Coherent waveform design and efficient accumulation method for extended target phase cancellation

Abstract

The invention provides an extended target phase offset coherent waveform design and efficient accumulation method. The method comprises the following steps: acquiring a pulse signal of a JFPA waveform received by a target, returning echo signals of a plurality of extended targets, and searching a target coarse velocity by using a minimum envelope entropy, constructing a matching function to perform motion compensation on the echo signal to obtain a two-dimensional time domain signal; taking the jitter initial phase of the echo signal corresponding to the reference waveform as a matched filter, and compensating the jitter initial phase of the echo signal corresponding to the coherent accumulation waveform; and designing the echo signal after initial compensation as a coherent echo signal, and performing Fourier transform on the coherent echo signal along slow time to obtain a coherent accumulation result of the target. According to the method, accurate initial phase jitter compensation is completed without target distance information, the method is suitable for an extended target, and after the echo signal of the JFPA waveform is subjected to initial phase jitter compensation, the phase is controlled to be uniform, so that the complexity of FFT coherent processing can be reduced.

Description

Technical Field

[0001] This application belongs to the field of radar signal processing technology, specifically relating to a coherent waveform design and efficient accumulation method for extended target phase cancellation. Background Technology

[0002] Linear frequency modulation (LFM) waveforms, as the most classic radar detection waveforms, have a fixed carrier frequency and pulse repetition frequency. However, these characteristics make them vulnerable to interception by jammers, leading to radar detection mission failure. Therefore, to improve the radar's anti-jamming capability, it is necessary to develop effective anti-jamming countermeasures to enable the radar to adapt to complex jamming environments.

[0003] Frequency agile waveforms are the most effective and representative active jamming countermeasures, transmitting a set of time-varying carrier frequencies to prevent jammers from acquiring coherent integral gain. Frequency agile technology makes the radar's transmitted waveform unpredictable, significantly reducing the probability of the transmitted signal being intercepted and suppressing various types of jamming, such as narrowband jamming and false target jamming. Furthermore, interleaved PRFs can prevent jammers from intercepting radar parameters, and are therefore widely used in anti-jamming. As a combination of these two methods, JFPA waveforms not only enhance the flexibility of radar waveform parameters but also make radar signals more difficult to intercept in both time and frequency dimensions. Therefore, JFPA waveforms are an effective countermeasure against active radar jamming.

[0004] However, despite the strong anti-interference capability of JFPA waveforms and the reduced signal interception probability, the following technical problems still exist in signal processing: Jitter initial phase compensation based on target range estimation is limited by the number of range sampling points and is only applicable to single-point target detection scenarios. JFPA waveform coherent processing is highly complex. Random agility of frequency and PRF leads to non-uniform sampling of the echo, making traditional Fast Fourier Transform (FFT) algorithms unsuitable. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, this application provides a coherent waveform design and efficient accumulation method for extended target phase cancellation. The technical problem to be solved by this application is achieved through the following technical solution: A coherent waveform design and efficient accumulation method for extended target phase cancellation includes: S100: Acquire the pulse signal of the JFPA waveform received by the target, and the echo signals of multiple extended targets returned; estimate the coarse velocity of the target using the minimum envelope entropy and construct a matching function, and use the matching function to perform motion compensation on the echo signals to obtain a two-dimensional time domain signal; wherein, the JFPA waveform is divided into a reference waveform and a coherent accumulation waveform; S200, the initial phase of the jitter of the echo signal corresponding to the reference waveform in the two-dimensional time domain signal is used as a matched filter to compensate for the initial phase of the jitter of the echo signal corresponding to the coherent accumulation waveform, so as to obtain the initially compensated echo signal. S300, the initial compensated echo signal is designed as a coherent echo signal, and the coherent echo signal is subjected to a Fourier transform along slow time to obtain the coherent accumulation result of the target.

[0006] Beneficial effects: This application achieves accurate initial phase jitter compensation without requiring target distance information and is applicable to extended targets. Furthermore, after initial phase jitter compensation, the echo signal of the JFPA waveform is controlled to have a uniform phase, allowing for coherent accumulation of the target using the FFT algorithm, thus reducing the complexity of coherent processing. In the JFPA waveform, the number of different frequencies is less than the number of pulses, which facilitates the implementation of the proposed same-frequency signal phase cancellation method to compensate for the initial phase jitter. Simulation data verifies that, compared with existing compensation and accumulation methods, the JFPA waveform design method of this application significantly improves the detection performance of moving targets.

[0007] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0008] Figure 1 This is a flowchart illustrating a coherent waveform design and efficient accumulation method for extended target phase cancellation provided in this application; Figure 2 This is a schematic diagram of the process of a coherent waveform design and efficient accumulation method for extended target phase cancellation provided in this application. Detailed Implementation

[0009] The present application will be described in further detail below with reference to specific embodiments, but the implementation of the present application is not limited thereto.

[0010] To improve radar anti-jamming capabilities, frequency agility or pulse repetition frequency (PRF) agility waveform design can be employed to reduce the probability of signal interception. However, frequency agility introduces initial phase jitter, while PRF agility leads to slow-time non-uniform sampling. These two problems are coupled, resulting in incoherent echo signals. Furthermore, existing parameter and scale transformation coherent processing methods reduce signal-to-noise ratio gain and increase processing complexity. Based on these issues, this application proposes a joint frequency and pulse repetition frequency agile waveform (JFPA) design method based on efficient coherent accumulation. This method reduces the complexity of coherent processing by combining initial phase jitter compensation and coherent accumulation. In the JFPA waveform, the number of different frequencies is less than the number of pulses, which facilitates the implementation of the proposed same-frequency signal phase cancellation method to compensate for the initial phase jitter. Furthermore, the JFPA echo signal after initial phase jitter compensation is designed as a coherent signal, allowing for coherent accumulation of the proposed waveform using the FFT algorithm. Finally, simulation data verifies that this waveform design method significantly improves the detection performance of moving targets compared to existing compensation and accumulation methods.

[0011] Combination Figure 1 and Figure 2 This application provides a method for designing and efficiently accumulating coherent waveforms for extended target phase cancellation, including: S100: Acquire the pulse signal of the JFPA waveform received by the target, and the echo signals of multiple extended targets returned; estimate the coarse velocity of the target using the minimum envelope entropy and construct a matching function; use the matching function to perform motion compensation on the echo signals to obtain a two-dimensional time-domain signal; wherein, the JFPA waveform is divided into a reference waveform and a coherent accumulation waveform; S200, the initial phase of the jitter of the echo signal corresponding to the reference waveform in the two-dimensional time domain signal is used as a matched filter to compensate for the initial phase of the jitter of the echo signal corresponding to the coherent accumulation waveform, so as to obtain the initially compensated echo signal. S300, the initial compensated echo signal is designed as a coherent echo signal, and the coherent echo signal is subjected to a Fourier transform along slow time to obtain the coherent accumulation result of the target.

[0012] This application provides a coherent waveform design and efficient accumulation method for extended target phase cancellation, comprising: acquiring the pulse signal of the target receiving the JFPA waveform, the echo signals of multiple extended targets, and using the minimum envelope entropy to find the target coarse velocity; constructing a matched function to perform motion compensation on the echo signals to obtain a two-dimensional time-domain signal; using the jittered initial phase of the echo signal corresponding to the reference waveform in the two-dimensional time-domain signal as a matched filter to compensate for the jittered initial phase of the echo signal corresponding to the coherent accumulation waveform; designing the initially compensated echo signal as a coherent echo signal, and performing a Fourier transform on the coherent echo signal along slow time to obtain the coherent accumulation result of the target. This application achieves accurate initial phase jitter compensation without target distance information and is applicable to extended targets. After initial phase jitter compensation, the echo signal of the JFPA waveform is phase-controlled to a uniform phase, which can reduce the complexity of FFT coherent processing.

[0013] In one specific embodiment of this application, S100 includes: S110 utilizes radar to transmit pulse signals of the JFPA waveform and receives echo signals returned from multiple extended targets; wherein, the pulse signal of the JFPA waveform includes in each coherent processing interval (CPI) The first pulse, the target consists of multiple scattering points; the second... The echo signal of each pulse is represented as: (1); In the formula, Indicates the first The echo signal of each pulse, Indicates the first The scattering coefficient at each scattering point It is the carrier frequency. These refer to fast time, pulse width, and linear frequency modulation, respectively. It is the total number of scattering points. It is the first The time delay in the range direction of each scattering point, when the target maintains a constant speed of motion. Represented as: (2); In the formula, Indicates radar and the first The instantaneous distance between each scattering point Indicates the speed of the target. To represent slow time, it is expressed as: (3); In the formula, Indicates the first Each pulse repetition interval; S120, demodulates, compresses, and performs Fourier transform on the echo signal of each pulse to obtain the frequency domain signal of each pulse; After demodulation and pulse compression, the echo signal of each pulse is represented as: (4); In the formula, It is the range bandwidth of the echo signal. It is the speed at which electromagnetic waves propagate in the air; By fast time domain Performing a Fourier transform on the above yields the first... A frequency domain signal of pulses is represented as: (5); In the formula, yes Fourier transform pairs, The frequency band range is .

[0014] S130, using the minimum average range profile and the frequency domain signal, estimate the rough velocity of the target; In one specific embodiment of this application, S130 includes: S131, Based on the time shift invariance of Fourier transform, the sum of the envelopes of the frequency domain signal is re-represented to obtain an expression for the echo envelope with the slow time offset as the independent variable; In equation (5), the first exponential term represents the frequency band cell migration caused by the radar's moving speed, which must be corrected. The third exponential term contains the target's range information. Furthermore, due to the random agility of frequency and PRF, the echo signals are incoherent. In this application, the minimum envelope entropy can be used to obtain the approximate speed of the moving target, thereby correcting the range cell migration. The sum of the echo envelopes in the pulse-compressed CPI (coherent processing interval) is expressed as: (6); In the formula, This represents the time offset of the distance distribution relative to each slow time. ; The expression for the echo envelope, with the slow time offset as the independent variable, is as follows: (7); In the formula, yes The distance frequency domain.

[0015] S132, substitute the expression for the echo envelope with the slow time offset as the independent variable into the expression for the global minimum entropy, and solve for the expression for the distance offset. Image focus quality is evaluated using Shannon entropy; in this application, envelope entropy can be used to measure envelope alignment quality. The minimum envelope entropy is expressed as: (8); When the entropy gradient is 0, the entropy reaches its global minimum. The expression for the global minimum entropy is: (9); The distance offset expression is as follows: (10); In the formula, Through the along Obtained by performing a Fourier transform.

[0016] S133, the differential property of the Fourier transform is used to rewrite the distance offset expression, resulting in the rewritten expression, which is: (11); S134, solved iteratively and The distance offset at which the entropy reaches its global minimum is obtained by determining the peak position between these points. ; According to formula (11), Iterative solutions are possible. and The correlation between peak positions is estimated. When all pulses have moved to their corresponding positions, the envelope entropy reaches its global minimum, at which point the value can be obtained. .

[0017] S135, based on the distance offset when the entropy reaches its global minimum, calculate the target's coarse velocity, expressed as: (12); In the formula, Indicates the coherent accumulation time; S140, construct a matching function based on the coarse velocity, and use the matching function to perform motion compensation on the frequency domain signal to obtain a two-dimensional time domain signal.

[0018] get Then, the first exponential term of equation (5) can be compensated, and a matching function can be constructed to correct the distance cell migration. The matching function is expressed as: (13); This will multiply (13) and (5), and along After performing an inverse Fourier transform on the direction, the two-dimensional time-domain signal is represented as: (14).

[0019] In the formula, Indicates the pulse carrier frequency; The second exponential term in equation (14) represents the initial phase jitter at different carrier frequencies. The lower the sampling rate, the lower the ranging accuracy; the higher the sampling rate, the more the computational load of subsequent signal processing will increase exponentially, making it difficult to efficiently complete jitter compensation. The first exponential term represents the coupling between the agile frequency and the agile PRF term, which leads to incoherence of the echo signal, thereby increasing the complexity of coherent processing.

[0020] Based on the preceding analysis, initial phase jitter compensation and efficient coherent accumulation processing between different carrier frequencies are crucial for achieving JFPA waveform detection of moving targets. However, traditional initial phase jitter compensation methods, based on target range estimation, have low accuracy, leading to significant loss of target coherent accumulation gain. By eliminating initial phase jitter through phase synchronization, efficient coherent accumulation can then be achieved using the FFT algorithm.

[0021] In one specific embodiment of this application, S200 includes: S210, Obtain the echo signal of the equivalent complex scattering point based on the two-dimensional time-domain signal; This application S210 includes: S211, the two-dimensional time-domain signal is rewritten to obtain a rewritten expression for the two-dimensional time-domain signal. To reduce the amount of initial phase jitter and compensate using the same-frequency signal phase cancellation method, the JFPA waveform is divided into two groups: a reference waveform and a coherent accumulation waveform (CAW). The reference waveform and CAW each contain... pulse and The CAW frequency is selected from the frequency used in the reference waveform. The frequency used in the reference waveform limits the number of initial jitter phases in the CPI.

[0022] Since the sinc term in (14) represents the first The focusing position of each scattering point will not affect the compensation for the initial phase jitter. Therefore, it can be rewritten as: (15); In the formula, Indicates the first Each pulse has its own carrier frequency; S212, rewrite the expression for the complex scattering point to obtain the new expression for the negative scattering point, where the expression for the complex scattering point is: (16); The superposition of multiple complex numbers can be represented as an equivalent complex number. Therefore, the rewritten expression for the complex scattering point of equation (16) is as follows: (17); S213, Substitute the rewritten expression of the complex scattering point into the rewritten expression of the two-dimensional time-domain signal to obtain the echo signal of the equivalent complex scattering point. Substituting (17) into (15), we obtain the echo signal of the equivalent complex scattering point, which is expressed as: (18).

[0023] Based on the above analysis, the sum of the initial jitter phases of the extended target can be re-expressed as a jitter complex phase, which is beneficial for compensation through phase cancellation. When the radar tracks the target or during short-term observation, the initial agility phases at the same frequency remain completely identical. Therefore, this application uses the jitter initial phase of the reference waveform echo as a matching function to compensate for the jitter initial phase of the CAW echo.

[0024] S220, extract the echo signal corresponding to the reference waveform from the echo signal of the equivalent complex scattering point; the first echo signal corresponding to the reference waveform... The echo signal of each pulse is represented as: (19).

[0025] In the formula, It is the first The slow time of a reference waveform, . Indicates the first Each reference waveform has its own carrier frequency; S230, the conjugate complex number of the echo signal corresponding to the reference waveform is used as a matched filter, expressed as: (20); S240, the initial phase of the jitter in the echo signal corresponding to the coherent accumulation waveform is compensated using the matched filter to obtain the initially compensated echo signal. The first... The echo signal of each pulse is represented as: (twenty one); In the formula, It is the first in CAW The slow time of each pulse , and ; Assume the first in CAW The pulse and the reference waveform of the first pulse Each pulse has the same carrier frequency, that is... Multiplying Equation 21 by Equation 20 yields the initially compensated echo signal, expressed as: (twenty two); In the formula, In the new slow time, the initial jitter of all pulse echoes in CAW is sequentially compensated using reference waveform echoes.

[0026] In one specific embodiment of this application, S300 includes: S310, Design the phase of adjacent pulse echo signals in the initially compensated echo signal to satisfy the coherence constraint and obtain a coherent echo signal; After initial phase jitter compensation, the JFPA waveform needs to undergo coherent accumulation to achieve target detection under low signal-to-noise ratio. Observing equation (21), since the PRF of the original waveform is agile, the new slow time is also agile. In this application, the carrier frequency and PRF will be designed as follows: the JFPA signal with the new slow time is coupled with the coherently designed carrier frequency to satisfy the characteristics of a coherent signal. First, the phase of adjacent pulses in equation (22) is designed to meet the signal coherence constraint, and then the limitations of its coherence design are analyzed. Finally, the accumulation of target energy is achieved through the FFT method.

[0027] As is well known, in the case of pulses with the same frequency and a fixed PRF sampling, the signals of adjacent pulses have a fixed phase difference, which is a constraint on signal coherence. Therefore, the phases of adjacent pulses in equation (22) are designed to satisfy the constraint.

[0028] S310 of this application includes: S311, Design the constraint conditions for the echo signals of adjacent pulses; wherein, the constraint conditions are expressed as: (twenty three); In the formula, and Representing the equivalent carrier frequency and PRI respectively, Indicates the first Each coherently accumulated waveform has its own carrier frequency; S312, using the constraints, determine the agile carrier frequency of the echo signal after initial compensation and the fixed phase difference satisfied by the new slow time.

[0029] Specifically, in order for the phase of the first pulse to be continuous with the phase of the second pulse, the frequency of the first pulse and the new slow time must satisfy the following conditions: (twenty four); Next, the frequency of the second pulse and the new slow time need to meet the following requirements: (25); By substituting (24) into (25), we get: (26); Therefore, based on (22) and (23), (26) can be derived as follows: (27); S313, the initially compensated echo signal is rewritten using the fixed phase difference to obtain a coherent echo signal. As can be seen from equation (27), by designing the carrier frequency and PRF of the transmitted waveform, the agile carrier frequency and the new slow time of the CAW signal after initial phase jitter compensation can satisfy the fixed phase difference, which is consistent with the fixed carrier frequency of radar transmission. and PRI The effect is the same. Let , It is a uniformly slow time. By substituting (27) into (22), the echo signal in (22) can be rewritten as: (28); S320, Perform a Fourier transform on the coherent echo signal along slow time to obtain the coherent accumulation result of the target.

[0030] To prevent the target energy from drifting with the carrier frequency, the energy of all pulses is normalized to the first pulse. The target scattered energy. Ultimately, through along... By performing an FFT operation, the cumulative result of the target can be obtained, represented as: (29); In the formula, Indicates and The corresponding Doppler frequency, This represents the target scattering energy of the first pulse echo.

[0031] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of this application and should not be construed as limiting the specific implementation of this application to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of this application, and all such modifications or substitutions should be considered within the scope of protection of this application.

Claims

1. A method for designing and efficiently accumulating coherent waveforms with extended target phase cancellation, characterized in that, include: S100: Acquire the pulse signal of the JFPA waveform received by the target, and the echo signals of multiple extended targets returned; The target coarse velocity is estimated using the minimum envelope entropy and a matching function is constructed. The matching function is then used to perform motion compensation on the echo signal to obtain a two-dimensional time-domain signal. The JFPA waveform is divided into a reference waveform and a coherent accumulation waveform. S200, the initial phase of the jitter of the echo signal corresponding to the reference waveform in the two-dimensional time domain signal is used as a matched filter to compensate for the initial phase of the jitter of the echo signal corresponding to the coherent accumulation waveform, so as to obtain the initially compensated echo signal. S300, the initial compensated echo signal is designed as a coherent echo signal, and the coherent echo signal is subjected to a Fourier transform along slow time to obtain the coherent accumulation result of the target.

2. The method for designing and efficiently accumulating extended target phase cancellation coherent waveforms according to claim 1, characterized in that, S100 includes: S110 utilizes radar to transmit pulse signals of the JFPA waveform and receives echo signals from multiple extended targets returning from the target; wherein, the pulse signal of the JFPA waveform includes multiple pulses in each coherent processing interval, and the extended targets consist of multiple scattering points; The echo signal of each pulse is represented as: ； In the formula, Indicates the first The echo signal of each pulse, Indicates the first The scattering coefficient at each scattering point It is the carrier frequency. These refer to fast time, pulse width, and linear frequency modulation, respectively. It is the total number of scattering points. It is the first The time delay in the range direction of each scattering point is expressed as: ； In the formula, Indicates radar and the first The instantaneous distance between each scattering point Represents the radial velocity of the extended target relative to the radar. To represent slow time, it is expressed as: ； In the formula, Indicates the first Each pulse repetition interval; S120, demodulates, compresses, and performs Fourier transform on the echo signal to obtain the frequency domain signal of each pulse; After demodulation and pulse compression, the echo signal of each pulse is represented as: In the formula, It is the range bandwidth of the echo signal. It is the speed at which electromagnetic waves propagate in the air, the first The frequency domain signal of a pulse is represented as: In the formula, yes Fourier transform pairs, The frequency band range is . S130, using the minimum average range profile and the frequency domain signal, estimate the rough velocity of the target; S140, construct a matching function based on the coarse velocity, and use the matching function to perform motion compensation on the frequency domain signal to obtain a two-dimensional time domain signal.

3. The extended target phase cancellation coherent waveform design and efficient accumulation method according to claim 2, characterized in that, S130 includes: S131, Based on the time shift invariance of Fourier transform, the sum of the envelopes of the frequency domain signal is re-represented to obtain an expression for the echo envelope with the slow time offset as the independent variable; The sum of the envelopes of the frequency domain signals is expressed as: ； In the formula, This represents the time offset of the distance distribution relative to each slow time. ; The expression for the echo envelope, with the slow time offset as the independent variable, is as follows: ； In the formula, yes The distance frequency domain; S132, substituting the expression for the echo envelope with the slow time offset as the independent variable into the expression for the global minimum entropy, solve for the distance offset expression; where the minimum envelope entropy is expressed as: ； When the entropy gradient is 0, the entropy reaches its global minimum. The expression for the global minimum entropy is: ； The distance offset expression is as follows: ； In the formula, Through the along Obtained by performing a Fourier transform; S133, the differential property of the Fourier transform is used to rewrite the distance offset expression, resulting in the rewritten expression, which is: ； S134, solved iteratively and The distance offset at which the entropy reaches its global minimum is obtained by determining the peak position between these points. ; S135, based on the distance offset when the entropy reaches its global minimum, calculate the target's coarse velocity, expressed as: ； In the formula, This indicates the time for coherent accumulation.

4. The method for designing and efficiently accumulating extended target phase cancellation coherent waveforms according to claim 3, characterized in that, The matching function in S140 is expressed as follows: ； The two-dimensional time-domain signal is represented as follows: ； In the formula, Indicates the pulse carrier frequency.

5. The extended target phase cancellation coherent waveform design and efficient accumulation method according to claim 4, characterized in that, S200 includes: S210, Obtain the echo signal of the equivalent complex scattering point based on the two-dimensional time-domain signal; S220, extract the echo signal corresponding to the reference waveform from the echo signal of the equivalent complex scattering point; S230, the conjugate complex number of the echo signal corresponding to the reference waveform is used as a matched filter; S240, the matched filter is used to compensate for the jitter initial phase of the echo signal corresponding to the coherent accumulation waveform to obtain the initially compensated echo signal.

6. The method for designing and efficiently accumulating extended target phase cancellation coherent waveforms according to claim 5, characterized in that, S210 includes: S211, the two-dimensional time-domain signal is rewritten to obtain a rewritten expression for the two-dimensional time-domain signal, which is expressed as: ； In the formula, Indicates the first Each pulse has its own carrier frequency; S212, rewrite the expression for the complex scattering point to obtain the new expression for the negative scattering point, where the expression for the complex scattering point is: ； The rewritten expression for the complex scattering point is: ； S213, Substitute the rewritten expression for the complex scattering point into the rewritten expression for the two-dimensional time-domain signal to obtain the echo signal of the equivalent complex scattering point, expressed as: 。 7. The extended target phase cancellation coherent waveform design and efficient accumulation method according to claim 6, characterized in that, The reference waveform in S220 corresponds to the first The echo signal of each pulse is represented as: ； In the formula, Indicates the first Each reference waveform has its own carrier frequency; The matched filter in S230 is represented as follows: ； The first corresponding to the coherent accumulation waveform in S240 The echo signal of each pulse is represented as: ； In the formula, It is the first in CAW The slow time of each pulse , and ; The echo signal after initial compensation in S240 is represented as follows: ； In the formula, It's a new slow time.

8. The method for designing and efficiently accumulating extended target phase cancellation coherent waveforms according to claim 7, characterized in that, The S300 includes: S310, Design the phase of adjacent pulse echo signals in the initially compensated echo signal to satisfy the coherence constraint and obtain a coherent echo signal; S320, Perform a Fourier transform on the coherent echo signal along slow time to obtain the coherent accumulation result of the target.

9. The method for designing and efficiently accumulating extended target phase cancellation coherent waveforms according to claim 8, characterized in that, S310 includes: S311, Design the constraint conditions for the echo signals of adjacent pulses; wherein, the constraint conditions are expressed as: In the formula, and Representing the equivalent carrier frequency and PRI respectively, Indicates the first Each coherently accumulated waveform has its own carrier frequency; S312, using the aforementioned constraints, determine the agile carrier frequency of the initially compensated echo signal and the fixed phase difference satisfied by the new slow time, expressed as: ； S313, the echo signal after initial compensation is rewritten using the fixed phase difference to obtain a coherent echo signal, represented as: 。 10. The method for designing and efficiently accumulating extended target phase cancellation coherent waveforms according to claim 9, characterized in that, S320 includes: All energy in the coherent echo signal is normalized to the target scattering energy of the first pulse echo, and then along... Performing an FFT operation yields the coherent cumulative result of the target, represented as: ； In the formula, Indicates and The corresponding Doppler frequency, This represents the target scattering energy of the first pulse echo.

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