, s m (t) represents the multipath clutter signal received by the monitor channel, and w (t) is white gaussian noise. Target echo signal s echo (t) can be expressed as:
where A is the complex amplitude of the target echo signal, u (t) is the complex envelope of the reference signal, τ is the time delay of the target echo signal relative to the reference signal, f d Is Doppler of the echo signal of the targetFrequency.
S3: and estimating the number of the multipath clutter signals in the monitoring channel by using the baseband reference signal and the baseband monitoring signal.
It should be noted that the multipath clutter signal s in the monitoring channel m (t) can be considered as a reference signal with a certain time delay and a certain amplitude, and thus can be expressed as:
wherein, ω is m Is the complex amplitude, Δ t, of the mth multipath clutter signal m The M-th time delay of the multipath clutter signal relative to the reference signal, M is the number of the multipath clutter signals.
The existing time domain projection clutter cancellation method can cancel multi-path clutter of a time delay unit within an order K. In general, the value of K is large, which results in a large number of signals in the multipath clutter subspace, and high subsequent computation complexity. If the number of multipath clutter signals can be estimated in advance, a large number of redundant calculations can be avoided. The multipath clutter signal can be regarded as a reference signal with a certain time delay and amplitude, so that the multipath clutter signal and the reference signal have correlation in time, and the number of the multipath clutter signals can be determined by the number of cross-correlation peaks of the reference signal and the monitoring signal (the monitoring signal contains the multipath clutter signal). However, when the time delays of two or more multipath clutter signals are very close, there may be only one correlation peak in the cross-correlation result, so that the upper limit of the number of multipath clutter signals needs to be estimated according to the number of correlation peaks.
Specifically, step S3 of the present embodiment includes the following sub-steps:
s3a: calculating a cross-correlation function of the baseband reference signal and the baseband monitoring signal:
χ 0 (n)＝IFFT{FFT[s ref (n),2N]·FFT * [s surv (n),2N]}
where n is a discrete point in time, s ref (n) is a base band reference signal s ref (t) discretization of the representation, s surv (n) is a baseband monitor signal s surv (t) is a discretization representation, N is the length of the baseband reference signal and the baseband monitor signal, FFT (-) represents fourier transform, IFFT (-) represents inverse fourier transform, please refer to fig. 3, fig. 3 is a slice diagram of a zero-frequency cross-ambiguity function before clutter cancellation by the cancellation method of the embodiment of the present invention, that is, a cross-correlation result of the reference signal and the monitor signal.
S3b: recording the cross-correlation function χ 0 (n) in a time delay unit [ d ] min ,d max ]Inner correlation result exceeds the detection threshold T h Partial averages, see fig. 4, fig. 4 is a schematic representation of the cross-correlation result exceeding the detection threshold in the time delay unit, d in fig. 4 min ，d max And T h Average of data above the enclosed region, i.e.
A ve ＝mean(χ 0 (n)＞T h )。
S3c: will be x 0 (n) in time delay units [ d ] min ,d max ]Inner correlation results exceed gamma. A ve The parts of (A) form a new array x 1 Wherein γ is a constant factor, and the value of this embodiment is 1.75.
S3d: counting the new array χ 1 The number of the maximum values cnt in the multipath clutter signals can be obtained, namely, the upper limit of the number of the multipath clutter signals is M 0 = η · cnt, where η is a constant factor and is 2 in this embodiment.
S4: and according to the number of the estimated multipath clutter signals, performing sparse matching cancellation on the multipath clutter signals by using an orthogonal matching tracking method to obtain a multipath clutter sparse coefficient.
The multipath clutter signals can be regarded as reference signals with certain time delay and amplitude, so that multipath clutter subspaces can be constructed by adding time delay to the reference signals, and the multipath clutter signals are eliminated through projection of the multipath clutter signals on the multipath clutter subspaces. In the projection process, the calculated amount can be greatly reduced by utilizing the number of the multipath clutter signals estimated by the S3 and an orthogonal matching tracking method, and any two clutter signals in a clutter subspace do not need to be orthogonal to each other.
Specifically, step S4 of this embodiment includes:
s4a: from a discretized baseband reference signal s ref (n) generating a multipath clutter word space matrix D:
wherein K = d max -d min N represents discrete time, N represents signal length, f s S representing the sampling frequency of the radar receiver of the external source, first column in matrix D ref (1) Front portion has d min 0, s of the last column ref (1) The front face has a total of K + d min +1 0.
S4b: performing unitized representation on each column of the multipath clutter word space matrix D:
D＝[a 1 ,a 2 ,…,a K+1 ]，
wherein, a i (i = 1.., K + 1) represents the unitized multipath clutter signal.
S4c: residual signal r after initialization cancellation 0 ＝s surv And initializing a multipath clutter matrix index set Lambda and iteration times m:
m＝1。
s4d: calculating a position index lambda of the current multipath clutter signal in the multipath clutter word space matrix D m That is, the position corresponding to the unitized multipath clutter signal with the maximum correlation in the residual signal and the multipath clutter word space matrix D is expressed as:
where m denotes the number of iterative loops, e.g. r 0 Representing the residual signal at the first cycle, r 1 Representing the residual signal at the second cycle.
S4e: indexing the obtained position by lambda m Adding multipath clutter matrix index sets
Λ m ＝Λ m-1 ∪{λ m }；
S4f: updating a residual signal with the multipath clutter matrix index set:
wherein, the first and the second end of the pipe are connected with each other,
is part of the multipath clutter word space matrix D,
is composed of index set Λ m The corresponding column signals constitute a new spatial matrix.
Assuming that the multipath clutter word space matrix D has 10 columns of signals, the index set Λ m =2,4,7, then
I.e. a new matrix of the 2 nd, 4 th and 7 th column signals inside D.
S4g: let M = M +1, repeat steps S4d-S4g, when the iteration exit condition M = M is satisfied 0 Then, the loop is exited to obtain the multipath clutter word space matrix after the iterative update
Wherein M is 0 The upper limit of the number of multipath clutter signals estimated in step S3.
S4h: using iteratively updated multipath clutter word space matrix
Calculating a multipath clutter sparse coefficient:
wherein s is surv Representing a baseband supervisory signal.
S5: and performing sparse matching cancellation on the multipath clutter by using the multipath clutter sparse coefficient to obtain a signal after multipath clutter cancellation:
the effect of the cancellation method for multipath clutter in the monitoring channel signal of the radar with an external radiation source according to the embodiment of the present invention is further described through a simulation experiment. The signal selected in this embodiment is a digital television direct broadcast satellite signal (DVB-S), and the parameters of the relevant part are shown in table 1.
TABLE 1 parameters relevant to the examples of the invention
| Parameter(s) | Value taking |
| f s | 100MHz |
| d min | 10 |
| d max | 500 |
| τ | 10.10us |
| f d | 0Hz |
| M | 16 |
| T h | 13dB |
| γ | 1.75 |
| η | 2 |
TABLE 2 interference-to-signal ratio of multipath clutter signals
| Multipath numbering | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| Interference-to-signal ratio (dB) | 16.99 | 25.54 | 24.12 | 18.14 | 25.52 | 18.53 | 25.03 | 22.52 |
| Multipath numbering | 8 | 10 | 11 | 12 | 13 | 14 | 15 | 16 |
| Interference-to-signal ratio (dB) | 24.48 | 25.35 | 20.27 | 19.57 | 25.96 | 26.93 | 26.91 | 23.31 |
The interference-to-signal ratios of the 16 multipath clutters in the monitor signal of the present embodiment are shown in table 2. The signal-to-noise ratio of the target echo signal is-35 dB. The fuzzy result shown in fig. 3 is obtained by calculating the cross-fuzzy function (i.e. cross-correlation result) of the monitoring signal and the reference signal at zero frequency, and the upper limit M of the number of multipath signals is obtained by step S3 0 =24. Fig. 5 is a cross-ambiguity function of the signal after the multipath clutter cancellation and the reference signal at the target echo doppler frequency in step S4, so that the method of the embodiment of the present invention has an ideal effect on multipath clutter cancellation, and the signal-to-noise ratio after accumulation of the target echo signal is improved by 14.32dB.
According to the orthogonal matching pursuit multipath clutter cancellation method adopted by the embodiment of the invention, the dimension of the clutter filter matrix is only related to the number of multipath clutter contained in the monitoring channel signal, and the filter matrix of the existing method is the whole dictionary matrix, so that the complexity of solving the sparse matching coefficient can be greatly reduced, and the calculation efficiency is improved. In addition, the multipath clutter cancellation method of the embodiment of the invention has no special requirement on the correlation of the column vectors of the multipath clutter filter matrix, and the existing multipath clutter cancellation method needs to ensure that the column vectors of the filter matrix are not correlated with each other, so the method provided by the embodiment of the invention is suitable for more practical application scenes.
A further embodiment of the present invention provides a storage medium having stored therein a computer program for executing the steps of the cancellation method of multipath clutter in a surveillance channel signal of an external radiation source radar of the above-described embodiments. A further aspect of the present invention provides an electronic device, including a memory and a processor, where the memory stores a computer program, and the processor, when calling the computer program in the memory, implements the steps of the cancellation method for multipath clutter in a monitoring channel signal of an external radiation source radar according to the above embodiment. Specifically, the integrated module implemented in the form of a software functional module may be stored in a computer readable storage medium. The software functional module is stored in a storage medium and includes several instructions to enable an electronic device (which may be a personal computer, a server, or a network device) or a processor (processor) to execute some steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.
Claims (8)
1. A method for canceling multipath clutter in a radar surveillance channel signal of an external radiation source, comprising:
s1: respectively obtaining a reference signal and a monitoring signal by using a reference channel and a monitoring channel of an external radiation source radar, wherein the monitoring signal is a signal which is reflected by a target and then received by the monitoring channel;
s2: performing down-conversion processing on the reference signal and the monitoring signal to obtain a baseband reference signal and a baseband monitoring signal after down-conversion;
s3: estimating the number of multipath clutter signals in a monitoring channel by using the baseband reference signal and the baseband monitoring signal;
s4: according to the number of the estimated multipath clutter signals, sparse matching cancellation is carried out on the multipath clutter signals by using an orthogonal matching tracking method to obtain a multipath clutter sparse coefficient;
s5: and performing sparse matching cancellation on the multipath clutter by using the multipath clutter sparse coefficient to obtain a signal after multipath clutter cancellation.
2. The method for canceling multipath clutter in a radar surveillance channel signal according to claim 1, wherein said S1 comprises:
s1a: setting the sampling frequency f of an external radiation source radar receiver s Direction of beam reception
Receiving bandwidth B and detection threshold T h ；
S1b: setting the minimum value d of the time delay unit of the multipath clutter signals according to the double-base detection range of different scenes min And maximum value d max ；
S1c: and receiving a reference signal by using a reference channel of the external radiation source radar, and receiving a monitoring signal by using a monitoring channel of the external radiation source radar.
3. The method for canceling multipath clutter in a radar surveillance channel signal according to claim 1, wherein said S2 comprises:
carrying out digital down-conversion on the received reference signal and the monitoring signal to obtain a baseband reference signal s after down-conversion ref (t) and a baseband monitor signal s surv (t)：
s surv (t)＝s echo (t)+s m (t)+w(t)
Wherein f is 0 Is the center frequency, s, of the baseband signal echo (t) target echo signals received by the monitoring channel, s m (t) represents a multipath clutter signal received by the monitoring channel, w (t) is white Gaussian noise, and the target echo signal s echo (t) is expressed as:
wherein A is the complex amplitude of the target echo signal, u (t) is the complex envelope of the reference signal, τ is the time delay of the target echo signal relative to the reference signal, f d Is the doppler frequency of the target echo signal.
4. The method for canceling multipath noise in a radar monitor channel signal as recited in claim 1, wherein said S3 comprises:
s3a: calculating a cross-correlation function of the baseband reference signal and the baseband monitoring signal:
χ 0 (n)＝IFFT{FFT[s ref (n),2N]·FFT * [s surv (n),2N]}
where n is a discrete point in time, s ref (n) is a baseband reference signal s ref (t) discretization of the representation, s surv (n) is a baseband monitor signal s surv (t), N is the length of the baseband reference signal and the baseband supervisory signal, FFT (-) represents fourier transform, IFFT (-) represents inverse fourier transform;
s3b: recording the cross-correlation function χ 0 (n) in a time delay unit [ d ] min ,d max ]Inner correlation result exceeds detection threshold T h Average value of the portions:
A ve ＝mean(χ 0 (n)＞T h )；
s3c: will be Chi 0 (n) in time delay units [ d ] min ,d max ]Inner correlation results exceed gamma. A ve The parts of the array form a new array x 1 Wherein γ is a constant factor;
s3d: counting the new array χ 1 The number of maximum values cnt is estimated, and the number of multipath clutter signals is M 0 = η · cnt, where η is a constant factor.
5. The method for canceling multipath clutter in a radar surveillance channel signal according to claim 4, wherein said S4 comprises:
s4a: from a discretized baseband reference signal s ref (n) generating a multipath clutter word space matrix D:
wherein K = d max -d min N denotes discrete time, N denotes signal length, f s Representing the sampling frequency of radar receivers with external radiation sourcesRate, s of the first column in matrix D ref (1) Front is given by d min 0, s of the last column ref (1) Front total K + d min +1, 0;
s4b: and performing unit representation on each column of the multipath clutter word space matrix D:
D＝[a 1 ,a 2 ,…,a K ]，
wherein, a i Representing the unitized multipath clutter signal, i = 1.., K;
s4c: residual signal r after initialization cancellation 0 ＝s surv And initializing a multipath clutter matrix index set Lambda and iteration times m:
m＝1；
s4d: calculating a position index lambda of the current multipath clutter signal in the multipath clutter word space matrix D m ：
Wherein m represents the number of iterative loops;
s4e: indexing the obtained position by lambda m Adding multipath clutter matrix index set
Λ m ＝Λ m-1 ∪{λ m }；
S4f: updating a residual signal with the multipath clutter matrix index set:
wherein, the first and the second end of the pipe are connected with each other,
is part of the multipath clutter word space matrix D,
is composed of index set Λ m A new spatial matrix composed of corresponding column signals;
s4g: let M = M +1, repeat steps S4d-S4g, when the iteration exit condition M = 0 The loop is exited to obtain the multi-path clutter word space matrix after iterative update
Wherein M is 0 The number of the multipath clutter signals is estimated.
S4h: using iteratively updated multipath clutter word space matrix
Calculating a multipath clutter sparse coefficient:
wherein s is surv Representing a baseband supervisory signal.
6. The method of canceling multipath clutter in an external radiation source radar surveillance channel signal as claimed in claim 5, wherein said S5 comprises:
and performing sparse matching cancellation on the multipath clutter by using the multipath clutter sparse coefficient to obtain a signal after multipath clutter cancellation:
7. a storage medium having stored thereon a computer program for executing the steps of the method for canceling multipath clutter in a surveillance channel signal for an external radiation source radar according to any one of claims 1 to 6.
8. An electronic device comprising a memory having a computer program stored therein and a processor, the processor when invoking the computer program in the memory implementing the steps of the method of canceling multipath clutter in a surveillance channel signal of an external radiation source radar according to any one of claims 1 to 6.
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