Intra-pulse fast forwarding deception interference suppression method and device

Abstract

The invention discloses an intra-pulse fast forwarding deception interference suppression method and device. The method comprises the following steps: transmitting a mixed signal formed by spatial domain superposition of a first signal transmitted by a first sub-array and a second signal transmitted by a second sub-array; the transmitting carrier frequency of the transmitting array element in the first sub-array is smaller than the reference carrier frequency; the transmitting carrier frequency of the transmitting array element in the second sub-array is greater than the reference carrier frequency; receiving an echo signal of the mixed signal, and separating an echo signal of the first signal and an echo signal of the second signal from the echo signal through matched filtering processing; performing fuzzy number calculation and compensation processing by using the echo signal of the first signal and the echo signal of the second signal to obtain a main value distance difference estimation value; constructing an interference and noise covariance matrix of the echo signal according to the main value distance difference estimation value; and calculating a spatial filtering vector according to the interference and noise covariance matrix, and realizing high-efficiency and high-performance inhibition of intra-pulse fast forwarding deception interference by using the spatial filtering vector to obtain a real echo signal.

Description

Technical Field

[0001] The invention belongs to the technical field of radar signal processing, and in particular relates to a method and a device for suppressing intra-pulse fast forwarding deceptive interference. Background Art

[0002] With the continuous development of radar countermeasure technology, the technical means of electronic interference and anti-interference are becoming increasingly complex. Forwarding deceptive interference is that the jammer intercepts the radar transmission signal, modulates it in multiple domains such as airspace, time domain, frequency domain, polarization domain, etc. according to the needs, and forwards the modulated interference signal. Deceptive interference will induce the radar to mistake the modulated interference signal for the real target signal when receiving and processing, thereby achieving the purpose of confusing the real with the fake, which has a serious impact on the radar's target monitoring and tracking.

[0003] At present, domestic and foreign scholars have proposed many waveform diversity countermeasures for cross-pulse forwarding deceptive interference, such as frequency diversity, time diversity, array element pulse coding, etc. However, due to the continuous development of jammer technology, when the interference generated by the jammer is in the same pulse repetition period as the target, such methods lack sufficient degrees of freedom and are difficult to distinguish and suppress the target and interference.

[0004] In 2017, Zhang Zhaojian et al. proposed a false target identification method in the "Distance Deception Interference Identification Method Based on FDA-MIMO" published in the Journal of Beijing University of Aeronautics and Astronautics. They theoretically derived the phase difference and spatial angular frequency of target echoes and multiple types of false targets at the FDA-MIMO (Frequency diverse array-multiple input multiple output) receiving end, analyzed in detail the influence of factors such as up and down frequency conversion, matched filtering, signal mixing, and frequency shift, and gave a specific process for false target identification. This method can accurately extract the phase difference and spatial angular frequency information of the mixed signal. However, this method is only effective for frequency shift interference of linear frequency modulation signals, and requires that the deceptive interference is forwarded across pulses. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a method and device for suppressing intra-pulse fast forwarding deceptive interference.

[0006] The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0007] In a first aspect, the present invention provides a method for suppressing intra-pulse fast forwarding deceptive interference, the method comprising:

[0008] Transmitting a mixed signal; the mixed signal is a signal in which a first signal transmitted by a first subarray and a second signal transmitted by a second subarray are spatially superimposed; the transmitting array elements in the first subarray are transmitting array elements whose transmitting carrier frequency is less than a reference carrier frequency; the transmitting array elements in the second subarray are transmitting array elements whose transmitting carrier frequency is greater than the reference carrier frequency;

[0009] receiving an echo signal of the mixed signal, and separating the echo signal of the first signal and the echo signal of the second signal from the echo signal by matched filtering; the echo signal includes a real echo signal and an interference signal;

[0010] Using the echo signal of the first signal and the echo signal of the second signal to perform fuzzy number calculation and compensation processing to obtain a principal value distance difference estimate;

[0011] Constructing an interference plus noise covariance matrix of the echo signal according to the principal value distance difference estimate;

[0012] A spatial domain filter vector is calculated according to the interference plus noise covariance matrix, and the spatial domain filter vector is used to suppress intra-pulse fast forwarding deceptive interference to obtain the real echo signal.

[0013] Optionally, receiving the echo signal of the mixed signal, and separating the echo signal of the first signal and the echo signal of the second signal from the echo signal through matched filtering, comprises:

[0014] receiving an echo signal of the mixed signal and performing down-conversion processing on the echo signal;

[0015] The echo signal after the down-conversion processing is subjected to bandpass filtering and pulse compression processing to obtain an echo signal of the first signal and an echo signal of the second signal.

[0016] Optionally, the echo signal of the first signal is a first echo signal, the echo signal of the second signal is a second echo signal, and fuzzy number calculation and compensation processing are performed using the echo signal of the first signal and the echo signal of the second signal to obtain a principal value distance difference estimate, including:

[0017] Using the first echo signal to search the fuzzy area, obtaining fuzzy number information; the fuzzy number information includes the angle and fuzzy distance number of the target;

[0018] performing compensation processing on the second echo signal by using the fuzzy number information to obtain a compensated second echo signal;

[0019] A main value distance difference estimation is performed based on the fuzzy number information and the compensated second echo signal to obtain a main value distance difference estimation value.

[0020] Optionally, constructing an interference plus noise covariance matrix of the echo signal according to the principal value distance difference estimate includes:

[0021] Constructing a covariance matrix of the compensated second echo signal;

[0022] The interference plus noise covariance matrix of the echo signal is extracted from the covariance matrix using a spatial smoothing method.

[0023] Optionally, the expression of the mixed signal is:

[0024]

[0025] Where t represents the fast time within a pulse; s sum (t) represents the mixed signal; s m represents the transmission signal of the mth transmitting array element; τ m represents the one-way delay from the mth transmitting array element to the target; E represents the transmitting power of the radar; M1 represents the total number of transmitting array elements in the first subarray; M2 represents the total number of transmitting array elements in the second subarray; φ represents the baseband waveform; j is the imaginary symbol; f m represents the transmitting carrier frequency of the mth transmitting array element; τ0 represents the one-way delay from the reference array element to the target.

[0026] Optionally, the expression of the echo signal is:

[0027]

[0028] Where t represents the fast time within a pulse; r n (t) represents the echo signal received by the nth receiving element; represents a real echo signal in the echo signal; represents the interference signal in the echo signal; q(t) represents the receiving antenna noise.

[0029] Optionally, the expression of the echo signal of the first signal is:

[0030]

[0031] The expression of the echo signal of the second signal is:

[0032]

[0033] Among them, θ s Indicates the angle of the target; R s represents the distance ambiguity number of the target; z represents the echo signal; N represents the total number of receiving array elements; represents the echo signal transmitted by the M1th transmitting array element and received by the Nth receiving array element; T represents the transpose of the matrix; η s represents the complex scattering coefficient of the target; b(θ s ) represents the steering vector of the receiving antenna; a sub1 (θ s ) represents the angle-dependent steering vector of the first subarray; d sub1 (R s ) represents the distance-dependent steering vector of the first sub-array; represents the Kronecker product; ⊙ represents the Hadamard product; a sub2 (θ s ) represents the angle-dependent steering vector of the second subarray; d sub2 (R s ) represents the distance-related steering vector of the second sub-array; M1 represents the total number of transmitting array elements in the first sub-array; M2 represents the total number of transmitting array elements in the second sub-array.

[0034] Optionally, the expression of the spatial domain filter vector is:

[0035]

[0036] in, represents the interference plus noise covariance matrix; θ s Indicates the angle of the target; r Δ represents the estimated value of the principal value distance difference; u(θ s ,r Δ ) represents the adaptive weight of the second submatrix; H represents the conjugate transpose of the matrix.

[0037] In a second aspect, the present invention provides an intra-pulse fast forwarding deceptive interference suppression device, the intra-pulse fast forwarding deceptive interference suppression device comprising:

[0038] A mixed signal transmitting module, used to transmit a mixed signal; the mixed signal is a signal in which a first signal transmitted by a first subarray and a second signal transmitted by a second subarray are spatially superimposed; the transmitting array elements in the first subarray are transmitting array elements whose transmitting carrier frequency is less than a reference carrier frequency; the transmitting array elements in the second subarray are transmitting array elements whose transmitting carrier frequency is greater than the reference carrier frequency;

[0039] A matched filter processing module, used for receiving the echo signal of the mixed signal, and separating the echo signal of the first signal and the echo signal of the second signal from the echo signal through matched filter processing; the echo signal includes a real echo signal and an interference signal;

[0040] A fuzzy number calculation and compensation processing module, used to perform fuzzy number calculation and compensation processing using the echo signal of the first signal and the echo signal of the second signal to obtain a principal value distance difference estimation value;

[0041] An interference plus noise covariance matrix construction module, used to construct the interference plus noise covariance matrix of the echo signal according to the principal value distance difference estimate;

[0042] The interference suppression module is used to calculate the spatial domain filter vector according to the interference plus noise covariance matrix, and use the spatial domain filter vector to suppress the intra-pulse fast forwarding deceptive interference to obtain the real echo signal.

[0043] Optionally, a matched filter processing module is specifically used for:

[0044] receiving an echo signal of the mixed signal and performing down-conversion processing on the echo signal;

[0045] The echo signal after the down-conversion processing is subjected to bandpass filtering and pulse compression processing to obtain an echo signal of the first signal and an echo signal of the second signal.

[0046] Optionally, the echo signal of the first signal is a first echo signal, the echo signal of the second signal is a second echo signal, and the fuzzy number calculation and compensation processing module is specifically used to:

[0047] Using the first echo signal to search the fuzzy area, obtaining fuzzy number information; the fuzzy number information includes the angle and fuzzy distance number of the target;

[0048] performing compensation processing on the second echo signal by using the fuzzy number information to obtain a compensated second echo signal;

[0049] A main value distance difference estimation is performed based on the fuzzy number information and the compensated second echo signal to obtain a main value distance difference estimation value.

[0050] Optionally, an interference plus noise covariance matrix building module is specifically used to:

[0051] Constructing a covariance matrix of the compensated second echo signal;

[0052] The interference plus noise covariance matrix of the echo signal is extracted from the covariance matrix using a spatial smoothing method.

[0053] Optionally, the expression for the mixed signal is:

[0054]

[0055] Where t represents the fast time within a pulse; s sum(t) represents the mixed signal; s m represents the transmission signal of the mth transmitting array element; τ m represents the one-way delay from the mth transmitting array element to the target; E represents the transmitting power of the radar; M1 represents the total number of transmitting array elements in the first subarray; M2 represents the total number of transmitting array elements in the second subarray; φ represents the baseband waveform; j is the imaginary symbol; f m represents the transmitting carrier frequency of the mth transmitting array element; τ0 represents.

[0056] Optionally, the expression of the echo signal is:

[0057]

[0058] Where t represents the fast time within a pulse; r n (t) represents the echo signal received by the nth receiving element; represents a real echo signal in the echo signal; represents the interference signal in the echo signal; q(t) represents the receiving antenna noise.

[0059] Optionally, the expression of the echo signal of the first signal is:

[0060]

[0061] The expression of the echo signal of the second signal is:

[0062]

[0063] Among them, θ s Indicates the angle of the target; R s represents the distance ambiguity number of the target; z represents the echo signal; N represents the total number of receiving array elements; represents the echo signal transmitted by the M1th transmitting array element and received by the Nth receiving array element; T represents the transpose of the matrix; η s represents the complex scattering coefficient of the target; b(θ s ) represents the steering vector of the receiving antenna; a sub1 (θ s ) represents the angle-dependent steering vector of the first subarray; d sub1 (R s ) represents the distance-dependent steering vector of the first sub-array; represents the Kronecker product; ⊙ represents the Hadamard product; Indicates; a sub2 (θ s ) represents the angle-dependent steering vector of the second subarray; d sub2 (R s) represents the distance-related steering vector of the second sub-array; M1 represents the total number of transmitting array elements in the first sub-array; M2 represents the total number of transmitting array elements in the second sub-array.

[0064] Optionally, the expression of the spatial domain filter vector is:

[0065]

[0066] in, represents the interference plus noise covariance matrix; θ s Indicates the angle of the target; r Δ represents the estimated value of the principal value distance difference; u(θ s ,r Δ ) represents the adaptive weight of the second submatrix; H represents the conjugate transpose of the matrix.

[0067] In a method for suppressing intra-pulse fast forwarding deceptive interference provided by the present invention, a mixed signal is a signal obtained by superimposing a first signal and a second signal with different frequency offsets in the spatial domain, wherein the first signal is transmitted by a first subarray composed of transmitting array elements whose transmitting carrier frequency is less than a reference carrier frequency, and the second signal is transmitted by a second subarray composed of transmitting array elements whose transmitting carrier frequency is greater than a reference carrier frequency. After receiving the echo signal of the mixed signal, the receiving antenna of the radar separates the echo signal of the first signal and the echo signal of the second signal from the echo signal through matched filtering. In the process of performing fuzzy number calculation and compensation processing using the echo signal of the first signal and the echo signal of the second signal to obtain the main value distance difference estimate, the fuzzy number calculation can be realized through the echo signal of the first signal, and then the real echo signal and the interference signal can be distinguished from the power spectrum using the echo signal of the second signal after the compensation processing based on the fuzzy number, thereby obtaining the main value distance difference estimate. Furthermore, after calculating the spatial filter vector based on the interference plus noise covariance matrix of the echo signal constructed according to the principal value distance difference estimate, the spatial filter vector can be used to achieve efficient and high-performance suppression of intra-pulse fast forwarding deceptive interference, thereby obtaining a true echo signal.

[0068] The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 It is a flow chart of a method for suppressing intra-pulse fast forwarding deceptive interference provided by an embodiment of the present invention;

[0070] Figure 2 is a model diagram of a transmitting antenna provided in an embodiment of the present invention;

[0071] Figure 3 This is the power spectrum distribution diagram of the traditional frequency diversity MIMO radar;

[0072] Figure 4 is the power spectrum distribution diagram of the first subarray;

[0073] Figure 5 is the power spectrum distribution diagram of the second sub-array;

[0074] Figure 6 is the adaptive beamforming diagram of the first subarray;

[0075] Figure 7 is the adaptive beamforming diagram of the second subarray;

[0076] Figure 8 It is a structural schematic diagram of an intra-pulse fast forwarding deceptive interference suppression device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0077] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0078] In order to solve the problem that the existing interference suppression methods are all deceptive interference suppression methods for cross-pulse forwarding, and it is difficult to solve the problem of intra-pulse fast forwarding deceptive interference, the embodiment of the present invention provides an intra-pulse fast forwarding deceptive interference suppression method, see Figure 1 , Figure 1 1 is a flow chart of a method for suppressing intra-pulse fast forwarding deceptive interference provided by an embodiment of the present invention, which specifically includes the following steps:

[0079] Step S101, transmitting a mixed signal; the mixed signal is a signal in which a first signal transmitted by a first subarray and a second signal transmitted by a second subarray are spatially superimposed; the transmitting array elements in the first subarray are transmitting array elements whose transmitting carrier frequency is less than a reference carrier frequency; the transmitting array elements in the second subarray are transmitting array elements whose transmitting carrier frequency is greater than the reference carrier frequency.

[0080] In the embodiment of the present invention, the radar is a MIMO (Multiple-input Multiple-output) radar based on frequency diversity, including a transmitting antenna and a receiving antenna, wherein the transmitting antenna includes M transmitting array elements, and the receiving antenna includes N receiving array elements. The M transmitting array elements are used to transmit orthogonal signals, that is, mixed signals, to the target; and the N receiving array elements are used to receive echo signals scattered and returned from the target.

[0081] The transmitting antenna of the mixed signal can be divided into two non-overlapping sub-arrays, namely a first sub-array and a second sub-array.

[0082] The transmitting array elements in the first subarray are transmitting array elements whose transmitting carrier frequency is less than the reference carrier frequency; the transmitting array elements in the second subarray are transmitting array elements whose transmitting carrier frequency is greater than the reference carrier frequency. The first subarray can be understood as a small frequency offset subarray, and the second subarray can be understood as a large frequency offset subarray.

[0083] Specifically, for the mth transmitting array element in the transmitting antenna array, the transmitting carrier frequency f of the array element is m It can be expressed as:

[0084]

[0085] Where f0 represents the reference carrier frequency, which is the carrier frequency of the transmitting array element labeled m=0; Δf m represents the frequency deviation of the mth transmitting array element; Δf1 represents the first frequency increment; Δf2 represents the second frequency increment; M1 represents the total number of transmitting array elements in the first sub-array; M2 represents the total number of transmitting array elements in the second sub-array.

[0086] According to the transmit carrier frequency of the mth transmit array element calculated by the above formula, it can be determined whether the mth transmit array element is a transmit array element in the first sub-array or a transmit array element in the second sub-array.

[0087] The total number of transmit array elements in the first subarray is M1, and the transmit array elements in the first subarray are respectively m=-M1+1 transmit array element, m=-M1+2 transmit array element...m=0 transmit array element; the transmit array elements in the second subarray are respectively m=0 transmit array element, m=1 transmit array element...m=M2-1 transmit array element. Among them, the m=0 transmit array element is also a reference array element.

[0088] In the embodiment of the present invention, the signals transmitted by each transmitting array element in the first subarray are mixed into a first signal, and the signals transmitted by each transmitting array element in the second subarray are mixed into a second signal. The first signal and the second signal are two signals with different frequency offsets.

[0089] In the embodiment of the present invention, the transmission signal s of the mth transmitting array element m (t) can be expressed as:

[0090]

[0091] Where t represents the fast time within a pulse; E represents the radar's transmit power; φ(t) represents the baseband waveform; T w represents the pulse width; j is the imaginary number symbol; f m Represents the transmit carrier frequency of the mth transmit array element.

[0092] By calculating the transmission signal of each transmitting array element, the first signal and the second signal can be determined, and then a mixed signal can be obtained.

[0093] See also Figure 2 , Figure 2 d is a model diagram of a transmitting antenna provided in an embodiment of the present invention. Tx represents a transmitting array element, and the distance between the transmitting array elements is d t , T w Indicates the pulse width, T p represents the pulse repetition interval, Figure 2 In the provided coordinate system, the horizontal axis represents Time, and the vertical axis represents Frequency. Subarray 1 represents the first subarray, and the transmitting array element in the first subarray is m=-M1+1,-M1+2,…,0. Subarray 2 represents the second subarray, and the transmitting array element in the second subarray is m=0,1,…,M2-1. The transmitting signals corresponding to the transmitting array element m=-M1+1,-M1+2,…,0 in the first subarray are The transmitting carrier frequencies corresponding to the transmitting array elements m=-M1+1,-M1+2,…,0 in the first subarray are The transmission signals corresponding to the transmission elements m=0,1,…,M2-1 in the second subarray are The transmitting carrier frequencies corresponding to the transmitting array elements m=0,1,…,M2-1 in the second subarray are Among them, m=0 is also the reference array element, and the corresponding f0 is the reference carrier frequency.

[0094] Step S102, receiving the echo signal of the mixed signal, and separating the echo signal of the first signal and the echo signal of the second signal from the echo signal through matched filtering; the echo signal includes a real echo signal and an interference signal.

[0095] The echo signal is the signal returned after the mixed signal emitted by the radar's transmitting antenna interacts with the target. However, due to the existence of forwarding deceptive interference, the echo signal includes the real echo signal and the interference signal. Among them, the real echo signal is the signal of the mixed signal backscattered by the target and propagated back to the radar's receiving antenna array, and the interference signal is the deceptive interference signal that is quickly forwarded within the pulse generated by the jammer sampling, modulating and forwarding the mixed signal emitted by the radar.

[0096] In the embodiment of the present invention, the deceptive jamming signal The expression is:

[0097]

[0098] Among them, τ j0 represents the modulation delay of the jth interference signal compared to the reference element, i.e. the element labeled 0; τ jm represents the modulation delay of the jth interference signal compared to the mth transmitting array element.

[0099] In the embodiment of the present invention, the echo signal is subjected to data rearrangement through matched filtering, thereby separating the echo signal of the first signal and the echo signal of the second signal from the echo signal.

[0100] Step S103, using the echo signal of the first signal and the echo signal of the second signal to perform fuzzy number calculation and compensation processing to obtain a principal value distance difference estimation value.

[0101] In the embodiment of the present invention, the echo signal of the first signal is the first echo signal, the echo signal of the second signal is the second echo signal, and the specific steps of performing fuzzy number calculation and compensation processing using the echo signal of the first signal and the echo signal of the second signal to obtain the principal value distance difference estimation value are as follows:

[0102] a) Use the first echo signal to search the fuzzy area and obtain fuzzy number information; the fuzzy number information includes the angle and fuzzy distance of the target.

[0103] In the embodiment of the present invention, the first echo signal is an echo signal of a first signal sent by a first subarray composed of transmit array elements whose transmit carrier frequency is less than a reference carrier frequency. Therefore, according to the characteristics of a small frequency offset, the two-dimensional parameter search problem of performing fuzzy zone search using the first echo signal can be expressed as:

[0104]

[0105] in, Indicates the estimated angle value; Represents the estimated fuzzy distance number; θ s Indicates the angle of the target; p s represents the fuzzy distance number of the target; w represents the spatial filter vector; represents the first echo signal; p represents the fuzzy number; r Δ Represents the principal value distance difference estimate.

[0106] b) Using the fuzzy number information to perform compensation processing on the second echo signal to obtain a compensated second echo signal.

[0107] First, the compensation vector is constructed using fuzzy number information for:

[0108]

[0109] in, Represents the target's pulse pressure distance measurement value; R u represents the maximum unambiguous distance; c represents the speed of light.

[0110] The second echo signal is compensated according to the compensation vector to obtain a compensated second echo signal. It can be expressed as:

[0111]

[0112] Among them, z sub2 (θ s ,R s ) represents the second echo signal; ⊙ represents the Hadamard product; N represents the total number of receiving elements in the receiving antenna; η s represents the complex scattering coefficient of the target; b(θ s ) represents the steering vector of the receiving antenna; represents the Kronecker product; a sub2 (θ s ) represents the angle-dependent steering vector of the second subarray; d sub2 (R s ) represents the distance-dependent steering vector of the second subarray; d sub2 (r Δ ) represents the steering vector associated with the distance difference between the second subarray and the principal value.

[0113] c) performing a principal value distance difference estimation based on the fuzzy number information and the compensated second echo signal to obtain a principal value distance difference estimation value.

[0114] In the embodiment of the present invention, there is a difference between the actual distance of the target and the estimated distance after matched filtering and fuzzy number estimation, namely, the principal value distance difference. It can be expressed as:

[0115]

[0116] Where H represents the conjugate transpose of the matrix.

[0117] Step S104: construct an interference plus noise covariance matrix of the echo signal according to the principal value distance difference estimate.

[0118] In the embodiment of the present invention, the interference plus noise covariance matrix refers to a covariance matrix used to describe interference and noise in the field of signal processing. By analyzing the interference plus noise covariance matrix, the interference and noise in the signal can be accurately eliminated. Since the main value distance difference is the difference between the actual distance of the target and the distance estimation value after matched filtering and fuzzy number estimation, when the main value distance difference estimation value is obtained, the interference plus noise covariance matrix of the echo signal can be constructed according to the main value distance difference estimation value.

[0119] Step S105, calculating a spatial domain filter vector according to the interference plus noise covariance matrix, and using the spatial domain filter vector to suppress intra-pulse fast forwarding deceptive interference to obtain a true echo signal.

[0120] In the embodiment of the present invention, the spatial domain filter vector is calculated according to the interference plus noise covariance matrix using the MVDR (Minimum Variance Distortionless Response) criterion, wherein MVDR is an adaptive beamforming algorithm based on the maximum signal to interference noise ratio criterion.

[0121] In the embodiment of the present invention, suppressing the intra-pulse fast forwarding deceptive interference according to the spatial domain filter vector specifically refers to using the spatial domain filter vector to act on the echo data to suppress the intra-pulse fast forwarding deceptive interference that does not match the filter vector.

[0122] In an embodiment of the present invention, the mixed signal is a signal obtained by spatially superimposing a first signal and a second signal with different frequency offsets, wherein the first signal is transmitted by a first subarray composed of transmitting array elements whose transmitting carrier frequency is less than a reference carrier frequency, and the second signal is transmitted by a second subarray composed of transmitting array elements whose transmitting carrier frequency is greater than a reference carrier frequency. After receiving the echo signal of the mixed signal, the receiving antenna of the radar separates the echo signal of the first signal and the echo signal of the second signal from the echo signal through matched filtering. In the process of performing fuzzy number calculation and compensation processing using the echo signal of the first signal and the echo signal of the second signal to obtain the main value distance difference estimation value, the fuzzy number calculation can be realized by the echo signal of the first signal, and then the echo signal of the second signal after compensation processing based on the fuzzy number can be used to distinguish the real echo signal and the interference signal from the power spectrum, thereby obtaining the main value distance difference estimation value. Furthermore, after calculating the spatial filter vector based on the interference plus noise covariance matrix of the echo signal constructed according to the main value distance difference estimation value, the spatial filter vector can be used to achieve efficient and high-performance suppression of intra-pulse fast forwarding deceptive interference, thereby obtaining the real echo signal.

[0123] In one implementation, receiving an echo signal of a mixed signal, and separating an echo signal of a first signal and an echo signal of a second signal from the echo signal by matched filtering, includes:

[0124] receiving an echo signal of the mixed signal and performing down-conversion processing on the echo signal;

[0125] The echo signal after the down-conversion processing is subjected to band-pass filtering and pulse compression processing to obtain an echo signal of the first signal and an echo signal of the second signal.

[0126] In the embodiment of the present invention, performing down-conversion processing on the echo signal refers to down-converting the received echo signal to an intermediate frequency. The purpose of down-conversion is to reduce the carrier frequency of the signal to obtain a baseband signal.

[0127] The echo signal after the down-conversion processing is subjected to bandpass filtering and pulse compression processing to obtain the echo signal of the first signal and the echo signal of the second signal. Among them, the pulse compression processing can improve the distance resolution capability of the radar.

[0128] In the embodiment of the present invention, the filter frequency domain response H m The expression of (f) is:

[0129]

[0130] Where rect[·] represents the rectangular window function; B sub Represents the signal bandwidth of a single array element; represents the conjugate of the Fourier transform of the transmitted signal of the mth transmitting array element; Δf m Represents the frequency increment of the mth transmitting array element.

[0131] In the embodiment of the present invention, the expression of the filtered signal obtained after the echo signal after down-conversion processing is band-pass filtered is:

[0132]

[0133] Among them, z mn (t) represents the filtered signal obtained by bandpass filtering the echo signal of the transmission signal of the mth transmitting array element received by the nth receiving array element; d t Indicates the distance between transmitting array elements; d r represents the receiving array element spacing; c represents the speed of light; R s Indicates the true distance to the target.

[0134] All filtered signals are rearranged to obtain the echo signal of the first signal and the echo signal of the second signal respectively.

[0135] In one implementation, the echo signal z of the first signal sub1 (θ s ,R s ) is:

[0136]

[0137] The echo signal z of the second signal sub2 (θ s ,R s ) is:

[0138]

[0139] Among them, θ s Indicates the angle of the target; R sIndicates the real distance of the target; z indicates the echo signal; N indicates the total number of receiving array elements; represents the echo signal transmitted by the M1th transmitting array element and received by the Nth receiving array element; N represents the total number of receiving array elements; η s represents the complex scattering coefficient of the target; b(θ s ) represents the steering vector of the receiving antenna; a sub1 (θ s ) represents the angle-dependent steering vector of the first subarray; d sub1 (R s ) represents the distance-dependent steering vector of the first subarray; a sub2 (θ s ) represents the angle-dependent steering vector of the second subarray; d sub2 (R s ) represents the distance-related steering vector of the second sub-matrix; T represents the transpose of the matrix.

[0140] In one implementation, constructing an interference plus noise covariance matrix of the echo signal according to the principal value distance difference estimate includes:

[0141] constructing a covariance matrix of the compensated second echo signal;

[0142] The interference plus noise covariance matrix of the echo signal is extracted from the covariance matrix using the spatial smoothing method.

[0143] In the embodiment of the present invention, the covariance matrix R of the compensated second echo signal is sub2 The expression is:

[0144] R sub2 =R t +R j +R n ;

[0145] Among them, R t is the echo signal covariance matrix; R j +R n represents the interference plus noise covariance matrix.

[0146] In the embodiment of the present invention, in order to avoid the influence of the real target on the beamforming, spatial smoothing is used to eliminate the real target signal component, so as to extract the interference plus noise covariance matrix of the echo signal from the covariance matrix. First, the following selection matrix is ​​constructed:

[0147]

[0148] Wherein, J1 and J2 represent the selection matrices of the first and last M2 transmitting array elements; I N and Both represent the identity matrix; represents the zero matrix.

[0149] Using the selection matrix and the compensated second echo signal to cancel the target, we get:

[0150]

[0151] in, represents the second echo signal after eliminating the target signal component; γ represents the estimated target transmission and reception spatial frequency difference; Represents the second echo signal after compensation.

[0152] According to the second echo signal after target cancellation, the interference plus noise covariance matrix can be reconstructed as:

[0153]

[0154] in, represents the interference plus noise covariance matrix; H represents the conjugate transpose of the matrix.

[0155] In the embodiment of the present invention, the spatial domain filtering vector w based on the MVDR criterion can be expressed as:

[0156]

[0157] Among them, u(θ s ,r Δ ) represents the adaptive weight of the second sub-matrix.

[0158] The effect of the intra-pulse fast forwarding deceptive interference suppression method provided by the embodiment of the present invention will be described below in conjunction with simulation experiments.

[0159] 1. Simulation parameter settings:

[0160] In this simulation experiment, the simulation parameters used are shown in Table 1. Table 1 is the simulation parameters of the FDA-MIMO radar system.

[0161] Table 1

[0162]

[0163]

[0164] 2. Simulation content:

[0165] The performance of the method proposed in the embodiment of the present invention in FDA-MIMO radar is evaluated through several simulation results of intra-pulse fast forwarding deception jamming. In the simulation experiment, all array elements are used to transmit and receive radar signals, and the jammer intercepts and forwards the radar signal, forming 4 jamming signals in one receiving pulse.

[0166] 3. Simulation results and analysis:

[0167] Simulation 1, under the above simulation parameters, the conventional frequency diversity MIMO and the intra-pulse fast forwarding deceptive interference suppression method provided by the embodiment of the present invention are used to compare, and different frequency modulations are used to detect the transmission and reception two-dimensional spatial frequencies of the echo signal. The results are as follows: Figure 3 , Figure 4 , Figure 5 As shown. Among them, Figure 3 This is the power spectrum distribution diagram of the traditional frequency diversity MIMO radar. Figure 4 is the power spectrum distribution diagram of the first sub-array, Figure 5 It is the power spectrum distribution diagram of the second sub-array. The horizontal axis represents the transmit frequency domain, and the vertical axis represents the receive frequency domain.

[0168] Depend on Figure 3 It can be seen that for the traditional frequency diversity MIMO radar, the real target and the four interferences completely overlap to form a single point target, which shows that the traditional frequency diversity MIMO radar does not have the ability to distinguish between the target and the interference.

[0169] Depend on Figure 4 and Figure 5 It can be seen that although the first sub-array does not have the ability to distinguish between targets and interference, it can be seen from its transmit and receive two-dimensional power spectrum that the first sub-array can achieve the resolution of distance fuzzy numbers. The second sub-array based on fuzzy number estimation can distinguish targets and interference from the power spectrum.

[0170] Simulation 2: Under the above simulation parameters, the method of the present invention is used to perform adaptive beamforming on the received signal. Adaptive beamforming is performed based on the subarray with small transmitting frequency deviation and the subarray with large transmitting frequency deviation. The results are as follows: Figure 6 and Figure 7 As shown. Among them, Figure 6 is the adaptive beamforming pattern of the first subarray, Figure 7 It is the adaptive beamforming diagram of the second subarray. The horizontal axis represents the transmit frequency domain, and the vertical axis represents the receive frequency domain. Figure 6 and Figure 7 The real target echo signal and interference signals (interference 1, interference 2, interference 3 and interference 4) are included. Figure 6 and Figure 7 The results show that the fast forwarding deceptive interference is located at the beam notch, indicating that the intra-pulse fast forwarding deceptive interference suppression method provided by the embodiment of the present invention has the ability to suppress the intra-pulse fast forwarding deceptive interference.

[0171] The above simulation results show that in the presence of intra-pulse fast forwarding deceptive interference, the existing method is completely ineffective, and the intra-pulse fast forwarding deceptive interference suppression method provided by the embodiment of the present invention has superior performance.

[0172] Based on the same inventive concept, the embodiment of the present invention also provides an intra-pulse fast forwarding deceptive interference suppression device, see Figure 8 , Figure 8 1 is a schematic diagram of the structure of an intra-pulse fast forwarding deceptive interference suppression device provided by an embodiment of the present invention, the device comprising:

[0173] A mixed signal transmission module 801 is used to transmit a mixed signal; the mixed signal is a signal in which a first signal transmitted by a first subarray and a second signal transmitted by a second subarray are spatially superimposed; the transmitting array element in the first subarray is a transmitting array element whose transmitting carrier frequency is less than a reference carrier frequency; the transmitting array element in the second subarray is a transmitting array element whose transmitting carrier frequency is greater than the reference carrier frequency;

[0174] A matched filter processing module 802 is used to receive the echo signal of the mixed signal, and separate the echo signal of the first signal and the echo signal of the second signal from the echo signal through matched filter processing; the echo signal includes a real echo signal and an interference signal;

[0175] A fuzzy number calculation and compensation processing module 803 is used to perform fuzzy number calculation and compensation processing using the echo signal of the first signal and the echo signal of the second signal to obtain a principal value distance difference estimation value;

[0176] An interference plus noise covariance matrix construction module 804 is used to construct an interference plus noise covariance matrix of the echo signal according to the principal value distance difference estimation value;

[0177] The interference suppression module 805 is used to calculate the spatial domain filter vector according to the interference plus noise covariance matrix, and use the spatial domain filter vector to suppress the intra-pulse fast forwarding deceptive interference to obtain a real echo signal.

[0178] In an embodiment of the present invention, the mixed signal is a signal obtained by spatially superimposing a first signal and a second signal with different frequency offsets, wherein the first signal is transmitted by a first subarray composed of transmitting array elements whose transmitting carrier frequency is less than a reference carrier frequency, and the second signal is transmitted by a second subarray composed of transmitting array elements whose transmitting carrier frequency is greater than a reference carrier frequency. After receiving the echo signal of the mixed signal, the receiving antenna of the radar separates the echo signal of the first signal and the echo signal of the second signal from the echo signal through matched filtering. In the process of performing fuzzy number calculation and compensation processing using the echo signal of the first signal and the echo signal of the second signal to obtain the main value distance difference estimation value, the fuzzy number calculation can be realized by the echo signal of the first signal, and then the echo signal of the second signal after compensation processing based on the fuzzy number can be used to distinguish the real echo signal and the interference signal from the power spectrum, thereby obtaining the main value distance difference estimation value. Furthermore, after calculating the spatial filter vector based on the interference plus noise covariance matrix of the echo signal constructed according to the main value distance difference estimation value, the spatial filter vector can be used to achieve efficient and high-performance suppression of intra-pulse fast forwarding deceptive interference, thereby obtaining the real echo signal.

[0179] Optionally, a matched filter processing module is specifically used for:

[0180] receiving an echo signal of the mixed signal and performing down-conversion processing on the echo signal;

[0181] The echo signal after the down-conversion processing is subjected to bandpass filtering and pulse compression processing to obtain an echo signal of the first signal and an echo signal of the second signal.

[0182] Optionally, the echo signal of the first signal is a first echo signal, the echo signal of the second signal is a second echo signal, and the fuzzy number calculation and compensation processing module is specifically used to:

[0183] Using the first echo signal to search the fuzzy area, obtaining fuzzy number information; the fuzzy number information includes the angle and fuzzy distance number of the target;

[0184] performing compensation processing on the second echo signal by using the fuzzy number information to obtain a compensated second echo signal;

[0185] A main value distance difference estimation is performed based on the fuzzy number information and the compensated second echo signal to obtain a main value distance difference estimation value.

[0186] Optionally, an interference plus noise covariance matrix building module is specifically used to:

[0187] Constructing a covariance matrix of the compensated second echo signal;

[0188] The interference plus noise covariance matrix of the echo signal is extracted from the covariance matrix using a spatial smoothing method.

[0189] Optionally, the expression for the mixed signal is:

[0190]

[0191] Where t represents the fast time within a pulse; s sum (t) represents the mixed signal; s m represents the transmission signal of the mth transmitting array element; τ m represents the one-way delay from the mth transmitting array element to the target; E represents the transmitting power of the radar; M1 represents the total number of transmitting array elements in the first subarray; M2 represents the total number of transmitting array elements in the second subarray; φ represents the baseband waveform; j is the imaginary symbol; f m represents the transmitting carrier frequency of the mth transmitting array element; τ0 represents.

[0192] Optionally, the expression of the echo signal is:

[0193]

[0194] Where t represents the fast time within a pulse; r n (t) represents the echo signal received by the nth receiving element; represents a real echo signal in the echo signal; represents the interference signal in the echo signal; q(t) represents the receiving antenna noise.

[0195] Optionally, the expression of the echo signal of the first signal is:

[0196]

[0197] The expression of the echo signal of the second signal is:

[0198]

[0199] Among them, θ s Indicates the angle of the target; R s represents the distance ambiguity number of the target; z represents the echo signal; N represents the total number of receiving array elements; represents the echo signal transmitted by the M1th transmitting array element and received by the Nth receiving array element; T represents the transpose of the matrix; η s represents the complex scattering coefficient of the target; b(θ s ) represents the steering vector of the receiving antenna; a sub1 (θ s ) represents the angle-dependent steering vector of the first subarray; dsub1 (R s ) represents the distance-dependent steering vector of the first sub-array; represents the Kronecker product; ⊙ represents the Hadamard product; Indicates; a sub2 (θ s ) represents the angle-dependent steering vector of the second subarray; d sub2 (R s ) represents the distance-related steering vector of the second sub-array; M1 represents the total number of transmitting array elements in the first sub-array; M2 represents the total number of transmitting array elements in the second sub-array.

[0200] Optionally, the expression of the spatial domain filter vector is:

[0201]

[0202] in, represents the interference plus noise covariance matrix; θ s Indicates the angle of the target; r Δ represents the estimated value of the principal value distance difference; u(θ s ,r Δ ) represents the adaptive weight of the second submatrix; H represents the conjugate transpose of the matrix.

[0203] It should be noted that the terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention.

[0204] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0205] Although the present invention is described herein in conjunction with various embodiments, in the process of implementing the claimed invention, those skilled in the art can understand and implement other changes to the disclosed embodiments by viewing the drawings and the disclosed content. In the description of the present invention, the term "comprising" does not exclude other components or steps, "one" or "an" does not exclude multiple situations, and "multiple" means two or more, unless otherwise clearly and specifically limited. In addition, certain measures are recorded in different embodiments, but this does not mean that these measures cannot be combined to produce good results.

[0206] As for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0207] It should be noted that the device of an embodiment of the present invention is a device that applies the above-mentioned intra-pulse fast forwarding deceptive interference suppression method. All embodiments of the above-mentioned intra-pulse fast forwarding deceptive interference suppression method are applicable to the device and can achieve the same or similar beneficial effects.

[0208] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for suppressing interference by fast intra-pulse forwarding deception. It is characterized in that The intra-pulse fast forwarding deceptive interference suppression method comprises: Transmitting a mixed signal; the mixed signal is a signal in which a first signal transmitted by a first subarray and a second signal transmitted by a second subarray are spatially superimposed; the transmitting array elements in the first subarray are transmitting array elements whose transmitting carrier frequency is less than a reference carrier frequency; the transmitting array elements in the second subarray are transmitting array elements whose transmitting carrier frequency is greater than the reference carrier frequency; receiving an echo signal of the mixed signal, and separating the echo signal of the first signal and the echo signal of the second signal from the echo signal by matched filtering; the echo signal includes a real echo signal and an interference signal; Using the echo signal of the first signal and the echo signal of the second signal to perform fuzzy number calculation and compensation processing to obtain a principal value distance difference estimate; Constructing an interference plus noise covariance matrix of the echo signal according to the principal value distance difference estimate; A spatial domain filter vector is calculated according to the interference plus noise covariance matrix, and the spatial domain filter vector is used to suppress intra-pulse fast forwarding deceptive interference to obtain the real echo signal.

2. The intra-pulse fast forwarding deceptive interference suppression method according to claim 1, It is characterized in that Receiving the echo signal of the mixed signal, and separating the echo signal of the first signal and the echo signal of the second signal from the echo signal through matched filtering, comprising: receiving an echo signal of the mixed signal and performing down-conversion processing on the echo signal; The echo signal after the down-conversion processing is subjected to bandpass filtering and pulse compression processing to obtain an echo signal of the first signal and an echo signal of the second signal.

3. The intra-pulse fast forwarding deceptive interference suppression method according to claim 1, It is characterized in that The echo signal of the first signal is a first echo signal, the echo signal of the second signal is a second echo signal, and fuzzy number calculation and compensation processing are performed using the echo signal of the first signal and the echo signal of the second signal to obtain a principal value distance difference estimation value, including: Using the first echo signal to search the fuzzy area, obtaining fuzzy number information; the fuzzy number information includes the angle and fuzzy distance number of the target; performing compensation processing on the second echo signal by using the fuzzy number information to obtain a compensated second echo signal; A main value distance difference estimation is performed based on the fuzzy number information and the compensated second echo signal to obtain a main value distance difference estimation value.

4. The intra-pulse fast forwarding deceptive interference suppression method according to claim 3, It is characterized in that Constructing an interference plus noise covariance matrix of the echo signal according to the principal value distance difference estimate, including: Constructing a covariance matrix of the compensated second echo signal; The interference plus noise covariance matrix of the echo signal is extracted from the covariance matrix using a spatial smoothing method.

5. The intra-pulse fast forwarding deceptive interference suppression method according to claim 1, It is characterized in that The expression of the mixed signal is: Where t represents the fast time within a pulse; s sum (t) represents the mixed signal; s m represents the transmission signal of the mth transmitting array element; τ m represents the one-way delay from the mth transmitting array element to the target; E represents the radar's transmitting power; M 1 represents the total number of transmitting array elements in the first sub-array; M 2 represents the total number of transmitting array elements in the second subarray; φ represents the baseband waveform; j is the imaginary number symbol; f m represents the transmitting carrier frequency of the mth transmitting array element; τ 0 represents the one-way delay from the reference array element to the target.

6. The intra-pulse fast forwarding deceptive interference suppression method according to claim 1, It is characterized in that The expression of the echo signal is: Where t represents the fast time within a pulse; r n (t) represents the echo signal received by the nth receiving element; represents a real echo signal in the echo signal; represents the interference signal in the echo signal; q(t) represents the receiving antenna noise.

7. The intra-pulse fast forwarding deceptive interference suppression method according to claim 1, It is characterized in that The expression of the echo signal of the first signal is: The expression of the echo signal of the second signal is: Among them, θ s Indicates the angle of the target; R s represents the distance ambiguity number of the target; z represents the echo signal; N represents the total number of receiving array elements; Indicates the Mth 1 The transmitting array element transmits the echo signal received by the Nth receiving array element; T represents the transpose of the matrix; η s represents the complex scattering coefficient of the target; b(θ s ) represents the steering vector of the receiving antenna; a sub1 (θ s ) represents the angle-dependent steering vector of the first subarray; d sub1 (R s ) represents the distance-dependent steering vector of the first sub-array; represents the Kronecker product; ⊙ represents the Hadamard product; a sub2 (θ s ) represents the angle-dependent steering vector of the second subarray; d sub2 (R s ) represents the distance-dependent steering vector of the second sub-array; M 1 represents the total number of transmitting array elements in the first sub-array; M 2 represents the total number of transmitting array elements in the second sub-array.

8. The intra-pulse fast forwarding deceptive interference suppression method according to claim 1, It is characterized in that The expression of the spatial domain filter vector is: in, represents the interference plus noise covariance matrix; θ s Indicates the angle of the target; r Δ represents the estimated value of the principal value distance difference; u(θ s ,r Δ ) represents the adaptive weight of the second submatrix; H represents the conjugate transpose of the matrix.

9. An intra-pulse fast forwarding deceptive interference suppression device, It is characterized in that The intra-pulse fast forwarding deceptive interference suppression device comprises: A mixed signal transmitting module, used to transmit a mixed signal; the mixed signal is a signal in which a first signal transmitted by a first subarray and a second signal transmitted by a second subarray are spatially superimposed; the transmitting array elements in the first subarray are transmitting array elements whose transmitting carrier frequency is less than a reference carrier frequency; the transmitting array elements in the second subarray are transmitting array elements whose transmitting carrier frequency is greater than the reference carrier frequency; A matched filter processing module, used for receiving the echo signal of the mixed signal, and separating the echo signal of the first signal and the echo signal of the second signal from the echo signal through matched filter processing; the echo signal includes a real echo signal and an interference signal; A fuzzy number calculation and compensation processing module, used to perform fuzzy number calculation and compensation processing using the echo signal of the first signal and the echo signal of the second signal to obtain a principal value distance difference estimation value; An interference plus noise covariance matrix construction module, used to construct the interference plus noise covariance matrix of the echo signal according to the principal value distance difference estimate; The interference suppression module is used to calculate the spatial domain filter vector according to the interference plus noise covariance matrix, and use the spatial domain filter vector to suppress the intra-pulse fast forwarding deceptive interference to obtain the real echo signal.

10. The intra-pulse fast forwarding deceptive interference suppression device according to claim 9, It is characterized in that The matched filtering processing module is specifically used for: receiving an echo signal of the mixed signal and performing down-conversion processing on the echo signal; The echo signal after the down-conversion processing is subjected to bandpass filtering and pulse compression processing to obtain an echo signal of the first signal and an echo signal of the second signal.

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