Method, device and system for airborne radar to resist dense unintentional interference

Abstract

The present invention relates to the field of radar technology, and provides a method, device and system for airborne radar to resist dense unintentional interference. The method comprises: processing the first echo signal received in the passive mode to obtain prior knowledge; in the active mode, constructing a target function according to the prior knowledge; solving the target function to obtain a sparse spectrum waveform, and using the sparse spectrum waveform as the transmission waveform in the active mode; performing sub-band dimension reduction processing on the second echo signal in the active mode to obtain a sub-band echo signal, performing interference filtering and clutter suppression on each sub-band echo signal to obtain the output signal of each sub-band, and then performing splicing and synthesis to obtain the output signal after interference suppression. The present invention obtains prior knowledge by pre-processing in the passive mode, so that the prior knowledge is involved in the construction of the sparse spectrum waveform, and then performs sub-band dimension reduction processing on the echo signal, and then performs interference filtering and clutter suppression, thereby achieving the suppression of dense interference.

Description

Technical Field

[0001] The present invention relates to the field of radar technology, and in particular to a method, device and system for airborne radar to resist intensive unintentional interference. Background Art

[0002] As the main electronic equipment of early warning aircraft, airborne early warning radar not only has a high platform height, which can overcome the influence of the earth's curvature, but also has a large range of activities and a long visual distance, playing a very important role in the early warning system. Since airborne radars usually work over land, they will inevitably be affected by strong ground clutter. In addition, due to the movement of the carrier platform, the clutter presents space-time coupling characteristics in range-azimuth. The broadening of clutter in the Doppler domain leads to the performance degradation of traditional clutter suppression methods. Space-time adaptive processing technology is a technology that uses space-time two-dimensional echo data to generate adaptive filters to suppress clutter. It is usually used in airborne early warning radars and can significantly improve the clutter suppression performance of airborne radars. However, with the development of electronic warfare technology and equipment and the rapid progress of communication technology, airborne radars are not only affected by strong ground clutter, but also face various threats of unintentional interference, especially over land, where there are many radiation sources, resulting in the widespread existence of main lobe interference in airborne early warning radars. Although the use of STAP technology can suppress some clutter and interference, STAP technology alone cannot guarantee that the target signal can be reliably detected after processing. Especially when the number of interferences is large, that is, in the case of intensive unintentional interference, interference suppression will also consume a large number of system degrees of freedom, reduce the system's clutter suppression capability, and reduce the target detection performance of the airborne radar.

[0003] In view of this, overcoming the defects of the prior art is an urgent problem to be solved in the field of this technology. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for airborne radar to resist intensive unintentional interference.

[0005] The present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides an airborne radar anti-intensive unintentional interference method, comprising:

[0007] Processing the first echo signal received in the passive mode to obtain the interference angle information and the frequency band information;

[0008] In the active mode, the angle information and the frequency band information of the interference are used as prior knowledge, and the objective function is constructed based on the prior knowledge. ;in, is the FFT transformation matrix, is the weighting factor, is the weight vector, According to the prior knowledge, It means to arrange the elements in a diagonal matrix. is the zero-padded matrix, is the amplitude of the ideal spectrum, To assist in optimizing variables, is the phase auxiliary vector, represents the Hadamard product, The radar transmits the waveform Discrete signal after point sampling;

[0009] Solving the objective function to obtain a sparse spectrum waveform, and using the sparse spectrum waveform as a transmission waveform in an active mode;

[0010] The second echo signal in the active mode is subjected to sub-band dimension reduction processing to obtain Q sub-band echo signals, interference filtering and clutter suppression are performed on each sub-band echo signal to obtain an output signal of each sub-band, and the output signals of each sub-band are spliced ​​and synthesized to obtain an output signal after interference suppression.

[0011] Preferably, the processing of the first echo signal received in the passive mode to obtain the interference angle information and the frequency band information specifically includes:

[0012] Divide the spatial orientation into Angle, yes The interference signals at each angle are processed respectively to obtain the interference signals at each angle, thereby determining the frequency and azimuth information of the interference according to the interference signals at each angle; wherein, is the default value;

[0013] Among them, the Each angle is processed separately to obtain the interference signal of each angle, including:

[0014] Build Angle The weight at ;in, , is the received signal of the airborne radar in passive mode, is the number of fast time (distance dimension) sampling points, represents the spatial steering vector, is a constant;

[0015] Use Angle The weights at the first echo signal are processed by adaptive digital beamforming to obtain the angle The output signal at , for angle The output signal at is converted to the frequency domain to obtain the angle The interference signal ;in, is the FFT transformation matrix.

[0016] Preferably, the It is generated according to the prior knowledge, specifically:

[0017] The frequency band information of the interference is obtained from the prior knowledge, the vector value corresponding to the interference frequency band is set to 0, and the vector values ​​of other frequency bands are set to 1, and the .

[0018] Preferably, performing sub-band dimension reduction processing on the second echo signal in the active mode to obtain Q sub-band echo signals specifically includes:

[0019] The second echo signal is converted from the pulse domain to the Doppler domain to obtain echo data ,in Represents slow-time FFT transform;

[0020] The echo data is processed in the frequency domain by sub-banding and dimensionality reduction to obtain Q sub-band echo signals; among them, the qth sub-band echo signal ; represents the Kronecker product, is the result of range dimension transformation of echo data corresponding to a single array element and a single Doppler channel. , represents the fast-time FFT transform, is the subband dimension reduction matrix, is the frequency domain subband dimension reduction matrix, , and are N-order and K-order unit matrices respectively, The dimension of , The dimension of , The dimension of , The dimension of , is the number of sampling points in the distance dimension, is the number of distance dimension sampling points after sub-band dimensionality reduction, is the number of array elements, is the number of pulses.

[0021] Preferably, the step of filtering out interference and suppressing clutter on each sub-band echo signal to obtain an output signal of each sub-band specifically includes:

[0022] Using the angle information of the interference, construct a dimension reduction transformation matrix ;in, Multiple main beams formed by spatial sliding windows, Auxiliary beams formed for each interference direction;

[0023] The sub-band echo signal is subjected to sub-band adaptive digital beamforming processing using the dimension reduction transformation matrix to obtain the qth sub-band echo data after interference filtering. ;in, represents the subband spatial adaptive weight, The dimension of , represents the number of main beams after sliding window, is the qth sub-band echo signal, is the number of pulses, is the number of sampling points in the distance dimension after sub-band dimensionality reduction;

[0024] Clutter suppression is performed on the qth sub-band echo data after interference filtering to obtain an output signal of the qth sub-band.

[0025] Preferably, performing clutter suppression on the qth sub-band echo data after interference filtering to obtain the output signal of the qth sub-band specifically includes:

[0026] Construct sub-band clutter noise covariance matrix ;

[0027] According to the sub-band clutter noise covariance matrix, the qth sub-band The space-time adaptive weight vector corresponding to the distance dimension sampling point ;in, is the preset target-oriented vector after dimension reduction, The dimension of ;

[0028] The space-time adaptive weight vector is used to perform space-time adaptive processing on the sub-band echo data after the qth interference filtering, and the qth sub-band is obtained. The output signal of the distance dimension sampling point ;

[0029] The output signals of the qth sub-band at each distance dimension sampling point are spliced ​​and synthesized to obtain the output signal of the qth sub-band .

[0030] Preferably, the step of splicing and synthesizing the output signals of each sub-band to obtain the output signal after interference suppression specifically includes:

[0031] The output signals of Q sub-bands are spliced ​​and synthesized to obtain the total output signal ;

[0032] Perform inverse fast Fourier transform on the total output signal to obtain the output signal after interference suppression ;in represents the IFFT operation, It represents the distance dimension data corresponding to a certain Doppler channel, and its dimension is L×1.

[0033] In a second aspect, the present invention further provides an airborne radar anti-intensive unintentional interference device, which is used to implement the airborne radar anti-intensive unintentional interference method described in the first aspect, and the device includes:

[0034] At least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the processor to execute the airborne radar anti-dense unintentional interference method described in the first aspect.

[0035] In a third aspect, the present invention further provides a non-volatile computer storage medium, wherein the computer storage medium stores computer executable instructions, which are executed by one or more processors to complete the airborne radar anti-dense unintentional interference method described in the first aspect.

[0036] In a fourth aspect, the present invention further provides an airborne radar anti-intensive unintentional interference system, comprising a construction module, a solution module and a processing module;

[0037] The construction module is used to process the first echo signal received in the passive mode to obtain the angle information and frequency band information of the interference; and in the active mode, the angle information and frequency band information of the interference are used as prior knowledge to construct the objective function according to the prior knowledge ;in, is the FFT transformation matrix, is the weighting factor, is the weight vector, According to the prior knowledge, It means to arrange the elements in a diagonal matrix. is the zero-padded matrix, is the amplitude of the ideal spectrum, To assist in optimizing variables, is the phase auxiliary vector, represents the Hadamard product, The radar transmits the waveform Discrete signal after point sampling;

[0038] The solution module is used to solve the objective function to obtain a sparse spectrum waveform, and use the sparse spectrum waveform as the transmission waveform in the active mode;

[0039] The processing module is used to perform sub-band dimensionality reduction processing on the second echo signal in the active mode to obtain Q sub-band echo signals, perform interference filtering and clutter suppression on each sub-band echo signal to obtain an output signal of each sub-band, and splice and synthesize the output signals of each sub-band to obtain an output signal after interference suppression.

[0040] The present invention obtains the angle information and the frequency band information of the interference by pre-processing in a passive mode, and then uses the angle information and the frequency band information of the interference as prior knowledge to participate in the construction of a sparse spectrum waveform, thereby achieving the suppression of dense interference, and also performs sub-band dimensionality reduction processing on the second echo signal, and performs interference filtering and clutter suppression on the sub-band echo signal obtained after the sub-band dimensionality reduction processing, thereby further reducing interference and optimizing the interference suppression effect in a dense interference environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0042] Figure 1 It is a flowchart of a first method for airborne radar to resist intensive unintentional interference provided by an embodiment of the present invention;

[0043] Figure 2 It is a flowchart of a second method for airborne radar to resist intensive unintentional interference provided by an embodiment of the present invention;

[0044] Figure 3 is a flow chart of a third method for airborne radar to resist intensive unintentional interference provided by an embodiment of the present invention;

[0045] Figure 4 is a flowchart of a fourth method for airborne radar to resist intensive unintentional interference provided by an embodiment of the present invention;

[0046] Figure 5 is a schematic diagram of a fifth method for airborne radar to resist intensive unintentional interference provided by an embodiment of the present invention;

[0047] Figure 6 is a schematic diagram of another method for airborne radar to resist intensive unintentional interference provided by an embodiment of the present invention;

[0048] Figure 7 1 is a schematic diagram of the architecture of an airborne radar anti-intensive unintentional interference system provided by an embodiment of the present invention;

[0049] Figure 8It is a schematic diagram of the architecture of an airborne radar anti-intensive unintentional interference device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0051] Unless the context requires otherwise, throughout the specification and claims, the term "including" is to be interpreted as open inclusion, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "examples", "specific examples" or "some examples" and the like are intended to indicate that specific features, structures, materials or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present disclosure. The schematic representation of the above terms does not necessarily refer to the same embodiment or example. In addition, the specific features, structures, materials or characteristics may be included in any one or more embodiments or examples in any appropriate manner, that is, although they may be carried in the embodiments or examples of the above terms due to reasons such as the order and position of appearance, it is not limited to that they can be carried in combination by one embodiment or example.

[0052] In the description of the present invention, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, the meaning of "multiple" is two or more. In addition, for example, the same type of nouns may be described as two independent individuals by adding "A" and "B" at the end. In this case, the corresponding features defined as "A" and "B" are only used to distinguish the same type of individuals for description purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features.

[0053] In the description of the present invention, the expression "A and / or B" (where A and B are used to formally represent specific characteristic contents) is involved, and the corresponding expressions include the following three combinations: only A, only B, and a combination of A and B.

[0054] As used herein, "about," "substantially," or "approximately" includes the stated value and an average value that is within an acceptable range of deviation from the particular value as determined by one of ordinary skill in the art taking into account the measurements in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system).

[0055] In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0056] Embodiment 1:

[0057] Embodiment 1 of the present invention provides a method for airborne radar to resist intensive unintentional interference, such as Figure 1 As shown, including:

[0058] In step 201, the first echo signal received in the passive mode is processed to obtain the angle information and the frequency band information of the interference.

[0059] In step 202, in the active mode, the angle information and the frequency band information of the interference are used as prior knowledge, and the objective function is constructed based on the prior knowledge. ;in, is the FFT transformation matrix, is the weighting factor, is the weight vector, According to the prior knowledge, It means to arrange the elements in a diagonal matrix. is the zero-padded matrix, is the amplitude of the ideal spectrum, is a known quantity, To assist in optimizing variables, is the phase auxiliary vector, represents the Hadamard product, The radar transmits the waveform The discrete signal after point sampling, , It is a preset value obtained by a person skilled in the art based on empirical analysis; is the spectral stopband constraint objective function, is the low sidelobe constraint objective function for a specific distance unit, is the weighting factor that controls the weight of the two. It is a 0-1 weighted vector set according to the prior information of the interference frequency band, where the passband is set to 1 and the stopband, i.e., the frequency band where the interference is located, is set to 0; the spectral stopband constraint is mainly considered here. For the low sidelobe constraint, the entire range sidelobe is suppressed by default, and the specific range unit is not considered, that is, the The method is generated according to the prior knowledge, specifically: obtaining the frequency band information where the interference is located from the prior knowledge, setting the vector value corresponding to the interference frequency band to 0, and setting the vector values ​​of other frequency bands to 1, and obtaining the .

[0060] In step 203, the objective function is solved to obtain a sparse spectrum waveform, and the sparse spectrum waveform is used as a transmission waveform to suppress interference. That is, a sparse spectrum waveform is designed as a transmission waveform based on prior information, interference is suppressed in the frequency domain, and main lobe interference is avoided. There are many methods for solving the objective function, all of which are prior arts and will not be described in detail here.

[0061] The sparse spectrum waveform obtained by solving the problem can not only effectively suppress dense interference and reduce the influence of strong isolated point clutter and interference, but also form low-range sidelobes at specific distance units to improve the detection performance of weak targets.

[0062] In a dense interference environment, effective interference suppression cannot be achieved only by using a sparse spectrum waveform. Sometimes, the number of interferences is large, and the spatial degrees of freedom of the interferences exceed the spatial system degrees of freedom. In this case, sub-band dimensionality reduction processing is required. Therefore, this embodiment further provides a preferred implementation method, that is, the method described in this embodiment also includes:

[0063] In step 204, the second echo signal in the active mode is subjected to sub-band dimension reduction processing to obtain Q sub-band echo signals, interference filtering and clutter suppression are performed on each sub-band echo signal to obtain an output signal of each sub-band, and the output signals of each sub-band are spliced ​​and synthesized to obtain an output signal after interference suppression. The first echo signal refers to the echo signal received in the passive mode, and the second echo signal refers to the echo signal received in the active mode. Q is obtained by those skilled in the art based on empirical analysis, specifically to make the interference spatial domain freedom of each sub-band after the sub-band dimension reduction processing less than the spatial domain system freedom.

[0064] This embodiment obtains the angle information and the frequency band information of the interference by pre-processing in a passive mode, and then uses the angle information and the frequency band information of the interference as prior knowledge to participate in the construction of a sparse spectrum waveform, thereby achieving suppression of dense interference. In consideration of the application in a dense interference environment, this embodiment also performs sub-band dimensionality reduction processing on the second echo signal, and performs interference filtering and clutter suppression on the sub-band echo signal obtained after the sub-band dimensionality reduction processing, thereby further reducing interference and optimizing the interference suppression effect in a dense interference environment.

[0065] The processing of the first echo signal received in the passive mode to obtain the interference angle information and the frequency band information specifically includes:

[0066] Divide the spatial orientation into Angle, yes The interference signals at each angle are processed respectively to obtain the interference signals at each angle, thereby determining the frequency and azimuth information of the interference according to the interference signals at each angle; wherein, It is a preset value, which is obtained by technicians in this field according to demand analysis.

[0067] Among them, the Each angle is processed separately to obtain the interference signal of each angle, including:

[0068] Build Angle The weight at ;in, , is the received signal of the airborne radar in passive mode, is the number of fast time (distance dimension) sampling points, represents the spatial steering vector, is a constant.

[0069] Use Angle The weights at the first echo signal are used to perform adaptive digital beam forming (Adaptive Digital Beam Forming, referred to as ADBF) to obtain the angle The output signal at , for angle The output signal at is converted to the frequency domain to obtain the angle The interference signal ;in, is the FFT transformation matrix. After the above processing, Contains the perspective The incoming interference signal is suppressed, and the interference from other directions is suppressed. After ADBF processing is performed on each angle, the frequency and azimuth information of the interference can be obtained.

[0070] The performing sub-band dimension reduction processing on the second echo signal in the active mode to obtain Q sub-band echo signals specifically includes:

[0071] The second echo signal is converted from the pulse domain to the Doppler domain to obtain echo data ; That is, perform slow time FFT transformation on the second echo signal.

[0072] The echo data is processed in the frequency domain by sub-banding and dimensionality reduction to obtain Q sub-band echo signals; among them, the qth sub-band echo signal ; q is less than or equal to Q, represents the Kronecker product, is the result of range dimension transformation of echo data corresponding to a single array element and a single Doppler channel. , represents the fast-time FFT transform, is the subband dimension reduction matrix, is the frequency domain subband dimension reduction matrix, , and are N-order and K-order unit matrices respectively, The dimension of , The dimension of , The dimension of , The dimension of , is the number of sampling points in the distance dimension, is the number of distance dimension sampling points after sub-band dimensionality reduction, is the number of array elements, is the number of pulses.

[0073] After the sub-band dimensionality reduction processing, the interference spatial freedom of each sub-band is less than the spatial system freedom. At this time, the adaptive-adaptive method can be used to suppress the remaining interference. According to the interference angle information obtained in the passive mode, an auxiliary beam is formed in the interference direction, and multiple main beams are formed in the spatial domain through a sliding window. The interference filtering and clutter suppression of each sub-band echo signal are performed to obtain the output signal of each sub-band, such as Figure 2 As shown, specifically including:

[0074] In step 401, the angular information of the interference is used to construct a dimension reduction transformation matrix ;in, Multiple main beams formed by spatial sliding windows, Auxiliary beams are formed for each interference direction.

[0075] In step 402, the sub-band echo signal is subjected to sub-band adaptive digital beamforming processing using the dimension reduction transformation matrix to obtain the qth sub-band echo data after interference filtering. ;in, represents the subband spatial adaptive weight, The dimension of , represents the number of main beams after sliding window, is the qth sub-band echo signal, is the number of pulses, is the number of sampling points in the distance dimension after sub-band dimension reduction; that is, the echo data is subjected to sub-band adaptive digital beamforming processing on the basis of dimension reduction to achieve complete suppression of interference. After the above processing, Contains clutter signals, noise signals and target signals.

[0076] In step 403, clutter suppression is performed on the qth sub-band echo data after interference removal to obtain an output signal of the qth sub-band.

[0077] In an optional implementation manner, clutter suppression is performed on the qth sub-band echo data after interference filtering to obtain an output signal of the qth sub-band, such as Figure 3 As shown, specifically including:

[0078] In step 501, construct the sub-band clutter noise covariance matrix .

[0079] In step 502, the qth subband is constructed according to the subband clutter noise covariance matrix. The space-time adaptive weight vector corresponding to the distance dimension sampling point ;in, is the preset target-oriented vector after dimension reduction, The dimension of .

[0080] In step 503, the space-time adaptive weight vector is used to perform space-time adaptive processing (STAP) on the qth sub-band echo data after interference filtering, and the qth sub-band is obtained. The output signal of the distance dimension sampling point .

[0081] In step 504, the output signals of the qth sub-band at each distance dimension sampling point are spliced ​​and synthesized to obtain the output signal of the qth sub-band .

[0082] In an actual application scenario, the output signals of each sub-band are spliced ​​and synthesized to obtain an output signal after interference suppression, which specifically includes:

[0083] The output signals of Q sub-bands are spliced ​​and synthesized to obtain the total output signal ; Perform inverse fast Fourier transform on the total output signal to obtain the output signal after interference suppression ;in represents the IFFT operation, It represents the distance dimension data corresponding to a certain Doppler channel, and its dimension is L×1.

[0084] Embodiment 2:

[0085] The present invention is based on the method described in Example 1, combined with specific application scenarios, and uses technical descriptions in related scenarios to illustrate the implementation process of the present invention in characteristic scenarios.

[0086] This embodiment provides a method for airborne radar to resist dense unintentional interference, such as Figure 4 As shown, specifically including:

[0087] In step 601, the received echo data is processed using adaptive digital beamforming technology in a passive mode to obtain interference angle information and frequency band information, and store the information as prior knowledge.

[0088] In step 602, in the active mode, a sparse spectrum waveform is designed as a transmission waveform according to prior information to suppress interference in the frequency domain, thereby avoiding main lobe interference.

[0089] In step 603, the interference degree of freedom is reduced by sub-banding dimension reduction processing.

[0090] In step 604, sub-band adaptive digital beamforming processing is performed on the echo data based on the dimensionality reduction to achieve complete interference suppression.

[0091] In step 605, STAP processing is performed on the echo signal that has undergone anti-interference processing.

[0092] In step 606, each sub-band is spliced ​​and synthesized.

[0093] Among them, Figure 5 As shown, in step 601, adaptive digital beamforming technology is used in the passive mode to obtain the prior information of interference, that is, the spatial azimuth angle is divided, and then ADBF processing is performed on each angle. When all the divided angles are processed, the frequency and azimuth information of the interference can be obtained.

[0094] In step 602, in the active mode, a sparse spectrum waveform is designed as the transmission waveform according to the prior information, that is, according to the prior information of interference, the stopband resources are first allocated to the frequency band where the mainlobe interference is located, and then the remaining stopband resources are allocated to the sidelobe interference with larger amplitude, so as to avoid the mainlobe interference and maximize the interference suppression effect.

[0095] In step 603, the interference degrees of freedom are reduced by sub-band dimensionality reduction processing, that is, firstly, a slow-time FFT transform is performed on the space-time data of each range unit to transform it from the pulse domain to the Doppler domain; then, an FFT transform is performed on the range dimension data of the single-element single Doppler channel to transform the echo data into the frequency domain, and finally, a sub-band division process is performed to make the interference spatial domain degrees of freedom of each sub-band smaller than the spatial system degrees of freedom.

[0096] In step 604, sub-band adaptive digital beamforming processing is performed on the echo data based on dimensionality reduction, that is, auxiliary beams are formed in each sub-band interference direction according to the prior information of interference, and multiple main beams are formed by spatial sliding windows to effectively suppress the remaining sidelobe interference.

[0097] In step 605, STAP processing is performed on the echo signal after anti-interference processing to achieve effective suppression of clutter.

[0098] In step 606, each sub-band is spliced ​​and synthesized. The sub-bands after the above processing are spliced ​​together and converted into the distance dimension by inverse fast Fourier transform.

[0099] The step 601 specifically includes:

[0100] When the airborne radar works in passive mode, the spatial azimuth is divided into For each angle, ADBF processing is performed. The weight at , is the received signal of the airborne radar in passive mode, is the number of fast time (distance dimension) sampling points, represents the spatial steering vector; represents a constant, the interference noise covariance matrix ; Angle after ADBF processing The output signal at ; The angle after the ADBF processing The output signal at the position is transformed into the frequency domain by Fast Fourier Transformation (FFT) to obtain the angle The interference signal ;in is the FFT transformation matrix.

[0101] After the above processing, Contains the perspective The incoming interference signal is suppressed, and the interference from other directions is suppressed. After ADBF processing is performed on each angle, the frequency and azimuth information of the interference can be obtained.

[0102] The step 602 specifically includes:

[0103] Assumptions The radar transmits the waveform The discrete signal form after point sampling is used, and the minimum mean square error criterion is used to make the optimized waveform power spectrum density (PSD) approach the PSD of the ideal waveform, where the spectrum gap of the ideal waveform PSD is represented by a 0-1 weighted vector, which can be obtained through the interference prior information obtained in the passive mode in step 1. The constructed optimization objective function can be expressed as ;in, is the FFT transformation matrix, is the weighting factor, is the weight vector, According to the prior knowledge, It means to arrange the elements in a diagonal matrix. is the zero-padded matrix, is the amplitude of the ideal spectrum, To assist in optimizing variables, is the phase auxiliary vector, Denotes the Hadamard product.

[0104] The sparse spectrum waveform obtained by solving the problem can not only effectively suppress dense interference and reduce the influence of strong isolated point clutter and interference, but also form low-range sidelobes at specific distance units to improve the detection performance of weak targets.

[0105] The step 603 specifically includes: using the sparse spectrum waveform as the transmission waveform to form a coherent pulse train, the number of pulses is , the number of array elements is , and then the received echo data is processed by matched filtering to obtain the received signal , the dimension is .

[0106] In a dense interference environment, effective interference suppression cannot be achieved only through sparse spectrum waveforms. Sometimes the number of interferences is large and the spatial degrees of freedom of interference exceed the spatial system degrees of freedom. In this case, sub-band dimensionality reduction processing is required, such as Figure 6 As shown, specifically including:

[0107] 1) Perform a slow-time FFT transform on the received signal, transforming it from the pulse domain to the Doppler domain, that is, .

[0108] 2) Perform range-dimensional FFT transformation on the echo data corresponding to a single array element and a single Doppler channel, that is, .

[0109] 3) Sub-band dimensionality reduction processing is performed in the frequency domain to form Q sub-bands. The echo data of the qth sub-band after dimensionality reduction is ; represents the Kronecker product, where .

[0110] in, is the subband dimension reduction matrix, is the frequency domain subband dimension reduction matrix, and are N-order and K-order unit matrices respectively, The dimension of , The dimension of , The dimension of , The dimension of , is the number of sampling points in the distance dimension, is the number of sampling points in the distance dimension after sub-band dimensionality reduction.

[0111] The step 604 specifically includes:

[0112] After the sub-band dimensionality reduction processing, the interference spatial freedom of each sub-band is less than the spatial system freedom. At this time, the adaptive-adaptive method can be used to suppress the remaining interference. According to the interference angle information obtained in the passive mode, an auxiliary beam is formed in the interference direction, and multiple main beams are formed in the spatial domain through sliding windows. The dimensionality reduction transformation matrix is ;in, Multiple main beams formed by spatial sliding windows, Auxiliary beams are formed for each interference direction.

[0113] After sub-band adaptive digital beamforming processing, the echo data of the qth sub-band is ;in represents the subband spatial adaptive weight, The dimension of , Indicates the number of main beams after sliding window.

[0114] The step 605 specifically includes:

[0115] After the above processing, It contains clutter signal, noise signal and target signal. Next, clutter suppression processing is performed. The space-time adaptive weight vector corresponding to the distance dimension sampling point is: ;in is the preset target-oriented vector after dimension reduction, The dimension of .

[0116] The sub-band clutter noise covariance matrix is ;in, Indicates the qth subband The echo data corresponding to the distance dimension sampling points. Then the space-time weight vector corresponding to the sub-band is ; The output signal of a certain distance unit of a Doppler channel after space-time adaptive processing of the qth subband is .

[0117] The step 606 specifically includes: splicing and synthesizing each sub-band. First, the output signal of a certain distance unit of a certain Doppler channel after the space-time adaptive processing of the qth sub-band is synthesized on a certain Doppler channel to obtain the output signal of the qth sub-band. .

[0118] The data of Q sub-bands are spliced ​​and synthesized to obtain ;right Perform Inverse Fast Fourier Transformation (IFFT) to obtain ;in represents the IFFT operation, It represents the distance dimension data corresponding to a certain Doppler channel, and its dimension is L×1.

[0119] This embodiment uses ADBF technology in passive mode to obtain prior information of interference, which can not only accurately estimate the angle of the interference signal, but also estimate the frequency information of the interference. This embodiment also uses the orthogonality of the frequency domain to match the interference echo signal with the sparse spectrum waveform to avoid the main lobe interference. And through sub-band dimensionality reduction processing, the suppression of the ultra-freedom dense sidelobe interference is achieved, so that the interference freedom is less than the freedom of the spatial system, solving the problem of ultra-freedom interference suppression.

[0120] Embodiment 3:

[0121] Based on Embodiment 1 and Embodiment 2, this embodiment further provides an airborne radar anti-intensive unintentional interference system, such as Figure 7 As shown, it includes a building module, a solving module and a processing module.

[0122] The construction module is used to process the first echo signal received in the passive mode to obtain the angle information and frequency band information of the interference; and in the active mode, the angle information and frequency band information of the interference are used as prior knowledge to construct the objective function according to the prior knowledge ;in, is the FFT transformation matrix, is the weighting factor, is the weight vector, According to the prior knowledge, It means to arrange the elements in a diagonal matrix. is the zero-padded matrix, is the amplitude of the ideal spectrum, To assist in optimizing variables, is the phase auxiliary vector, represents the Hadamard product, The radar transmits the waveform The discrete signal after point sampling.

[0123] The solution module is used to solve the objective function to obtain a sparse spectrum waveform, and use the sparse spectrum waveform as the transmission waveform in the active mode.

[0124] The processing module is used to perform sub-band dimensionality reduction processing on the second echo signal in the active mode to obtain Q sub-band echo signals, perform interference filtering and clutter suppression on each sub-band echo signal to obtain an output signal of each sub-band, and splice and synthesize the output signals of each sub-band to obtain an output signal after interference suppression.

[0125] This embodiment also provides an airborne radar anti-intensive unintentional interference device, such as Figure 8 , is a schematic diagram of the architecture of an airborne radar anti-dense unintentional interference device according to an embodiment of the present invention. The airborne radar anti-dense unintentional interference device according to this embodiment includes one or more processors 21 and a memory 22. Figure 8 A processor 21 is taken as an example.

[0126] The processor 21 and the memory 22 may be connected via a bus or other means. Figure 8 The example of connecting through bus is taken in the following.

[0127] The memory 22 is a non-volatile computer-readable storage medium that can be used to store non-volatile software programs and non-volatile computer executable programs, such as the airborne radar anti-intensive unintentional interference method in Example 1. The processor 21 executes the airborne radar anti-intensive unintentional interference method by running the non-volatile software programs and instructions stored in the memory 22.

[0128] The memory 22 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage devices. In some embodiments, the memory 22 may optionally include a memory remotely arranged relative to the processor 21, and these remote memories may be connected to the processor 21 via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0129] The program instructions / modules are stored in the memory 22, and when executed by the one or more processors 21, the airborne radar anti-dense unintentional interference method in the above-mentioned embodiment 1 is executed.

[0130] It is worth noting that the information interaction, execution process, etc. between the modules and units within the above-mentioned devices and systems are based on the same concept as the processing method embodiment of the present invention. The specific contents can be found in the description of the method embodiment of the present invention and will not be repeated here.

[0131] A person skilled in the art may understand that all or part of the steps in the various methods of the embodiments may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, and the storage medium may include: a read-only memory (ROM), a random access memory (RAM), a disk or an optical disk, etc.

[0132] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preventing airborne radar from intensive unintentional interference, characterized in that: include: Processing the first echo signal received in the passive mode to obtain the interference angle information and the frequency band information; In the active mode, the angle information and the frequency band information of the interference are used as prior knowledge, and the objective function is constructed based on the prior knowledge. ;in, is the FFT transformation matrix, is the weighting factor, is the weight vector, According to the prior knowledge, It means to arrange the elements in a diagonal matrix. is the zero-padded matrix, is the amplitude of the ideal spectrum, To assist in optimizing variables, is the phase auxiliary vector, represents the Hadamard product, The radar transmits the waveform The discrete signal after point sampling, is the default value; Solving the objective function to obtain a sparse spectrum waveform, and using the sparse spectrum waveform as a transmission waveform in an active mode; Performing sub-band dimension reduction processing on the second echo signal in the active mode to obtain Q sub-band echo signals, performing interference filtering and clutter suppression on each sub-band echo signal to obtain an output signal of each sub-band, and splicing and synthesizing the output signals of each sub-band to obtain an output signal after interference suppression; The first echo signal received in the passive mode is processed to obtain the interference angle information and the frequency band information, specifically including: Divide the spatial orientation into Angle, yes The interference signals at each angle are processed respectively to obtain the interference signals at each angle, thereby determining the frequency and azimuth information of the interference according to the interference signals at each angle; wherein, is the default value; Among them, the Each angle is processed separately to obtain the interference signal of each angle, including: Build Angle The weight at ;in, , is the first echo signal, is the number of fast time sampling points, represents the spatial steering vector, is a constant, is the interference noise covariance matrix in passive mode; Use Angle The weights at the first echo signal are processed by adaptive digital beamforming to obtain the angle The output signal at , for angle The output signal at is converted to the frequency domain to obtain the angle The interference signal ;in, is the FFT transformation matrix.

2. The method for preventing airborne radar from intensive unintentional interference according to claim 1, characterized in that: Said It is generated according to the prior knowledge, specifically: The frequency band information of the interference is obtained from the prior knowledge, the vector value corresponding to the interference frequency band is set to 0, and the vector values ​​of other frequency bands are set to 1, and the .

3. The method for preventing airborne radar from being jammed unintentionally due to intensive interference according to claim 1, characterized in that: The performing sub-band dimension reduction processing on the second echo signal in the active mode to obtain Q sub-band echo signals specifically includes: The second echo signal is converted from the pulse domain to the Doppler domain to obtain echo data ,in Represents slow-time FFT transform; The echo data is processed in the frequency domain by sub-banding and dimensionality reduction to obtain Q sub-band echo signals; among them, the qth sub-band echo signal ; represents the Kronecker product, is the result of range dimension transformation of echo data corresponding to a single array element and a single Doppler channel. , is the receiving signal in active mode, represents the fast-time FFT transform, is the subband dimension reduction matrix, is the frequency domain subband dimension reduction matrix, , and are N-order and K-order unit matrices respectively, The dimension of , The dimension of , The dimension of , The dimension of , is the number of sampling points in the distance dimension, is the number of distance dimension sampling points after sub-band dimensionality reduction, is the number of array elements, is the number of pulses.

4. The method for preventing airborne radar from intensive unintentional interference according to claim 1, characterized in that: The interference filtering and clutter suppression of each sub-band echo signal to obtain the output signal of each sub-band specifically includes: Using the angle information of the interference, construct a dimension reduction transformation matrix ;in, Multiple main beams formed by spatial sliding windows, Auxiliary beams formed for each interference direction; The sub-band echo signal is subjected to sub-band adaptive digital beamforming processing using the dimension reduction transformation matrix to obtain the qth sub-band echo data after interference filtering. ;in, represents the subband spatial adaptive weight, The dimension of , represents the number of main beams after sliding window, is the qth sub-band echo signal, is the number of pulses, is the number of sampling points in the distance dimension after sub-band dimensionality reduction; Clutter suppression is performed on the qth sub-band echo data after interference filtering to obtain an output signal of the qth sub-band.

5. The method for preventing airborne radar from intensive unintentional interference according to claim 4, characterized in that: The performing clutter suppression on the qth sub-band echo data after the interference filtering to obtain the output signal of the qth sub-band specifically includes: Construct sub-band clutter noise covariance matrix ,in, is the qth subband The echo data corresponding to the sampling points in the distance dimension; According to the sub-band clutter noise covariance matrix, the qth sub-band The space-time adaptive weight vector corresponding to the distance dimension sampling point ;in, is the preset target-oriented vector after dimension reduction, The dimension of ; The space-time adaptive weight vector is used to perform space-time adaptive processing on the sub-band echo data after the qth interference filtering, and the qth sub-band is obtained. The output signal of the distance dimension sampling point , is the qth subband The echo data corresponding to the sampling points in the distance dimension; The output signals of the qth sub-band at each distance dimension sampling point are spliced ​​and synthesized to obtain the output signal of the qth sub-band .

6. The method for preventing airborne radar from intensive unintentional interference according to claim 1, characterized in that: The step of combining the output signals of each sub-band to obtain the output signal after interference suppression specifically includes: The output signals of Q sub-bands are spliced ​​and synthesized to obtain the total output signal ;in, is the output signal of the qth subband; Perform inverse fast Fourier transform on the total output signal to obtain the output signal after interference suppression ;in represents the IFFT operation, It represents the distance dimension data corresponding to a certain Doppler channel, and its dimension is L×1.

7. An airborne radar anti-intensive unintentional interference device, characterized in that: include: at least one processor; And, a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the processor to execute the airborne radar anti-dense unintentional interference method described in any one of claims 1-6.

8. A non-volatile computer storage medium, characterized in that: The computer storage medium stores computer executable instructions, which are executed by one or more processors to implement the airborne radar anti-dense unintentional interference method described in any one of claims 1-6.

9. An airborne radar anti-intensive unintentional interference system, characterized in that: It includes building module, solving module and processing module; The construction module is used to process the first echo signal received in the passive mode to obtain the angle information and the frequency band information of the interference; In the active mode, the angle information and the frequency band information of the interference are used as prior knowledge, and the objective function is constructed based on the prior knowledge. ;in, is the FFT transformation matrix, is the weighting factor, is the weight vector, According to the prior knowledge, It means to arrange the elements in a diagonal matrix. is the zero-padded matrix, is the amplitude of the ideal spectrum, To assist in optimizing variables, is the phase auxiliary vector, represents the Hadamard product, The radar transmits the waveform Discrete signal after point sampling; The solution module is used to solve the objective function to obtain a sparse spectrum waveform, and use the sparse spectrum waveform as the transmission waveform in the active mode; The processing module is used to perform sub-band dimension reduction processing on the second echo signal in the active mode to obtain Q sub-band echo signals, perform interference filtering and clutter suppression on each sub-band echo signal to obtain an output signal of each sub-band, and splice and synthesize the output signals of each sub-band to obtain an output signal after interference suppression; The first echo signal received in the passive mode is processed to obtain the interference angle information and the frequency band information, specifically including: Divide the spatial orientation into Angle, yes The interference signals at each angle are processed respectively to obtain the interference signals at each angle, thereby determining the frequency and azimuth information of the interference according to the interference signals at each angle; wherein, is the default value; Among them, the Each angle is processed separately to obtain the interference signal of each angle, including: Build Angle The weight at ;in, , is the first echo signal, is the number of fast time sampling points, represents the spatial steering vector, is a constant, is the interference noise covariance matrix in passive mode; Use Angle The weights at the first echo signal are processed by adaptive digital beamforming to obtain the angle The output signal at , for angle The output signal at is converted to the frequency domain to obtain the angle The interference signal ;in, is the FFT transformation matrix.

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