A method and device for suppressing intra-pulse fast forwarding deceptive interference

Abstract

The present invention discloses a method and device for suppressing intra-pulse fast forwarding deceptive interference. The method includes transmitting a mixed signal of a first signal transmitted by a first subarray and a second signal transmitted by a second subarray in spatial domain superposition; the transmitting carrier frequency of the transmitting array elements in the first subarray is less than the reference carrier frequency; the transmitting carrier frequency of the transmitting array elements in the second subarray 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 through matched filtering; performing fuzzy number calculation and compensation processing on the echo signal of the first signal and the echo signal of the second signal to obtain a principal value distance difference estimate; constructing an interference plus noise covariance matrix of the echo signal based on the principal value distance difference estimate; calculating a spatial domain filtering vector based on the interference plus noise covariance matrix, and using the spatial domain filtering vector to achieve efficient and high-performance suppression of intra-pulse fast forwarding deceptive interference to obtain a true echo signal.

Description

Technical Field

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

[0002] With the continuous advancement of radar countermeasures, electronic jamming and anti-jamming techniques are becoming increasingly sophisticated. Relay deception jamming involves a jammer intercepting radar transmissions and modulating them in multiple domains, including spatial, temporal, frequency, and polarization domains, as needed. The jammer then retransmits the modulated jamming signal. Deceptive jamming tricks radars into mistaking the modulated jamming signal for a real target signal during reception and processing, effectively deceiving the real thing and severely impacting target detection and tracking.

[0003] Currently, domestic and international scholars have proposed numerous waveform diversity countermeasures to cross-pulse forwarding deceptive jamming, such as frequency diversity, time diversity, and array element pulse coding. However, due to the continuous development of jammer technology, when the jammer's interference and the target have the same pulse repetition period, these methods lack sufficient degrees of freedom to distinguish and suppress the target from the jammer.

[0004] In 2017, Zhang Zhaojian et al. proposed a false target identification method in their paper "Distance Deception Jamming Identification Method Based on FDA-MIMO" published in the Journal of Beijing University of Aeronautics and Astronautics. They theoretically derived the phase differences and spatial angular frequencies of target echoes and multiple types of false targets at the FDA-MIMO (Frequency Diverse Array - Multiple Input Multiple Output) receiver. They also analyzed in detail the impact of factors such as up- and down-conversion, matched filtering, signal mixing, and frequency shifting, and presented a specific false target identification process. This method can accurately extract the phase difference and spatial angular frequency information of the mixed signal. However, this method is only effective against frequency-shifted interference of linear frequency-modulated signals and requires that the deceptive jamming be 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 having a transmitting carrier frequency less than a reference carrier frequency; the transmitting array elements in the second subarray are transmitting array elements having a transmitting carrier frequency greater than the reference carrier frequency;

[0009] 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; the echo signal includes a true echo signal and an interference signal;

[0010] 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 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 true 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 includes:

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

[0015] Bandpass filtering and pulse compression processing are performed on the echo signal after the down-conversion processing to obtain the echo signal of the first signal and the 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] Performing a fuzzy area search using the first echo signal to obtain fuzzy number information; the fuzzy number information includes an angle and a fuzzy distance number of the target;

[0018] performing compensation processing on the second echo signal 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 mixed signal is expressed as:

[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 element to the target; E represents the radar's transmitting power; M1 represents the total number of transmitting elements in the first sub-array; M2 represents the total number of transmitting elements in the second sub-array; φ represents the baseband waveform; j is the imaginary number 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 echo signal is expressed as:

[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 range 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 element and received by the Nth receiving 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 sub-array; d sub1 (R s ) represents the range-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 sub-array; d sub2 (R s ) represents the distance-dependent steering vector of the second sub-array; M1 represents the total number of transmitting elements in the first sub-array; and M2 represents the total number of transmitting 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, configured to transmit a mixed signal; the mixed signal being a spatial superposition of a first signal transmitted by a first subarray and a second signal transmitted by a second subarray; the transmitting array elements in the first subarray being transmitting array elements having a transmitting carrier frequency less than a reference carrier frequency; and the transmitting array elements in the second subarray being transmitting array elements having a transmitting carrier frequency greater than the reference carrier frequency;

[0039] a matched filtering processing module, configured 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 filtering; the echo signal includes a true echo signal and an interference signal;

[0040] a fuzzy number calculation and compensation processing module, configured 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 estimate;

[0041] An interference plus noise covariance matrix construction module, configured to construct an 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 a spatial filter vector according to the interference plus noise covariance matrix, and use the spatial filter vector to suppress the intra-pulse fast forwarding deceptive interference to obtain the true echo signal.

[0043] Optional matched filter processing module, specifically used for:

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

[0045] Bandpass filtering and pulse compression processing are performed on the echo signal after the down-conversion processing to obtain the echo signal of the first signal and the 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 configured to:

[0047] Performing a fuzzy area search using the first echo signal to obtain fuzzy number information; the fuzzy number information includes an angle and a fuzzy distance number of the target;

[0048] performing compensation processing on the second echo signal 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 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 element to the target; E represents the radar's transmitting power; M1 represents the total number of transmitting elements in the first sub-array; M2 represents the total number of transmitting elements in the second sub-array; φ represents the baseband waveform; j is the imaginary number symbol; f m represents the transmitting carrier frequency of the mth transmitting array element; τ0 represents.

[0056] Optionally, the echo signal is expressed as:

[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 range 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 element and received by the Nth receiving 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 sub-array; d sub1 (R s ) represents the range-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 sub-array; d sub2 (R s) represents the distance-dependent steering vector of the second sub-array; M1 represents the total number of transmitting elements in the first sub-array; and M2 represents the total number of transmitting 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-forward deceptive interference provided by the present invention, a mixed signal is a spatially superimposed signal of a first signal and a second signal with different frequency offsets. The first signal is transmitted by a first subarray consisting of transmitting array elements having a transmission carrier frequency less than a reference carrier frequency, and the second signal is transmitted by a second subarray consisting of transmitting array elements having a transmission carrier frequency greater than the reference carrier frequency. After receiving the echo signal of the mixed signal, the radar's receiving antenna 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 a principal value range difference estimate, the fuzzy number calculation can be achieved using the echo signal of the first signal. Furthermore, the echo signal of the second signal, after compensation processing based on the fuzzy number, can be used to distinguish the true echo signal from the interference signal in terms of the power spectrum, thereby obtaining a principal value range 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 the 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 This 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 sub-array;

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

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

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

[0076] Figure 8 It is a structural 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 will be further described in detail below with reference to specific examples, 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 are 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; and 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 an embodiment of the present invention, the radar is a frequency diversity-based MIMO (Multiple-Input Multiple-Output) radar, comprising a transmitting antenna and a receiving antenna. The transmitting antenna comprises M transmitting elements, and the receiving antenna comprises N receiving elements. The M transmitting elements are used to transmit orthogonal signals, i.e., mixed signals, toward a target; the N receiving elements are used to receive echo signals scattered back 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 transmit elements in the first subarray have a transmit carrier frequency less than the reference carrier frequency, while the transmit elements in the second subarray have a transmit carrier frequency greater than the reference carrier frequency. The first subarray can be considered a small frequency offset subarray, and the second subarray can be considered a large frequency offset subarray.

[0083] Specifically, for the mth transmitting element in the transmitting antenna array, the transmitting carrier frequency f 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 with the label m=0; Δf m represents the frequency deviation of the mth transmitting element; Δf1 represents the first frequency increment; Δf2 represents the second frequency increment; M1 represents the total number of transmitting elements in the first sub-array; M2 represents the total number of transmitting 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 elements in the first subarray is M1. The transmit elements in the first subarray are m=-M1+1, m=-M1+2, ..., and m=0. The transmit elements in the second subarray are m=0, m=1, ..., and m=M2-1. The m=0 transmit element is also a reference element.

[0088] In the embodiment of the present invention, the signals transmitted by each transmitting element in the first subarray are mixed into a first signal, and the signals transmitted by each transmitting 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 is 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 This is a model diagram of the transmitting antenna provided by the embodiment of the present invention. Wherein, Tx represents the transmitting array element, and the transmitting array element spacing 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 transmit array elements in the first subarray are m = -M1+1, -M1+2, ..., 0. Subarray 2 represents the second subarray, and the transmit array elements in the second subarray are m = 0, 1, ..., M2-1. The transmit signals corresponding to the transmit array elements m = -M1+1, -M1+2, ..., 0 in the first subarray are The transmitting carrier frequencies corresponding to the transmitting 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 sub-array are The transmitting carrier frequencies corresponding to the transmitting 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 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 through matched filtering; the echo signal includes a true echo signal and an interference signal.

[0095] The echo signal is the return signal from the mixed signal emitted by the radar's transmit antenna and the target. However, due to the presence of forwarding deceptive jamming, this echo signal includes both the true echo signal and the jamming signal. The true echo signal is the mixed signal backscattered by the target and propagated back to the radar's receive antenna array, while the jamming signal is the deceptive jamming signal generated by the jammer through sampling, modulation, and forwarding of the radar's mixed signal, resulting in rapid intra-pulse forwarding.

[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 numbered 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, data rearrangement is performed on the echo signal 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 : 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 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, and the echo signal of the second signal is the second echo signal. 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 estimate 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 target angle and fuzzy distance number.

[0103] In this embodiment of the present invention, the first echo signal is an echo signal of the first signal transmitted by a first subarray composed of transmit array elements having a transmit carrier frequency lower than the reference carrier frequency. Therefore, based on the characteristic of small frequency offset, the two-dimensional parameter search problem for performing ambiguity zone search using the first echo signal can be expressed as:

[0104]

[0105] in, Indicates the estimated angle value; represents the estimated fuzzy distance; θ s Indicates the angle of the target; p s Indicates 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) performing compensation processing on the second echo signal using the fuzzy number information to obtain a compensated second echo signal.

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

[0108]

[0109] in, Indicates 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 sub-array; d sub2 (R s ) represents the distance-dependent steering vector of the second sub-array; d sub2 (r Δ ) represents the steering vector associated with the distance difference between the second sub-array 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: constructing an interference plus noise covariance matrix of the echo signal according to the principal value distance difference estimate.

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

[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 an embodiment of the present invention, a spatial filter vector is calculated based on the interference plus noise covariance matrix using the MVDR (Minimum Variance Distortionless Response) criterion, which is an adaptive beamforming algorithm based on the maximum signal-to-interference-and-noise ratio criterion.

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

[0122] In an embodiment of the present invention, a mixed signal is a spatially superimposed signal of a first signal and a second signal with different frequency offsets. The first signal is transmitted by a first subarray composed of transmitting array elements having a transmit carrier frequency less than a reference carrier frequency, and the second signal is transmitted by a second subarray composed of transmitting array elements having a transmit carrier frequency greater than the reference carrier frequency. After receiving the echo signal of the mixed signal, the radar's receiving antenna separates 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 of the first signal is used to calculate fuzzy numbers and perform compensation processing to obtain a principal value range difference estimate. Furthermore, the echo signal of the second signal, after compensation based on the fuzzy numbers, can be used to distinguish the true echo signal from the interference signal from the power spectrum, thereby obtaining a principal value range difference estimate. Furthermore, after calculating the spatial filter vector based on the interference plus noise covariance matrix of the echo signal constructed from the principal value range 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 the true 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 through 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 the echo signal of the first signal and the 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 down-conversion 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. The pulse compression processing can improve the range 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 Indicates 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 by bandpass filtering the echo signal after down-conversion processing 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 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 true distance 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 element and received by the Nth receiving element; N represents the total number of receiving 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 sub-array; d sub1 (R s ) represents the distance-dependent steering vector of the first sub-array; a sub2 (θ s ) represents the angle-dependent steering vector of the second sub-array; d sub2 (R s ) represents the distance-dependent 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 based on the principal value range 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] Where J1 and J2 represent the selection matrices for the first and last M2 transmitting elements; I N and Both represent the identity matrix; represents the zero matrix.

[0149] The target is cancelled by using the selection matrix and the compensated second echo signal, and the result is:

[0150]

[0151] in, represents the second echo signal after eliminating the target signal component; γ represents the estimated target transmit and receive 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 with reference to 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] Several simulation results using intra-pulse fast-forwarding deceptive jamming were used to evaluate the performance of the proposed method in an FDA-MIMO radar. In these simulations, all array elements were used to transmit and receive radar signals. The jammer intercepted and forwarded the radar signals, generating four jamming signals within a single received 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 the two-dimensional spatial frequencies of the transmitted and received echo signals using different frequency modulations. 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 This 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 traditional frequency diversity MIMO radar, the real target and the four interferences completely overlap, forming a single point target. This shows that traditional frequency diversity MIMO radar cannot distinguish between targets and interferences.

[0169] Depend on Figure 4 and Figure 5 It can be seen that although the first sub-array cannot distinguish between targets and interference, its transmit and receive two-dimensional power spectrum shows that the first sub-array can resolve the range ambiguity number. The second sub-array, based on ambiguity number estimation, can distinguish between 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 frequency offset and the subarray with large frequency offset. 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 sub-array. 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 methods are 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 structural diagram 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 transmitting module 801 is configured to transmit a mixed signal; the mixed signal is a spatial superposition of a first signal transmitted by a first subarray and a second signal transmitted by a second subarray; the transmitting array elements in the first subarray are transmitting array elements having a transmitting carrier frequency less than a reference carrier frequency; and the transmitting array elements in the second subarray are transmitting array elements having a transmitting carrier frequency greater than the reference carrier frequency.

[0174] A matched filtering processing module 802 is configured 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 filtering; the echo signal includes a true echo signal and an interference signal;

[0175] A fuzzy number calculation and compensation processing module 803 is configured 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 estimate;

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

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

[0178] In an embodiment of the present invention, a mixed signal is a spatially superimposed signal of a first signal and a second signal with different frequency offsets. The first signal is transmitted by a first subarray composed of transmitting array elements having a transmit carrier frequency less than a reference carrier frequency, and the second signal is transmitted by a second subarray composed of transmitting array elements having a transmit carrier frequency greater than the reference carrier frequency. After receiving the echo signal of the mixed signal, the radar's receiving antenna separates 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 of the first signal is used to calculate fuzzy numbers and perform compensation processing to obtain a principal value range difference estimate. Furthermore, the echo signal of the second signal, after compensation based on the fuzzy numbers, can be used to distinguish the true echo signal from the interference signal from the power spectrum, thereby obtaining a principal value range difference estimate. Furthermore, after calculating the spatial filter vector based on the interference plus noise covariance matrix of the echo signal constructed from the principal value range 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 the true echo signal.

[0179] Optional matched filter processing module, specifically used for:

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

[0181] Bandpass filtering and pulse compression processing are performed on the echo signal after the down-conversion processing to obtain the echo signal of the first signal and the 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 configured to:

[0183] Performing a fuzzy area search using the first echo signal to obtain fuzzy number information; the fuzzy number information includes an angle and a fuzzy distance number of the target;

[0184] performing compensation processing on the second echo signal 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 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 element to the target; E represents the radar's transmitting power; M1 represents the total number of transmitting elements in the first sub-array; M2 represents the total number of transmitting elements in the second sub-array; φ represents the baseband waveform; j is the imaginary number symbol; f m represents the transmitting carrier frequency of the mth transmitting array element; τ0 represents.

[0192] Optionally, the echo signal is expressed as:

[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 range 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 element and received by the Nth receiving 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 sub-array; dsub1 (R s ) represents the range-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 sub-array; d sub2 (R s ) represents the distance-dependent steering vector of the second sub-array; M1 represents the total number of transmitting elements in the first sub-array; and M2 represents the total number of transmitting 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," and the like are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in sequences 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 reference terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" mean 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 representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine 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 variations of the disclosed embodiments by viewing the drawings and the disclosed content. In the description of the present invention, the word "comprising" does not exclude other components or steps, "one" or "a" does not exclude multiple situations, and "multiple" means two or more, unless otherwise clearly and specifically defined. 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, so 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 is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A method for suppressing interference by fast intra-pulse forwarding deception, 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 having a transmitting carrier frequency less than a reference carrier frequency; the transmitting array elements in the second subarray are transmitting array elements having a transmitting carrier frequency 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; the echo signal includes a true echo signal and an interference signal; 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 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; Calculating a spatial filter vector according to the interference plus noise covariance matrix, and using the spatial filter vector to suppress intra-pulse fast forwarding deceptive interference to obtain the true echo signal; 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: Performing a fuzzy area search using the first echo signal to obtain fuzzy number information; the fuzzy number information includes an angle and a fuzzy distance number of the target; performing compensation processing on the second echo signal 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.

2. The intra-pulse fast forwarding deceptive interference suppression method according to claim 1, 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; Bandpass filtering and pulse compression processing are performed on the echo signal after the down-conversion processing to obtain the echo signal of the first signal and the echo signal of the second signal.

3. The intra-pulse fast forwarding deceptive interference suppression method according to claim 1, characterized in that: Constructing an interference plus noise covariance matrix of the echo signal according to the principal value distance difference estimate, comprising: 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.

4. The intra-pulse fast forwarding deceptive interference suppression method according to claim 1, 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 element to the target; E represents the radar's transmitting power; M1 represents the total number of transmitting elements in the first sub-array; M2 represents the total number of transmitting elements in the second sub-array; φ represents the baseband waveform; j is the imaginary number 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.

5. The intra-pulse fast forwarding deceptive interference suppression method according to claim 1, 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.

6. The intra-pulse fast forwarding deceptive interference suppression method according to claim 1, 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 range 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 element and received by the Nth receiving 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 sub-array; d sub1 (R s ) represents the range-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 sub-array; d sub2 (R s ) represents the distance-dependent steering vector of the second sub-array; M1 represents the total number of transmitting elements in the first sub-array; and M2 represents the total number of transmitting elements in the second sub-array.

7. The intra-pulse fast forwarding deceptive interference suppression method according to claim 1, 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.

8. An intra-pulse fast forwarding deceptive interference suppression device, characterized in that: The intra-pulse fast forwarding deceptive interference suppression device comprises: A mixed signal transmitting module, configured to transmit a mixed signal; the mixed signal being a spatial superposition of a first signal transmitted by a first subarray and a second signal transmitted by a second subarray; the transmitting array elements in the first subarray being transmitting array elements having a transmitting carrier frequency less than a reference carrier frequency; and the transmitting array elements in the second subarray being transmitting array elements having a transmitting carrier frequency greater than the reference carrier frequency; a matched filtering processing module, configured 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 filtering; the echo signal includes a true echo signal and an interference signal; a fuzzy number calculation and compensation processing module, configured 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 estimate; An interference plus noise covariance matrix construction module, configured to construct an interference plus noise covariance matrix of the echo signal according to the principal value distance difference estimate; An interference suppression module is used to calculate a spatial filter vector according to the interference plus noise covariance matrix, and use the spatial filter vector to suppress intra-pulse fast forwarding deceptive interference to obtain the true echo signal; 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: The first echo signal is used to perform a fuzzy area search to obtain fuzzy number information; the fuzzy number information includes the angle of the target and the fuzzy distance number; the second echo signal is compensated using the fuzzy number information to obtain a compensated second echo signal; and a principal value distance difference is estimated based on the fuzzy number information and the compensated second echo signal to obtain a principal value distance difference estimate.

9. The intra-pulse fast forwarding deceptive interference suppression device according to claim 8, characterized in that: The matched filtering processing module is specifically used to: receiving an echo signal of the mixed signal and performing down-conversion processing on the echo signal; Bandpass filtering and pulse compression processing are performed on the echo signal after the down-conversion processing to obtain the echo signal of the first signal and the echo signal of the second signal.

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