Clutter signal generation method and device

Abstract

The invention relates to a clutter signal generation method and device. The method comprises the following steps: generating two groups of uniformly distributed random sequences u1 and u2; converting the two groups of uniformly distributed random sequences into a Gaussian white noise sequence through a Box-Muller algorithm; generating a Gaussian color noise sequence from the Gaussian white noise sequence through a linear filter; performing nonlinear transformation on the Gaussian color noise sequence to obtain a clutter basic model sequence; and performing amplitude modulation, distance modulation and speed modulation on the clutter basic model sequence to generate a clutter signal with amplitude, time domain and frequency domain information. According to the invention, amplitude modulation, distance modulation and speed modulation are respectively carried out on the clutter basic model sequence by using the clutter sequence modulation module, so that the generated clutter signal has amplitude, time domain and frequency domain information coupled with a simulation scene, and the accuracy and fidelity of clutter simulation are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of digital signal processing, and particularly to a clutter signal generation method and device. Background Art

[0002] When a radar system detects a target, it not only receives the echo signal of the target itself but also receives the echoes from non-target objects. These non-target echoes are clutter. The presence of clutter will interfere with the detection and tracking of the real target by the radar. Therefore, researching clutter generation technology is crucial for improving the performance of the radar system.

[0003] Clutter can originate from a variety of natural and man-made environments, and these different sources produce clutter signals with different statistical characteristics, such as amplitude distribution, power spectral density, etc. Therefore, clutter generation technology needs to be able to simulate clutter signals with these different statistical characteristics. Commonly used amplitude distribution statistical models for clutter simulation include Rayleigh distribution model, lognormal distribution model, Weibull distribution model, and K distribution model, and the commonly used power spectral density is Gaussian spectrum.

[0004] In the existing clutter signal generation technology, usually a random sequence is first generated, and then the random sequence is successively passed through a Gaussian sequence transformation and an FIR filter to transform it into a Gaussian random sequence with a specific power spectral density, and then a non-linear transformation is performed to obtain a clutter signal sequence with specific amplitude distribution characteristics.

[0005] For example, in the prior art, the Chinese invention patent with the publication number CN117761644A discloses a method for simulating and generating coherent lognormal distributed radar point clutter. First, a look-up table is constructed, and then two n-stage m-sequences are generated by an improved linear feedback shift register. Then, based on the constructed look-up table, the two n-stage m-sequences are transformed into a complex Gaussian white noise sequence by Box-Muller. Next, the complex Gaussian white noise random sequence is low-pass filtered by a Gaussian spectrum filter to obtain a complex Gaussian colored noise random sequence. Finally, the coherent lognormal distributed radar point clutter satisfying the radar parameters and environmental parameters is generated from the complex Gaussian colored noise random sequence, thereby realizing the real-time simulation and generation of coherent lognormal distributed radar point clutter.

[0006] The clutter signal sequence generated by the above technology is only a simulation data of a basic clutter model and cannot reflect the amplitude, distance, and speed change information of clutter in the environment or scene. In actual clutter signal data generation, it is usually necessary to consider adapting to various simulation scenarios. Therefore, the above technology cannot meet the actual needs. Summary of the Invention

[0007] To solve the technical problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a clutter signal generation method and device, which are applicable to processing and generating a clutter signal sequence modulated by amplitude, distance, and speed using an FPGA chip, so as to solve the problem that the generated clutter signal in the prior art lacks amplitude, time-domain, and frequency-domain information, and improve the accuracy and fidelity of clutter simulation.

[0008] To achieve the above-mentioned invention purpose, the present invention provides a clutter signal generation method, including the following steps:

[0009] Step S1: Generate two groups of uniformly distributed random sequences u1 and u2;

[0010] Step S2: Convert the two groups of uniformly distributed random sequences into Gaussian white noise sequences through the Box-Muller algorithm;

[0011] Step S3: Generate a Gaussian colored noise sequence by passing the Gaussian white noise sequence through a linear filter;

[0012] Step S4: Perform a non-linear transformation on the Gaussian colored noise sequence to obtain a clutter basic model sequence;

[0013] Step S5: Perform amplitude modulation, distance modulation, and speed modulation on the clutter basic model sequence to generate a clutter signal with amplitude, time-domain, and frequency-domain information.

[0014] According to a technical solution of the present invention, in the step S1, the uniformly distributed random sequence is generated by a linear feedback shift register, and the uniformly distributed random sequence is:

[0015]

[0016] where c i represents the feedback coefficient of the i-th stage, c0 and c n must be 1, indicating participation in feedback, and the other coefficients c1, c2,..., c n-1 if it is 1, it indicates participation in feedback, and if it is 0, it indicates non-participation in feedback.

[0017] According to a technical solution of the present invention, in the step S2, the Box-Muller algorithm is expressed as:

[0018]

[0019] where x1 and x2 represent two groups of Gaussian white noise sequences.

[0020] According to a technical solution of the present invention, in the step S3, the linear filter is an FIR filter, and the transfer function is:

[0021]

[0022] Among them, x(n) and y(n) are the input sequence and output sequence of the filter respectively; N is the length of the designed filter; x(i) is the input signal at the i-th moment; h(i) is the i-th tap coefficient of the filter;

[0023] The system transfer function is:

[0024]

[0025] where a n is the tap coefficient of each order of the filter.

[0026] According to a technical solution of the present invention, in the step S5, it specifically includes:

[0027] Step S51: Amplitude-modulate the clutter basic model sequence to obtain an amplitude-modulated clutter sequence;

[0028] Step S52: Distance-modulate the amplitude-modulated clutter sequence to obtain a distance-modulated clutter sequence;

[0029] Step S53: Velocity-modulate the distance-modulated clutter sequence to obtain a velocity-modulated clutter sequence.

[0030] According to a technical solution of the present invention, in the step S51, it specifically includes:

[0031] Multiply the clutter basic model sequence obtained in the step S4 by the amplitude modulation parameter to obtain the amplitude-modulated clutter sequence:

[0032] I i (n) = I(n) × A i

[0033] Q i (n) = Q(n) × A i

[0034] where A i is the amplitude modulation parameter, represented by an unsigned binary number and is a normalized parameter.

[0035] According to a technical solution of the present invention, in the step S52, it specifically includes:

[0036] Write the amplitude-modulated clutter sequence obtained in the step S51 into the memory in the FPGA, and read it out after delaying it by a certain number of clock cycles according to the distance modulation parameter to obtain the distance-modulated clutter sequence. The specific number of clock cycles of the delay is:

[0037]

[0038] Among them, R max is the simulated distance of clutter, c is the speed of light, and f s is the sampling rate of the FPGA.

[0039] According to a technical solution of the present invention, in the step S53, it specifically includes:

[0040] Mix the orthogonal distance-modulated clutter sequence obtained in the step S52 with two orthogonal Doppler signals to obtain a speed-modulated clutter sequence;

[0041] The two orthogonal Doppler signals are generated by the DDS core embedded in the FPGA.

[0042] According to an aspect of the present invention, there is provided a clutter signal generation device, including:

[0043] A uniformly distributed random sequence generation module for generating a uniformly distributed random sequence;

[0044] A Gaussian distributed random sequence generation module for generating a Gaussian white noise sequence by passing the uniformly distributed random sequence through the Box-Muller algorithm;

[0045] An FIR filter module for generating a Gaussian colored noise sequence by passing the Gaussian white noise sequence through a linear filter;

[0046] A non-linear transformation module for performing a non-linear transformation on the Gaussian colored noise sequence to obtain a clutter basic model sequence with specific amplitude statistical distribution characteristics;

[0047] A clutter sequence modulation module for respectively performing amplitude modulation, distance modulation, and speed modulation on the clutter basic model sequence generated by the non-linear transformation module to obtain a clutter signal with amplitude, time domain, and frequency domain information;

[0048] A host computer for configuring modulation parameters.

[0049] According to a technical solution of the present invention, the modulation parameters at least include: an amplitude control word, a delay control word, and a frequency control word.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] The present invention proposes a clutter signal generation method and device, which respectively perform amplitude modulation, distance modulation, and speed modulation on the clutter basic model sequence by using the clutter sequence modulation module, so that the generated clutter signal has amplitude, time domain, and frequency domain information coupled with the simulation scenario, improving the accuracy and fidelity of clutter simulation.

[0052] The present invention can be used in a radar simulator to improve the performance of a radar system. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0054] Figure 1 Schematically showing a flowchart of a clutter signal generation method in an embodiment of the present invention;

[0055] Figure 2 Schematically showing a structural diagram of a clutter signal generation device in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0056] The description of the embodiments of this specification should be combined with the corresponding drawings, and the drawings should be part of the complete specification. In the drawings, the shape or thickness of the embodiments can be enlarged and simplified or conveniently marked. Furthermore, each part of the structure in the drawings will be described separately. It should be noted that the elements not shown or described in words in the drawings are in the forms known to those of ordinary skill in the art.

[0057] Any reference to directions and orientations in the description of the embodiments herein is for the convenience of description only and should not be construed as any limitation to the protection scope of the present invention. The following description of the preferred embodiments involves combinations of features, which may exist independently or in combination. The present invention is not particularly limited to the preferred embodiments. The scope of the present invention is defined by the claims.

[0058] As Figure 1 shown, a clutter signal generation method of the present invention includes the following steps:

[0059] Step S1, generating two groups of uniformly distributed random sequences u1 and u2; the uniformly distributed random sequences are generated by a linear feedback shift register, and the uniformly distributed random sequences are:

[0060]

[0061] where c i represents the feedback coefficient of the i-th stage, which determines the feedback connection of the registers in the FPGA and the structure of the sequence. c0 and c n must be 1, indicating participation in the feedback. For other coefficients c1, c2,..., c n-1 if it is 1, it indicates participation in the feedback, and if it is 0, it indicates non-participation in the feedback.

[0062] Step S2: Convert the two groups of the uniformly distributed random sequences into Gaussian white noise sequences through the Box - Muller algorithm; the Box - Muller algorithm is expressed as:

[0063]

[0064] where x1 and x2 represent two groups of Gaussian white noise sequences.

[0065] Step S3: Generate Gaussian colored noise sequences by passing the Gaussian white noise sequences through a linear filter; the linear filter is an FIR filter, and the transfer function is:

[0066]

[0067] where x(n) and y(n) are the input sequence and output sequence of the filter respectively; N is the length (number of taps) of the designed filter; x(i) is the input signal at the i - th moment; h(i) is the i - th tap coefficient of the filter;

[0068] The system transfer function is:

[0069]

[0070] where a n is the tap coefficient of each order of the filter.

[0071] Step S4: Perform a non - linear transformation on the Gaussian colored noise sequences to obtain the clutter basic model sequences;

[0072] Step S5: Perform amplitude modulation, range modulation, and velocity modulation on the clutter basic model sequences to generate clutter signals with amplitude, time - domain, and frequency - domain information, specifically including:

[0073] Step S51: Perform amplitude modulation on the clutter basic model sequences to obtain amplitude - modulated clutter sequences, specifically including:

[0074] Multiply the clutter basic model sequences obtained in Step S4 by the amplitude modulation parameter to obtain the amplitude - modulated clutter sequences:

[0075] I i (n)=I(n)×A i

[0076] Q i (n)=Q(n)×A i

[0077] where A i is the amplitude modulation parameter, represented by an unsigned binary number and is a normalized parameter.

[0078] Step S52: Perform range modulation on the amplitude-modulated clutter sequence to obtain a range-modulated clutter sequence, specifically including:

[0079] Write the amplitude-modulated clutter sequence obtained in the above step S51 into the memory in the FPGA, and read it out after delaying it by a certain number of clock cycles according to the range modulation parameters to obtain the range-modulated clutter sequence. The specific number of clock cycles for the delay is:

[0080]

[0081] where R max is the simulated range of the clutter, c is the speed of light, and f s is the sampling rate of the FPGA.

[0082] Step S53: Perform velocity modulation on the range-modulated clutter sequence to obtain a velocity-modulated clutter sequence, specifically including:

[0083] Mix the quadrature range-modulated clutter sequence obtained in the above step S52 with two channels of quadrature Doppler signals to obtain a velocity-modulated clutter sequence;

[0084] The two channels of quadrature Doppler signals are generated by the DDS core embedded in the FPGA. Specifically:

[0085] I f (t) = cos(2πf d t)

[0086] Q f (t) = sin(2πf d t)

[0087] The two channels of quadrature range-modulated clutter sequences are:

[0088]

[0089] Specifically, the mixing process is:

[0090]

[0091] By S 11 (t) - S 22 (t), the I-channel clutter signal of the velocity modulation can be obtained as:

[0092]

[0093] By S 12 (t) + S 21 (t), the Q-channel clutter signal of the velocity modulation can be obtained as:

[0094]

[0095] wherein, is the frequency modulation parameter. Wherein, v is the radial motion speed between the radar platform and the clutter target, and λ is the wavelength of the radar.

[0096] As Figure 2 shown, according to one aspect of the present invention, there is provided a clutter signal generation device, including:

[0097] A uniformly distributed random sequence generation module for generating a uniformly distributed random sequence;

[0098] A Gaussian distributed random sequence generation module for generating a Gaussian white noise sequence from the uniformly distributed random sequence through the Box-Muller algorithm;

[0099] An FIR filter module for generating a Gaussian colored noise sequence from the Gaussian white noise sequence through a linear filter;

[0100] A non-linear transformation module for performing a non-linear transformation on the Gaussian colored noise sequence to obtain a clutter basic model sequence with specific amplitude statistical distribution characteristics;

[0101] A clutter sequence modulation module for modulating the clutter basic model sequence generated by the non-linear transformation module through amplitude modulation, range modulation, and speed modulation respectively to obtain a clutter signal with amplitude, time domain, and frequency domain information;

[0102] An upper computer for configuring modulation parameters.

[0103] According to one technical solution of the present invention, the modulation parameters at least include: an amplitude control word, a delay control word, and a frequency control word.

[0104] A clutter signal generation method and device of the present invention use a clutter sequence modulation module to perform amplitude modulation, range modulation, and speed modulation on a clutter basic model sequence respectively, so that the generated clutter signal has amplitude, time domain, and frequency domain information coupled with the simulation scenario, improving the accuracy and fidelity of clutter simulation. In the application field, the present invention is mainly used in radar simulators to improve the performance of radar systems.

[0105] It should be noted that in this article, the term "comprising", "including" or any other variant thereof is intended to cover a non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or terminal device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, article or terminal device including the said element.

[0106] Finally, it should be noted that the above description is the preferred embodiment of the present invention. It should be pointed out that although the preferred embodiments of the present invention have been described, for those skilled in the art of this technology, once the basic creative concept of the present invention is known, several improvements and refinements can be made without departing from the principle described in the present invention, and these improvements and refinements should also be regarded as the protection scope of the present invention. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present invention.

Claims

1. A method for generating clutter signals, characterized in that, It includes the following steps: Step S1: Generate two groups of uniformly distributed random sequences u1 and u2; Step S2: Convert the two groups of uniformly distributed random sequences into Gaussian white noise sequences through the Box-Muller algorithm; Step S3: Generate Gaussian colored noise sequences by passing the Gaussian white noise sequences through a linear filter; Step S4: Perform a non-linear transformation on the Gaussian colored noise sequences to obtain clutter basic model sequences; Step S5: Perform amplitude modulation, range modulation, and velocity modulation on the clutter basic model sequences to generate clutter signals with amplitude, time-domain, and frequency-domain information.

2. The clutter signal generation method according to claim 1, wherein In step S1, the uniformly distributed random sequences are generated by a linear feedback shift register, and the uniformly distributed random sequences are: Among them, c i represents the feedback coefficient of the i-th level. c0 and c n must be 1, indicating participation in feedback. The other coefficients c1, c2, …, c n-1 If it is 1, it means participation in feedback; if it is 0, it means non-participation in feedback.

3. The clutter signal generation method according to claim 1, characterized in that, In step S2, the Box-Muller algorithm is expressed as: where x1 and x2 represent two groups of Gaussian white noise sequences.

4. The clutter signal generation method according to claim 1, characterized in that In step S3, the linear filter is an FIR filter, and the transfer function is: where x(n) and y(n) are the input sequence and output sequence of the filter respectively; N is the length of the designed filter; x(i) is the input signal at the i-th moment; h(i) is the i-th tap coefficient of the filter; The system transfer function is: where a n is the tap coefficient of each order of the filter.

5. The clutter signal generation method according to claim 1, wherein In step S5, it specifically includes: Step S51: Perform amplitude modulation on the clutter basic model sequences to obtain amplitude-modulated clutter sequences; Step S52: Perform range modulation on the amplitude-modulated clutter sequences to obtain range-modulated clutter sequences; Step S53: Perform velocity modulation on the range-modulated clutter sequences to obtain velocity-modulated clutter sequences.

6. The clutter signal generation method according to claim 5, wherein In step S51, it specifically includes: Multiply the clutter basic model sequences obtained in step S4 by the amplitude modulation parameters to obtain amplitude-modulated clutter sequences: I i (n) = I(n) × A i Q i (n) = Q(n) × A i Among them, A i is the amplitude modulation parameter, represented by an unsigned binary number and is a normalized parameter.

7. The clutter signal generation method according to claim 5, wherein In step S52, it specifically includes: Write the amplitude-modulated clutter sequences obtained in step S51 into the memory in the FPGA, and read them out after delaying a certain number of clock cycles according to the range modulation parameters to obtain range-modulated clutter sequences. The specific number of clock cycles for delay is: where R max is the simulated distance of clutter, c is the speed of light, and f s is the sampling rate of the FPGA.

8. The clutter signal generation method according to claim 5, wherein In step S53, it specifically includes: Mix the orthogonal range-modulated clutter sequences obtained in step S52 with two orthogonal Doppler signals to obtain velocity-modulated clutter sequences; The two orthogonal Doppler signals are generated by the DDS core embedded in the FPGA.

9. A clutter signal generating device, characterized in that, It includes: A uniformly distributed random sequence generation module for generating uniformly distributed random sequences; A Gaussian distributed random sequence generation module for generating Gaussian white noise sequences by passing uniformly distributed random sequences through the Box-Muller algorithm; An FIR filter module for generating Gaussian colored noise sequences by passing Gaussian white noise sequences through a linear filter; A non-linear transformation module for performing a non-linear transformation on Gaussian colored noise sequences to obtain clutter basic model sequences with specific amplitude statistical distribution characteristics; A clutter sequence modulation module for performing amplitude modulation, range modulation, and velocity modulation on the clutter basic model sequences generated by the non-linear transformation module respectively to obtain clutter signals with amplitude, time-domain, and frequency-domain information; A host computer for configuring modulation parameters.

10. The clutter signal generating device according to claim 9, wherein The modulation parameters at least include: an amplitude control word, a time delay control word, and a frequency control word.

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