Main lobe deception jamming resisting method and system for 2D-FDA-MIMO radar

Abstract

The embodiment of the invention provides a main lobe deception jamming resisting method and system for a 2D-FDA-MIMO radar, and belongs to the technical field of radar signal processing. According to the invention, transmitting terminal information can be set; setting an echo signal according to the transmitting end information; preprocessing the echo signal to obtain a received signal; performing clutter separation processing according to the received signal to obtain filtering data; and performing projection suppression processing according to the filtering data to obtain a target signal. According to the invention, suppression of main lobe deception jamming can be completed.

Description

Technical Field

[0001] The present application relates to the field of radar signal processing technology, and in particular to a method and system for resisting mainlobe deception interference for 2D-FDA-MIMO radar. Background Art

[0002] Current radar systems can employ digital beamforming (DBF) and STAP technologies to suppress sidelobe interference, but mainlobe interference remains a challenge. For traditional phased arrays, mainlobe interference and targets cannot be effectively separated in the angular domain or the transmit / receive frequency domain, making research on mitigating mainlobe interference extremely challenging. When airborne radars look downward, they receive a large amount of ground clutter signals. This not only affects the radar's performance, but also exposes it to local mainlobe deceptive jammers, making target detection extremely difficult. Summary of the Invention

[0003] The main purpose of the embodiments of the present application is to provide a method and system for resisting mainlobe deception interference for 2D-FDA-MIMO radar.

[0004] The technical solution adopted by the present invention is:

[0005] In one aspect, an embodiment of the present invention provides a method for resisting mainlobe deception jamming for a 2D-FDA-MIMO radar. The method for resisting mainlobe deception jamming for a 2D-FDA-MIMO radar comprises the following steps:

[0006] Set transmitter information;

[0007] Setting an echo signal according to the transmitting end information;

[0008] Preprocessing the echo signal to obtain a received signal;

[0009] performing clutter separation processing according to the received signal to obtain filtered data;

[0010] A projection suppression process is performed based on the filtered data to obtain a target signal.

[0011] Furthermore, the setting of the transmitter information includes the following steps:

[0012] Set up the transmitting end array;

[0013] According to the transmitting end array, a frequency increment is set between each column and each row of the carrier frequency of the transmitting end; the frequency increment includes a pitch dimension frequency increment and an azimuth dimension frequency increment;

[0014] Obtaining a transmission carrier frequency according to the frequency increment;

[0015] Acquiring a transmission signal according to the transmission carrier frequency;

[0016] The transmitting end array, the frequency increment, the transmitting carrier frequency and the transmitting signal are used as transmitting end information.

[0017] Furthermore, the formula used to obtain the transmission signal according to the transmission carrier frequency includes:

[0018]

[0019] in, For the (m t ,n t ) the transmitting carrier frequency of the transmitting array element; m t is the elevation dimension of the transmitting array element; n t is the azimuth dimension of the transmitting array element; f0 is the reference carrier frequency; Δf e is the pitch dimension frequency increment; Δf a is the azimuth frequency increment; For the (m t ,n t ) transmit signals of the transmit elements; T represents the pulse duration; is the baseband modulation signal; j is the imaginary unit; t is the time variable.

[0020] Furthermore, the echo signal is set according to the transmitting end information, and the formula used includes:

[0021]

[0022] in, For nth r The echo signal received by the receiving antenna; ξ′ represents the complex scattering coefficient of the echo; M t is the number of rows of the transmitting end array; N t is the number of columns of the transmitting end array; τ Δ is the time delay; is the baseband signal.

[0023] Furthermore, the echo signal is preprocessed to obtain a received signal, and the formula used includes:

[0024]

[0025] Wherein, r represents the received signal after the echo signal is subjected to down-conversion, mixing and matched filtering; ξ is the complex scattering coefficient after pulse compression; represents the time domain steering vector; represents the receiving azimuth steering vector; represents the launch azimuth steering vector; Represents the launch pitch steering vector.

[0026] Furthermore, performing clutter separation processing based on the received signal to obtain filtered data includes the following steps:

[0027] Calculating interference information based on the received signal to obtain a radar received signal; the radar received signal includes a target signal, a noise signal, a clutter signal and an interference signal;

[0028] Get the main value sampling distance;

[0029] Obtaining a space-time compensation vector according to the main value sampling distance;

[0030] performing secondary distance-dependent compensation on the radar received signal according to the space-time compensation vector to obtain compensation data;

[0031] Acquiring a transmitting azimuth frequency and a transmitting elevation frequency according to the compensation data;

[0032] Acquiring pitch steering vectors of different fuzzy areas according to the transmitting azimuth frequency and the transmitting pitch frequency;

[0033] obtaining a filter according to the pitch steering vector;

[0034] According to the filter, obtaining a space-time filtering full vector;

[0035] Filter data is obtained according to the space-time filtering full vector.

[0036] Furthermore, the radar received signal is subjected to secondary distance-dependent compensation based on the space-time compensation vector to obtain compensation data, and the formula used includes:

[0037]

[0038] Among them, h l is the space-time compensation vector; I K and Represented as a vector of all 1s; h t,a is the compensation vector of the range gate orientation; h t,e is the compensation vector of the range gate pitch; x l receiving signals for said radar; To compensate data.

[0039] Furthermore, performing projection suppression processing based on the filtered data to obtain a target signal includes the following steps:

[0040] Get the slant range of the target;

[0041] Acquiring a target transmitting end azimuth spatial frequency and a target receiving end azimuth spatial frequency according to the slant range of the target;

[0042] Get the distance of main lobe deceptive jamming;

[0043] Obtaining, according to the distance of the main lobe deceptive interference, an azimuth spatial domain frequency of a transmitting end of the main lobe deceptive interference and an azimuth spatial domain frequency of a receiving end of the main lobe deceptive interference;

[0044] Acquire a target transmission steering vector and a target reception steering vector according to the target transmission end azimuth spatial frequency and the target reception end azimuth spatial frequency;

[0045] Obtaining a transmit steering vector of the mainlobe deceptive interference and a receive steering vector of the mainlobe deceptive interference according to the transmit end azimuth spatial domain frequency of the mainlobe deceptive interference and the receive end azimuth spatial domain frequency of the mainlobe deceptive interference;

[0046] performing projection processing on each range gate of received data according to the transmit steering vector of the target, the receive steering vector of the target, the transmit steering vector of the mainlobe deceptive jammer, and the receive steering vector of the mainlobe deceptive jammer to obtain a projection matrix corresponding to each range gate;

[0047] A target signal is obtained according to the projection matrix and the filtering data.

[0048] On the other hand, an embodiment of the present invention also provides an anti-mainlobe deception interference system for 2D-FDA-MIMO radar, including a memory, a processor, and a computer program stored in the memory and runnable on the processor. When the processor executes the computer program, it implements the anti-mainlobe deception interference method for 2D-FDA-MIMO radar as described above.

[0049] On the other hand, an embodiment of the present invention further provides a computer-readable storage medium, which stores computer-executable instructions, and the computer-executable instructions are used to enable a computer to execute the anti-mainlobe deception interference method for 2D-FDA-MIMO radar as described above.

[0050] Embodiments of the present application include at least the following beneficial effects: This application provides a method and system for combating mainlobe deceptive jamming for 2D-FDA-MIMO radars. The present invention can set transmitter information; set an echo signal based on the transmitter information; preprocess the echo signal to obtain a received signal; perform clutter separation processing based on the received signal to obtain filtered data; and perform projection suppression processing based on the filtered data to obtain a target signal. The present invention can effectively suppress mainlobe deceptive jamming. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 2 is a schematic diagram of an anti-mainlobe deceptive jamming method for 2D-FDA-MIMO radar provided by an embodiment of the present invention;

[0052] Figure 2 is a schematic diagram of the geometric structure of a 2D-FDA-MIMO radar provided by an embodiment of the present invention;

[0053] Figure 3 This is a 2D-FDA-MIMO radar transmit-receive interference target distribution diagram provided by an embodiment of the present invention;

[0054] Figure 4 is a non-adaptive elevation pattern provided by an embodiment of the present invention;

[0055] FIG5( a ) is a schematic diagram of the target-interference-clutter space-time spectrum distribution before orthogonal projection processing provided by an embodiment of the present invention;

[0056] FIG5( b ) is a schematic diagram of the target-interference-clutter space-time spectrum distribution after orthogonal projection processing provided by an embodiment of the present invention;

[0057] FIG6( a ) is a schematic diagram of an unprocessed two-dimensional space-time spectrum provided by an embodiment of the present invention;

[0058] FIG6( b ) is a schematic diagram of an unprocessed three-dimensional space-time spectrum provided by an embodiment of the present invention;

[0059] FIG6( c ) is a schematic diagram of a three-dimensional space-time spectrum after pitch filtering according to an embodiment of the present invention;

[0060] FIG6( d ) is a schematic diagram of a two-dimensional space-time spectrum after pitch filtering according to an embodiment of the present invention;

[0061] FIG6( e ) is a schematic diagram of a three-dimensional space-time spectrum after orthogonal projection processing provided by an embodiment of the present invention;

[0062] FIG6( f ) is a schematic diagram of a two-dimensional space-time spectrum after orthogonal projection processing provided by an embodiment of the present invention;

[0063] Figure 7 It is a schematic diagram of SCJNRloss comparison provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the embodiments of the present application. They are merely examples of devices and methods consistent with some aspects of the embodiments of the present application as detailed in the appended claims.

[0065] It will be understood that the terms "first", "second", etc. used in this application may be used herein to describe various concepts, but unless otherwise specified, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the words "if" and "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0066] The terms "at least one", "plurality", "each", "any", etc. used in this application include "at least one", "two" or more, "plurality" or "each", "any" or "any one", "each" or "any one" as used herein.

[0067] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein are for the purpose of describing the embodiments of this application only and are not intended to limit this application.

[0068] Before explaining the embodiments of the present application in detail, some of the nouns and terms involved in the embodiments of the present application are first explained. The nouns and terms involved in the embodiments of the present application are subject to the following explanations.

[0069] 1) 2D-FDA-MIMO: 2 Dimension Frequency Diversity Array Multiple Input Multiple Output, two-dimensional multiple input multiple output frequency diversity array;

[0070] 2) STAP: space-time adaptive processing;

[0071] 3) FTG: false target generator;

[0072] 4) DBF: digital beamforming;

[0073] 5) SCJNR loss: Signal-to-Clutter-plus-Jammer-plus-Noise Ratio Loss, signal-to-clutter-plus-jammer-plus-noise ratio loss.

[0074] The present invention takes into account that airborne radars, when looking downward, are not only affected by ground clutter but also by various interference threats. Based on this scenario, different interferences need to be suppressed. The present invention proposes a 2D-FDA-MIMO radar system, which adds different frequency increments to the azimuth and elevation dimensions of the transmitter. The pitch-adaptive full vector is designed to separate the range fuzzy clutter in different fuzzy regions using the transmit azimuth degree of freedom, and implements pitch pre-filtering. At the same time, the transmit azimuth degree of freedom is utilized to suppress mainlobe deceptive interference on the two-dimensional transmit and receive planes, ultimately completing target detection.

[0075] Existing anti-mainlobe interference work is mainly carried out in airspace scenarios. The present invention mainly studies the mainlobe deception interference in clutter scenarios. In this scenario, it is necessary not only to deal with the range fuzzy clutter from different fuzzy areas, but also to suppress the mainlobe deception clutter and enrich the experimental scenarios.

[0076] To address the aforementioned range-ambiguous clutter suppression and mainlobe deceptive interference mitigation, the present invention proposes a novel 2D-FDA-MIMO radar architecture. Specifically, the transmitter employs a two-dimensional FDA array with different frequency increments added to the elevation and azimuth dimensions. This architecture not only separates range-ambiguous clutter in the elevation dimension but also mitigates mainlobe interference mitigation in the azimuth dimension at both the transmitter and receiver, ultimately achieving enhanced target detection performance.

[0077] The embodiments of the present invention are further described below with reference to the accompanying drawings.

[0078] On the one hand, the embodiment of the present invention provides an anti-main lobe deception jamming method for 2D-FDA-MIMO radar, referring to Figure 1 , an anti-mainlobe deception jamming method for 2D-FDA-MIMO radar includes the following steps:

[0079] S100, setting transmitter information;

[0080] S200, setting an echo signal according to the transmitting end information;

[0081] S300, pre-processing the echo signal to obtain a received signal;

[0082] S400, performing clutter separation processing according to the received signal to obtain filtered data;

[0083] S500: Perform projection suppression processing according to the filtered data to obtain a target signal.

[0084] The step S100 of setting the transmitter information disclosed in the embodiment of the present invention includes the following steps:

[0085] S110, setting the transmitting end face array;

[0086] S120. According to the transmitting end array, a frequency increment is set between each column and each row of the transmitting end carrier frequency; the frequency increment includes a pitch dimension frequency increment and an azimuth dimension frequency increment;

[0087] S130, obtaining a transmission carrier frequency according to the frequency increment;

[0088] S140, obtaining a transmission signal according to the transmission carrier frequency;

[0089] S150: Use the transmitting end array, frequency increment, transmitting carrier frequency and transmitting signal as transmitting end information.

[0090] S140 disclosed in the embodiment of the present invention obtains the transmission signal according to the transmission carrier frequency, and the formula used includes:

[0091]

[0092] in, For the (m t ,n t ) transmit carrier frequency of each transmit array element; m t is the elevation dimension of the transmitting array element; n t is the azimuth dimension of the transmitting array element; f0 is the reference carrier frequency; Δf e is the pitch frequency increment; Δf a is the azimuth frequency increment; For the (m t ,n t ) transmit signals of the transmit array elements; T represents the pulse duration; is the baseband modulation signal; j is the imaginary unit; t is the time variable.

[0093] S200 disclosed in the embodiment of the present invention sets the echo signal according to the transmitting end information, and the formula used includes:

[0094]

[0095] in, For nthr The echo signal received by the receiving antenna; ξ′ represents the complex scattering coefficient of the echo; M t is the number of rows of the transmitting end array; N t is the number of columns of the transmitting end array; τ Δ is the time delay; is the baseband signal.

[0096] S300 disclosed in the embodiment of the present invention pre-processes the echo signal to obtain the received signal, and the formula used includes:

[0097]

[0098] Where r represents the received signal after downconversion, mixing, and matched filtering of the echo signal; ξ is the complex scattering coefficient after pulse compression; represents the time domain steering vector; represents the receiving azimuth steering vector; represents the launch azimuth steering vector; Represents the launch pitch steering vector.

[0099] S400 disclosed in the embodiment of the present invention performs clutter separation processing based on the received signal to obtain filtered data, including the following steps:

[0100] S410. Calculate interference information based on the received signal to obtain a radar received signal; the radar received signal includes a target signal, a noise signal, a clutter signal, and an interference signal;

[0101] S420, obtaining a main value sampling distance;

[0102] S430, obtaining a space-time compensation vector according to the main value sampling distance;

[0103] S440, performing secondary distance-dependent compensation on the radar received signal according to the space-time compensation vector to obtain compensation data;

[0104] S450, acquiring a transmitting azimuth frequency and a transmitting elevation frequency according to the compensation data;

[0105] S460, obtaining pitch steering vectors for different fuzzy areas according to the transmit azimuth frequency and the transmit pitch frequency;

[0106] S470, obtaining a filter according to the pitch steering vector;

[0107] S480, obtaining a space-time filtering full vector according to the filter;

[0108] S490: Obtain filtering data according to the space-time filtering full vector.

[0109] As an optional implementation, the principal value sampling distance in this embodiment of the present invention is the maximum distance that the radar can measure unambiguously within a pulse repetition interval. Its compensation and deambiguation are the foundation of the 2D-FDA-MIMO radar's ability to suppress range ambiguity clutter. The ambiguity region refers to the range of range measurement ambiguity caused by the radar's pulse repetition frequency limitations.

[0110] S440 disclosed in the embodiment of the present invention performs quadratic distance-dependent compensation on the radar received signal based on the space-time compensation vector to obtain compensation data. The formula used includes:

[0111]

[0112] Among them, h l When it is empty, the compensation vector is: K and Represented as a vector of all 1s; h t,a is the compensation vector of the range gate orientation; h t,e is the compensation vector of the range gate pitch; x l Receive signals for radar; To compensate data.

[0113] As an optional implementation, the range gate in the embodiment of the present invention is a basic unit of radar signal processing, which is used to discretize the continuous detection range to achieve accurate resolution of the target distance and suppression of clutter / interference.

[0114] S500 disclosed in the embodiment of the present invention performs projection suppression processing based on the filtered data to obtain a target signal, including the following steps:

[0115] S510, obtaining the slant range of the target;

[0116] S520. Acquire a target transmitting end azimuth spatial frequency and a target receiving end azimuth spatial frequency according to the target slant range;

[0117] S530, obtaining a distance of main lobe deceptive jamming;

[0118] S540. Obtain, according to the distance of the main lobe deceptive interference, an azimuth spatial frequency of the transmitting end of the main lobe deceptive interference and an azimuth spatial frequency of the receiving end of the main lobe deceptive interference;

[0119] S550: Obtain a target transmission steering vector and a target reception steering vector according to the target transmission end azimuth spatial frequency and the target reception end azimuth spatial frequency;

[0120] S560: Obtain a transmit steering vector of the mainlobe spoofing interference and a receive steering vector of the mainlobe spoofing interference according to the azimuth spatial frequency of the transmitting end of the mainlobe spoofing interference and the azimuth spatial frequency of the receiving end of the mainlobe spoofing interference;

[0121] S570: Perform projection processing on each range gate of the received data based on the target's transmit steering vector, the target's receive steering vector, the transmit steering vector of the mainlobe spoofing jammer, and the receive steering vector of the mainlobe spoofing jammer to obtain a projection matrix corresponding to each range gate.

[0122] S580: Obtain a target signal according to the projection matrix and the filtered data.

[0123] The slant range of a target in the embodiment of the present invention refers to the straight-line distance of the target relative to the radar.

[0124] As an optional implementation, refer to Figure 2 The 2D-FDA-MIMO radar geometry structure, the transmitter is an M t ×N t There is a small frequency increment between each column and each row of the carrier frequency at the transmitting end. t ,n t The transmission carrier frequency of each element can be expressed as:

[0125]

[0126] Take the (1,1)th transmitting element as the reference element, and the (m t ,n t The transmission signal of the transmitting array element can be expressed as:

[0127]

[0128] Where T is the pulse duration, The baseband modulated signal and the transmitted signals between different array elements satisfy the orthogonality, that is:

[0129]

[0130] The receiving end is composed of N r uniform linear array, the nth r The echo signal about the target received by the receiving antenna can be expressed as:

[0131]

[0132] Where ξ′ represents the complex scattering coefficient of the echo, relative to the mth t n t Transmitting elements, nth r The time delay of the receiving element at the kth pulse can be expressed as:

[0133]

[0134] Among them, R,θ, are the slant range, azimuth and elevation angle of any scattering target respectively.

[0135] Furthermore, the nth r The received signal of the receiving element is all M t N t The linear combination of the transmitting array elements, substituting equation (5) into equation (4), and taking into account that the frequency increment is much smaller than the transmitting carrier frequency, and after down-conversion, mixing and matched filtering, the final received signal can be expressed in the form of a vector:

[0136]

[0137] Where ξ is the complex scattering coefficient after pulse compression, and They are time domain steering vector, receiving azimuth steering vector, transmitting azimuth steering vector and transmitting elevation steering vector:

[0138]

[0139] Among them, f d is the Doppler frequency, f r,a is the transmitting azimuth frequency, f t,a Receive azimuth frequency, f t,e To receive the pitch frequency, they are:

[0140]

[0141]

[0142] Due to the existence of range ambiguity, the clutter signal received by the lth range gate can be expressed as the superposition of clutter in different ambiguity areas, that is:

[0143]

[0144] Among them, ξ l,pq is the complex scattering coefficient of the lth range gate, the pth range ambiguity, and the qth clutter block. r is the number of distance blurs, N c The number of clutter blocks into which the clutter within a single range gate is divided.

[0145] In radar systems, radars typically track targets within a small range based on prior information about the target. Once the radar realizes it is being tracked, it switches to electronic countermeasures mode. The false target generator stores the intercepted radar waveform and retransmits it to the radar receiver. The echo data received in the radar system is randomly stored in range cells. Assuming the jammer is located in the far field The radar's transmitted waveform is intercepted by the jammer. The corresponding space-time signal can be expressed in vector form as:

[0146]

[0147] Among them, ξ j is the complex scattering coefficient of the deceptive jammer. Meanwhile, the space-time steering vector of the target signal is:

[0148]

[0149] ξ0 is the complex scattering coefficient of the target. The final radar received signal x l It can be seen as consisting of target signal, noise signal, clutter and interference:

[0150] x l =r t +r j +c l +n l (18)

[0151] Principles of clutter suppression and anti-mainlobe deceptive jamming of the 2D-FDA-MIMO radar according to an embodiment of the present invention:

[0152] (1) Clutter separation and clutter suppression methods

[0153] In the presence of range ambiguity, the slant range can be expressed as:

[0154] R=R l +(p-1)R u (19)

[0155] where R l is the main value sampling distance, R u is the maximum number of unambiguous times.

[0156] This embodiment of the present invention takes into account the range-angle coupling problem of 2D-FDA-MIMO radar. To better separate clutter in different range fuzzy regions, this embodiment of the present invention adopts a distance-based quadratic distance-dependent compensation method. By performing spatial distance compensation on different range gates, the terms related to the main value distance are compensated, so that the pitch frequency of the clutter can be more effectively separated in the spatial domain. The compensation vectors for azimuth and pitch are:

[0157]

[0158] Written in the form of space-time compensation vector:

[0159]

[0160] Among them I K and Represented as a vector of all 1s, the data after quadratic distance dependence compensation can be expressed as:

[0161]

[0162] After compensation, the transmit azimuth frequency and transmit elevation frequency are:

[0163]

[0164] The pitch steering vectors for different fuzzy regions are:

[0165]

[0166] After quadratic distance-dependent compensation, the present embodiment has achieved separation of clutter in different fuzzy regions at the pitch frequency. At this point, the present embodiment extracts clutter in a specific fuzzy region in the pitch dimension while suppressing clutter in other fuzzy regions. Therefore, the filter can be designed according to the following criteria:

[0167]

[0168] Among them, N t For the range fuzzy clutter area to be extracted, the pitch filter weight vector is obtained by solving equation (27):

[0169]

[0170] in, Indicates the pseudo-inverse operation of the matrix, and the corresponding space-time filtering full vector is:

[0171]

[0172] The data after filtering is:

[0173]

[0174] (2) Main lobe deception interference suppression method

[0175] By constructing an adaptive weight vector at the transmitter, we have preliminarily achieved the separation of clutter and the extraction of clutter in the target area. On this basis, the embodiment of the present invention will further utilize the information of the transmitter's azimuth and the receiver's azimuth to achieve more effective suppression of mainlobe deceptive interference in clutter scenarios. Specifically, the azimuth of the transmitter can provide information related to angle and distance, and the azimuth of the receiver can provide information about the transmitter's angle. By comprehensively utilizing these two aspects of information, the embodiment of the present invention can more accurately identify and distinguish mainlobe deceptive interference signals from different distances. The specific mainlobe deceptive interference suppression method will be described in detail below.

[0176] Assume the slant range of the target is R t =R0+(N t -1)R u , where R0 is the sampling distance of the target. After the secondary distance dependence compensation, the target's transmitting end azimuth spatial frequency and receiving end azimuth spatial frequency are respectively:

[0177]

[0178]

[0179] Assume that the distance of the main lobe deceptive jammer is R j Since the deceptive jammer will randomly fall on any range gate of the radar receiving data, there will still be a range-frequency error after the secondary range-dependent compensation of the received data. At this time, the azimuth spatial domain frequency of the transmitter and the azimuth spatial domain frequency of the main lobe deceptive jammer are:

[0180]

[0181] Among them, R t -R j =-R Δ -p′R u and R Δ ∈[0,R u ].

[0182] Since the radar tracks the target within a small range and the interference is main lobe deception interference, it can be considered that the azimuth and elevation angles of the main lobe deception interference are basically the same, but there is a difference in distance. After distance compensation, the target's launch azimuth guidance vector is only related to the maximum unambiguous distance and the fuzzy area where the target is located. This part is the radar's prior information. However, since the distance of the main lobe deception interference is unknown and randomly falls into any range gate, the distance dependence caused by the point main value distance cannot be compensated after the main value distance is compensated, and it will be clearly distinguished in the two-dimensional plane of transmission and reception. For reference, Figure 3 2D-FDA-MIMO radar transmit-receive interference target distribution map.

[0183] After the secondary range dependency compensation, the target and the interference have obvious differences in the transmit and receive directions. The transmit and receive steering vectors of the target are:

[0184]

[0185] The transmit steering vector and receive steering vector of the main lobe deceptive jammer are:

[0186]

[0187] After compensating the target, the target information is known. However, when performing secondary distance-dependent compensation, for main lobe deceptive jamming, since its distance dimension information cannot be effectively compensated, the distance-angle coupling problem still exists, resulting in differences between the target and the jammer in the transmit-receive two-dimensional plane, such as Figure 3 As shown. Based on this characteristic, embodiments of the present invention can perform projection processing on each range gate of received data. Through this processing, the target signal is retained within the range gate where the target is located, and for the range gate where the main lobe deceptive interference falls, the interference signal will be effectively filtered out after projection processing, thereby achieving the suppression of main lobe deceptive interference. The projection matrix corresponding to each range gate is:

[0188]

[0189] in, θ0 is the main beam azimuth, is the lth range gate, the Nth t The pitch angle corresponding to the blurred area.

[0190] The data y after pitch filtering l Converted to N r N t ×K matrix, that is, Y l =mat(y l ), at this time, the data Y is projected, that is:

[0191]

[0192] Therefore, the embodiment of the present invention completes the data processing flow.

[0193] Simulation experiments and analysis of the embodiments of the present invention:

[0194] The simulation data is shown in Table 1:

[0195] Table 1 Simulation parameters

[0196]

[0197] First, the embodiment of the present invention analyzes the characteristics of the pitch pattern, taking the 200th range gate as an example, Figure 4 The adaptive elevation filtering pattern of the 2D-FDA-MIMO radar transmitter is clearly displayed. The purple vertical lines represent clutter in different ambiguity zones. It can be seen that significant gain is achieved at the elevation frequency corresponding to the target's range ambiguity zone, while a notch is created in the non-target clutter zone, achieving effective suppression. This filtering mechanism effectively improves the radar's target detection performance.

[0198] Because deceptive jamming is generated randomly by the false target generator (FTG) after the enemy intercepts the target signal, and the Doppler frequency of the forwarded false target differs from that of the real target, the angular Doppler plane can be used to distinguish false targets from real targets. Taking the 200th range gate as an example, the interference suppression within a single range gate is analyzed. Assume that the target in the second ambiguity zone is the real target, while the target in the fourth ambiguity zone is the false target. Figures 5(a) and 5(b) show the spatial and temporal spectral distribution of the clutter-interference-target radar before and after orthogonal projection processing.

[0199] The unprocessed data reveals the distribution characteristics of clutter, target, and mainlobe deceptive interference. To account for the differences in the distribution of target and deceptive interference on the transmit-receive plane, the present invention constructs a corresponding projection matrix and performs orthogonal projection processing on the data. After processing, the energy of the mainlobe deceptive interference is significantly reduced, leaving only the power distribution of the target and clutter. This result demonstrates the effectiveness of the orthogonal projection method proposed in this embodiment of the present invention in suppressing mainlobe deceptive interference.

[0200] When all range gates are considered, assuming that both the target and the jammer are located within the main lobe of the radar beam, the target distance is 40 km and the main lobe deceptive jammer distance is 55 km. Figure 6(a)-Figure 6(f) The space-time spectrum distribution of clutter-target-interference at different processing stages of received data is given.

[0201] Observing the two-dimensional space-time spectrum distribution of the original echo data, as shown in Figures 6(a) and 6(b), range-ambiguous clutter, targets, and interference all appear in the space-time spectrum, and the clutter power is significantly higher than that of the target and mainlobe deceptive interference. Due to the presence of range-ambiguous clutter, the clutter spectrum trajectory in the space-time spectrum fills the entire diagonal of the two-dimensional space-time spectrum. First, quadratic range-dependent compensation is performed on the original data, and pitch pre-filtering is performed using the pitch degree of freedom of the transmitter. The results are shown in Figures 6(c) and 6(d). Simulation results show that after pre-filtering, most of the undesired clutter is suppressed, with only some residual clutter remaining in the undesired area. Based on the pitch pre-filtering, the data of each range gate is further projected, and the results are shown in Figures 6(e) and 6(f). It can be seen that the energy of the mainlobe deceptive interference is significantly reduced, verifying the effectiveness of the method proposed in this embodiment of the present invention in interference suppression.

[0202] Signal-to-Clutter-Jam-Noise Ratio (SCJNR) loss is often used as an indicator to evaluate radar clutter and interference suppression performance. It is specifically defined as:

[0203]

[0204] Figure 7 The SCJNR loss results at different processing stages are given, starting from Figure 7 As can be seen in the image, the SCJNR loss after processing has improved by approximately 15dB compared to the unprocessed version. The notch in the curve is at the Doppler center of the main clutter, which is zero due to the straight-on side view. The other notch is at the Doppler frequency of the interference, which is 0.22. While elevation filtering improves SCJNR loss, it still suffers from mainlobe deceptive interference. However, after orthogonal projection processing, the output SCJNR loss only forms a notch at the clutter, significantly improving the radar system's suppression of clutter and interference.

[0205] When a radar is tracking a target, it is not only affected by strong ground clutter but also by mainlobe deceptive interference. The present invention addresses this situation where both clutter and interference exist. A clutter suppression and anti-interference processing method for 2D-FDA-MIMO radar is proposed. The key points of the present invention include:

[0206] 1) By introducing frequency increments in both the azimuth and elevation array elements at the transmitter, and range frequency in the elevation dimension, the clutter in different fuzzy regions is separated through compensation. A non-adaptive elevation filtering method is then constructed to suppress clutter.

[0207] 2) Using the transmitter and receiver azimuth information, and taking into account the difference between the target and the mainlobe deceptive interference, a subspace projection matrix is constructed to ultimately suppress the mainlobe deceptive interference.

[0208] On the other hand, an embodiment of the present invention also provides an anti-mainlobe deception interference system for 2D-FDA-MIMO radar, including a memory, a processor, and a computer program stored on the memory and runnable on the processor. When the processor executes the computer program, it implements the anti-mainlobe deception interference method for 2D-FDA-MIMO radar as described above.

[0209] The processor and the memory can be connected via a bus or other means. The memory, as a non-transient computer-readable storage medium, can be used to store non-transient software programs and non-transient computer executable programs. In addition, the memory may include a high-speed random access memory and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some embodiments, the memory may optionally include a memory remotely arranged relative to the processor, and these remote memories may be connected to the processor via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0210] On the other hand, an embodiment of the present invention further provides a computer-readable storage medium, which stores computer-executable instructions, and the computer-executable instructions are used to enable a computer to execute the anti-mainlobe deception interference method for 2D-FDA-MIMO radar as described above.

[0211] Those skilled in the art will appreciate that all or some of the steps and systems in the method disclosed above can be implemented as software, firmware, hardware, and appropriate combinations thereof. Some physical components or all physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, and the computer-readable medium can include computer storage media (or non-transitory media) and communication media (or temporary media). As known to those skilled in the art, the term computer storage media is included in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data) and is volatile and non-volatile, removable, and non-removable. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory, or other memory technology, CD-ROM, digital versatile disks (DVD), or other optical disk storage, magnetic cassettes, magnetic tapes, disk storage, or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, as is well known to those skilled in the art, communication media typically embodies computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0212] The preferred embodiments of the present invention are described above with reference to the accompanying drawings, but are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and essence of the present invention should be within the scope of the present invention.

Claims

1. Anti-mainlobe deception jamming method for 2D-FDA-MIMO radar, characterized by: The anti-mainlobe deceptive jamming method for 2D-FDA-MIMO radar includes the following steps: Set transmitter information; Setting an echo signal according to the transmitting end information; Preprocessing the echo signal to obtain a received signal; performing clutter separation processing according to the received signal to obtain filtered data; A projection suppression process is performed based on the filtered data to obtain a target signal.

2. The anti-mainlobe deception jamming method for 2D-FDA-MIMO radar according to claim 1 is characterized in that: The step of setting the transmitter information includes the following steps: Set up the transmitting end array; According to the transmitting end array, a frequency increment is set between each column and each row of the carrier frequency of the transmitting end; the frequency increment includes a pitch dimension frequency increment and an azimuth dimension frequency increment; Obtaining a transmission carrier frequency according to the frequency increment; Acquiring a transmission signal according to the transmission carrier frequency; The transmitting end array, the frequency increment, the transmitting carrier frequency and the transmitting signal are used as transmitting end information.

3. The anti-mainlobe deception jamming method for 2D-FDA-MIMO radar according to claim 2, characterized in that: The formula used to obtain the transmission signal according to the transmission carrier frequency includes: in, For the (m t ,n t ) the transmitting carrier frequency of the transmitting array element; m t is the elevation dimension of the transmitting array element; n t is the azimuth dimension of the transmitting array element; f0 is the reference carrier frequency; Δf e is the pitch dimension frequency increment; Δf a is the azimuth frequency increment; For the (m t ,n t ) transmit signals of the transmit elements; T represents the pulse duration; is the baseband modulation signal; j is the imaginary unit; t is the time variable.

4. The anti-mainlobe deception jamming method for 2D-FDA-MIMO radar according to claim 1, characterized in that: The echo signal is set according to the transmitting end information, and the formula used includes: Among them, r nr (t) is the nth r The echo signal received by the receiving antenna; ξ′ represents the complex scattering coefficient of the echo; M t is the number of rows of the transmitting end array; N t is the number of columns of the transmitting end array; τ Δ is the time delay; is the baseband signal.

5. The anti-mainlobe deception jamming method for 2D-FDA-MIMO radar according to claim 1, characterized in that: The echo signal is preprocessed to obtain a received signal, and the formula used includes: Wherein, r represents the received signal after the echo signal is subjected to down-conversion, mixing and matched filtering; ξ is the complex scattering coefficient after pulse compression; represents the time domain steering vector; represents the receiving azimuth steering vector; represents the launch azimuth steering vector; Represents the launch pitch steering vector.

6. The anti-mainlobe deception jamming method for 2D-FDA-MIMO radar according to claim 1, characterized in that: The method of performing clutter separation processing on the received signal to obtain filtered data includes the following steps: Calculating interference information based on the received signal to obtain a radar received signal; the radar received signal includes a target signal, a noise signal, a clutter signal and an interference signal; Get the main value sampling distance; Obtaining a space-time compensation vector according to the main value sampling distance; performing secondary distance-dependent compensation on the radar received signal according to the space-time compensation vector to obtain compensation data; Acquiring a transmitting azimuth frequency and a transmitting elevation frequency according to the compensation data; Acquiring pitch steering vectors of different fuzzy areas according to the transmitting azimuth frequency and the transmitting pitch frequency; obtaining a filter according to the pitch steering vector; According to the filter, obtaining a space-time filtering full vector; Filter data is obtained according to the space-time filtering full vector.

7. The anti-mainlobe deception jamming method for 2D-FDA-MIMO radar according to claim 6, characterized in that: The radar received signal is subjected to secondary distance-dependent compensation according to the space-time compensation vector to obtain compensation data, and the formula used includes: Among them, h l is the space-time compensation vector; I K and Represented as a vector of all 1s; h t,a is the compensation vector of the range gate orientation; h t,e is the compensation vector of the range gate pitch; x l receiving signals for said radar; To compensate data.

8. The method for anti-mainlobe deception jamming for 2D-FDA-MIMO radar according to claim 1, characterized in that: The method of performing projection suppression processing on the filtered data to obtain a target signal comprises the following steps: Get the slant range of the target; Acquiring a target transmitting end azimuth spatial frequency and a target receiving end azimuth spatial frequency according to the slant range of the target; Get the distance of main lobe deceptive jamming; Obtaining, according to the distance of the main lobe deceptive interference, an azimuth spatial domain frequency of a transmitting end of the main lobe deceptive interference and an azimuth spatial domain frequency of a receiving end of the main lobe deceptive interference; Acquire a target transmission steering vector and a target reception steering vector according to the target transmission end azimuth spatial frequency and the target reception end azimuth spatial frequency; Obtaining a transmit steering vector of the mainlobe deceptive interference and a receive steering vector of the mainlobe deceptive interference according to the transmit end azimuth spatial domain frequency of the mainlobe deceptive interference and the receive end azimuth spatial domain frequency of the mainlobe deceptive interference; performing projection processing on each range gate of received data according to the transmit steering vector of the target, the receive steering vector of the target, the transmit steering vector of the mainlobe deceptive jammer, and the receive steering vector of the mainlobe deceptive jammer to obtain a projection matrix corresponding to each range gate; A target signal is obtained according to the projection matrix and the filtering data.

9. An anti-mainlobe deception jamming system for 2D-FDA-MIMO radar, characterized in that: The invention comprises a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the anti-main lobe deception jamming method for 2D-FDA-MIMO radar according to any one of claims 1 to 8 is implemented.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used to enable a computer to execute the anti-mainlobe deception jamming method for 2D-FDA-MIMO radar according to any one of claims 1 to 8.

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