CN-115656928-B - Method for improving positioning accuracy of ultra-short baseline system by multi-path delay resistance estimation

Abstract

The method for improving the positioning precision of the ultra-short baseline system comprises the steps of when the ultra-short baseline positioning is carried out by adopting a broadband correlation time delay estimation method, respectively having a plurality of correlation peaks in the change curves of R13 (tau x) and R24 (tau x), firstly finding the maximum peak position, then forwardly finding the correlation peak with the peak height of the first peak being more than 0.707 times of the peak height of the maximum peak and the peak width being a certain range of the peak width corresponding to the response signal frequency band from the position, wherein the time delay difference corresponding to the correlation peak position is the time delay difference tau x or tau y of the direct wave, and respectively substituting the time delay difference tau x or tau y into the time delay difference tau x or tau y And In the formula, the accurate positioning of the measured target T on a coordinate system established by the ultra-short baseline array is obtained, the method carries out interference suppression on the received signals, then carries out matched filtering to calculate the correlation, then carries out amplitude discrimination and wide discrimination on the correlation sequence, finds the direct wave time delay, reduces the misjudgment probability and ensures the ultra-short baseline positioning accuracy.

Inventors

• CHENG HONG
• WANG KUN
• YANG SHENGQUAN

Assignees

• 中国船舶重工集团公司七五0试验场

Dates

Publication Date

20260512

Application Date

20221020

Claims (4)

1. 1. The ultra-short baseline system comprises an ultra-short baseline array (6), signal processing equipment (7), a host (8) and an underwater transponder (9), wherein the ultra-short baseline array (6) adopts an orthogonal cross array, the ultra-short baseline system comprises a first array element (1), a second array element (2), a third array element (3), a fourth array element (4) and a transmitting transducer (5), the ultra-short baseline array (6) is rigidly arranged on a lifting rod at the center or the side of a mother ship, the ultra-short baseline system is placed under water when in operation, the underwater transponder (9) is arranged on an underwater measured target T, an array coordinate system is established on the ultra-short baseline array (6), the transmitting transducer (5) is taken as an origin of the coordinate system, the first array element (1) and the third array element (3) are taken as X axes, the second array element (2) and the fourth array element (4) are taken as Y axes, the ultra-short baseline array (6) is taken as Z axes in a direction perpendicular to the ultra-short baseline array (6), and the aperture 1 between the first array element (1) and the third array element (3) is calibrated in advance; when the ultra-short baseline positioning system works, the host (8) controls the transmitting transducer (5) to transmit a broadband query sound signal through the signal processing equipment (7), and the broadband query sound signal is received by the underwater transponder (9) after being transmitted by the underwater sound, after being confirmed by the underwater transponder (9), the system response signals which are different from the broadband query sound signals are returned, the response signals are respectively received by the first array element (1), the second array element (2), the third array element (3) and the fourth array element (4), the coordinate position of the measured target T relative to the ultra-short baseline array (6) is calculated by using the formula (1) and the formula (2), Formula (1); formula (2); Wherein, C-sound velocity in water; D 1 is the distance between the first array element (1) and the third array element (3); D 2 is the interval between the second array element (2) and the fourth array element (4); R-distance between the measured target T and the origin of coordinates, T is the time required to send a signal from the transmitting transducer (5), to the underwater transponder (9) to receive the signal and back to the transmitting transducer (5); -in the X-axis direction, the first array element (1) and the third array element (3) receive a delay difference of signals; In the Y-axis direction, the second array element (2) and the fourth array element (4) receive the time delay difference of signals, and the time delay difference Obtained by time delay estimation of the received signals of the first array element (1) and the third array element (3), wherein the formula (3) is a cross-correlation time delay estimation formula, Formula (3); Wherein: Is used to determine the complex number of the conjugate, X 1 (t)、x 3 (t) are the received signals from the first array element (1) and the third array element (3) of the matrix coordinate system X-axis respectively, For the cross-correlation function of the first array element (1) and the third array element (3), the signal processing device (7) respectively carries out the conjugate multiplication of the received signals of the first array element (1) and the third array element (3) on the X axis of the basic array coordinate system after carrying out the Fourier transformation to obtain a cross-power spectrum, carries out the inverse Fourier transformation of the cross-power spectrum of the first array element (1) and the third array element (3) to obtain a correlation function, inputs the correlation function into a detection module, and displays the correlation function in the detection module Wherein the abscissa represents time and the ordinate represents the variation of the correlation function, and finding the time delay corresponding to the maximum peak position in the variation ; Time delay difference The signal time delay estimation received by the second array element (2) and the fourth array element (4) is obtained, the formula (4) is a cross-correlation time delay estimation formula, Formula (4); Wherein: Is used to determine the complex number of the conjugate, 、 The signals received by the second array element (2) and the fourth array element (4) are respectively from the Y-axis of the matrix coordinate system, As the cross-correlation function of the second array element (2) and the fourth array element (4), the signal processing equipment (7) respectively carries out the conjugate multiplication of the received signals of the second array element (2) and the fourth array element (4) on the Y axis of the matrix coordinate system after carrying out the Fourier transform to obtain a cross-power spectrum, carries out the inverse Fourier transform of the cross-power spectrum of the second array element (2) and the fourth array element (4) to obtain a correlation function, inputs the correlation function into the detection module, and displays the correlation function in the detection module Wherein the abscissa represents time and the ordinate represents the variation of the correlation function, and finding the time delay corresponding to the maximum peak position in the variation ; It is characterized in that in the cross-correlation function And The variation curve of (a) has multiple correlation peaks respectively, the maximum peak position is found firstly, then the position is found forward to find the correlation peak with the peak height of the first peak being more than 0.707 times of the peak height of the highest peak and the peak width being a certain range of the peak width corresponding to the response signal frequency band, and the delay difference corresponding to the correlation peak position is the delay difference of the direct wave Or (b) Will delay the time difference Or (b) And (3) respectively substituting the formula (1) and the formula (2) to obtain the accurate positioning of the measured target T on the coordinate system established by the ultra-short baseline array.
2. 2. The method for improving the positioning accuracy of an ultra-short baseline system by multi-path delay estimation according to claim 1, wherein the finally selected correlation peak is a peak which is in a change curve and meets the first appearance of a certain peak width condition that the peak height is more than 0.707 times of the peak height of the highest peak and the peak width is corresponding to a response signal frequency band.
3. 3. The method for improving the positioning accuracy of the ultra-short baseline system by the multi-path delay estimation according to claim 2, wherein the signal processing equipment (7) further performs adaptive line spectrum enhancement processing between performing Fourier transform to calculate a cross power spectrum and performing inverse Fourier transform, and the adaptive line spectrum enhancement processing reduces interference and misjudgment probability.
4. 4. The method for improving positioning accuracy of ultra-short baseline system by multi-path delay estimation according to claim 3, wherein the peak width selection condition is 0.9 to 1.1 times of the correlation peak width corresponding to the response signal frequency band.

Description

Method for improving positioning accuracy of ultra-short baseline system by multi-path delay resistance estimation Technical Field The invention belongs to the field of underwater target positioning, and particularly relates to a method for improving positioning accuracy of an ultra-short baseline system by means of multi-path delay resistance estimation. Background The ultra-short baseline positioning system has the characteristics of small volume, convenient installation, flexible use and the like, thereby playing an increasingly important role in the aspects of detection and development of ocean resources. The ultra-short baseline array is generally rigidly arranged on a lifting rod at the center or on the side of the working mother ship, is placed under water during working, and the transponder is arranged on an under-water tested target T, so that the under-water target positioning and tracking are realized through an ultra-short baseline positioning principle. The working principle diagram is shown in fig. 1, wherein an ultra-short baseline array adopts an orthogonal cross array, 4 receiving array elements are distributed as shown in fig. 1, and T is an underwater target provided with a transponder. The traditional ultra-short baseline positioning usually adopts CW pulses as response signals and utilizes the phase difference among array elements to perform target positioning, but the method is often afflicted by problems of phase ambiguity, quadrant distortion, multi-path interference and the like, and in addition, the positioning accuracy is very limited. The wideband spread spectrum response scheme is adopted for international ultra-short baseline positioning in the last twenty years, and can enhance the anti-interference capability of the system, improve the processing gain of signals and improve the positioning accuracy. The underwater sound channel is a time-varying and space-varying multi-path channel, in a multi-path channel model, R represents the distance from a sound source to a receiving point, direct signals and reflection signals are mutually overlapped at the receiving point, and in general, the direct wave arrives earlier than the reflection wave, and the multi-path influence brings difficulty to the detection and parameter estimation of the direct signals (along a direct sound line R). The conventional delay estimation adopts a method for searching the maximum value position of the correlation peak, but under the condition of serious multi-path influence, the situation that the correlation peak overlapped in multiple paths is larger than the correlation peak of the direct wave often occurs, if the position of the correlation peak is determined by a method for searching the maximum value of the correlation sequence, errors obviously occur, positioning data are scattered, and the real situation cannot be reflected. Disclosure of Invention The application aims to provide a method for improving the positioning precision of an ultra-short baseline system by resisting multi-path time delay estimation, which overcomes time delay estimated value jump caused by shallow water strong multi-path, accurately estimates direct wave time delay, eliminates false peaks, reduces false judgment probability and ensures the positioning precision of the ultra-short baseline. In order to achieve the aim of the application, the application adopts the following technical scheme: The invention relates to a method for improving the positioning precision of an ultra-short baseline system by anti-multi-path time delay estimation, which comprises an ultra-short baseline array, signal processing equipment, a host and an underwater transponder, wherein the ultra-short baseline array adopts an orthogonal cross array and comprises a first array element, a second array element, a third array element, a fourth array element and a transmitting transducer, the ultra-short baseline array is rigidly arranged on a lifting rod at the center or the side of a mother ship, is placed under water when in operation, the underwater transponder is arranged on an underwater tested target T, a basic array coordinate system is established on the ultra-short baseline array, the transmitting transducer is taken as an origin of the coordinate system, the first array element and the third array element are taken as X-axes, the second array element and the fourth array element are taken as Y-axes, and a basic array aperture D 1 between the first array element and the third array element is calibrated in advance by taking a vertical ultra-short baseline array as a Z-axis; when the ultra-short baseline positioning system works, the host computer controls the transmitting transducer to transmit a broadband query sound signal through the signal processing equipment, the broadband query sound signal is received by the underwater transponder after being transmitted by the underwater sound, the response signal with different systems with the broadban