Array element phase difference digital compensation method for sonar array detection system

Abstract

The invention discloses an array element phase difference digital compensation method for a sonar array detection system, belongs to the technical field of underwater target detection, and is applied to a sonar array to measure the phase difference between array elements and perform compensation during beam forming, thereby improving the target orientation estimation precision of the sonar array detection system. According to the invention, the phase difference generated by each channel of the sonar array filtering and amplifying circuit is estimated through an adaptive phase difference algorithm, the sonar array signal direction vector is updated through the estimated phase difference, and finally beam forming is carried out according to the compensated array signal direction vector. The influence of the phase difference generated when the signal passes through the filtering and amplifying circuit on beam forming is effectively reduced, and the target orientation estimation precision of the sonar array detection system is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of sonar array detection system element phase difference digital compensation method, belong to underwater target detection technical field, it is applied to the phase difference measurement between each array element of sonar array and compensation when beam forming, to improve the accuracy of sonar array detection system target azimuth estimation. BACKGROUND

[0002] In the sonar array detection system, the sound signal received by each array element needs to be sampled and processed after passing through the filter amplification circuit. The filter amplification circuit causes changes in signal phase due to the presence of electronic devices such as capacitors, resulting in inconsistent phases among the array elements. The premise of target detection and azimuth estimation through digital beam forming algorithm is to assume that the signal phases received by each array channel are consistent. Therefore, analog signal filter amplification can reduce the target detection capability and azimuth estimation accuracy of the sonar system.

[0003] Currently, there is little research on digital compensation technology for phase differences between channels caused by filter amplification circuits. Most of them use methods such as designing Bessel filters to reduce phase differences between channels. This method is not only complex to debug, but also cannot achieve zero phase error in a wide frequency band. SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art and provide a sonar array detection system element phase difference digital compensation method that can effectively reduce the influence of phase differences caused by signal passing through the filter amplification circuit on beam forming and improve the accuracy of target azimuth estimation of the sonar array detection system.

[0005] The technical solution of the present application is as follows:

[0006] A sonar array detection system element phase difference digital compensation method, the steps are as follows:

[0007] Step 1: the number of sonar array elements is , the number of filter amplification circuit channels corresponding to the number of array elements is , and all channels of the filter amplification circuit are connected to the same channel of the signal source at the same time.

[0008] Step 2: the frequency to be processed by the sonar array when beam forming is , the unit is , the signal source is controlled to emit frequency signals in sequence, and the output signals of the filter amplification circuit are sampled to record groups of sampling signals, the sampling rate is , the unit is , the sampling time is , the unit is .

[0009] Step 3: For the sample signal of the 1th channel of the 1th frequency, the sequence is , containing elements. For each frequency sample signal, taking the 1th channel as reference, the phase difference of the 2th to th channels relative to the 1th channel is calculated respectively by adaptive phase difference estimation algorithm, as follows:

[0010] a) The sample signal of the 1th channel of the 1th frequency is the sequence , and the sample signal of the 1th channel of the 2th frequency is the sequence , the signal frequency is , and the unit is .

[0011] b) Two reference signals and are generated respectively, is a sequence of 0s divided at equal intervals.

[0012] c) Set the adaptive compensation coefficient , the filter order , and use the adaptive filter algorithm to filter the input signal signal and the reference signal , the input signal signal and the reference signal , the input signal signal and the reference signal , and the input signal signal and the reference signal , respectively, to obtain the tap coefficient sequence , , , as follows:

[0013] 1) The input signal of the adaptive filter algorithm is , and the reference signal is .

[0014] 2) Initialize the filter input signal vector , which is a 0 sequence with a length of the filter order ; construct the tap coefficient vector , which is a 0 sequence with a length of the filter order ; construct the filter output signal vector , which is a 0 sequence with a length of the reference signal length ; and construct the signal error vector​​​​​​ a sequence of 0s with length equal to the reference signal length ;

[0015] 3) Perform the th loop, the th loop is: update the filter input signal ; , the transpose of ; update the error vector , ; update the tap coefficient vector ;

[0016] 4) After the loop is completed, take the final as the tap coefficient sequence result.

[0017] d) Calculate the phase difference sequence ; ;

[0018] e) Take the last value of the sequence as the phase difference estimation result, with the unit of °.

[0019] Step 4: Update the array signal direction vector of beamforming, as follows:

[0020] For the th frequency , the uncompensated array signal direction vector is:

[0021] ;

[0022] wherein is the unit of ; is the test of the th element relative to the 1st element receiving signal when the incident angle is , with the unit of , and the unit of °.

[0023] For a uniform linear array, the uncompensated array signal direction vector is:

[0024] ;

[0025] wherein is the unit of ; is the element spacing, with the unit of ; is the incident angle, with the unit of ; is the sound velocity, unit is .

[0026] The phase difference of the first frequency of the first channel relative to the first channel is calculated by the adaptive filtering algorithm The phase difference of the first frequency of the first channel relative to the first channel is calculated by the adaptive filtering algorithm The phase difference of the first frequency of the first channel relative to the first channel is calculated by the adaptive filtering algorithm The compensated array signal direction vector of the first frequency is The compensated array signal direction vector of the first frequency is :

[0027] .

[0028] Step 5: Connect the filter amplification circuit channels to the corresponding transducers of the sonar array, and perform beam forming according to the compensated array signal direction vector during operation to realize the azimuth estimation of the target.

[0029] A computer readable storage medium having a computer program stored thereon, the program being executed by a processor to implement the steps of the method for compensating the phase difference of the elements of a sonar array detection system.

[0030] The beneficial effects of the present application include:

[0031] The present application estimates the phase difference generated by each channel of the filter amplification circuit of the sonar array through an adaptive phase difference algorithm, updates the sonar array signal direction vector through the estimated phase difference, and finally performs beam forming according to the compensated array signal direction vector, effectively reducing the influence of the phase difference generated by the signal passing through the filter amplification circuit on the beam forming, and improving the target azimuth estimation accuracy of the sonar array detection system. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a flowchart of the method of the present application.

[0033] Figure 2 is the result of conventional beam forming by the uncompensated array signal direction vector.

[0034] Figure 3 is the result of conventional beam forming by the compensated array signal direction vector. DETAILED DESCRIPTION

[0035] The present application will be further described in conjunction with the embodiments, drawings, and the present application includes but is not limited to the following embodiments.

[0036] Embodiment 1

[0037] Referring to Figure 1As shown, taking a uniform linear array with 20 elements and an element spacing of 0.15 m as an example, a signal processing frequency of 2 kHz single frequency signal, a random phase difference of -10°~+10° added to each element relative to the first element, a sampling rate of 20 kHz, and a sampling time of 10 ms, 20 channels of signals are generated as the output signals of the filter amplification circuit.

[0038] The phase difference of all channels relative to the first channel is 0°, -8.61°, -7.27°, 5.77°, -8.15°, -5.24°, -5.12°, -7.90°, 7.16°, 3.96°, 4.67°, 3.01°, 0.32°, -3.47°, 3.23°, -7.64°, -7.04°, -9.60°, 9.28°, 9.40°.

[0039] Meanwhile, an array receiving signal with an incident angle of 10° and a frequency of 2 kHz is generated.

[0040] Step 1: the number of elements of the uniform linear array sonar array is 20, the element spacing is 0.15 m, the number of channels of the filter amplification circuit corresponds to the number of elements, which is 20, and in this embodiment, a simulation method is used to simulate that all channels of the filter amplification circuit are simultaneously connected to the same channel of the signal source.

[0041] Step 2: the frequency to be processed when the sonar array is beamformed is 2 kHz, and in this embodiment, a simulation method is used to generate a 2 kHz signal, a random phase difference of -10°~+10° is added to each element relative to the first element, and a group of sampling signals is generated, with a sampling time of 0.01 s.

[0042] Step 3: for the 2 kHz frequency channel sampling signal, each channel contains elements. For each frequency sampling signal, taking the first channel as a reference, setting the adaptive compensation coefficient , the filter order , the phase difference of the second to channels relative to the first channel is calculated by the adaptive phase difference estimation algorithm, and the results are , , , , , , , , , , , , , , , , , , , unit: °.

[0043] Step 4: update the array signal direction vector of beamforming, for 2000 the phase difference of the frequency of the 1th channel relative to the 1th channel is , the frequency compensated array signal direction vector is:

[0044] ;

[0045] wherein ; ; is the incident angle, unit: °. ; .

[0046] Step 5: this embodiment simulates the connection of the filter amplification circuit channels to the corresponding transducers of the sonar array by simulation, and works according to the updated array signal direction vector , which is expressed as:

[0047] ;

[0048] performs beamforming, the simulation target incident angle is 10°, the conventional beamforming result through the uncompensated array signal direction vector is shown in Figure 2 , and the conventional beamforming result through the compensated array signal direction vector is shown in Figure 3 . It can be seen from the figure that the target direction estimation result is 10.2° through the uncompensated array signal direction vector for beamforming, and 0.2° error is generated; the target direction estimation result is 10° through the compensated array signal direction vector for beamforming, and high-precision direction estimation of the target can still be achieved.​

Claims

1. A method for digital compensation of phase difference between elements of a sonar array detection system, characterized in that, The method comprises the following steps: Step 1: the number of sonar array elements is , the number of filter amplification circuit channels corresponds to the number of array elements , all channels of the filter amplification circuit are simultaneously connected to the same channel of the signal source; Step 2: the frequency to be processed when the sonar array is beamformed is , the control signal source emits frequency signals in turn, and the output signals of the filter and amplifier circuit are sampled, and groups of sampling signals are recorded, the sampling rate is , and the sampling time is ; Step 3: for the sample signal of the first frequency, the first channel is taken as a reference, and the phase difference of the second to the nth channel is calculated by using the adaptive phase difference estimation algorithm. ​​​​​ Step 4: updating the array signal direction vector of beam forming, specifically as follows: For the first frequency uncompensated array signal direction vector is: ； wherein, in units of ; is the angle of incidence the first array element the test signal received by the array element relative to the first array element; For a uniform linear array, the uncompensated array signal direction vector is: ； wherein in units of ; is an array element spacing, is an angle of incidence, is a sound speed; The phase difference of the first frequency of the second channel relative to the first channel is calculated by an adaptive filter algorithm The compensated array signal direction vector of the first frequency is The phase difference of the first frequency of the second channel relative to the first channel is calculated by an adaptive filter algorithm The compensated array signal direction vector of the first frequency is The compensated array signal direction vector of the first frequency is ​ ； Step 5: connecting each channel of the filter amplification circuit to the corresponding transducer of the sonar array, and performing beam forming according to the compensated array signal direction vector during operation to realize the azimuth estimation of the target.

2. The method of claim 1, wherein, In step 3, the adaptive phase difference estimation algorithm calculates the phase difference of the 2nd channel with respect to the 1st channel, and the phase difference of the 3rd channel with respect to the 1st channel, respectively. The phase difference of the channels with respect to the 1st channel specifically includes: a) the first channel sample signal of the first frequency is the sequence , the first channel sample signal of the second frequency is the sequence , the first channel sample signal of the third frequency is the sequence , the first channel sample signal of the fourth frequency is the sequence , the first channel sample signal of the fifth frequency is the sequence , and the signal frequency is ; b) generating two reference signals, respectively and , is 0 to an equally spaced sequence; c) setting an adaptive compensation coefficient , filter order , using an adaptive filter algorithm to filter the input signal and the reference signal , the input signal and the reference signal , the input signal and the reference signal , the input signal and the reference signal , , , , respectively, to obtain tap coefficient sequences d) by calculating the phase difference sequence ; e) take The last value of the sequence is the phase difference estimate.

3. The method of claim 2, wherein, The step c) specifically comprises: 1) The adaptive filter algorithm input signal is , and the reference signal is ; 2) initialize a filter input signal vector of length 0 ; initialize a tap coefficient vector of length 0 ; initialize a filter output signal vector of length 0 ; initialize a signal error vector of length 0 ; initialize a signal error vector of length 0 ; initialize a signal error vector of length 0 ; initialize a signal error vector of length 0 ; initialize a signal error vector of length 0 ; 3) perform the secondary loop, the secondary loop is to update the filter input signal is ; update the filter output signal , is the transpose of ; update the error vector , is the input reference signal; update the tap coefficient vector ; 4) Take final is the tap coefficient sequence result.

4. The method of claim 2, wherein, In step 2, the adaptive compensation coefficient is set filter order .

5. A computer-readable storage medium having stored thereon a computer program, characterized in that, The program is executed by the processor to realize the steps of the phase difference digital compensation method of the array element of the sonar array detection system according to any one of claims 1-4.

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