Multi-carrier radar deception interference suppression method and device and multi-carrier radar

Abstract

The invention discloses a deception jamming suppression method of a multicarrier radar. According to the invention, through a signal form of multi-carrier radar frequency diversity, the frequency domain degree of freedom is obtained only through a single antenna; a frequency domain processing dimension provided by a multi-carrier radar is utilized to successfully distinguish true and false targets in a frequency domain; spatial smoothing and PCA are combined to realize accurate estimation of an interference and noise covariance matrix; and finally, constructing a frequency domain self-adaptive filter by using an MVDR algorithm to suppress deception interference. The invention further discloses a deception jamming suppression device of the multi-carrier radar and the multi-carrier radar. According to the method, deception jamming is effectively suppressed based on the frequency domain freedom degree of the multi-carrier radar, the technical blank of deception jamming suppression of the multi-carrier radar is filled up, and practical application of the multi-carrier radar is greatly promoted.

Description

Technical Field

[0001] The present invention relates to a radar interference suppression method, in particular to a deceptive interference suppression method and device for a multi-carrier radar, and belongs to the technical field of radar signal processing. Background Art

[0002] With the rapid development of modern electronic warfare technology, airborne radars must contend with various forms of electronic jamming from the enemy. Sidelobe interference can be effectively suppressed through techniques such as sidelobe cancellation and space-time adaptive processing (STAP). Despite these advances, countering mainlobe deceptive jamming remains a significant challenge. Mainlobe deceptive jamming is typically generated by enemy aircraft using modern digital radiofrequency memory (DRFM) systems to capture, delay, and forward radar signals. The jamming signal typically appears in the radar mainlobe direction. Because the characteristics of the deceptive jamming are highly similar to those of the true target echo, it can cause the radar to mistrack the false target. Although techniques such as blind source separation and frequency agility have been proposed to counter mainlobe deceptive jamming, these methods are primarily based on traditional radar waveforms, whose inherently limited degrees of freedom fundamentally restrict the effectiveness of jamming suppression.

[0003] Frequency diverse array (FDA) radars have attracted widespread attention due to their frequency-dependent array factor, which introduces an additional dimension for range processing. However, FDA radars face the problem of coupling range and angle information at the receiver. To address this challenge, researchers have proposed combining FDA with multiple-input multiple-output (MIMO) radars. By utilizing independent spatial steering vectors at the receiver, FDA-MIMO radars effectively decouple range and angle information, achieving independent degrees of freedom in the range dimension. Although numerous studies have confirmed the effectiveness of FDA-MIMO radars in suppressing mainlobe deceptive jamming, the complex array structure required to achieve range processing capabilities presents practical challenges. In particular, inter-channel time delay errors can reduce the accuracy of angle estimation, which in turn affects range estimation performance and ultimately weakens the effectiveness of deceptive jamming suppression.

[0004] As a new radar system, multi-carrier radar can simultaneously transmit multiple phase-coherent subcarrier signals through a single antenna, ensuring efficient spectrum utilization while simplifying the system structure. Compared to FDA-MIMO radars, which use array antennas to transmit signals at different frequencies, multi-carrier radars can achieve range processing without relying on an array structure. Furthermore, the single-channel reception mechanism of multi-carrier radars fundamentally eliminates the inter-channel delay error inherent in FDA-MIMO radar multi-channel reception. It is worth noting that current research focuses primarily on improving range resolution through subcarrier synthesis, while insufficient attention has been paid to the additional degrees of freedom provided by the unique frequency diversity characteristics of multi-carrier radars in the range dimension. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology and provide a deceptive interference suppression method for a multi-carrier radar, which effectively suppresses deceptive interference based on the frequency domain degrees of freedom of the multi-carrier radar.

[0006] The present invention specifically adopts the following technical solutions to solve the above technical problems:

[0007] A deceptive interference suppression method for a multi-carrier radar, wherein the frequency interval Δf between adjacent sub-carriers of the multi-carrier radar transmission signal is equal to the repetition frequency f PRF The ratio has a decimal part; the method comprises the following steps:

[0008] S1. Extract the distance of each target from the multi-carrier channel data of the received echo signal;

[0009] S2, construct a corresponding frequency domain distance compensation vector for each target, and multiply each frequency domain distance compensation vector by the frequency domain steering vector of the corresponding target in the multi-carrier channel data to obtain the multi-carrier channel data after distance compensation; the distance is r a The frequency domain distance compensation vector expression of the target is:

[0010]

[0011] Where c is the speed of light, M is the number of subcarriers in the multicarrier radar transmission signal, and the superscript T represents the transpose operation;

[0012] S3. Convert the multi-carrier channel data after distance compensation to the frequency domain, and use the data in the frequency range of 0 to B in the obtained frequency domain data as sample data, first perform a spatial smoothing process on the sample data, and then calculate the sample covariance matrix using the spatially smoothed sample data, where B is the subcarrier bandwidth of the multi-carrier radar transmit signal;

[0013] S4, performing eigenvalue decomposition on the sample covariance matrix, and replacing all elements in the decomposed small eigenvalue diagonal matrix corresponding to the noise with the average value of these elements, thereby obtaining a processed sample covariance matrix;

[0014] S5. Construct a minimum variance distortionless response (MVDR) filter based on the processed sample covariance matrix, and use the constructed MVDR filter to filter the multi-carrier channel data after distance compensation to obtain a target range image with deceptive interference suppressed.

[0015] Preferably, the multi-carrier radar is a multi-carrier radar using a single co-located transmitting and receiving antenna.

[0016] Preferably, the multi-carrier channel data of the received echo signal is obtained specifically by the following method: performing analog mixing on the received echo signal and the local oscillator signal, down-converting the received echo signal to the baseband and then sampling it, and then dividing the sampled multi-carrier echo into M subcarrier channels, digitally down-converting different subcarriers to the baseband and performing matched filtering on them respectively, to obtain M subcarrier range images.

[0017] Preferably, the distance of each target is extracted by the following method: performing frequency domain non-coherent accumulation on the time domain range image of each subcarrier in the multi-carrier channel data of the received echo signal, and then using a constant false alarm rate (CFAR) detection method to detect the distance of each target.

[0018] Based on the same inventive concept, the following technical solutions can also be obtained:

[0019] A deceptive interference suppression device for a multi-carrier radar, comprising:

[0020] The target distance extraction module is used to extract the distance of each target from the multi-carrier channel data of the received echo signal;

[0021] The distance compensation module is used to construct a corresponding frequency domain distance compensation vector for each target, and multiply each frequency domain distance compensation vector with the frequency domain steering vector of the corresponding target in the multi-carrier channel data to obtain the multi-carrier channel data after distance compensation; the distance is r a The frequency domain distance compensation vector expression of the target is:

[0022]

[0023] Where c is the speed of light, M is the number of subcarriers in the multicarrier radar transmission signal, and the superscript T represents the transpose operation;

[0024] a frequency domain sample processing module for converting the multi-carrier channel data after distance compensation into the frequency domain, and using the data in the frequency range of 0 to B in the obtained frequency domain data as sample data, first performing a spatial smoothing process on the sample data, and then calculating the sample covariance matrix using the spatially smoothed sample data, where B is the subcarrier bandwidth of the multi-carrier radar transmit signal;

[0025] A covariance matrix correction module is used to perform eigenvalue decomposition on the sample covariance matrix and replace all elements in the decomposed small eigenvalue diagonal matrix corresponding to the noise with the average value of these elements, thereby obtaining a processed sample covariance matrix;

[0026] The frequency domain adaptive filter is a minimum variance distortionless response (MVDR) filter constructed based on the processed sample covariance matrix, which is used to filter the multi-carrier channel data after distance compensation to obtain a target range image with deceptive interference suppressed.

[0027] Preferably, the multi-carrier radar is a multi-carrier radar using a single co-located transmitting and receiving antenna.

[0028] Preferably, the multi-carrier channel data of the received echo signal is obtained specifically by the following method: performing analog mixing on the received echo signal and the local oscillator signal, down-converting the received echo signal to the baseband and then sampling it, and then dividing the sampled multi-carrier echo into M subcarrier channels, digitally down-converting different subcarriers to the baseband and performing matched filtering on them respectively, to obtain M subcarrier range images.

[0029] Preferably, the distance of each target is extracted by the following method: performing frequency domain non-coherent accumulation on the time domain range image of each subcarrier in the multi-carrier channel data of the received echo signal, and then using a constant false alarm rate (CFAR) detection method to detect the distance of each target.

[0030] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0031] The present invention uses the frequency domain freedom of multi-carrier radar to effectively suppress deceptive interference, filling the technical gap in deceptive interference suppression for multi-carrier radars and significantly advancing the practical application of multi-carrier radars.

[0032] The multi-carrier radar proposed in the present invention has much lower hardware system complexity than the FDA-MIMO radar, and because it avoids the delay error between multiple channels of the array, it can more effectively improve the effect of deceptive interference suppression. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1A schematic diagram of the structure of the transmitting and receiving ends of a specific embodiment of the multi-carrier radar of the present invention;

[0034] Figure 2 This is a flow chart of a deceptive interference suppression method for a multi-carrier radar according to the present invention;

[0035] Figure 3 The single-carrier range image before processing provided by the present invention;

[0036] Figure 4 The single-carrier range image provided by the present invention is the result of frequency domain non-coherent accumulation and CFAR detection;

[0037] Figure 5 A schematic diagram of extracting samples in the frequency domain of the range image provided by the present invention;

[0038] Figure 6 The Capon power spectrum distribution in the frequency domain calculated by the selected samples provided by the present invention;

[0039] Figure 7 The Capon power spectrum distribution after spatial smoothing and PCA processing provided by the present invention;

[0040] Figure 8 The MVDR frequency domain adaptive filter image provided by the present invention;

[0041] Figure 9 This is the range image result after frequency domain adaptive filtering of the present invention. DETAILED DESCRIPTION

[0042] In response to the technical gap in multi-carrier radar deceptive interference suppression, the solution of the present invention is to effectively suppress deceptive interference based on the frequency domain freedom of the multi-carrier radar.

[0043] The technical solutions proposed in the present invention are as follows:

[0044] A deceptive interference suppression method for a multi-carrier radar, wherein the frequency interval Δf between adjacent sub-carriers of the multi-carrier radar transmission signal is equal to the repetition frequency f PRF The ratio has a decimal part; the method comprises the following steps:

[0045] S1. Extract the distance of each target from the multi-carrier channel data of the received echo signal;

[0046] S2, construct a corresponding frequency domain distance compensation vector for each target, and multiply each frequency domain distance compensation vector by the frequency domain steering vector of the corresponding target in the multi-carrier channel data to obtain the multi-carrier channel data after distance compensation; the distance is r a The frequency domain distance compensation vector expression of the target is:

[0047]

[0048] Where c is the speed of light, M is the number of subcarriers in the multicarrier radar transmission signal, and the superscript T represents the transpose operation;

[0049] S3. Convert the multi-carrier channel data after distance compensation to the frequency domain, and use the data in the frequency range of 0 to B in the obtained frequency domain data as sample data, first perform a spatial smoothing process on the sample data, and then calculate the sample covariance matrix using the spatially smoothed sample data, where B is the subcarrier bandwidth of the multi-carrier radar transmit signal;

[0050] S4, performing eigenvalue decomposition on the sample covariance matrix, and replacing all elements in the decomposed small eigenvalue diagonal matrix corresponding to the noise with the average value of these elements, thereby obtaining a processed sample covariance matrix;

[0051] S5. Construct a minimum variance distortionless response (MVDR) filter based on the processed sample covariance matrix, and use the constructed MVDR filter to filter the multi-carrier channel data after distance compensation to obtain a target range image with deceptive interference suppressed.

[0052] To facilitate public understanding, the technical solution of the present invention is described in detail below through a specific embodiment with reference to the accompanying drawings:

[0053] The multi-carrier radar of this embodiment is a multi-carrier radar using a single co-located transmit and receive antenna, such as Figure 1 As shown in the figure, the transmission and reception of multi-carrier radar signals are controlled by an RF switch. At the radar receiving end, the received multi-carrier echo signal is first mixed with the local oscillator signal and analog down-converted to baseband to reduce the sampling rate requirement of the ADC. After the baseband multi-carrier signal is fully sampled, it is then divided into M subcarrier channels for digital down-conversion, where M is the number of subcarriers. Different subcarriers are down-converted to baseband in each of the M channels, and then matched filtered with the corresponding baseband waveform to obtain the time domain range image corresponding to the M subcarriers. Here, each subcarrier waveform takes the LFM signal as an example, and the output range image expression of the mth subcarrier is given as

[0054]

[0055] Where ξ represents the complex scattering coefficient, Δf is the frequency spacing between adjacent subcarriers (uniform spacing), τ0 = 2r0 / c represents the round-trip delay of the radar signal, r0 is the distance of the target from the radar, and χ(t-τ0,0) represents the cross-correlation result of the LFM waveform. Therefore, we can combine the output range images of multiple subcarriers to obtain the following expression for the target frequency-domain steering vector:

[0056]

[0057] This gives the frequency domain degrees of freedom (range processing dimension). For the range processing dimension in multi-carrier radar, the output response of different range units r is given by the following formula

[0058]

[0059] Formula (3) shows that the obtained frequency domain range image presents a main peak at the target real distance r0, and is expressed as R a = c / (2Δf) is the fuzzy period and other peaks appear. It is worth noting that this fuzzy period is different from the traditional pulse system with R u =c / (2f PRF ) has significant differences in the fuzzy characteristics of the period, which provides a theoretical basis for the recognition of true and false targets in deceptive interference suppression.

[0060] Deceptive jamming occurs when an enemy aircraft detects radar tracking and locks on, intercepting the radar signal through an onboard false target generator (FTG) and forwarding it after a delay. This behavior generates multiple false targets in the fast time dimension, causing the radar to incorrectly obtain the distance parameters of the real target. FTG usually delays the radar signal by one or more pulse periods, causing the generated false target to lead or lag behind the real target. Assume that the FTG is located at a distance of r0, and generates Q false targets with a fast time distance of r q For a false target (q=1,2,…,Q), assuming that it is delayed by p pulse periods relative to the real target, the distance of the false target in the frequency domain steering vector can be expressed as R q =r q +pR u The frequency domain steering vector of the deceptive interference is as follows:

[0061]

[0062] Therefore, the received signal of the qth false target can be expressed as:

[0063]

[0064] where ξ q represents the complex scattering coefficient of the qth false target. Therefore, in a multi-carrier radar, the received echo signal after matched filtering can be expressed as

[0065]

[0066] Among them, Y(t), Y q (t) and N(t) represent the target signal, deceptive interference and noise components, respectively.

[0067] For the received echo signal X(t) after matched filtering, the present invention implements deceptive interference suppression based on the frequency domain degree of freedom, such as Figure 2 The specific processing flow is as follows:

[0068] Before performing deceptive interference suppression, the time domain range image of each subcarrier after matched filtering can be subjected to frequency domain incoherent accumulation to improve the target signal-to-noise ratio; then, the distance corresponding to the peak value of each target (regardless of true or false target) (i.e., target distance) r is obtained by constant false alarm rate (CFAR) detection. a , thereby constructing multiple frequency domain distance compensation vectors corresponding to different frequency domain distance offsets. a The frequency domain distance compensation vector expression of the target is:

[0069]

[0070] By applying the corresponding distance compensation vector to different target signals in formula (6), the data matrix after distance compensation can be obtained as follows:

[0071]

[0072] in, and They represent the frequency domain steering vectors of the real target and false target after frequency domain distance compensation, and ⊙ represents the Hadamard product. and The expression is as follows

[0073]

[0074] From equations (9) and (10), we can see that the frequency domain distribution of the real target is compensated to the distance zero point, while the frequency domain distribution of the false target after compensation still has a certain residual fuzzy distance pR u To ensure the distinguishability of true and false targets in the frequency domain, the residual distance after false target compensation (pR u ) falls into the zero value point caused by frequency domain range ambiguity. Therefore, pR u The maximum unambiguous distance R in the frequency domain a The ratio should meet the following conditions:

[0075]

[0076] Where z represents R u / R aThe integer part of , and u is the decimal part. Since the phase difference has a periodicity of 2π, the frequency domain normalized distance is in the interval [0,1], and the influence of z can be ignored. Therefore, the distribution of false targets in the normalized frequency domain is determined by the decimal part u, so that the compensated false target is located at pu and must satisfy like The frequency domain distribution of the false target will overlap with the real target and cannot be distinguished. Therefore, in the multi-carrier signal parameter design, the frequency interval Δf between adjacent sub-carriers of the multi-carrier radar transmission signal and the repetition frequency f PRF The ratio between them should have a fractional part u, which is crucial for distinguishing true and false targets in the frequency domain.

[0077] In order to suppress false targets, a frequency domain adaptive filter needs to be designed to process the compensated data matrix. Although true and false targets have been distinguished based on the frequency domain distribution, false targets exhibit a pseudo-random distribution in the time domain range profile, resulting in the time domain samples not meeting the conditions of independent and identically distributed (iid) data, making it difficult to obtain an accurate covariance matrix of interference plus noise. Since the modulation signal of each subcarrier of the true target and the false target is the same, and each subcarrier undergoes the same down-conversion and matched filtering processing, they have the same spectral distribution. Therefore, the compensated time domain data matrix can be first converted to the range frequency domain through Fourier transform, and its expression is:

[0078]

[0079] Equation (12) proves that the true and false targets have the same spectral distribution, which is approximately a rectangular function in the frequency range from 0 to B. In this case, the frequency domain steering vectors of the true and false targets overlap with each other in the spectrum, resulting in each data unit in the rectangular spectrum maintaining a frequency domain response close to independent and identically distributed. Therefore, when the pulse repetition period T r When determined, we can select BT from each subcarrier spectrum at most r The covariance matrix is ​​estimated by using data from the original source as training samples. However, these samples contain contributions from the true target, which can degrade the performance of the frequency-domain adaptive filter. Before using these samples to estimate the interference plus noise covariance matrix, the frequency-domain response of the true target must be removed from the samples.

[0080] The data in the frequency range of 0 to B are selected from the obtained frequency domain data as sample data, which is expressed as Perform a spatial smoothing process on it, specifically: Divided into two subsamples: and in consists of the first M–1 elements, It consists of the last M–1 elements. According to equations (9) and (10), by Subtract The frequency domain response of the real target will be completely canceled, while the frequency domain steering vector of the false target will remain unchanged, although the dimension is reduced by one. The expression of this spatial smoothing process is:

[0081]

[0082] in Indicates the selected sample data The samples obtained after a frequency domain spatial smoothing are calculated based on the spatially smoothed samples as follows:

[0083]

[0084] where N s is the number of samples selected in the distance frequency domain, It represents the lth sample selected from the range frequency domain, and the superscript H represents the conjugate transpose.

[0085] For frequency domain samples generated by spatial smoothing, their power spectrum will produce a notch near the zero-frequency region. This notch introduces redundant features, thereby reducing the accuracy of the interference covariance matrix estimation. To address the limitations of spatial smoothing, a processing method combined with principal component analysis (PCA) is introduced to correct the sample covariance matrix after spatial smoothing. Specifically, we perform the following eigenvalue decomposition on the sample covariance matrix after spatial smoothing:

[0086]

[0087] where Λ S =diag{λ1,λ2,…,λ k} represents the diagonal matrix corresponding to the large eigenvalue of the deceptive interference after eigenvalue decomposition, U S =[u1,u2,…,u k ] represents the subspace corresponding to the deceptive interference. N =diag{λ k+1 ,λ k+2 ,…,λ M-1} represents the diagonal matrix of small eigenvalues ​​corresponding to noise, U N =[u k+1 ,u k+2 ,…,u M-1 ] is the noise subspace. Ideally, Λ N The eigenvalue in should be much smaller than Λ SThe eigenvalue in is approximately equal to the receiver noise level, indicating that the contribution of the noise eigenvalue to the overall covariance matrix can be ignored. However, the spatial smoothing operation will introduce a depression in the zero-frequency region of the frequency domain power spectrum, resulting in the inability to form a clear noise floor. Therefore, the contribution of the noise eigenvalue to the overall covariance matrix increases, reducing the estimation accuracy of the interference covariance matrix. To solve this problem, the present invention redefines the noise eigenvalue as Λ′ N =diag{σ 2 ,σ 2 ,…,σ 2}(where σ 2 is the average noise power, that is, Λ N The average value of all elements in ), while keeping the noise subspace unchanged, thus obtaining the processed covariance matrix:

[0088]

[0089] The resulting covariance matrix While retaining the main features of deceptive interference, the influence of noise is effectively reduced, thereby improving the stability of the covariance matrix and the accuracy of weight calculation.

[0090] The denoising covariance matrix is ​​obtained by the above method Finally, the frequency domain adaptive filter is designed in combination with the minimum variance distortionless response (MVDR) algorithm. The core idea of ​​the MVDR algorithm is to minimize the output power while ensuring that the desired signal is distortion-free. The expression of the MVDR filter is as follows

[0091]

[0092] in, represents the steering vector of the real target after frequency domain compensation, which determines the main lobe direction of the adaptive filter. In addition, is the optimal weight vector, which can be calculated by the Lagrange multiplier method.

[0093]

[0094] in, Due to the spatial smoothing, one dimension of freedom is lost in the frequency domain. Therefore, when w is applied to filter the distance-compensated data, it only affects the first M-1 dimensions of the data matrix. The output is therefore given by the following expression:

[0095]

[0096] After being processed by the frequency domain adaptive filter, the deceptive interference is suppressed due to the range mismatch in the frequency domain, and only the real target will be retained in the range image obtained after processing.

[0097] In order to illustrate the effectiveness of the technical solution of the present invention, a simulation was conducted to verify the technical solution of the present invention. The multi-carrier radar parameters used in the simulation are as follows:

[0098] The multi-carrier radar has an initial carrier frequency of 10 GHz and contains 16 subcarriers. Adjacent subcarrier frequencies are spaced 10 MHz apart, the subcarrier signal bandwidth is 8 MHz, and the signal pulse repetition period is set to 100.02 μs. The simulation considers a detection scenario consisting of one real target and three decoy targets. The real target is located at 6 km, and the three decoy targets are located at 4 km, 9 km, and 13 km, respectively. The first two decoy targets (denoted as Decoy Targets 1 and 2) have a pulse delay, while the third decoy target (denoted as Decoy Target 3) has a two-pulse delay. Figure 3 It is a single-carrier range image, showing the positional relationship between the real target and three false targets.

[0099] Figure 4 The solid line in the figure shows the range image after frequency domain non-coherent accumulation. It can be observed that the noise floor is significantly reduced, making the target easier to identify. Subsequently, the CFAR detection threshold with a false alarm rate of 1% is calculated, as shown in Figure 4 The dotted line shows the area where the non-coherent accumulation result exceeds the CFAR threshold, which is the fast time distance position of the true and false targets. Based on the obtained fast time distance, the corresponding frequency domain distance compensation is performed on each target. To facilitate sample selection, the spectrum corresponding to the fast time range image is obtained by FFT, as shown in the following figure: Figure 5 As shown in Figure 2, since each subcarrier has been digitally downconverted to baseband, the samples are selected within the subcarrier bandwidth starting from zero frequency.

[0100] Through the selected samples, the frequency domain Capon spectrum distribution of true and false targets can be calculated, such as Figure 6 As shown in the figure, simulation results demonstrate that, leveraging the additional frequency domain degrees of freedom provided by a multi-carrier radar, after range compensation, the frequency domain distribution of true and false targets can be distinguished: the true target is located at frequency zero, false targets 1 and 2, spanning one pulse cycle, are located at 0.2, and false target 3, spanning two pulse cycles, is located at 0.4. To accurately estimate the interference covariance matrix, the true target response must be removed from the selected samples. To address this issue, a method combining spatial smoothing and PCA was employed. Figure 7 The Capon power spectrum distribution of the samples after spatial smoothing combined with PCA method is displayed. It can be seen that the real target is effectively suppressed in the frequency domain, and only the frequency domain responses of three false targets are retained.

[0101] The interference plus noise covariance matrix calculated from the processed samples is then applied to the MVDR algorithm to generate Figure 8The frequency-domain adaptive filter shown in Figure 1 is oriented toward the frequency domain zero point where the true target resides, while deep nulls are formed at normalized distances of 0.2 and 0.4, corresponding to the locations of false targets. This filter maximizes the output power of the true target while simultaneously suppressing deceptive jammers.

[0102] Figure 9 Demonstrated application Figure 8 The range image after the frequency-domain adaptive filter described in

[15] suppresses the deceptive jamming. It can be seen that the three false targets are effectively suppressed, leaving only the real target.

[0103] In summary, the present invention utilizes a multi-carrier radar to simultaneously transmit multiple frequency component signals, and achieves the acquisition of frequency domain degrees of freedom with only a single antenna; utilizes the frequency domain processing dimension provided by the multi-carrier radar to successfully distinguish between true and false targets in the frequency domain; combines spatial smoothing with PCA to achieve accurate estimation of the interference plus noise covariance matrix; finally, uses the MVDR algorithm to construct a frequency domain adaptive filter to suppress deceptive interference.

Claims

1. A deceptive interference suppression method for a multi-carrier radar, characterized in that: The frequency interval Δf between adjacent subcarriers of the multicarrier radar transmission signal and the repetition frequency f PRF The ratio has a decimal part; the method comprises the following steps: S1. Extract the distance of each target from the multi-carrier channel data of the received echo signal; S2, construct a corresponding frequency domain distance compensation vector for each target, and multiply each frequency domain distance compensation vector by the frequency domain steering vector of the corresponding target in the multi-carrier channel data to obtain the multi-carrier channel data after distance compensation; the distance is r a The frequency domain distance compensation vector expression of the target is: Where c is the speed of light, M is the number of subcarriers in the multicarrier radar transmission signal, and the superscript T represents the transpose operation; S3. Convert the multi-carrier channel data after distance compensation to the frequency domain, and use the data in the frequency range of 0 to B in the obtained frequency domain data as sample data, first perform a spatial smoothing process on the sample data, and then calculate the sample covariance matrix using the spatially smoothed sample data, where B is the subcarrier bandwidth of the multi-carrier radar transmit signal; S4, performing eigenvalue decomposition on the sample covariance matrix, and replacing all elements in the decomposed small eigenvalue diagonal matrix corresponding to the noise with the average value of these elements, thereby obtaining a processed sample covariance matrix; S5. Construct a minimum variance distortionless response (MVDR) filter based on the processed sample covariance matrix, and use the constructed MVDR filter to filter the multi-carrier channel data after distance compensation to obtain a target range image with deceptive interference suppressed.

2. The deceptive interference suppression method for a multi-carrier radar according to claim 1, wherein: The multi-carrier radar is a multi-carrier radar using a single co-located transmitting and receiving antenna.

3. The deceptive interference suppression method for a multi-carrier radar according to claim 1, wherein: The multi-carrier channel data of the received echo signal is specifically obtained by the following method: analog mixing is performed on the received echo signal and the local oscillator signal, the received echo signal is down-converted to the baseband and then sampled, and then the sampled multi-carrier echo is divided into M subcarrier channels, different subcarriers are digitally down-converted to the baseband and matched filtered respectively, to obtain M subcarrier range images.

4. The deceptive interference suppression method for a multi-carrier radar according to claim 1, wherein: The distance of each target is extracted by the following method: performing frequency domain non-coherent accumulation on the time domain range image of each subcarrier in the multi-carrier channel data of the received echo signal, and then using a constant false alarm rate (CFAR) detection method to detect the distance of each target.

5. A deceptive interference suppression device for a multi-carrier radar, characterized in that: include: The target distance extraction module is used to extract the distance of each target from the multi-carrier channel data of the received echo signal; The distance compensation module is used to construct a corresponding frequency domain distance compensation vector for each target, and multiply each frequency domain distance compensation vector with the frequency domain steering vector of the corresponding target in the multi-carrier channel data to obtain the multi-carrier channel data after distance compensation; the distance is r a The frequency domain distance compensation vector expression of the target is: Where c is the speed of light, M is the number of subcarriers in the multicarrier radar transmission signal, and the superscript T represents the transpose operation; a frequency domain sample processing module for converting the multi-carrier channel data after distance compensation into the frequency domain, and using the data in the frequency range of 0 to B in the obtained frequency domain data as sample data, first performing a spatial smoothing process on the sample data, and then calculating the sample covariance matrix using the spatially smoothed sample data, where B is the subcarrier bandwidth of the multi-carrier radar transmit signal; A covariance matrix correction module is used to perform eigenvalue decomposition on the sample covariance matrix and replace all elements in the decomposed small eigenvalue diagonal matrix corresponding to the noise with the average value of these elements, thereby obtaining a processed sample covariance matrix; The frequency domain adaptive filter is a minimum variance distortionless response (MVDR) filter constructed based on the processed sample covariance matrix, which is used to filter the multi-carrier channel data after distance compensation to obtain a target range image with deceptive interference suppressed.

6. The deceptive interference suppression device for a multi-carrier radar according to claim 5, characterized in that: The multi-carrier radar is a multi-carrier radar using a single co-located transmitting and receiving antenna.

7. The deceptive interference suppression device for a multi-carrier radar according to claim 5, characterized in that: The multi-carrier channel data of the received echo signal is specifically obtained by the following method: analog mixing is performed on the received echo signal and the local oscillator signal, the received echo signal is down-converted to the baseband and then sampled, and then the sampled multi-carrier echo is divided into M subcarrier channels, different subcarriers are digitally down-converted to the baseband and matched filtered respectively, to obtain M subcarrier range images.

8. The deceptive interference suppression device for a multi-carrier radar as claimed in claim 5, characterized in that: The distance of each target is extracted by the following method: performing frequency domain non-coherent accumulation on the time domain range image of each subcarrier in the multi-carrier channel data of the received echo signal, and then using a constant false alarm rate (CFAR) detection method to detect the distance of each target.

9. A multi-carrier radar, characterized in that: The method comprises the deceptive interference suppression device as described in any one of claims 5 to 8.

Images