Airborne radar non-uniform clutter suppression method based on integrated waveform of perception probe

Abstract

The application discloses an airborne radar non-uniform clutter suppression method based on a perception detection integrated waveform, and comprises the following steps: separating a perception detection echo signal to obtain a perception echo signal and a detection echo signal; the perception detection echo signal is obtained by reflecting a perception detection transmitting signal by an object; the perception detection transmitting signal comprises a perception signal and a detection signal; optimal weight values of a space-time two-dimensional adaptive filter are determined according to the perception echo signal; the detection echo signal is filtered by the optimal space-time two-dimensional adaptive filter to filter the clutter signal in the detection echo signal, and a target echo signal is obtained. According to the method provided by the application, the perception detection transmitting signal comprising the perception signal and the detection signal is simultaneously transmitted, then the clutter of the detection echo signal in the perception detection echo signal is filtered, and the target signal is obtained; the method can avoid switching between the perception mode and the detection mode, and improve the detection performance of the radar.

Description

Technical Field

[0001] This invention belongs to the field of signal processing technology, specifically relating to a method for suppressing non-uniform clutter in airborne radar based on an integrated sensing and detection waveform. Background Technology

[0002] Due to the inherent motion of airborne radar platforms and the downward-looking nature of their radar perspective, the spatial and Doppler spectra of airborne radar clutter are significantly broadened, sometimes even filling the entire frequency band. Therefore, time-domain or spatial-domain processing alone is insufficient to effectively filter out clutter. However, because the radial velocity of the clutter block relative to the radar platform is related to its spatial angle, the clutter spectrum exhibits certain coupling characteristics in the space-time two-dimensional plane. This provides the possibility for joint processing in the space-time two-dimensional plane. Specifically, if a filter can be rationally designed to form a slanted notch on the space-time two-dimensional plane that matches the clutter spectrum, then clutter can be effectively suppressed. This is the basic principle of Space-Time Adaptive Signal Processing (STAP).

[0003] However, the clutter suppression performance of space-time two-dimensional adaptive processing mainly depends on the accurate estimation of the clutter covariance matrix (CCM). Accurate CCM estimation, in turn, relies on a sufficient number of independently and identically distributed (IID) samples, generally requiring at least twice the number of IID samples as the system's degrees of freedom to guarantee system performance. However, in practical applications, airborne radars often face non-uniform clutter scenarios, such as land-sea interfaces, urban edges, and complex mountainous areas. In these clutter scenarios, the number of samples satisfying the IID condition decreases dramatically, making the requirement of twice the number of IID samples as the system's degrees of freedom extremely stringent. Therefore, it is no longer possible to obtain an unbiased estimate of the clutter covariance matrix using echoes from nearby range cells as training samples. This leads to a mismatch between the STAP filter's concave location, depth, and width and the actual clutter spectrum, resulting in a sharp decline in clutter suppression performance. Therefore, some scholars have proposed using prior knowledge of the environment perceived by airborne radar to improve the clutter suppression performance of the STAP algorithm, namely, a space-time adaptive algorithm based on environmental perception. In this method, the clutter covariance matrix no longer depends on the maximum likelihood estimation of the training data. Instead, it uses environmental perception to understand the real clutter environment in real time, estimate and solve the scattering parameters of the clutter block as prior information, and then directly reconstruct the prior clutter covariance matrix of the cell. This fundamentally solves the problem that the estimation of the clutter covariance matrix depends on IID samples, and greatly improves the clutter suppression performance of the STAP algorithm in non-uniform environments.

[0004] However, in practical applications, the space-time adaptive algorithm based on environmental perception must switch the radar system to MIMO sensing mode to acquire prior knowledge of the clutter environment and obtain full-scene sensing echoes to solve for the clutter scattering coefficients in order to obtain prior knowledge of the clutter environment. Furthermore, due to the continuous movement of the airborne platform, the clutter block RCS information will decorrelate once the radar platform's displacement exceeds the relevant distance. Therefore, to ensure the timeliness of the prior information, the radar needs to be constantly switched back to sensing mode to update the clutter block scattering coefficients. Thus, in this operating mode, frequent clutter sensing will significantly consume radar resources and affect radar detection performance, which would be a fatal flaw in practical airborne radar applications.

[0005] Therefore, current clutter suppression methods suffer from poor radar detection performance due to frequent switching between sensing and detection modes. Summary of the Invention

[0006] This invention provides a non-uniform clutter suppression method for airborne radar based on an integrated sensing and detection waveform, which can solve the problem of poor radar detection performance caused by frequent switching between sensing and detection modes in current clutter suppression methods.

[0007] In a first aspect, embodiments of the present invention provide a method for suppressing non-uniform clutter in airborne radar based on an integrated sensing and detection waveform, the method comprising:

[0008] The sensing and detection echo signals are separated to obtain sensing echo signals and detection echo signals. The sensing and detection echo signals are obtained by reflecting the sensing and detection transmission signals from the object. The sensing and detection transmission signals include sensing signals and detection signals.

[0009] The optimal weights of the space-time two-dimensional adaptive filter are determined based on the sensed echo signal, thus obtaining the optimal space-time two-dimensional adaptive filter.

[0010] The probe echo signal is filtered by an optimal space-time two-dimensional adaptive filter to remove clutter signals and obtain the target echo signal.

[0011] In one possible implementation of the first aspect, the sensing and detection transmission signal can be transmitted by multiple transmission elements of a radar, with the first and last transmission elements of the radar transmitting sensing and detection signals, and the remaining transmission elements transmitting detection signals.

[0012] In one possible implementation of the first aspect, the sensing echo signal can be high-pass filtered to obtain the detection echo signal; the sensing echo signal can be low-pass filtered to obtain the sensing echo signal.

[0013] In one possible implementation of the first aspect, the sensed echo signal can be subjected to a space-time two-dimensional beam scan to obtain the scanned sensed echo signal; based on the scanned sensed echo signal, the clutter scattering coefficient is estimated; based on the clutter scattering coefficient, the clutter-noise prior covariance matrix is ​​determined; based on the clutter-noise prior covariance matrix, the optimal weights are determined to obtain the optimal space-time two-dimensional adaptive filter.

[0014] In one possible implementation of the first aspect, the clutter prior covariance matrix can satisfy the following formula:

[0015]

[0016] Among them, R u Let α be the noise prior covariance matrix. j Let σ be the amplitude of the j-th clutter block. 2 For noise power, I MN Let v be an identity matrix of dimension M×N. j is the space-time steering vector of the j-th clutter block.

[0017] In one possible implementation of the first aspect, the optimal weights can satisfy the following formula:

[0018]

[0019] Among them, W opt For optimal weights, v t The spacetime steering vector for the target.

[0020] In one possible implementation of the first aspect, the probe echo signal can be sequentially subjected to pulse compression and demodulation processing to obtain the processed probe echo signal; the processed probe echo signal can then be filtered by an optimal space-time two-dimensional adaptive filter to filter out clutter signals in the probe echo signal and obtain the target echo signal.

[0021] Secondly, embodiments of the present invention provide a radar, the radar including a processing unit; the processing unit is used for:

[0022] The sensing and detection echo signals are separated to obtain sensing echo signals and detection echo signals. The sensing and detection echo signals are obtained by reflecting the sensing and detection transmitted signals from the target object. The sensing and detection signals include sensing signals and detection signals.

[0023] The optimal weights of the space-time two-dimensional adaptive filter are determined based on the sensed echo signal, thus obtaining the optimal space-time two-dimensional adaptive filter.

[0024] The probe echo signal is filtered by an optimal space-time two-dimensional adaptive filter to remove clutter signals and obtain the target echo signal.

[0025] In one possible implementation of the second aspect, the sensing and detection transmission signal can be transmitted by multiple transmission elements of a radar, with the first and last transmission elements of the radar transmitting sensing and detection signals, and the remaining transmission elements transmitting detection signals.

[0026] In one possible implementation of the second aspect, the processing unit may specifically be used to perform high-pass filtering on the sensing and detection echo signal to obtain the detection echo signal; and to perform low-pass filtering on the sensing and detection echo signal to obtain the sensing echo signal.

[0027] In one possible implementation of the second aspect, the processing unit can specifically be used to perform a space-time two-dimensional beam scan on the sensed echo signal to obtain the scanned sensed echo signal; estimate the clutter scattering coefficient based on the scanned sensed echo signal; determine the clutter prior covariance matrix based on the clutter scattering coefficient; and determine the optimal weights based on the clutter prior covariance matrix to obtain the optimal space-time two-dimensional adaptive filter.

[0028] In one possible implementation of the second aspect, the clutter prior covariance matrix can satisfy the following formula:

[0029]

[0030] Among them, R u Let α be the noise prior covariance matrix. j Let σ be the amplitude of the j-th clutter block. 2 For noise power, I MN Let v be an identity matrix of dimension M×N. j is the space-time steering vector of the j-th clutter block.

[0031] In one possible implementation of the second aspect, the optimal weights can satisfy the following formula:

[0032]

[0033] Among them, W opt For optimal weights, v t The spacetime steering vector for the target.

[0034] In one possible implementation of the second aspect, the processing unit can be used to sequentially perform pulse compression and demodulation processing on the probe echo signal to obtain the processed probe echo signal; and to filter the processed probe echo signal through an optimal space-time two-dimensional adaptive filter to filter out clutter signals in the probe echo signal to obtain the target echo signal.

[0035] Thirdly, embodiments of the present invention provide an electronic device, including a processor and a memory, wherein the memory is used to store a computer program; the processor can be used to execute a calculator program (instructions) stored in the memory to implement the method of the first aspect described above.

[0036] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing a computer program that, when executed, can implement the method described in the first aspect above.

[0037] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows: According to the method provided by the present invention, by simultaneously transmitting a sensing and detection transmission signal including a sensing signal and a detection signal, and then filtering out the clutter of the detection echo signal in the sensing and detection echo signal, the target signal is obtained; it can avoid constantly switching between sensing mode and detection mode, thereby improving the detection performance of the radar; at the same time, the simultaneous transmission of the two signals can avoid the errors caused by asynchronous transmission and improve the detection accuracy. Attached Figure Description

[0038] Figure 1 A flowchart illustrating a non-uniform clutter suppression method for airborne radar based on an integrated sensing and detection waveform, provided for an embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of a sensing and detection transmission signal provided in an embodiment of the present invention;

[0040] Figure 3 This is a waveform diagram of a sensing and detection transmission signal provided in an embodiment of the present invention;

[0041] Figure 4 A schematic diagram of the spectrum of a sensing and detection echo signal provided in an embodiment of the present invention;

[0042] Figure 5 This is a schematic diagram of the spectrum of a detected echo signal provided in an embodiment of the present invention;

[0043] Figure 6 A schematic diagram of the spectrum of a sensed echo signal provided in an embodiment of the present invention;

[0044] Figure 7 This is a schematic diagram of a space-time two-dimensional matched filtering process provided in an embodiment of the present invention;

[0045] Figure 8 A schematic diagram of a spatiotemporal two-dimensional beam scanning process provided in an embodiment of the present invention;

[0046] Figure 9 This is a schematic diagram of the spatial angle corresponding to a beam scanning channel provided in an embodiment of the present invention;

[0047] Figure 10 An angular distribution diagram of clutter scattering coefficients provided in an embodiment of the present invention;

[0048] Figure 11 A schematic diagram of the spectrum of a processed detection echo signal provided in an embodiment of the present invention;

[0049] Figure 12 A schematic diagram of a radar structure provided in an embodiment of the present invention;

[0050] Figure 13 A schematic diagram of the spectrum of the transmitted waveform of a radar transmitting array provided in an embodiment of the present invention;

[0051] Figure 14 This is a schematic diagram of a target echo signal provided in an embodiment of the present invention;

[0052] Figure 15 A schematic diagram of a system improvement factor provided in an embodiment of the present invention;

[0053] Figure 16 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0054] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0055] The non-uniform clutter suppression method for airborne radar based on integrated sensing and detection waveforms provided in this embodiment of the invention can be applied to signal transmitting devices such as airborne radar. This embodiment of the invention does not impose any restrictions on the specific type of signal transmitting device.

[0056] Figure 1 The diagram shown illustrates a flowchart of an airborne radar non-uniform clutter suppression method based on an integrated sensing and detection waveform, according to an embodiment of the present invention. As an example and not a limitation, method 100 can be applied to the aforementioned radar, and method 100 may include steps S101-S105. Each step is described below.

[0057] S101, transmit sensing and detection signals.

[0058] In some embodiments, the sensing and detection transmission signal includes a sensing signal and a detection signal.

[0059] For example, the sensing signal can be a signal of two orthogonal waveforms (i.e., MIMO orthogonal waveforms), thereby enabling the acquisition of sensing echo signals for the entire scene.

[0060] For example, the detection signal can be a linear frequency modulated signal, which allows the radar to achieve the best processing performance.

[0061] In one possible implementation, the radar can include multiple transmitting elements that transmit sensing and detection signals. Since the sensing signal consists of two orthogonal waveforms, the first and last transmitting elements of the radar can be configured to transmit two signals from the sensing signal, respectively; the remaining elements transmit detection signals. This maximizes the aperture and resolution after virtual array aperture expansion in MIMO mode.

[0062] Optionally, since the pulse width of the sensing signal is short, less than one transmission cycle, the first and last transmitting elements of the radar can transmit the detection signal for the remainder of one transmission cycle.

[0063] For example, see Figure 2 The first and last transmitting elements of the radar can transmit a composite waveform consisting of two sub-pulses, with the first sub-pulse being the sensing signal and the second sub-pulse being the detection signal.

[0064] For example, the composite waveform transmitted by the first transmitting element of the radar and the composite waveform transmitted by the last transmitting element of the radar can satisfy the following formula:

[0065]

[0066]

[0067] Where x1(t) is the composite waveform transmitted by the first transmitting element of the radar, x N (t) represents the composite waveform transmitted by the last transmitting element of the radar, s1(t), s N (t) represents the sensing signal with orthogonal waveform, s L (t) represents the detection signal, τ1 represents the pulse width of the sensing signal, and τ2-τ1 represents the pulse width of the detection signal in these two array elements.

[0068] For example, see Figure 3 The composite waveform in (a) and Figure 3 The waveform of the probe signal in (b) is shown. It can be seen that the latter half of the composite waveform is the probe signal, and the first half of the composite waveform is the orthogonal phase encoded signal (i.e., the sensing signal with orthogonal waveforms).

[0069] In one example, the probe signal is obtained by modulating a linear frequency modulated baseband signal with an additional carrier frequency.

[0070] For example, the detection signal can satisfy the following formula:

[0071]

[0072] Where s0(t) is the fundamental frequency signal, f1 For additional carrier frequency, j It represents the imaginary unit.

[0073] For example, the sensing and detection transmitted signal can satisfy the following formula:

[0074] s(t)=[x1(t) s L (t) … s L (t) x N (t)] (1.4)

[0075] Where s(t) is the sensing and detection transmitted signal.

[0076] Optionally, transmission weights can be added to the waveforms transmitted by each transmitting element of the radar to form a transmission pattern. Since the sensing and detection transmission signals transmitted by the radar at this time are different from the single MIMO mode or phased array mode of traditional radar, adding transmission weights to the transmitted waveforms of each element can ensure the radar's detection performance.

[0077] For example, the transmission weights of the transmission array can satisfy the following formula:

[0078]

[0079] Among them, w t (θ0) is the transmission weight of the transmission array, θ0 is the spatial angle corresponding to the main lobe of the array transmission, and N is the number of radar transmission elements.

[0080] S102 receives the sensing and detection echo signal.

[0081] For example, the sensing and detection echo signal is obtained by the object reflecting the sensing and detection emitted signal.

[0082] For example, the sensing echo signal received by the i-th range element array of the radar can satisfy the following formula:

[0083]

[0084] Among them, y i Let β be the sensing echo signal received by the i-th range cell array of the radar. ij Let w be the clutter scattering coefficient of the j-th clutter block in the i-th range cell. t (θ0) represents the array transmission weights; p t For radar transmit power, b(θ) j Let r be the time-domain steering vector of the j-th clutter block.i Let a be the spatial slant distance of the i-th distance unit. r (θ j ) is the receiving spatial steering vector of the j-th clutter block, a t (θ j ) is the transmission spatial steering vector of the j-th clutter block, J is the total number of clutter blocks, and ⊙ represents the Hadema product operation.

[0085] For example, the sensing and detection echo signal received by the i-th range element array of the radar can include two parts: a sensing echo signal and a detection echo signal. It can also satisfy the following formula:

[0086]

[0087] in, To sense the waveform of the signal; The spatial steering vector for the sensed signal; The transmission weights for sensing signals.

[0088] S103, separate the sensing and detection echo signals to obtain the sensing echo signal and the detection echo signal.

[0089] In one possible implementation, since the detection signal and the sensing signal are already indistinguishable in the time domain (see...) Figure 4 Furthermore, the frequency of the probe echo signal with added carrier frequency is greater than that of the sensing echo signal; therefore, the sensing probe echo signal can be obtained by high-pass filtering and the sensing echo signal can be obtained by low-pass filtering.

[0090] For example, the frequency band for detecting echo signals is between 1.0MHz and 1.8MHz, while the frequency band for sensing echo signals is between -0.4MHz and 0.4MHz.

[0091] In one example, a high-pass filter can be used to filter the sensing echo signal from the sensing probe echo signal.

[0092] For example, see Figure 5 The amplitude-frequency response of the high-pass filter in (a) can be used to filter the sensing echo signal through a high-pass filter with this response to obtain the following result: Figure 5 The probe echo signal in (b) of the sample.

[0093] For example, the output of the high-pass filter (i.e., the probed echo signal) can satisfy the following formula:

[0094] y Ti =y i *h H (n)(1.8)

[0095] Among them, yTi To detect the echo signal, h H (n) represents the filter coefficients of the high-pass filter.

[0096] For example, the parameters of a high-pass filter can be designed as follows: stopband cutoff frequency 0.95MHz, passband cutoff frequency 1.0MHz, and stopband attenuation 120dB.

[0097] In one example, the sensing echo signal can be obtained by filtering the sensing echo signal from the sensing echo signal using a low-pass filter.

[0098] For example, see Figure 6 The amplitude-frequency response of the low-pass filter in (a) can be obtained by filtering the sensing echo signal through a low-pass filter with this response, as shown in the figure. Figure 6 The perceived signal in (b) of the text.

[0099] For example, the output of the low-pass filter (i.e., the sensed echo signal) can satisfy the following formula:

[0100]

[0101] in, To sense the echo signal, h L (n) represents the filter coefficients of the low-pass filter.

[0102] For example, according to formula (1.7), the sensed echo signal can also satisfy the following formula:

[0103]

[0104] For example, the parameters of a low-pass filter can be designed as follows: passband cutoff frequency 0.4MHz, stopband cutoff frequency 0.45MHz, and stopband attenuation 120dB.

[0105] S104. Determine the optimal weights of the space-time two-dimensional adaptive filter based on the sensed echo signal to obtain the optimal space-time two-dimensional adaptive filter.

[0106] In some embodiments, the sensed echo signal can be subjected to a spatiotemporal two-dimensional beam scan to obtain the scanned sensed echo signal; based on the scanned sensed echo signal, the clutter scattering coefficient is estimated; based on the clutter coefficient, the clutter-noise prior covariance matrix is ​​determined; based on the clutter-noise prior covariance matrix, the optimal weights are determined to obtain the optimal spatiotemporal two-dimensional adaptive filter.

[0107] In one possible implementation, see Figure 7Alternatively, the second processing flow of traditional MIMO radar (see Zhao Yongbo's MIMO radar technology overview) can be adopted to sequentially perform transmit beamforming and space-time two-dimensional matched filtering on the sensed echo signal, thereby completing the space-time two-dimensional beam scanning of the sensed echo signal.

[0108] For example, the matched filter coefficients in the second processing method are direction-dependent, only matching the echoes from the target direction. The matched filter coefficients for echoes from different directions should be different. Therefore, it can be proven that the second processing method is completely equivalent to the first, and the computational cost of the second is much less than that of the first. The only difference is that the second processing method hides the concept of virtual aperture extension of the MIMO radar array within the space-time two-dimensional matched filter processing, which cannot obtain N at the receiver. t N r The echo is 3D, so it is not suitable for sparse recovery processing. However, in this invention, only the echo data in the target direction is considered in a single beam channel. Therefore, the second processing method is most suitable for this invention.

[0109] For example, the sensed echo signal can be processed by transmit beamforming based on the digital beamforming (DBF) method.

[0110] In one example, to perform spatiotemporal two-dimensional matched filtering on the sensed echo signal in the θ direction, it is first necessary to determine the filter coefficients that match the echo in that direction.

[0111] For example, the matched filter coefficients can satisfy the following formula:

[0112]

[0113] Among them, h θ (t) represents the filtering coefficients of the sensed echo signal in the θ direction. The complex conjugate of the sensed signal s1(t) is represented. Represents the sensing signal s N The conjugate negative of (t).

[0114] In one possible implementation, the entire airspace can be divided into several channels according to system requirements (see [link]). Figure 8 ), to perform spatiotemporal two-dimensional beam scanning.

[0115] In one example, the scanned sensing echo signal can satisfy the following formula:

[0116]

[0117] in, Let θ be the sensed echo signal after scanning in the k-th beam scanning channel.k The spatial angle corresponding to the k-th beam scanning channel. For θ k The matched filter coefficients corresponding to the direction, w H (θ k ) represents the space-time weights corresponding to the k-th beam scanning channel.

[0118] For example, the spatiotemporal weights corresponding to the k-th beam scanning channel can satisfy the following formula:

[0119]

[0120] Where, b(θ) k ), a(θ k ) are respectively θ k The time-domain steering vector and the spatial-domain steering vector corresponding to the direction.

[0121] Optionally, let G(θ) j ) represents the k-th beam scanning channel at θ j If the combined transmit and receive gain in the direction is considered, then the scanned sensing signal can also satisfy the following formula:

[0122]

[0123] in,

[0124] In one possible implementation, see Figure 9 When the angular width D of the clutter block c The 3dB width of the array beam is Δθ 0.5 At that time, the beam pointing of the k-th beam channel is the geometric center of the j-th clutter block. Therefore, the clutter scattering coefficient of the entire scene can be obtained by performing beam scanning on all range cells at intervals of Δθ within the range of 0° to 180°. (see Figure 10 ).

[0125] In one example, when the beam of the k-th beam channel is pointed to the geometric center of the j-th clutter block, the scanned sensing signal can satisfy the following formula:

[0126]

[0127] The first term is the sensing echo signal corresponding to the clutter block in the main lobe of the beam, and the second term is the sensing echo signal corresponding to the clutter block in the sidelobe of the beam.

[0128] In one example, considering a sparse scene, when the scattering coefficient of the clutter block within the main lobe is large, the clutter echo intensity in the main lobe region is much greater than that in the side lobe region. In this case, the second term in the above formula (1.15) can be ignored. Therefore, the scattering coefficient of the j-th clutter block within this distance cell can be approximately estimated as:

[0129]

[0130] In one possible implementation, the clutter prior covariance matrix can satisfy the following formula:

[0131]

[0132] Among them, R u Let α be the noise prior covariance matrix. j Let σ be the amplitude of the j-th clutter block. 2 For noise power, I MN Let v be an identity matrix of dimension M×N. j is the space-time steering vector of the j-th clutter block.

[0133] in:

[0134]

[0135]

[0136] Among them, a H (θ j )·w t (θ0) represents the radar transmit gain at the j-th clutter block. Here is the estimated value of the clutter scattering coefficient, and G is the pulse compression gain. For distance attenuation, where This is the updated spatial slant range for the clutter block location.

[0137] In one possible implementation, after obtaining the clutter prior covariance matrix, the optimal weights of the space-time two-dimensional adaptive filter can be determined to suppress clutter in the probe echo.

[0138] For example, under the Minimum Variance Distortionless Response (MVDR) criterion, the optimal weights of the space-time two-dimensional adaptive filter can satisfy the following formula:

[0139]

[0140] Among them, v t W is the spacetime steering vector of the target. opt The optimal weights for a two-dimensional adaptive filter when empty.

[0141] S105 filters the probe echo signal using an optimal space-time two-dimensional adaptive filter to remove clutter signals and obtain the target echo signal.

[0142] In some embodiments, the probed echo signal can be sequentially subjected to pulse compression and demodulation processing to obtain a processed probed echo signal. Then, the processed probed echo signal is filtered by an optimal space-time two-dimensional adaptive filter to filter out non-uniform clutter signals and obtain the target echo signal.

[0143] In one possible implementation, pulse compression processing of the probe echo signal can improve its range resolution. Since the probe signal is a modulated linear frequency modulated signal, the pulse compression coefficient needs to be modulated onto the corresponding frequency band before pulse compression is applied to the probe signal.

[0144] In one example, the pulse pressure coefficient can satisfy the following formula:

[0145]

[0146] Among them, h l (t) is the pulse pressure coefficient. f1 An additional carrier frequency for detecting the signal, The conjugate negative of the detected signal.

[0147] For example, the pulse-compressed detection signal can satisfy the following formula:

[0148]

[0149] in, This is the probe echo signal after pulse compression.

[0150] In one example, after pulse compression, the pulse-compressed probe signal can be demodulated to the fundamental frequency for the next clutter suppression processing. The processed probe echo signal can satisfy the following formula:

[0151]

[0152] in, This is the processed probe echo signal.

[0153] For example, see Figure 11 The processed probe echo signal is shown in the image.

[0154] In one possible implementation, the target echo signal can satisfy the following formula:

[0155]

[0156] Among them, y c-out This is the output of the optimal space-time two-dimensional adaptive filter after clutter suppression (i.e., the target echo signal).

[0157] According to the method provided by the present invention, by simultaneously transmitting a sensing and detection transmission signal including a sensing signal and a detection signal, and then filtering out the clutter of the detection echo signal in the sensing and detection echo signal, the target signal is obtained; this can avoid constantly switching between sensing mode and detection mode, thereby improving the detection performance of the radar; at the same time, the simultaneous transmission of the two signals can avoid the errors caused by asynchronous transmission, thereby improving the detection accuracy.

[0158] Figure 12 The diagram shown is a structural schematic of a radar provided in an embodiment of the present invention. By way of example and not limitation, the radar 1200 may include a processing unit 1210.

[0159] Processing unit 1210 can be used for:

[0160] The sensing and detection echo signals are separated to obtain sensing echo signals and detection echo signals. The sensing and detection echo signals are obtained by reflecting the sensing and detection transmitted signals from the target object. The sensing and detection signals include sensing signals and detection signals.

[0161] The optimal weights of the space-time two-dimensional adaptive filter are determined based on the sensed echo signal, thus obtaining the optimal space-time two-dimensional adaptive filter.

[0162] The probe echo signal is filtered by an optimal space-time two-dimensional adaptive filter to remove clutter signals and obtain the target echo signal.

[0163] In one possible implementation, radar 1200 may include multiple transmitting elements. Sensing and detection signals may be transmitted through these multiple transmitting elements of radar 1200, with the first and last transmitting elements transmitting sensing and detection signals, and the remaining transmitting elements transmitting detection signals.

[0164] In one possible implementation, the processing unit 1210 can specifically be used to perform high-pass filtering on the sensing and detection echo signal to obtain the detection echo signal; and to perform low-pass filtering on the sensing and detection echo signal to obtain the sensing echo signal.

[0165] In one possible implementation, the processing unit 1210 can be specifically used to perform a space-time two-dimensional beam scan on the sensed echo signal to obtain the scanned sensed echo signal; estimate the clutter scattering coefficient based on the scanned sensed echo signal; determine the clutter prior covariance matrix based on the clutter scattering coefficient; and determine the optimal weights based on the clutter prior covariance matrix to obtain the optimal space-time two-dimensional adaptive filter.

[0166] In one possible implementation, the clutter prior covariance matrix can satisfy the following formula:

[0167]

[0168] Among them, R u Let α be the noise prior covariance matrix. j Let σ be the amplitude of the j-th clutter block. 2 For noise power, I MN Let v be an identity matrix of dimension M×N. j is the space-time steering vector of the j-th clutter block.

[0169] In one possible implementation, the optimal weights can satisfy the following formula:

[0170]

[0171] Among them, W opt For optimal weights, v t The spacetime steering vector for the target.

[0172] In one possible implementation, the processing unit 1210 can be used to sequentially perform pulse compression and demodulation processing on the probe echo signal to obtain the processed probe echo signal; and to filter the processed probe echo signal through an optimal space-time two-dimensional adaptive filter to filter out clutter signals in the probe echo signal to obtain the target echo signal.

[0173] To better illustrate the beneficial effects of the present invention, the following simulation experiments were conducted:

[0174] For example, the parameters of the radar used in the simulation experiment can be shown in Table 1.

[0175] Table 1 Simulation Parameters

[0176] Number of array elements 18 Carrier speed 267.85m / s Transmit pulse width 270us Carrier height 5000m Sub-pulse 1 pulse width 120us Distance unit range 1080～4000 Sub-pulse 2 pulse width 150us Distance resolution 37.5m bandwidth 24MHz noise ratio 30dB Orthogonal phase coded signal frequency band -0.4~0.4MHz Signal-to-noise ratio -10dB Detection signal frequency band 1.0~1.8MHz Target range unit 2079 Sampling rate 4MHz Target speed 150m / s pulse count 32 Pulse repetition frequency 1000

[0177] The parameters above can be used to obtain the following: Figure 3 The sensor transmission signal is shown. The first 120 microseconds are the quadrature phase coded signal (i.e., the sensing signal), and the last 150 microseconds are the modulated linear frequency modulated signal (i.e., the detection signal). The spectrum of the composite waveform of array element 1 and array element 18 (i.e., the last transmitting element) is shown below. Figure 13 As shown.

[0178] Depend on Figure 13 and Figure 3It can be seen that the bandwidth of the sensing signal is -0.4 to 0.4 MHz, while the bandwidth of the detection signal is 1.0 to 1.8 MHz, consistent with the detection signal in the composite waveform. Since the bandwidth of the detection signal is greater than that of the sensing signal, they can be separated using different frequency domain filters.

[0179] Figure 14 The diagram shown is a schematic representation of a target echo signal provided in an embodiment of the present invention.

[0180] See Figure 14 It can be seen that the signal intensity in the main lobe direction (0 degrees) of the target signal is much higher than the signal intensity in other directions. Therefore, it can be proven that the method provided by this invention has a good effect on suppressing clutter signals.

[0181] Figure 15 The diagram shown is a schematic representation of a system improvement factor provided in an embodiment of the present invention.

[0182] See Figure 15 ,Depend on Figure 15 It can be seen that the system improvement factor can approach the theoretical peak value of the optimal processor, and the clutter suppression effect is good.

[0183] According to the method provided by the present invention, by simultaneously transmitting a sensing and detection transmission signal including a sensing signal and a detection signal, and then filtering out the clutter of the detection echo signal in the sensing and detection echo signal, the target signal is obtained; this can avoid constantly switching between sensing mode and detection mode, thereby improving the detection performance of the radar; at the same time, the simultaneous transmission of the two signals can avoid the errors caused by asynchronous transmission, thereby improving the detection accuracy.

[0184] Figure 16 The diagram shown is a structural schematic of an electronic device provided in an embodiment of the present invention. Figure 16 The illustrated electronic device 1600 may include: at least one processor 1610 ( Figure 16 The diagram shows only one processor, a memory 1620, and a computer program 1630 stored in the memory 1620 and executable on the at least one processor 1610, which, when executing the computer program 1630, implements the steps of any of the above method embodiments.

[0185] The electronic device 1600 may be a robot or other processing device capable of implementing the above methods. This embodiment of the invention does not impose any restrictions on the specific type of electronic device.

[0186] This invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, can implement the steps described in the various method embodiments above.

[0187] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

Claims

1. A method for suppressing non-uniform clutter in airborne radar based on integrated sensing and detection waveforms, characterized in that, include: The sensing and detection echo signals are separated to obtain sensing echo signals and detection echo signals, wherein the sensing and detection echo signals are obtained by reflecting the sensing and detection transmission signals from the object, and the sensing and detection transmission signals include sensing signals and detection signals; The optimal weights of the space-time two-dimensional adaptive filter are determined based on the sensed echo signal, thus obtaining the optimal space-time two-dimensional adaptive filter. The probed echo signal is filtered by the optimal space-time two-dimensional adaptive filter to remove clutter signals and obtain the target echo signal. The step of determining the optimal weights of the space-time two-dimensional adaptive filter based on the sensed echo signal to obtain the optimal space-time two-dimensional adaptive filter includes: The sensed echo signal is subjected to a two-dimensional space-time beam scan to obtain the scanned sensed echo signal. Based on the scanned sensing echo signal, estimate the clutter scattering coefficient; Based on the clutter scattering coefficients, determine the clutter prior covariance matrix; Based on the noise prior covariance matrix, the optimal weights are determined to obtain the optimal space-time two-dimensional adaptive filter; The noise prior covariance matrix satisfies the following formula: in, Let be the noise prior covariance matrix. For the first j The amplitude of each clutter block For noise power, For dimension M × N The identity matrix, For the first j The space-time steering vector of a clutter block.

2. The method according to claim 1, characterized in that, The sensing and detection transmission signal is transmitted through multiple transmission elements of the radar. The first and last transmission elements of the radar transmit the sensing signal and the detection signal, while the remaining transmission elements transmit the detection signal.

3. The method according to claim 1, characterized in that, The separation of the sensing and detection echo signals to obtain the sensing echo signal and the detection echo signal includes: The sensing echo signal is high-pass filtered to obtain the sensing echo signal; The sensing echo signal is obtained by low-pass filtering the sensing and detection echo signal.

4. The method according to claim 1, characterized in that, The optimal weights satisfy the following formula: in, The optimal weight is... The spacetime steering vector for the target.

5. The method according to claim 1, characterized in that, The step of filtering the probed echo signal using the optimal space-time two-dimensional adaptive filter to remove clutter signals and obtain the target echo signal includes: The probe echo signal is sequentially subjected to pulse compression and demodulation processing to obtain the processed probe echo signal; The processed probe echo signal is filtered by the optimal space-time two-dimensional adaptive filter to remove clutter signals and obtain the target echo signal.

6. A radar, characterized in that, Includes a processing unit, the processing unit being used for: The sensing and detection echo signals are separated to obtain sensing echo signals and detection echo signals, wherein the sensing and detection echo signals are obtained by reflecting the sensing and detection transmission signals from the target object, and the sensing and detection signals include sensing signals and detection signals; The optimal weights of the space-time two-dimensional adaptive filter are determined based on the sensed echo signal, thus obtaining the optimal space-time two-dimensional adaptive filter. The probed echo signal is filtered by the optimal space-time two-dimensional adaptive filter to remove clutter signals and obtain the target echo signal. The step of determining the optimal weights of the space-time two-dimensional adaptive filter based on the sensed echo signal to obtain the optimal space-time two-dimensional adaptive filter includes: The sensed echo signal is subjected to a two-dimensional space-time beam scan to obtain the scanned sensed echo signal. Based on the scanned sensing echo signal, estimate the clutter scattering coefficient; Based on the clutter scattering coefficients, determine the clutter prior covariance matrix; Based on the noise prior covariance matrix, the optimal weights are determined to obtain the optimal space-time two-dimensional adaptive filter; The noise prior covariance matrix satisfies the following formula: in, Let be the noise prior covariance matrix. For the first j The amplitude of each clutter block For noise power, For dimension M × N The identity matrix, For the first j The space-time steering vector of a clutter block.

7. A processing apparatus, comprising a memory, a processor, and a computer program stored in the memory, characterized in that, When the processor executes the computer program, it implements the method as described in any one of claims 1-5.

8. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed, it implements the method as described in any one of claims 1-5.

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