Method, system and device for quantitative analysis of two-dimensional phase error of synthetic aperture sonar

Abstract

The invention discloses a two-dimensional phase error quantitative analysis method, system and device of a synthetic aperture sonar, and relates to the technical field of image processing. The two-dimensional phase error quantitative analysis method takes discrete targets of different distances within a range of a distance mapping zone, and for each subsystem composed of a receiving array element and a transmitting array element, calculates the phase of a two-dimensional frequency domain system function based on a numerical calculation method corresponding to a single distance target, then calculates the phase of the two-dimensional frequency domain system function of a method to be evaluated by other model errors, and calculates the phase difference between the two-dimensional frequency domain system function of the numerical calculation method and the method to be evaluated, performs absolute value and maximum value processing on the phase difference, and performs similar processing on all targets and different receiving array elements, so as to obtain the phase error of the two-dimensional frequency domain system function of the method to be evaluated.

Description

Technical Field

[0001] The present invention relates to the technical field of image processing, and in particular to a two-dimensional phase error quantitative analysis method, system and device for synthetic aperture sonar. Background Art

[0002] Synthetic aperture sonar obtains a virtual long-aperture array based on the uniform rectilinear motion of small-aperture array elements, thereby improving the resolution in the direction of motion and ultimately obtaining a constant resolution in the track direction that is independent of the operating frequency, detection distance, etc.

[0003] Imaging algorithm is the core of synthetic aperture sonar. Time domain algorithm focuses each pixel in the imaging area point by point, which takes a long time and is generally not used for real-time imaging processing of synthetic aperture sonar. At present, in order to meet the real-time imaging processing requirements of synthetic aperture sonar equipment or engineering prototypes, frequency domain imaging algorithm has become the first choice. The current practical synthetic aperture sonar mainly adopts a multi-subarray configuration in which multiple receiving array elements receive echo signals in the track direction. Due to the spatial distribution of the transmitting and receiving array elements, the phase dwell principle is used to solve the phase dwell point, which will face the problem of solving an octave equation. According to Abel's theorem, there is no general algebraic root formula for a quintic or higher univariate equation, which will make the analytical two-dimensional frequency domain system function not exist. In order to obtain the analytical two-dimensional frequency domain system function, it is generally necessary to perform certain approximate processing on the two-way slant range history, phase dwell point, etc., and on this basis, the analytical two-dimensional frequency domain system function and various frequency domain imaging algorithms are derived. There is no doubt that these approximate processing will bring errors to the design of imaging algorithms and affect imaging performance. In order to evaluate this error, the traditional method is to directly compare the peak sidelobe ratio, integrated sidelobe ratio, resolution and other indicators of the imaging results; in recent years, a method is to directly compare with the standard two-dimensional frequency domain system function based on numerical calculation to obtain the error. However, the two-dimensional frequency domain system function is a function of the spacing between transceiver array elements, target distance, Doppler frequency, and instantaneous frequency in the range direction. That is to say, this error will be a four-dimensional image. The error analysis has the disadvantages of being cumbersome and non-intuitive, which is not conducive to directly evaluating the advantages and disadvantages of various methods. Summary of the invention

[0004] In order to solve the problems that error evaluation of traditional imaging methods is cumbersome and non-intuitive, the two-dimensional phase error quantitative analysis method proposed in the present invention adopts operations such as taking absolute values ​​and finding maximum values ​​to convert the traditional four-dimensional error image related to the transceiver array element spacing, target distance, Doppler frequency, and instantaneous frequency in the range into a two-dimensional error image only related to the transceiver array element spacing and target distance. It can intuitively and easily perform error evaluation on various imaging algorithms, evaluate the errors of various imaging algorithms without imaging processing, and then predict the imaging performance of various imaging methods, greatly improving the error evaluation efficiency and providing a quantitative basis for users to select imaging algorithms according to the actual situation of their equipment.

[0005] The technical solution adopted by the present invention to solve the technical problem is as follows: the two-dimensional phase error quantitative analysis method of the present invention takes discrete targets of different distances within the range of the distance mapping zone, and for each subsystem composed of a receiving array element and a transmitting array element, calculates the phase of the two-dimensional frequency domain system function based on the numerical calculation method corresponding to the single distance target, and then calculates the phase of the two-dimensional frequency domain system function of the method to be evaluated by other model errors, and calculates the phase difference between the two-dimensional frequency domain system function of the numerical calculation method and the method to be evaluated, performs absolute value and maximum value processing on the phase difference, and performs similar processing on all targets and different receiving array elements to obtain the phase error of the two-dimensional frequency domain system function of the method to be evaluated, which specifically includes the following steps:

[0006] (1) Set multiple discrete point targets at different distances within the range of the upward mapping belt;

[0007] (2) According to the determined distance of the discrete point target and the receiving array element, for each subsystem composed of the receiving array element and the transmitting array element, the phase of the two-dimensional frequency domain system function based on the numerical calculation method is calculated;

[0008] (3) According to the determined distance of the discrete point target and the receiving array element, for each subsystem composed of the receiving array element and the transmitting array element, the phase of the two-dimensional frequency domain system function of the method to be evaluated is calculated, and the phase difference between the two-dimensional frequency domain system function of the numerical calculation method and the method to be evaluated is calculated;

[0009] (4) According to the determined distance of the discrete point target and the receiving array element, the maximum, minimum and maximum values ​​of the corresponding phase difference are calculated in sequence, and the corresponding maximum value is stored;

[0010] (5) Traverse all discrete point targets and all receiving array elements, calculate the maximum phase difference, and convert the error into a function of the receiving array element and distance.

[0011] According to one aspect of the present invention, the present invention provides a two-dimensional phase error quantitative analysis method of a synthetic aperture sonar, wherein the two-dimensional phase error quantitative analysis method comprises the following steps:

[0012] S1, set multiple discrete point targets at different distances within the range of the upward mapping band;

[0013] S2, according to the determined distance of the discrete point target and the receiving array element, for each subsystem composed of the receiving array element and the transmitting array element, calculate the phase of the two-dimensional frequency domain system function based on the numerical calculation method;

[0014] S3, according to the determined distance of the discrete point target and the receiving array element, for each subsystem composed of the receiving array element and the transmitting array element, based on the phase of the two-dimensional frequency domain system function of the method to be evaluated, calculate the phase difference between the numerical calculation method and the two-dimensional frequency domain system function of the method to be evaluated;

[0015] S4, according to the determined distance of the discrete point target and the receiving array element, the maximum value, the minimum value and the maximum value of the corresponding phase difference are calculated in sequence, and the corresponding maximum value is stored;

[0016] S5, traverse all discrete point targets and all receiving array elements, calculate the maximum value of the phase difference, and convert the error into a function of the receiving array element and the distance.

[0017] As a further improvement to the technical solution of the present invention, in step S1, the value of the discrete point target is ,in Indicates the target distance, subscript Indicates any point within the survey strip The distances of different targets, and all distances are arranged in order from small to large, the first distance value Greater than the minimum distance of the survey band, the last distance value Less than the maximum distance of the survey swath.

[0018] As a further improvement to the technical solution of the present invention, in step S2, the calculation formula for calculating the phase of the two-dimensional frequency domain system function based on the numerical calculation method is: ,in represents the signal center frequency, Indicates the two-way slant range history of the signal, Represents the index of the distance to the target at different distances, which satisfies , The speed at which sound waves propagate in water. Indicates The subsystem index consisting of receiving array elements and transmitting array elements satisfies , Represents the total number of receiving array elements, represents the precise propagation delay of the signal, Indicates The distance between the receiving and transmitting elements of each subsystem is and represent the instantaneous frequencies corresponding to fast and slow times, respectively, It represents the first The phase dwell point of a receiving array element is calculated as follows: ,in Indicates the platform moving speed.

[0019] As a further improvement to the technical solution of the present invention, in step S3, the calculation formula for calculating the phase difference between the two-dimensional frequency domain system function of the numerical calculation method and the method to be evaluated is: ,in represents the phase of the two-dimensional frequency-domain system function of the method to be evaluated, Indicates that for The receiving element A two-dimensional frequency domain system function based on numerical calculation method for calculating the distance to the target.

[0020] As a further improvement to the technical solution of the present invention, in step S4, the calculation formula for calculating the maximum value of the phase difference is: , the formula for calculating the minimum value of the phase difference is: ,in represents the maximum value of the phase difference, represents the minimum value of the phase difference, Indicates the maximum value of the phase difference. It means that the phase difference is processed at the minimum value. The calculation formula for the maximum value of the phase difference obtained by processing the maximum and minimum values ​​of the phase difference is: ,in It represents the phase error after taking the maximum value operation, Indicates the maximum value , minimum value Take the largest of two values.

[0021] As a further improvement to the technical solution of the present invention, in step S5, for all discrete point targets and all receiving array elements, all discrete point targets and all receiving array elements are traversed, the maximum value of the phase difference is calculated, and the error is converted into a function of the receiving array element and the distance. The processing method is: for different target distances and Receive array elements and calculate the corresponding phase errors , for all targets and all receiving array elements in the distance upward, calculate the corresponding phase error .

[0022] According to another aspect of the present invention, the present invention further provides a two-dimensional phase error quantitative analysis system of synthetic aperture sonar, comprising:

[0023] A setting unit is used to set a plurality of discrete point targets at different distances within the range of the distance upward mapping band;

[0024] A first calculation unit is used to calculate the phase of a two-dimensional frequency domain system function based on a numerical calculation method for each subsystem composed of a receiving array element and a transmitting array element according to the determined distance of the discrete point target and the receiving array element;

[0025] A second calculation unit is used to calculate the phase difference between the numerical calculation method and the two-dimensional frequency domain system function of the method to be evaluated based on the phase of the two-dimensional frequency domain system function of the method to be evaluated, for each subsystem composed of the receiving array element and the transmitting array element according to the determined distance of the discrete point target and the receiving array element;

[0026] A third calculation unit is used to calculate the maximum value, minimum value and maximum value of the corresponding phase difference in sequence according to the determined distance of the discrete point target and the receiving array element, and store the corresponding maximum value;

[0027] The fourth calculation unit is used to traverse all discrete point targets and all receiving array elements, calculate the maximum value of the phase difference, and convert the error into a function of the receiving array element and the distance.

[0028] As a further improvement to the technical solution of the present invention, the value of the discrete point target set by the setting unit is ,in Indicates the target distance, subscript Indicates any point within the survey strip The distances of different targets, and all distances are arranged in order from small to large, the first distance value Greater than the minimum distance of the survey band, the last distance value Less than the maximum distance of the survey swath.

[0029] As a further improvement to the technical solution of the present invention, the phase calculation formula of the two-dimensional frequency domain system function calculated by the first calculation unit based on the numerical calculation method is: ,in represents the signal center frequency, Indicates the two-way slant range history of the signal, Represents the index of the distance to the target at different distances, which satisfies , The speed at which sound waves propagate in water. Indicates The subsystem index consisting of receiving array elements and transmitting array elements satisfies , Represents the total number of receiving array elements, represents the precise propagation delay of the signal, Indicates The distance between the receiving and transmitting elements of each subsystem is and represent the instantaneous frequencies corresponding to fast and slow times, respectively, It represents the first The phase dwell point of a receiving array element is calculated as follows: ,in Indicates the platform moving speed.

[0030] According to another aspect of the present invention, the present invention further provides a computing device, which includes a processor and a memory, wherein computer program instructions are stored in the memory, and when the computer program instructions are executed in the processor, the processor executes a two-dimensional phase error quantitative analysis method, wherein the two-dimensional phase error quantitative analysis method includes the following steps: setting a plurality of discrete point targets at different distances within the surveying and mapping range in the distance upward; calculating the phase of a two-dimensional frequency domain system function based on a numerical calculation method for each subsystem consisting of a receiving array element and a transmitting array element according to the determined distance of the discrete point target and the receiving array element; calculating the phase difference between a numerical calculation method and a two-dimensional frequency domain system function of a method to be evaluated based on the phase of the two-dimensional frequency domain system function of a method to be evaluated for each subsystem consisting of a receiving array element and a transmitting array element according to the determined distance of the discrete point target and the receiving array element; calculating the maximum value, minimum value and maximum value of the corresponding phase difference in turn according to the determined distance of the discrete point target and the receiving array element, and storing the corresponding maximum value; traversing all discrete point targets and all receiving array elements, calculating the maximum value of the phase difference, and converting the error into a function of the receiving array element and the distance.

[0031] Compared with the prior art, the present invention has at least the following beneficial effects: the two-dimensional phase error quantitative analysis method of the present invention adopts operations such as taking absolute values ​​and finding maximum values ​​to convert the traditional four-dimensional error image related to the transceiver array element spacing, target distance, Doppler frequency, and instantaneous frequency in the range into a two-dimensional error image only related to the transceiver array element spacing and the target distance. It can intuitively and easily perform error evaluation on various imaging algorithms, and can evaluate the errors of various imaging algorithms without performing imaging processing, and then predict the imaging performance of each imaging method, which greatly improves the error evaluation efficiency and provides a quantitative basis for users to select imaging algorithms according to the actual situation of their equipment.

[0032] Other beneficial effects of the present invention will be further disclosed in the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The present invention provides a two-dimensional phase error quantitative analysis method calculation process.

[0034] Figure 2 For the Two-dimensional imaging geometry of a synthetic aperture sonar subsystem with two separate transmitters and receivers.

[0035] Figure 3 The error of the first synthetic aperture sonar system with the closest distance between the transmitting and receiving elements, where (a) is the error of the target at a distance of 30m, and (b) is the error of the target at a distance of 220m.

[0036] Figure 4 The error of the 40th synthetic aperture sonar system with the farthest distance between the transmitting and receiving elements, where (a) is the error of the target at a distance of 30m, and (b) is the error of the target at a distance of 220m.

[0037] Figure 5 It is the error calculated by the two-dimensional phase error quantitative analysis method of the present invention.

[0038] Figure 6 The figure is a flow chart of a two-dimensional phase error quantitative analysis method according to a preferred embodiment of the present invention.

[0039] Figure 7 The figure is a block diagram of a two-dimensional phase error quantitative analysis system according to a preferred embodiment of the present invention.

[0040] Figure 8 A block diagram of a computing device according to a preferred embodiment of the present invention is shown.

[0041] In the figure:

[0042] 700, two-dimensional phase error quantitative analysis system; 710, setting unit; 720, first calculation unit; 730, second calculation unit; 740, third calculation unit; 750, fourth calculation unit; 800, calculation device; 810, memory; 820, processor; 830, input device; 840, output device. DETAILED DESCRIPTION

[0043] Before describing in detail any embodiment of the present invention, it should be understood that the present invention is not limited in its application to the construction and arrangement details of the components described below or illustrated in the following figures. The present invention can have other embodiments and can be practiced or carried out in various ways. In addition, it should be understood that the words and terms used here are for descriptive purposes and should not be considered restrictive. The use of "including" or "having" and its variations herein is intended to cover the items and their equivalents and additional items displayed below. Unless otherwise specified or limited, the terms "install", "connect", "support" and "couple" and their variations are widely used and cover direct installation and indirect installation, connection, support and connection. In addition, "connect" and "couple" are not limited to physical or mechanical connections or connections.

[0044] Furthermore, on the first aspect, in the disclosure of the present invention, the orientations or positional relationships indicated by terms such as “longitudinal”, “transverse”, “upper”, “lower”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside” and “outside” are based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore the above terms cannot be understood as limitations on the present invention; on the second aspect, the term “one” should be understood as “at least one” or “one or more”, that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term “one” cannot be understood as a limitation on the quantity.

[0045] Figure 1 The calculation process of a two-dimensional phase error quantitative analysis method of the present invention is shown. Figure 2 The two-dimensional imaging geometry of multi-array SAS (multi-array synthetic aperture sonar) is given, where the horizontal direction is the range direction and the vertical direction is the azimuth direction. Assume that the sonar platform speed is , the speed of sound underwater is , the transmitting signal of the transmitting array is modulated frequency Chirp signal, then The echo signal received by a receiving array element can be expressed as: ,in and They represent the fast time in distance and the slow time in azimuth respectively. Indicates the transmitted Chirp signal, is the carrier wavelength.

[0046] To consider the two-way slant distance history of the "stop-go-stop" approximation, Indicates the distance of the point target, represents the distance between the transmitting and receiving array elements, and the joint directivity function of the transmitting and receiving array elements is ignored. It indicates the distance that the receiving element moves in azimuth during the transmission and reception of signals. Indicates that the transmitting array element transmits the signal to the The precise propagation time of the signal during the process of receiving the echo by the receiving array element is expressed as:

[0047] .

[0048] Set multiple discrete point targets at different distances within the range of the distance upward surveying band. The values ​​of the discrete point targets are ,in Indicates the target distance, subscript Indicates any point within the survey strip The distances of different targets, and all distances are arranged in order from small to large, that is, , the first distance value Greater than the minimum distance of the survey band, the last distance value Less than the maximum distance of the survey swath.

[0049] According to the determined distance of the discrete point target and the receiving array element, for each subsystem composed of the receiving array element and the transmitting array element, the phase of the two-dimensional frequency domain system function based on the numerical calculation method is calculated, and the calculation formula is: ,in represents the signal center frequency, Indicates the two-way slant range history of the signal, Represents the index of the distance to the target at different distances, which satisfies , The speed at which sound waves propagate in water. Indicates The subsystem index consisting of receiving array elements and transmitting array elements satisfies , Indicates the total number of receiving array elements, represents the precise propagation delay of the signal, Indicates The distance between the receiving and transmitting elements of each subsystem is and represent the instantaneous frequencies corresponding to fast and slow times, respectively, It represents the first The phase dwell point of a receiving array element is calculated as follows: ,in Indicates the platform moving speed.

[0050] Here, the present invention takes the two-dimensional frequency domain system function obtained by double root equivalent transformation as an example, and its expression is: .

[0051] According to the determined distance of the discrete point target and the receiving array element, for each subsystem composed of the receiving array element and the transmitting array element, based on the phase of the two-dimensional frequency domain system function of the above-mentioned method to be evaluated, the phase difference between the numerical calculation method and the two-dimensional frequency domain system function of the method to be evaluated is calculated, and the calculation formula is: ,in represents the phase of the two-dimensional frequency-domain system function of the method to be evaluated, Indicates that for The receiving element A two-dimensional frequency domain system function based on numerical calculation method for calculating the distance to the target.

[0052] According to the determined distance of the discrete point target and the receiving array element, the maximum, minimum and maximum values ​​of the corresponding phase difference are calculated in turn, where the operation of calculating the maximum and minimum values ​​of the phase difference is shown in the following formula: ,in represents the maximum value of the phase difference, represents the minimum value of the phase difference, Indicates the maximum value of the phase difference. It means that the phase difference is processed at the minimum value. The calculation formula for the maximum value of the phase difference obtained by processing the maximum and minimum values ​​of the phase difference is: ,in It represents the phase error after taking the maximum value operation, Indicates the maximum value , minimum value Take the largest of two values.

[0053] For all discrete point targets and all receiving array elements, traverse all discrete point targets and all receiving array elements, calculate the maximum phase difference, and convert the error into a function of the receiving array element and the distance. The processing method is: for different target distances and The receiving array element calculates the corresponding phase error according to the above steps By analogy, for all targets and all receiving array elements in the distance upward, the corresponding phase error can be calculated according to the above steps. , the phase error at this time It is simply a function of distance and receiving element index.

[0054] Assume that the carrier frequency is 120kHz, the length of the transmitting array element along the track is 0.08m, the length of a single receiving array element along the track is 0.04m, there are 40 receiving array elements in total, the bandwidth of the transmitted linear frequency modulation signal is 40kHz, the pulse repetition period is 0.32s, and the sonar towing speed is 2.5m / s. Within the surveying band, the minimum target distance is 30m and the maximum target distance is 220m in the distance direction. Considering these two targets, for the closest situation of the transmitting and receiving array elements, the simulated phase error proposed in the Chinese invention patent with authorization announcement number "CN106772326B" and invention name "A multi-subarray synthetic aperture sonar phase error analysis method" is adopted, such as Figure 4 As shown in the figure, it is not difficult to see that since the traditional method relies on four parameters: the spacing between the transmitting and receiving array elements, the target distance, the Doppler frequency, and the instantaneous frequency in the range direction, the phase error simulated by the traditional method is relatively complicated, and a large number of error images are required to analyze the important parameters affecting the phase error. According to the two-dimensional phase error quantitative analysis method of the present invention, the simulated phase error is as follows Figure 5 As shown in the figure, it is not difficult to see that the two-dimensional phase error quantitative analysis method based on the present invention can convert the traditional four-dimensional phase error into a two-dimensional phase error, so that the simulated phase error only depends on the spacing between the transmitting and receiving array elements and the target distance. Figure 5 The images shown are sufficient to evaluate the errors of the imaging method, greatly simplifying the evaluation method and greatly improving the efficiency of error evaluation.

[0055] like Figure 6 As shown, according to one aspect of the present invention, the present invention provides a two-dimensional phase error quantitative analysis method for a synthetic aperture sonar, wherein the two-dimensional phase error quantitative analysis method comprises the following steps: S1, setting a plurality of discrete point targets at different distances within a surveying band range in the distance upward; S2, calculating the phase of a two-dimensional frequency domain system function based on a numerical calculation method for each subsystem consisting of a receiving array element and a transmitting array element according to the determined distance of the discrete point target and the receiving array element; S3, calculating the phase difference between a numerical calculation method and a two-dimensional frequency domain system function of a method to be evaluated based on the phase of a two-dimensional frequency domain system function of a method to be evaluated for each subsystem consisting of a receiving array element and a transmitting array element according to the determined distance of the discrete point target and the receiving array element; S4, calculating the maximum value, minimum value and maximum value of the corresponding phase difference in turn according to the determined distance of the discrete point target and the receiving array element, and storing the corresponding maximum value; S5, traversing all discrete point targets and all receiving array elements, calculating the maximum value of the phase difference, and converting the error into a function of the receiving array element and the distance.

[0056] Through the above steps, the two-dimensional phase error quantitative analysis method of the present invention adopts operations such as taking absolute values ​​and finding maximum values ​​to convert the traditional four-dimensional error image related to the transceiver array element spacing, target distance, Doppler frequency, and instantaneous frequency in the range into a two-dimensional error image only related to the transceiver array element spacing and target distance. It can intuitively and easily perform error evaluation on various imaging algorithms, and can evaluate the errors of various imaging algorithms without imaging processing, and then predict the imaging performance of each imaging method, which greatly improves the error evaluation efficiency and provides a quantitative basis for users to select imaging algorithms according to the actual situation of their equipment.

[0057] In a specific example of the two-dimensional phase error quantitative analysis method of the present invention, in step S1, the value of the discrete point target is ,in Indicates the target distance, subscript Indicates any point within the survey strip The distances of different targets, and all distances are arranged in order from small to large, the first distance value Greater than the minimum distance of the survey band, the last distance value Less than the maximum distance of the survey swath.

[0058] In a specific example of the two-dimensional phase error quantitative analysis method of the present invention, in step S2, the phase calculation formula for calculating the two-dimensional frequency domain system function based on the numerical calculation method is: ,in represents the signal center frequency, Indicates the two-way slant range history of the signal, Represents the index of the distance to the target at different distances, which satisfies , The speed at which sound waves propagate in water. Indicates The subsystem index consisting of receiving array elements and transmitting array elements satisfies , Represents the total number of receiving array elements, represents the precise propagation delay of the signal, Indicates The distance between the receiving and transmitting elements of each subsystem is and represent the instantaneous frequencies corresponding to fast and slow times, respectively, It represents the first The phase dwell point of a receiving array element is calculated as follows: ,in Indicates the platform moving speed.

[0059] In a specific example of the two-dimensional phase error quantitative analysis method of the present invention, in step S3, the calculation formula for calculating the phase difference between the two-dimensional frequency domain system function of the numerical calculation method and the method to be evaluated is: ,in represents the phase of the two-dimensional frequency-domain system function of the method to be evaluated, Indicates that for The receiving element A two-dimensional frequency domain system function based on numerical calculation method for calculating the distance to the target.

[0060] In a specific example of the two-dimensional phase error quantitative analysis method of the present invention, in step S4, the calculation formula for calculating the maximum value of the phase difference is: , the formula for calculating the minimum value of the phase difference is: ,in represents the maximum value of the phase difference, represents the minimum value of the phase difference, Indicates the maximum value of the phase difference. It means that the phase difference is processed at the minimum value. The calculation formula for the maximum value of the phase difference obtained by processing the maximum and minimum values ​​of the phase difference is: ,in It represents the phase error after taking the maximum value operation, Indicates the maximum value , minimum value Take the largest of two values.

[0061] In a specific example of the two-dimensional phase error quantitative analysis method of the present invention, in step S5, for all discrete point targets and all receiving array elements, all discrete point targets and all receiving array elements are traversed to calculate the maximum value of the phase difference, and the error is converted into a function of the receiving array element and the distance in the following manner: for different target distances and Receive array elements and calculate the corresponding phase errors , for all targets and all receiving array elements in the distance upward, calculate the corresponding phase error .

[0062] like Figure 7As shown, according to one aspect of the present invention, the present invention provides a two-dimensional phase error quantitative analysis system 700 for synthetic aperture sonar, which includes a setting unit 710, a first calculation unit 720, a second calculation unit 730, a third calculation unit 740 and a fourth calculation unit 750. The two-dimensional phase error quantitative analysis system 700 of the present invention adopts operations such as taking absolute values ​​and finding maximum values ​​to convert the traditional four-dimensional error image related to the transceiver array element spacing, target distance, Doppler frequency, and instantaneous frequency in the range into a two-dimensional error image related only to the transceiver array element spacing and target distance, and can intuitively and easily evaluate the errors of various imaging algorithms, and can evaluate the errors of various imaging algorithms without imaging processing, and then predict the imaging performance of each imaging method, which greatly improves the error evaluation efficiency and provides a quantitative basis for users to select imaging algorithms according to the actual situation of their equipment.

[0063] The setting unit 710 is used to set a plurality of discrete point targets at different distances within the surveying and mapping range in the distance upward direction; the first calculation unit 720 is used to calculate the phase of the two-dimensional frequency domain system function based on the numerical calculation method for each subsystem composed of the receiving array element and the transmitting array element according to the determined distance of the discrete point target and the receiving array element; the second calculation unit 730 is used to calculate the phase difference between the numerical calculation method and the two-dimensional frequency domain system function of the method to be evaluated based on the phase of the two-dimensional frequency domain system function of the method to be evaluated for each subsystem composed of the receiving array element and the transmitting array element according to the determined distance of the discrete point target and the receiving array element; the third calculation unit 740 is used to calculate the maximum value, minimum value and maximum value of the corresponding phase difference in turn according to the determined distance of the discrete point target and the receiving array element, and store the corresponding maximum value; the fourth calculation unit 750 is used to traverse all discrete point targets and all receiving array elements, calculate the maximum value of the phase difference, and convert the error into a function of the receiving array element and the distance.

[0064] The value of the discrete point target set by the setting unit 710 is ,in Indicates the target distance, subscript Indicates any point within the survey strip The distances of different targets, and all distances are arranged in order from small to large, the first distance value Greater than the minimum distance of the survey band, the last distance value Less than the maximum distance of the survey swath.

[0065] The phase calculation formula of the two-dimensional frequency domain system function calculated by the first calculation unit 720 based on the numerical calculation method is: ,in represents the signal center frequency, Indicates the two-way slant range history of the signal, Represents the index of the distance to the target at different distances, which satisfies , The speed at which sound waves propagate in water. Indicates The subsystem index consisting of receiving array elements and transmitting array elements satisfies , Represents the total number of receiving array elements, represents the precise propagation delay of the signal, Indicates The distance between the receiving and transmitting elements of each subsystem is and represent the instantaneous frequencies corresponding to fast and slow times, respectively, It represents the first The phase dwell point of a receiving array element is calculated as follows: ,in Indicates the platform moving speed.

[0066] The calculation formula for calculating the phase difference between the two-dimensional frequency domain system function of the numerical calculation method and the method to be evaluated by the second calculation unit 730 is: ,in represents the phase of the two-dimensional frequency-domain system function of the method to be evaluated, Indicates that for The receiving element A two-dimensional frequency domain system function based on numerical calculation method for calculating the distance to the target.

[0067] The calculation formula for calculating the maximum value of the phase difference by the third calculation unit 740 is: , the formula for calculating the minimum value of the phase difference is: ,in represents the maximum value of the phase difference, represents the minimum value of the phase difference, Indicates the maximum value of the phase difference. It means that the phase difference is processed at the minimum value. The calculation formula for the maximum value of the phase difference obtained by processing the maximum and minimum values ​​of the phase difference is: ,in It represents the phase error after taking the maximum value operation, Indicates the maximum value , minimum value Take the largest of two values.

[0068] For all discrete point targets and all receiving array elements, the fourth calculation unit 750 calculates the maximum value of the phase difference and converts the error into a function of the receiving array element and the distance in the following manner: for different target distances and Receive array elements and calculate the corresponding phase errors , for all targets and all receiving array elements in the distance upward, calculate the corresponding phase error .

[0069] like Figure 8 As shown, according to another aspect of the present invention, the present invention further provides a computing device 800, wherein the computing device 800 includes a memory 810 and a processor 820 coupled to the memory 810, wherein the memory 810 is used to store computer program instructions, and when the computer program instructions are executed in the processor 820, the processor 820 executes a two-dimensional phase error quantitative analysis method, wherein the two-dimensional phase error quantitative analysis method includes the following steps: setting a plurality of discrete point targets at different distances within a range of a surveying band in a distance-upward direction; according to the determined distances of the discrete point targets and the receiving array elements, for each receiving array element and The subsystem composed of transmitting array elements calculates the phase of the two-dimensional frequency domain system function based on the numerical calculation method; according to the determined distance of the discrete point target and the receiving array element, for each subsystem composed of the receiving array element and the transmitting array element, based on the phase of the two-dimensional frequency domain system function of the method to be evaluated, calculate the phase difference between the two-dimensional frequency domain system function of the numerical calculation method and the method to be evaluated; according to the determined distance of the discrete point target and the receiving array element, calculate the maximum value, minimum value and maximum value of the corresponding phase difference in turn, and store the corresponding maximum value; traverse all discrete point targets and all receiving array elements, calculate the maximum value of the phase difference, and convert the error into a function of the receiving array element and the distance.

[0070] In one embodiment of the computing device 800 of the present invention, the memory 810 may include one or more computer program products, and the computer program product may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, a random access memory (RAM) and / or a cache memory (cache), etc. The non-volatile memory may include, for example, a read-only memory (ROM), a hard disk, a flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 820 may run the program instructions to implement the functions of the two-dimensional distance error analysis method of the present invention described above.

[0071] In one embodiment of the computing device 800 of the present invention, the processor 820 can be a central processing unit (CPU) or other forms of processing units with data processing capabilities and / or instruction execution capabilities, which can run the program instructions stored on the computer-readable storage medium to implement the functions of the one-dimensional error analysis method of the present invention described above.

[0072] In one embodiment of the computing device 800 of the present invention, the computing device 800 may also include an input device 830 and an output device 840. The input device 830 may be, but is not limited to, a keyboard or a mouse. The output device 840 may be, but is not limited to, a display, a speaker, or a printer. The input device 830 and the output device 840 may be connected to the processor 820 via a bus system.

[0073] It should be understood by those skilled in the art that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functional and structural principles of the present invention have been demonstrated and explained in the embodiments, and the embodiments of the present invention may be modified or altered in any way without departing from the principles.

Claims

1. A two-dimensional phase error quantitative analysis method for synthetic aperture sonar, characterized in that: The two-dimensional phase error quantitative analysis method comprises the following steps: S1, set multiple discrete point targets at different distances within the range of the upward mapping band; S2, according to the determined distance of the discrete point target and the receiving array element, for each subsystem composed of the receiving array element and the transmitting array element, calculate the phase of the two-dimensional frequency domain system function based on the numerical calculation method; S3, according to the determined distance of the discrete point target and the receiving array element, for each subsystem composed of the receiving array element and the transmitting array element, based on the phase of the two-dimensional frequency domain system function of the method to be evaluated, calculate the phase difference between the numerical calculation method and the two-dimensional frequency domain system function of the method to be evaluated; S4, according to the determined distance of the discrete point target and the receiving array element, the maximum value, the minimum value and the maximum value of the corresponding phase difference are calculated in sequence, and the corresponding maximum value is stored; S5, traverse all discrete point targets and all receiving array elements, calculate the maximum value of the phase difference, and convert the error into a function of the receiving array element and the distance; In step S1, the value of the discrete point target is ,in Indicates the target distance, subscript Indicates any point within the survey strip The distances of different targets, and all distances are arranged in order from small to large, the first distance value Greater than the minimum distance of the survey band, the last distance value Less than the maximum distance of the survey swath; In step S2, the calculation formula for calculating the phase of the two-dimensional frequency domain system function based on the numerical calculation method is: ， in represents the signal center frequency, Indicates the two-way slant range history of the signal, Represents the index of the distance to the target at different distances, which satisfies , represents the speed of sound waves in water. Indicates The subsystem index consisting of receiving array elements and transmitting array elements satisfies , Indicates the total number of receiving array elements, represents the precise propagation delay of the signal, Indicates The distance between the receiving and transmitting elements of each subsystem is and represent the instantaneous frequencies corresponding to fast and slow times, respectively, It represents the first The phase dwell point of a receiving array element is calculated as follows: ,in represents the platform moving speed; in the step S3, the calculation formula for calculating the phase difference between the two-dimensional frequency domain system function of the numerical calculation method and the method to be evaluated is: , in represents the phase of the two-dimensional frequency-domain system function of the method to be evaluated, Indicates that for The receiving element A two-dimensional frequency domain system function based on numerical calculation method for target calculation at a distance; In step S4, the calculation formula for calculating the maximum value of the phase difference is: , The formula for calculating the minimum value of the phase difference is: ,in represents the maximum value of the phase difference, represents the minimum value of the phase difference, Indicates the maximum value of the phase difference. It means that the phase difference is processed at the minimum value. The calculation formula for the maximum value of the phase difference obtained by processing the maximum and minimum values ​​of the phase difference is: ,in It represents the phase error after taking the maximum value operation, Indicates the maximum value , minimum value Take the largest value between two values; In step S5, for all discrete point targets and all receiving array elements, all discrete point targets and all receiving array elements are traversed to calculate the maximum value of the phase difference, and the error is converted into a function of the receiving array element and the distance. The processing method is: for different target distances and Receive array elements and calculate the corresponding phase errors , for all targets and all receiving array elements in the distance upward, calculate the corresponding phase error .

2. A two-dimensional phase error quantitative analysis system for synthetic aperture sonar, characterized in that: include: A setting unit is used to set a plurality of discrete point targets at different distances within the range of the distance upward mapping band; A first calculation unit is used to calculate the phase of a two-dimensional frequency domain system function based on a numerical calculation method for each subsystem composed of a receiving array element and a transmitting array element according to the determined distance of the discrete point target and the receiving array element; A second calculation unit is used to calculate the phase difference between the numerical calculation method and the two-dimensional frequency domain system function of the method to be evaluated based on the phase of the two-dimensional frequency domain system function of the method to be evaluated, for each subsystem composed of the receiving array element and the transmitting array element according to the determined distance of the discrete point target and the receiving array element; A third calculation unit is used to calculate the maximum value, minimum value and maximum value of the corresponding phase difference in sequence according to the determined distance of the discrete point target and the receiving array element, and store the corresponding maximum value; The fourth calculation unit is used to traverse all discrete point targets and all receiving array elements, calculate the maximum value of the phase difference, and convert the error into a function of the receiving array element and the distance; The value of the discrete point target set by the setting unit is ,in Indicates the target distance, subscript Indicates any point within the survey strip The distances of different targets, and all distances are arranged in order from small to large, the first distance value Greater than the minimum distance of the survey band, the last distance value Less than the maximum distance of the survey swath; The phase calculation formula of the two-dimensional frequency domain system function calculated by the first calculation unit based on the numerical calculation method is: ， in represents the signal center frequency, Indicates the two-way slant range history of the signal, Represents the index of the distance to the target at different distances, which satisfies , The speed at which sound waves propagate in water. Indicates The subsystem index consisting of receiving array elements and transmitting array elements satisfies , Represents the total number of receiving array elements, represents the precise propagation delay of the signal, Indicates The distance between the receiving and transmitting elements of each subsystem is and represent the instantaneous frequencies corresponding to fast and slow times, respectively, It represents the first The phase dwell point of a receiving array element is calculated as follows: ,in Indicates the platform moving speed; The calculation formula for calculating the phase difference between the two-dimensional frequency domain system function of the numerical calculation method and the method to be evaluated by the second calculation unit is: ,in represents the phase of the two-dimensional frequency-domain system function of the method to be evaluated, Indicates that for The receiving element A two-dimensional frequency domain system function based on numerical calculation method for target calculation at a distance; The calculation formula for calculating the maximum value of the phase difference by the third calculation unit is: , the formula for calculating the minimum value of the phase difference is: ,in represents the maximum value of the phase difference, represents the minimum value of the phase difference, Indicates the maximum value of the phase difference. It means that the phase difference is processed at the minimum value. The calculation formula for the maximum value of the phase difference obtained by processing the maximum and minimum values ​​of the phase difference is: ,in It represents the phase error after taking the maximum value operation, Indicates the maximum value , minimum value Take the largest value between two values; For all discrete point targets and all receiving array elements, all discrete point targets and all receiving array elements are traversed, and the fourth calculation unit calculates the maximum value of the phase difference, and the error is converted into a function of the receiving array element and the distance. The processing method is: for different target distances and Receive array elements and calculate the corresponding phase errors , for all targets and all receiving array elements in the distance upward, calculate the corresponding phase error .

3. A computing device, characterized in that The method comprises a processor and a memory, wherein the memory stores computer program instructions, and when the computer program instructions are executed in the processor, the processor executes the two-dimensional phase error quantitative analysis method as claimed in claim 1.

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