Buoy system, moving target measuring method and device thereof and storage medium

Abstract

The invention relates to a buoy system, a moving target measurement method and device thereof and a storage medium, and the method comprises the steps: respectively receiving target arrival time, Doppler scaling factors, target depth values and base station coordinate information sent by a plurality of water surface base stations, the target arrival time, the Doppler scaling factor, the target depth value and the base station coordinate information are obtained by receiving a composite beacon signal sent by a moving target by a water surface base station and performing signal processing on the composite beacon signal; the composite beacon signal comprises a composite hyperbolic frequency modulation waveform and a cyclic prefix orthogonal frequency division multiplexing symbol; estimating the target position of the moving target based on the target arrival time, the current coordinate information and the target depth value, and estimating the target speed of the moving target based on the Doppler scaling factor; compared with the prior art, the technical scheme of the invention can integrate the estimation of the position and the speed of the underwater moving target, and improves the estimation accuracy.

Description

Technical Field

[0001] This application relates to the technical field of underwater positioning, and in particular to a buoy system and its moving target measurement method, equipment and storage medium. Background Technology

[0002] Tracking technology for underwater vehicles is an important field in marine engineering and scientific research. With the widespread application of underwater vehicles in marine resource exploration, environmental monitoring and military reconnaissance, the demand for accurate tracking of their real-time position and speed is increasing.

[0003] Currently, underwater vehicle tracking solutions mainly employ the following technical approaches: positioning via a positioning system with multiple base stations deployed on the seabed; using surface buoys as base station platforms, acquiring their own position via GPS, and then locating underwater targets via acoustic ranging; positioning based on time difference of arrival; and measuring velocity by estimating the Doppler scaling factor. In the implementation of these technical solutions, a single hyperbolic frequency modulation signal is commonly used for ranging, traditional orthogonal frequency division multiplexing symbols are used for communication, and separate position and velocity estimation systems are employed.

[0004] However, the impulse noise interference in the underwater environment makes it easy for a single hyperbolic frequency modulated signal to produce false detections, resulting in abnormal ranging data. Traditional methods only use empty subcarriers of orthogonal frequency division multiplexing for Doppler estimation, which has limited accuracy under complex underwater channel conditions and insufficient Doppler estimation accuracy. Summary of the Invention

[0005] This application provides a buoy system and its moving target measurement method, device and storage medium, which can integrate the estimation of the position and velocity of underwater moving targets and improve the accuracy of the estimation.

[0006] In a first aspect, this application provides a method for measuring moving targets in a buoy system, comprising: receiving target arrival time, Doppler scaling factor, target depth value, and base station coordinate information transmitted by multiple surface base stations, wherein the target arrival time, the Doppler scaling factor, the target depth value, and the base station coordinate information are obtained by the surface base stations receiving a composite beacon signal transmitted by a moving target and processing the composite beacon signal, the composite beacon signal including a composite hyperbolic frequency modulated waveform and a cyclic prefix orthogonal frequency division multiplexing symbol; estimating the target position of the moving target based on the target arrival time, the base station coordinate information, and the target depth value, and estimating the target velocity of the moving target based on the Doppler scaling factor.

[0007] In one possible implementation, the surface base station receives a composite beacon signal transmitted by a moving target and performs signal processing on the composite beacon signal, including: receiving the composite beacon signal transmitted by the moving target, wherein the composite beacon signal includes a composite hyperbolic frequency modulated waveform and a cyclic prefix orthogonal frequency division multiplexing (CFD) symbol; estimating the arrival time of the composite hyperbolic frequency modulated waveform to obtain the target arrival time; estimating the Doppler scaling factor of the CFD symbol to obtain the Doppler scaling factor; and modulating the CFD symbol to obtain the target depth value of the moving target.

[0008] In one possible implementation, the generation process of the composite beacon signal includes: setting parameters for a first hyperbolic frequency modulated (HFM) waveform and a second hyperbolic frequency modulated (HFM) waveform; generating a first hyperbolic frequency modulated (HFM) waveform based on the first HFM waveform parameters, and generating a second hyperbolic frequency modulated (HFM) waveform based on the second HFM waveform parameters; splicing the first and second hyperbolic frequency modulated (HFM) waveforms based on a preset hyperbolic frequency modulated (HFM) waveform interval to obtain a composite hyperbolic frequency modulated (HFM) waveform; setting parameters for cyclic prefix orthogonal frequency division multiplexing (OFDM) symbols, constructing a frequency domain signal based on the cyclic prefix OFDM symbols, and performing an inverse Fourier transform on the frequency domain signal to obtain orthogonal frequency division multiplexing (OFDM) symbols; adding a cyclic prefix to the OFDM symbols to obtain cyclic prefix OFDM symbols; and splicing the composite hyperbolic frequency modulated (HFM) waveform and the cyclic prefix OFDM symbols to obtain the composite beacon signal.

[0009] In one possible implementation, before estimating the arrival time of the composite hyperbolic frequency modulated waveform to obtain the target arrival time, the method further includes: discretizing the composite hyperbolic frequency modulated waveform to obtain a composite hyperbolic frequency modulated waveform sequence; performing frame segmentation on the composite hyperbolic frequency modulated waveform sequence to obtain a first segment of hyperbolic frequency modulated waveform frame data and a second segment of hyperbolic frequency modulated waveform frame data; calculating a first sliding correlation value by sliding the first segment of hyperbolic frequency modulated waveform frame data according to a preset detection window, and calculating a first page detection decision value corresponding to the first sliding correlation value based on a preset page test recursive formula during the sliding process; and comparing the first page detection decision value with a first page detection decision value threshold. If the first pagination detection decision value is greater than the first pagination detection decision value threshold for the first time, the time domain position corresponding to the current hyperbolic frequency FM waveform frame data point is recorded; based on the time domain position corresponding to the current hyperbolic frequency FM waveform frame data point, the target time domain position is determined; at the target time domain position, the second sliding correlation value is calculated based on the detection window sliding through the second segment of hyperbolic frequency FM waveform frame data, and during the sliding process, the second pagination detection decision value corresponding to the second sliding correlation value is calculated based on the preset pagination test recursive formula; the second pagination detection decision value is compared with the second pagination detection decision value threshold, and if the second pagination detection decision value is greater than the second pagination detection decision value threshold, the composite beacon signal is determined to be valid.

[0010] In one possible implementation, estimating the Doppler scaling factor of the cyclic prefix orthogonal frequency division multiplexing (CFD) symbols to obtain the Doppler scaling factor includes: performing a set of resampling processes on the CFD symbols to obtain a resampled signal; performing a fast Fourier transform on the resampled signal to obtain a frequency domain resampled signal, and extracting data from the frequency domain resampled signal to obtain first empty subcarrier data; searching the frequency domain resampled signal with minimizing the energy of the first empty subcarrier as the first objective function to determine an optimized resampling factor; and based on the optimized resampling factor, estimating the Doppler scaling factor of the cyclic prefix orthogonal frequency division multiplexing (CFD) symbols to obtain the Doppler scaling factor. Prefix orthogonal frequency division multiplexing symbols are resampled to obtain the optimal resampled signal; the optimal resampled signal is then subjected to frequency offset compensation to obtain the compensated optimal resampled signal; the compensated optimal resampled signal is then subjected to fast Fourier transform to obtain the frequency domain compensated optimal resampled signal, and data is extracted from the frequency domain compensated optimal resampled signal to obtain the second empty subcarrier data; the frequency domain compensated optimal resampled signal is searched with minimizing the energy of the second empty subcarrier as the second objective function to determine the optimized frequency offset; and a Doppler scaling factor is synthesized based on the optimized resampled factor and the optimized frequency offset.

[0011] In one possible implementation, estimating the arrival time of the composite hyperbolic frequency-modulated waveform to obtain the target arrival time includes: constructing a matched filter; performing matched filtering on the composite hyperbolic frequency-modulated waveform based on the matched filter to obtain a filtered composite hyperbolic frequency-modulated waveform; and based on the peak position of the filtered composite hyperbolic frequency-modulated waveform, performing local fitting on the peak position of the waveform using a parabolic interpolation method to obtain a fitted parabolic equation; and determining the target arrival time based on the fitted parabolic equation.

[0012] In one possible implementation, estimating the target position of the moving target based on the target arrival time, the base station coordinate information, and the target depth value includes: selecting one of the multiple surface base stations as a reference surface base station based on the target arrival time corresponding to each of the multiple surface base stations; calculating the relative arrival time differences between the remaining surface base stations and the reference surface base station; and converting the relative arrival time differences into distance differences; constructing a system of nonlinear equations about the target position based on the base station coordinate information and the distance differences corresponding to each of the multiple surface base stations, wherein the system of nonlinear equations includes a target depth value constraint; and solving the system of nonlinear equations using a least squares iterative algorithm to obtain the target position of the moving target.

[0013] Secondly, this application provides a buoy system, comprising: a cooperative beacon installed on a moving target, multiple surface base stations deployed on the water surface, and a data center; wherein the cooperative beacon is used to generate and broadcast a composite beacon signal, wherein the composite beacon signal includes a composite hyperbolic frequency modulated waveform and a cyclic prefix orthogonal frequency division multiplexing symbol; the multiple surface base stations are respectively used to receive the composite beacon signal transmitted by the moving target, and to perform signal processing on the composite beacon signal to obtain target arrival time, Doppler scaling factor, target depth value, and base station coordinate information; the data center is used to respectively receive the target arrival time, Doppler scaling factor, target depth value, and base station coordinate information transmitted by the multiple surface base stations, estimate the target position of the moving target based on the target arrival time, the current coordinate information, and the target depth value, and estimate the target velocity of the moving target based on the Doppler scaling factor.

[0014] Thirdly, embodiments of this application also provide a computer device, which includes a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the above-described method.

[0015] Fourthly, embodiments of this application also provide a computer-readable storage medium storing a computer program that, when executed by a processor, can implement the above-described method.

[0016] This application provides a buoy system and its moving target measurement method, device, and storage medium, which have the following advantages compared with the prior art:

[0017] By receiving target arrival time, Doppler scaling factor, target depth, and base station coordinates from multiple surface base stations based on composite hyperbolic frequency modulated waveforms and cyclic prefix orthogonal frequency division multiplexing (CFD) symbols in composite beacon signals, and simultaneously using these parameters for position estimation and velocity estimation based on the Doppler scaling factor, the system not only improves estimation accuracy but also solves the problem of separation between position and velocity estimation in existing technologies. This provides more complete and accurate motion status information for real-time monitoring and navigation of underwater vehicles. Specifically, the composite hyperbolic frequency modulated waveform improves signal detection reliability and reduces false detection rate; the CFD symbols enable efficient transmission of Doppler estimation and key information, improving the system's spectral efficiency and response speed, thus meeting the high-precision tracking requirements in complex underwater environments. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0021] Figure 1 This is a flowchart illustrating an embodiment of a moving target measurement method for a buoy system provided in this application;

[0022] Figure 2 This is a schematic diagram of one embodiment of a buoy system provided in this application;

[0023] Figure 3This is a schematic diagram of the structure of a computer device provided in this application. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0026] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0027] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0028] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0029] As used in this specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrases "if determined" or "if [described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [described condition or event] is detected," or "in response to detection of [described condition or event]."

[0030] Example 1, see Figure 1 , Figure 1 This is a flowchart illustrating one embodiment of a moving target measurement method for a buoy system provided in this application, as shown below. Figure 1 As shown, the method includes steps 101-102, as detailed below:

[0031] Step 101: Receive target arrival time, Doppler scaling factor, target depth value, and base station coordinate information transmitted by multiple surface base stations, wherein the target arrival time, Doppler scaling factor, target depth value, and base station coordinate information are obtained by the surface base station receiving a composite beacon signal transmitted by a moving target and processing the composite beacon signal. The composite beacon signal includes a composite hyperbolic frequency modulated waveform and a cyclic prefix orthogonal frequency division multiplexing symbol.

[0032] In one embodiment, the moving target measurement method provided in this application is applicable to buoy systems.

[0033] The buoy system is a distributed intelligent buoy system.

[0034] In one embodiment, the buoy system includes a cooperative beacon mounted on a moving target, multiple surface base stations deployed on the water surface, and a data center; wherein the moving target includes, but is not limited to, an underwater vehicle.

[0035] Specifically, the cooperative beacon is installed on the underwater vehicle for periodically broadcasting composite beacon signals; the surface base station is deployed on the water surface for receiving and processing the composite beacon signals broadcast by the cooperative beacon; and the data center is used to collect the data obtained by each surface base station after processing the received composite beacon signals, and to evaluate the status of the underwater vehicle based on the processed data.

[0036] Specifically, the plurality of surface base stations are communicatively connected to the cooperative beacon on the moving target; the plurality of surface base stations are communicatively connected to the data center.

[0037] In one embodiment, the composite beacon signal generated by the cooperative beacon includes a composite hyperbolic frequency modulation waveform and a cyclic prefix orthogonal frequency division multiplexing symbol, wherein the composite hyperbolic frequency modulation waveform includes a first segment of hyperbolic frequency modulation waveform and a second segment of hyperbolic frequency modulation waveform.

[0038] Specifically, since the underwater environment is easily affected by pulse noise, in this embodiment of the application, a composite hyperbolic frequency modulation waveform is used when generating the composite beacon signal. The second segment of the hyperbolic frequency modulation waveform is used as redundancy for double checking, which can effectively reduce false alarms caused by pulse interference and improve the reliability of the system in complex underwater environments. At the same time, when generating the composite beacon signal, a cyclic prefix orthogonal frequency division multiplexing symbol is also used to realize Doppler estimation and key information transmission.

[0039] In one embodiment, the generation process of the composite beacon signal includes: setting parameters for a first hyperbolic frequency modulated (HFM) waveform and a second hyperbolic frequency modulated (HFMD) waveform; generating a first hyperbolic frequency modulated (HFMD) waveform based on the first HFM waveform parameters, and generating a second hyperbolic frequency modulated (HFMD) waveform based on the second HFM waveform parameters; splicing the first and second hyperbolic frequency modulated (HFMD) waveforms based on a preset hyperbolic frequency modulated (HFMD) waveform interval to obtain a composite hyperbolic frequency modulated (HFMD) waveform; setting parameters for cyclic prefix orthogonal frequency division multiplexing (OFDM) symbols, constructing a frequency domain signal based on the cyclic prefix OFDM symbols, and performing an inverse Fourier transform on the frequency domain signal to obtain an orthogonal frequency division multiplexing (OFDM) symbol; adding a cyclic prefix to the OFDM symbol to obtain a cyclic prefix OFDM symbol; and splicing the composite hyperbolic frequency modulated (HFMD) waveform and the cyclic prefix OFDM symbol to obtain a composite beacon signal.

[0040] Specifically, the parameters of the first hyperbolic frequency modulation waveform include, but are not limited to, a first start frequency, a first end frequency, and a first duration; preferably, the first start frequency is set to 18kHz, the first end frequency to 22kHz, and the first duration to 50ms.

[0041] Specifically, the parameters of the second hyperbolic frequency modulation waveform include, but are not limited to, the second start frequency, the second end frequency, and the second duration; preferably, the second start frequency is set to 22kHz, the second end frequency to 18kHz, and the second duration to 50ms.

[0042] Preferably, the frequency change direction of the first hyperbolic frequency modulation waveform is opposite to that of the second hyperbolic frequency modulation waveform. That is, the first hyperbolic frequency modulation waveform sweeps from a lower frequency to a higher frequency, while the second hyperbolic frequency modulation waveform sweeps from a higher frequency to a lower frequency.

[0043] Specifically, a hyperbolic frequency modulation waveform interval is set to avoid spectral aliasing when the first and second hyperbolic frequency modulation waveforms are spliced ​​together.

[0044] Specifically, when generating the first hyperbolic frequency modulation waveform based on the parameters of the first hyperbolic frequency modulation waveform, the first start frequency, the first end frequency, and the first duration are substituted into the preset modulation slope calculation formula to calculate the first modulation slope corresponding to the first hyperbolic frequency modulation waveform. Based on the first modulation slope, the time-domain sampling points of the first hyperbolic frequency modulation waveform are generated using the preset hyperbolic frequency modulation waveform discretization formula to obtain the time-domain signal of the first hyperbolic frequency modulation waveform.

[0045] Specifically, when generating the second hyperbolic frequency modulation waveform based on the parameters of the second hyperbolic frequency modulation waveform, the second start frequency, the second end frequency, and the second duration are substituted into the preset modulation slope calculation formula to calculate the second modulation slope corresponding to the second hyperbolic frequency modulation waveform. Based on the second modulation slope, the time-domain sampling points of the second hyperbolic frequency modulation waveform are generated using the preset hyperbolic frequency modulation waveform discretization formula to obtain the time-domain signal of the second hyperbolic frequency modulation waveform.

[0046] Specifically, the formula for calculating the frequency modulation slope is as follows:

[0047]

[0048] In the formula, μ is the frequency modulation slope, and f start f is the starting frequency. end For the termination frequency, T HFM For duration.

[0049] Specifically, the discretization formula for the hyperbolic frequency modulated waveform is as follows:

[0050]

[0051] In the formula, s HFM [n] represents the nth time-domain sampling point in the hyperbolic frequency modulation waveform, A is the amplitude normalization coefficient, μ is the frequency modulation slope, and f start T is the starting frequency. HFM For duration, f s The sampling rate.

[0052] Specifically, the hyperbolic frequency modulation waveform is spliced ​​together in the order of the first segment, the preset hyperbolic frequency modulation waveform interval, and the second segment to obtain a composite hyperbolic frequency modulation waveform, as shown below:

[0053] s dual-HFM =[s HFM1 ,zeros(T gap ·f s ),s HFM2];

[0054] In the formula, s dual-HFM For a composite hyperbolic frequency modulated waveform, s HFM1 The interval of the hyperbolic frequency modulated waveform is s. HFM2 For the second segment of the hyperbolic frequency FM waveform, T gap f is the interval of the hyperbolic frequency modulated waveform. s The sampling rate.

[0055] Specifically, the cyclic prefix orthogonal frequency division multiplexing symbol parameters include, but are not limited to, the number of subcarriers, the number of effective subcarriers allocated, the cyclic prefix length, and the symbol duration. The number of effective subcarriers allocated includes the number of data subcarriers, the number of pilot subcarriers, and the number of empty subcarriers.

[0056] Specifically, when constructing the frequency domain signal based on the cyclic prefix orthogonal frequency division multiplexing (CFD) symbol parameters, the depth value and period number of the moving target to be transmitted are converted from binary data into complex symbols using quadrature phase shift keying (QPSK) modulation. These complex symbols are then assigned to the data subcarriers in the CFD symbol. Simultaneously, a fixed set of pseudo-random sequences is acquired and assigned to the pilot subcarriers in the CFD symbol. The empty subcarriers in the CFD symbol are then zeroed out to obtain the frequency domain signal.

[0057] Specifically, the frequency domain signal is subjected to inverse Fourier transform processing to obtain orthogonal frequency division multiplexing symbols, wherein the inverse Fourier transform processing is as follows:

[0058]

[0059] In the formula, x[n] is the orthogonal frequency division multiplexing symbol, X[k] is the frequency domain signal, and N sc This represents the number of subcarriers.

[0060] Specifically, to reduce the impact of multipath effects and simplify signal synchronization processing, a cyclic prefix needs to be added before the orthogonal frequency division multiplexing (OFDM) symbol. This cyclic prefix is ​​obtained by truncating a segment of signal from the end of the OFDM symbol and inserting it at the beginning of the OFDM symbol; for example, truncating a segment of signal from the end of the OFDM symbol obtained after inverse Fourier transform processing. CP ×f s These sampling points are inserted at the beginning of the orthogonal frequency division multiplexing symbol x[n] to form the final cyclic prefix orthogonal frequency division multiplexing symbol s. OFDM .

[0061] Specifically, the composite hyperbolic frequency modulated waveform and the cyclic prefix orthogonal frequency division multiplexing symbol are concatenated to obtain the composite beacon signal s. beacon =[s dual-HFM ,s OFDM ].

[0062] Specifically, the total length of the composite beacon signal is:

[0063] T total =T HFM1 +T gap +T HFM2 +T CP +T OFDM ;

[0064] In the formula, T total T is the total length of the composite beacon signal. HFM1 T represents the length of the first hyperbolic frequency FM waveform. gap T represents the interval of the hyperbolic frequency modulated waveform. HFM2 T represents the length of the second hyperbolic frequency modulated waveform. CP T is the length of the cyclic prefix. OFDM The length of the orthogonal frequency division multiplexing symbol.

[0065] In one embodiment, after generating the composite beacon signal, the composite beacon signal is further subjected to spectral shaping. The purpose of spectral shaping is to reduce out-of-band leakage of the signal by using a windowing function. Out-of-band leakage refers to the portion of a signal that extends beyond its main frequency band in the frequency domain, which may interfere with signals in adjacent frequency bands. By using a windowing function, this leakage can be effectively reduced, thereby improving the spectral purity of the signal.

[0066] Specifically, when performing spectral shaping on the composite beacon signal, a Hanning window is applied to the composite beacon signal to obtain a windowed composite beacon signal, and the windowed composite beacon signal is then subjected to power normalization processing to obtain a normalized composite beacon signal.

[0067] Specifically, when applying the Hanning window to a composite beacon signal, each sampling point in the composite beacon signal is multiplied by the Hanning window value, as shown below:

[0068]

[0069] In the formula, s windowed [n] represents the nth sampling point in the windowed composite beacon signal, s beacon [n] represents the nth sampling point in the composite beacon signal, N total is the total length of the composite beacon signal, and n is the index of the discrete time point.

[0070] Specifically, when performing power normalization on the windowed composite beacon signal, the power normalization process is as follows:

[0071]

[0072] In the formula, s final For the normalized composite beacon signal, s windowed For the windowed composite beacon signal, P max This represents the maximum power allowed by the system.

[0073] In one embodiment, after the cooperative beacon generates a composite beacon signal, it is periodically broadcast to each surface base station so that each surface base station can process the received composite beacon signal.

[0074] In one embodiment, the surface base station receives a composite beacon signal transmitted by a moving target and performs signal processing on the composite beacon signal, including: receiving the composite beacon signal transmitted by the moving target, wherein the composite beacon signal includes a composite hyperbolic frequency modulated waveform and a cyclic prefix orthogonal frequency division multiplexing (CFD) symbol; estimating the arrival time of the composite hyperbolic frequency modulated waveform to obtain the target arrival time; estimating the Doppler scaling factor of the CFD symbol to obtain the Doppler scaling factor; and modulating the CFD symbol to obtain the target depth value of the moving target.

[0075] In one embodiment, the water surface base station estimates the arrival time of the composite hyperbolic frequency modulation waveform and, before obtaining the target arrival time, uses the Page test statistic to perform signal detection on the composite hyperbolic frequency modulation waveform to determine whether the composite hyperbolic frequency modulation waveform is valid.

[0076] Specifically, when performing signal detection on the composite hyperbolic frequency modulation waveform to determine its validity, the composite hyperbolic frequency modulation waveform is discretized to obtain a composite hyperbolic frequency modulation waveform sequence. The composite hyperbolic frequency modulation waveform sequence is then framed to obtain a first segment of hyperbolic frequency modulation waveform frame data and a second segment of hyperbolic frequency modulation waveform frame data. A first sliding correlation value is calculated by sliding the first segment of hyperbolic frequency modulation waveform frame data through a preset detection window. During the sliding process, based on a preset paging test recursive formula, a first paging detection decision value corresponding to the first sliding correlation value is calculated. The first paging detection decision value is compared with a first paging detection decision value threshold. If the... When the first pagination detection decision value first exceeds the first pagination detection decision value threshold, the time domain position corresponding to the current hyperbolic frequency FM waveform frame data point is recorded; based on the time domain position corresponding to the current hyperbolic frequency FM waveform frame data point, the target time domain position is determined; at the target time domain position, the second sliding correlation value is calculated based on the detection window sliding through the second segment of hyperbolic frequency FM waveform frame data, and during the sliding process, the second pagination detection decision value corresponding to the second sliding correlation value is calculated based on the preset pagination test recursive formula; the second pagination detection decision value is compared with the second pagination detection decision value threshold, and if the second pagination detection decision value is greater than the second pagination detection decision value threshold, the composite beacon signal is determined to be valid.

[0077] Specifically, the water surface base station discretizes the received composite hyperbolic frequency modulation waveform based on a preset sampling rate to obtain a composite hyperbolic frequency modulation waveform sequence r[n]; preferably, the preset sampling rate is 48kHz.

[0078] Specifically, the composite hyperbolic frequency modulation (HFM) waveform sequence is framed according to the length of a single hyperbolic frequency modulation (HFM) waveform segment of 50ms. The frame length contains 50ms × 48kHz = 2400 sampling points. Since the composite hyperbolic frequency modulation (HFM) waveform consists of "the first hyperbolic frequency modulation waveform segment + the hyperbolic frequency modulation waveform interval + the second hyperbolic frequency modulation waveform segment", when framing, the frame data of the corresponding first hyperbolic frequency modulation waveform segment can be extracted by using a forward frequency sweep method on the composite hyperbolic frequency modulation (HFM) waveform sequence, and the frame data of the corresponding second hyperbolic frequency modulation (HFM) waveform segment can be extracted by using a reverse frequency sweep method on the composite hyperbolic frequency modulation (HFM) waveform sequence.

[0079] Specifically, an ideal single-segment hyperbolic frequency modulation waveform consistent with the parameters of the data transmitter is generated, and the ideal single-segment hyperbolic frequency modulation waveform undergoes energy over-normalization processing to ensure that it meets the requirements.

[0080] Specifically, the first sliding correlation value is calculated by sliding the first hyperbolic frequency FM waveform frame data according to a preset detection window. The sliding window starts from position k=0 and moves by 1 sampling point each time until the window covers the first hyperbolic frequency FM waveform frame data. The formula for calculating the sliding correlation value is as follows:

[0081]

[0082] In the formula, y[k] is the sliding correlation value, L win To detect the window length, * represents conjugate, s HFM [n] represents the ideal single-segment hyperbolic frequency modulation waveform that matches the parameters of the data transmitter.

[0083] Specifically, the preset pagination test recursive formula is as follows:

[0084] P[k]=max(0,P[k-1]+ln(1+γ·y[k]));

[0085] In the formula, γ is the signal-to-noise ratio adjustment factor, P[k] is the paging detection decision quantity, and the initial value is P[0] = 0.

[0086] Specifically, when calculating the first page detection decision value corresponding to the first sliding correlation value based on the preset page test recursive formula, the page detection decision value P[k] is accumulated using the page test recursive formula to suppress random noise and enhance the continuous signal characteristics. This recursion converts the instantaneous correlation value into a cumulative value through logarithmic operation. When the signal continues to exist, the page detection decision value P[k] gradually increases.

[0087] Specifically, when the first page detection decision quantity P[k] exceeds the first page detection decision quantity threshold h1 for the first time, the current position k1 is recorded. This position corresponds to the arrival time domain position of the first hyperbolic frequency FM waveform frame data, i.e., the sampling point position; where the first page detection decision quantity threshold h1 = -ln(PFA), PFA = 10-4.

[0088] Specifically, based on the time-domain position k1 corresponding to the first hyperbolic frequency modulation waveform frame data point, plus the hyperbolic frequency modulation waveform interval time T... gap The corresponding number of sampling points is T gap ·f s The expected detection start position of the second hyperbolic frequency FM waveform frame data point is k1+T. gap ·f s And use it as the target time domain location.

[0089] Specifically, at the target time domain position, the detection of the second hyperbolic frequency FM waveform frame data points is initiated. The second sliding correlation value is calculated by repeatedly sliding the second hyperbolic frequency FM waveform frame data points according to the preset detection window. The second paging detection decision value corresponding to the second sliding correlation value is calculated based on the preset paging test recursive formula. If the second paging detection decision value of the second hyperbolic frequency FM waveform frame data points exceeds the second paging detection decision value threshold h2 within the expected time window, i.e., within the length of the second hyperbolic frequency FM waveform frame data points, then the composite hyperbolic frequency FM waveform is confirmed to be valid.

[0090] Specifically, the first pagination detection decision threshold is greater than the second pagination detection decision threshold; preferably, the first pagination detection decision threshold h1 is 9.21, corresponding to a false alarm rate ≤0.01%, and the second pagination detection decision threshold h2 is 6.91.

[0091] Specifically, by employing a dual mechanism of first detecting based on the data points of the first hyperbolic frequency FM waveform frame and then verifying based on the data points of the second hyperbolic frequency FM waveform frame, the false alarm rate is reduced by utilizing the temporal correlation of the hyperbolic frequency FM waveform frame data points. Compared with the single-segment hyperbolic frequency FM waveform scheme, the false detection rate can be reduced by more than 60%, ensuring that the detected signal is the real transmitted signal rather than random noise or multipath interference.

[0092] In one embodiment, after determining that the composite hyperbolic frequency modulated waveform is a valid signal, the arrival time of the composite hyperbolic frequency modulated waveform is estimated to obtain the target arrival time. Specifically, a matched filter is constructed, and the composite hyperbolic frequency modulated waveform is subjected to matched filtering processing based on the matched filter to obtain a filtered composite hyperbolic frequency modulated waveform. Based on the peak position of the filtered composite hyperbolic frequency modulated waveform, a parabolic interpolation method is used to perform local fitting processing on the peak position of the waveform to obtain a fitted parabolic equation. Based on the fitted parabolic equation, the target arrival time is determined.

[0093] Specifically, when constructing the matched filter, based on the ideal single-segment hyperbolic frequency FM waveform consistent with the parameters of the data transmitter, the filter impulse response h[n] = s is constructed. HFM[N-1-n], that is, time-domain reversal of the ideal single-segment hyperbolic frequency modulation waveform; the physical meaning of this operation is to maximize the filter's response to the target signal and suppress noise and non-target signals; and to convert the composite hyperbolic frequency modulation waveform and the filter impulse response to frequency domain signals through fast Fourier transform, multiply them, and then inversely transform them back to time domain signals to obtain the filtered composite hyperbolic frequency modulation waveform y[n]. The frequency domain realization process of the composite hyperbolic frequency modulation waveform is: Y(f)=R(f)·H(f),H(f)=FFT(h[n]), where h[n] is the filter impulse response, H(f) is the filter impulse response after Fourier transform, R(f) is the composite hyperbolic frequency modulation waveform after Fourier transform, and Y(f) is the frequency domain filtered composite hyperbolic frequency modulation waveform.

[0094] Specifically, the peak position of the filtered composite hyperbolic frequency modulated waveform is used as the initial estimated arrival time, wherein the peak position of the waveform...

[0095] Specifically, when using parabolic interpolation to perform local fitting processing on the waveform peak position, at the waveform peak position... Select three points in the vicinity: (n0-1, y0), (n0, y1), and (n0+1, y2). The three points form a local peak region, representing the integer positions after rounding. Using the coordinates of these three points, a parabola is fitted, yielding the equation of the fitted parabola:

[0096]

[0097] In the formula, n true To accurately pinpoint the peak position of the waveform.

[0098] Specifically, by using quadratic curve interpolation, the time resolution is improved to the subsampling level, with a theoretical error of less than 0.1 sampling points, which is significantly better than the accuracy of direct peak detection.

[0099] Specifically, by setting an amplitude threshold, only the first waveform peak position exceeding the threshold is retained, which can suppress interference from multipath reflection signals. In underwater environments, direct waves are usually the strongest signals and arrive earliest; this operation can effectively filter out false peaks of non-direct waves. Simultaneously, a system calibration offset calibrated experimentally is introduced to compensate for hardware latency and inherent algorithm errors. Based on the fitted parabolic equation, when determining the target arrival time, the precise waveform peak position corresponding to the first waveform peak position calculated by the fitted parabolic equation and the system calibration offset are substituted into the preset arrival time calculation formula to obtain the target arrival time. The arrival time calculation formula is as follows:

[0100]

[0101] In the formula, τ is the target arrival time, and n true To accurately pinpoint the waveform peak position, τ cal To calibrate the offset for the system.

[0102] In one embodiment, when estimating the Doppler scaling factor of the cyclic prefix orthogonal frequency division multiplexing (CFD) symbols to obtain the Doppler scaling factor, a set of resampling processes is performed on the CFD symbols to obtain a resampled signal; a fast Fourier transform is performed on the resampled signal to obtain a frequency domain resampled signal, and data extraction is performed on the frequency domain resampled signal to obtain the first empty subcarrier data; the frequency domain resampled signal is searched with minimizing the energy of the first empty subcarrier as the first objective function to determine an optimized resampling factor; based on the optimized resampling factor, the cyclic prefix orthogonal frequency division multiplexing (CFD) symbols are resampled. Frequency division multiplexing symbols are resampled to obtain an optimal resampled signal; frequency offset compensation is performed on the optimal resampled signal to obtain a compensated optimal resampled signal; a fast Fourier transform is performed on the compensated optimal resampled signal to obtain a frequency domain compensated optimal resampled signal, and data is extracted from the frequency domain compensated optimal resampled signal to obtain second empty subcarrier data; the frequency domain compensated optimal resampled signal is searched with minimizing the energy of the second empty subcarrier as the second objective function to determine an optimized frequency offset; and a Doppler scaling factor is synthesized based on the optimized resampling factor and the optimized frequency offset.

[0103] Specifically, based on the resampling factor to be optimized, a set of resampling processes is performed on the cyclic prefix orthogonal frequency division multiplexing symbols to obtain the resampled signal y. rx (1+at), where a is the resampling factor used to compensate for time-domain scaling. The physical meaning of resampling is to restore the time-domain distorted signal caused by Doppler to the standard duration by adjusting the time scale.

[0104] Specifically, the resampled signal undergoes a Fast Fourier Transform to obtain the frequency domain resampled signal Y. rx [k], extracts a preset set of empty subcarrier indices S from the frequency domain signal. N The corresponding first empty subcarrier data, since the empty subcarrier has been set to zero at the data transmitting end, should ideally have zero energy.

[0105] Specifically, with the goal of minimizing the energy of the first empty subcarrier, a first objective function is constructed. This function is found by scanning within a preset range (e.g., a ∈ [-0.02, 0.02]) with a step size Δa = 0.001, using the value of a that minimizes the total energy of the first empty subcarrier. opt This is used as the optimization resampling factor, where the first objective function is as follows:

[0106]

[0107] In the formula, a opt To optimize the resampling factor, Y rx [k] represents the frequency domain resampled signal, S N A set of empty subcarrier indexes reserved for future use.

[0108] Specifically, based on the optimized resampling factor, the cyclic prefix orthogonal frequency division multiplexing symbols are resampled to obtain the optimal resampled signal, denoted as y. resampled (t)=y rx (t / 1+a opt t); Since the time-domain scaling has been initially compensated at this point, but there is still residual frequency-domain offset, frequency offset compensation is still needed for the optimal resampled signal. The frequency offset compensation is as follows:

[0109]

[0110] In the formula, z(t) is the optimal resampled signal after frequency offset compensation, and f m This represents the frequency offset.

[0111] Specifically, the optimal resampled signal after frequency offset compensation is subjected to Fourier transform processing to obtain the optimal resampled signal in the frequency domain. A preset set of empty subcarrier indices S is then extracted from this optimal resampled signal. N The corresponding second empty subcarrier data, and with the goal of minimizing the energy of the second empty subcarrier, a second objective function is constructed, which is achieved within a preset range, such as f. m Scan the frequency range (∈[-50,50]Hz) to find the f that minimizes the energy of the empty subcarrier. opt This is used as the optimized frequency offset; the second objective function is as follows:

[0112]

[0113] In the formula, f opt To optimize frequency offset, Z[k] is the optimal resampled signal for frequency domain compensation, and S N A set of empty subcarrier indexes reserved for future use.

[0114] Specifically, when synthesizing the Doppler scaling factor based on the optimized resampling factor and the optimized frequency offset, the optimized resampling factor and the optimized frequency offset are substituted into the Doppler scaling factor determination formula to obtain the Doppler scaling factor. The Doppler scaling factor determination formula is as follows:

[0115]

[0116] In the formula, η is the Doppler scaling factor, and f optTo optimize frequency offset, a opt To optimize the resampling factor, f c The signal center frequency.

[0117] In one embodiment, a clock synchronization method is also used when estimating the target arrival time and the Doppler emission factor to provide a basic time reference for the system's time synchronization and signal processing.

[0118] Specifically, the clock synchronization method employs a dual-clock source approach, using the pulse-per-second signal provided by the Global Navigation Satellite System (GNSS) receiver as one synchronization clock source and the crystal oscillator built into the digital signal processor (DSP) as the other. Due to the high precision of the pulse-per-second signal, it can provide a synchronized time reference for multiple receivers, and its synchronization accuracy meets the time synchronization requirements of this invention. The pulse-per-second output is connected to the DSP's general-purpose input / output pins, and the DSP continuously counts the received pulse-per-second signals since system startup. Since the pulse-per-second signal frequency is only 1Hz, it is insufficient to meet the demand for a high-frequency clock; therefore, a crystal oscillator is introduced as another clock source. This crystal oscillator typically provides a 1kHz clock source to compensate for the insufficient frequency of the pulse-per-second signal.

[0119] Specifically, a hybrid clock source is generated by combining the pulse-per-second signal and the crystal oscillator output. This hybrid clock source output is named the clock tick count (CTC). Specifically, two variables, Cint and Cfrac, are defined, both initialized to zero when the digital signal processor (DSP) starts. Cint increments by 1 each time a pulse-per-second signal is received; Cfrac also increments by 1 each time a crystal oscillator pulse is received. Cint (the integer part of the clock tick count CTC) records the number of pulse-per-second signals received since the DSP started, while Cfrac (the fractional part of the clock tick count CTC) records the number of crystal oscillator outputs received since the most recent pulse-per-second signal. By combining Cint and Cfrac, the expression for the clock tick count CTC is: CTC = Cint + Cfrac / 1000. Thus, CTC becomes a decimal number with both an integer and a fractional part, representing the elapsed time since the digital signal processor started. Furthermore, to limit errors caused by crystal oscillator clock drift, Cfrac is reset to 0 each time a pulse signal per second is received, ensuring that the crystal oscillator output is valid for only one second. In this way, the error caused by crystal oscillator clock drift is kept within an acceptable range over a relatively short period.

[0120] In one embodiment, the cyclic prefix orthogonal frequency division multiplexing symbol is regulated to obtain not only the target depth value of the moving target, but also the period number information.

[0121] In one embodiment, when adjusting the cyclic prefix orthogonal frequency division multiplexing (OCFDM) symbol to obtain the target depth value and period number information of the moving target, the starting position of the OCFDM symbol in the composite beacon signal is determined, and the cyclic prefix is ​​removed from the OCFDM symbol to retain the OCFDM symbol; the OCFDM symbol is then subjected to Fourier transform processing to obtain the frequency domain OCFDM symbol; and the pilot subcarrier Y in the frequency domain OCFDM symbol is extracted according to a preset pilot pattern. p [k], based on pilot subcarriers and the already piloted sequence X p [k] Perform channel estimation to obtain the pilot channel response H[k]=X p [k] / Y p [k]; and interpolate the pilot channel response to obtain the channel responses H[k] of all subcarriers; extract the data subcarriers Y from the frequency domain orthogonal frequency division multiplexing symbols. d [k], Based on the channel responses of all subcarriers, frequency domain equalization is performed on the data subcarriers to obtain the frequency domain equalized symbol X. d [k] = H[k]Yd[k], for frequency domain data symbol X d [k] is used for QPSK demodulation to obtain the phase angle φ[k] = arg(X) of each frequency domain data symbol. d [k]), and according to the phase quadrant, the phase angle is mapped to bit data, and the bit data is spliced ​​in a preset order to obtain a bit sequence, and the target depth value and period number information are extracted from the bit sequence; for example, the first multiple bit values ​​in the bit sequence are used as the target depth value, and the last multiple bit values ​​in the bit sequence are used as the period number information.

[0122] Specifically, when mapping the phase angle to bit data according to the phase quadrant, if the phase range is (-π / 4, π / 4], the bit data is 00; if the phase range is (π / 4, 3π / 4], the bit data is 01; if the phase range is (3π / 4, -3π / 4], the bit data is 11; and if the phase range is (-3π / 4, -π / 4], the bit data is 10.

[0123] Specifically, after obtaining the bit sequence, a cyclic redundancy check (CRC) is performed on the bit sequence to verify data integrity. If the check fails, a retransmission is requested or an error-correcting code, such as a Hamming code, is used for repair.

[0124] Specifically, the period number information is used to mark the transmission period of the composite beacon signal. The receiving end can confirm the timing order of the composite beacon signal through the period number information to avoid frame disorder or duplication. If the period number jumps or is discontinuous, it can be determined that there is signal loss or reception error, triggering the retransmission mechanism or frame synchronization repair. Moreover, when different surface base stations receive beacon signals of the same moving target, the period number information can be used to confirm whether the data is from the same transmission period, avoiding misjudging signals from different periods as the same moment and ensuring the accuracy of subsequent time difference calculations.

[0125] Step 102: Estimate the target position of the moving target based on the target arrival time, the base station coordinate information and the target depth value, and estimate the target velocity of the moving target based on the Doppler scaling factor.

[0126] In one embodiment, when estimating the target position of the moving target based on the target arrival time, the base station coordinate information, and the target depth value, based on the target arrival time corresponding to each of the plurality of surface base stations, one surface base station is arbitrarily selected from the plurality of surface base stations as a reference surface base station. The relative arrival time differences between the remaining surface base stations and the reference surface base station are calculated, and the relative arrival time differences are converted into distance differences. Based on the base station coordinate information and the distance differences corresponding to each of the plurality of surface base stations, a nonlinear equation system about the target position is constructed, wherein the nonlinear equation system includes a target depth value constraint. The least squares iterative algorithm is used to solve the nonlinear equation system to obtain the target position of the moving target.

[0127] Specifically, when the depth of the moving target is known, the system accepts base station coordinate information and target arrival time that includes at least three surface base stations; preferably, when the depth of the moving target is unknown, the system accepts base station coordinate information and target arrival time that includes at least four surface base stations.

[0128] Specifically, one surface base station is selected from the plurality of surface base stations as a reference surface base station; preferably, taking the first surface base station among the plurality of surface base stations as an example, the relative arrival time difference between the remaining base stations and the reference surface base station is calculated: Δt i1 =t i -t1,i=2,…,M; where M is the number of surface base stations, t i Let t1 be the i-th surface base station and t1 be the 1-th surface base station; combining the speed of sound c, the relative time difference of arrival is converted into a distance difference: Δd i1 =c·Δt i1 .

[0129] Specifically, let the position of the underwater moving target be u = (x, y, z), where z is the target depth. According to the distance difference constraint, the target position must satisfy: Based on this, a nonlinear equation system is constructed as h(u)=0. Since the target depth value z is known, it is substituted as a fixed parameter into the nonlinear equation system, simplifying the three-dimensional positioning problem into the positioning of a two-dimensional plane (x,y), reducing the number of variables to be solved and improving computational efficiency.

[0130] Specifically, when solving the nonlinear equations using the least squares iterative algorithm, an initial position guess value u0 = (x0, y0, z) is selected, where the initial position guess is the coordinates of the nearest water surface base station or the historical position of the moving target to accelerate the iteration convergence speed; a Taylor expansion is performed on the nonlinear equations at the initial position guess value, retaining the first-order term: h(u) ≈ h(u0) + J(u0)(u-u0), where J is the Jacobian matrix; and the Levenberg-Marquardt algorithm is used iteratively to solve the equations, with the update formula being: u k+1 =u k -(J T J) -1 J T h(u k Each iteration corrects the position estimate through matrix operations until the position difference between two adjacent iterations is less than a preset threshold, i.e., ||u k+1 -u k If ||<∈, the iteration terminates after the convergence condition is met; preferably, ∈=0.1m.

[0131] In one embodiment, based on the acoustic Doppler principle, the radial velocity v r The relationship between v and the Doppler scaling factor η is: r ≈c·(η-1), where c is the speed of sound; therefore, the target velocity of the moving target can be estimated based on the Doppler scaling factor.

[0132] In one embodiment, when estimating the target velocity of the moving target based on the Doppler scaling factor, the first radial velocity v of the moving target relative to each surface base station is obtained. r,i Based on the first radial velocity and the base station coordinate information corresponding to each water surface base station, a geometric relationship between the radial velocity and the velocity vector is constructed and converted into a system of linear equations. The system of linear equations is solved by linear least squares to obtain the optimal target velocity of the moving target. Based on the estimated target position of the moving target, the optimal target velocity is optimized to obtain the optimized target position of the moving target.

[0133] Specifically, the geometric relationship between radial velocity and velocity vector is as follows: Where, d i Let be the distance from the moving target to the i-th surface base station, which can be transformed into a system of linear equations. Where A is the coefficient matrix, and the i-th row element of the coefficient matrix A is b is the observation vector, where observation vector b = (v r,1 ,v r,2 ,…,v r,M ) T .

[0134] Specifically, the optimal solution for the moving target is the target velocity.

[0135] Specifically, based on the target position estimation results, the coefficient matrix A is iteratively updated until the velocity estimation converges. If the velocity difference between adjacent iterations is less than 0.01 m / s, the final three-dimensional velocity vector of the target is obtained. It can be further decomposed into horizontal velocity and vertical velocity, which can be used for motion trajectory prediction and navigation control.

[0136] Example 2, see Figure 2 , Figure 2 This is a schematic diagram of one embodiment of a buoy system provided in this application, as shown below. Figure 2 As shown, the system includes a cooperative beacon 201 installed on a moving target, multiple surface base stations 202 deployed on the water surface, and a data center 203, as detailed below:

[0137] The cooperative beacon 201 is used to generate and broadcast a composite beacon signal, wherein the composite beacon signal includes a composite hyperbolic frequency modulated waveform and a cyclic prefix orthogonal frequency division multiplexing symbol.

[0138] The plurality of surface base stations 202 are respectively used to receive composite beacon signals sent by moving targets, and to process the composite beacon signals to obtain target arrival time, Doppler scaling factor, target depth value and base station coordinate information.

[0139] The data center 203 is used to receive the target arrival time, Doppler scaling factor, target depth value and base station coordinate information sent by the plurality of surface base stations, respectively, estimate the target position of the moving target based on the target arrival time, the current coordinate information and the target depth value, and estimate the target velocity of the moving target based on the Doppler scaling factor.

[0140] In one embodiment, the plurality of surface base stations 202 are communicatively connected to the cooperative beacon 201 installed on the moving target; the plurality of surface base stations 202 are communicatively connected to the data center 203.

[0141] In one embodiment, the surface base station 202 is configured to receive a composite beacon signal transmitted by a moving target and perform signal processing on the composite beacon signal, including: receiving the composite beacon signal transmitted by the moving target, wherein the composite beacon signal includes a composite hyperbolic frequency modulated waveform and a cyclic prefix orthogonal frequency division multiplexing (CFD) symbol; estimating the arrival time of the composite hyperbolic frequency modulated waveform to obtain the target arrival time; estimating the Doppler scaling factor of the CFD symbol to obtain the Doppler scaling factor; and adjusting the CFD symbol to obtain the target depth value of the moving target.

[0142] In one embodiment, the cooperative beacon 201 is used to generate a composite beacon signal, including: setting parameters for a first hyperbolic frequency modulated (HFM) waveform and a second hyperbolic frequency modulated (HFMD) waveform; generating a first hyperbolic frequency modulated (HFMD) waveform based on the first HFM waveform parameters, and generating a second hyperbolic frequency modulated (HFMD) waveform based on the second HFM waveform parameters; splicing the first and second hyperbolic frequency modulated (HFMD) waveforms based on a preset hyperbolic frequency modulated (HFMD) waveform interval to obtain a composite hyperbolic frequency modulated (HFMD) waveform; setting parameters for cyclic prefix orthogonal frequency division multiplexing (OFDM) symbols, constructing a frequency domain signal based on the cyclic prefix OFDM symbols, and performing an inverse Fourier transform on the frequency domain signal to obtain an orthogonal frequency division multiplexing (OFDM) symbol; adding a cyclic prefix to the OFDM symbol to obtain a cyclic prefix OFDM symbol; and splicing the composite hyperbolic frequency modulated (HFMD) waveform and the cyclic prefix OFDM symbol to obtain a composite beacon signal.

[0143] In one embodiment, before the plurality of surface base stations 202 are used to estimate the arrival time of the composite hyperbolic frequency modulation waveform to obtain the target arrival time, the method further includes: discretizing the composite hyperbolic frequency modulation waveform to obtain a composite hyperbolic frequency modulation waveform sequence; performing frame segmentation on the composite hyperbolic frequency modulation waveform sequence to obtain a first segment of hyperbolic frequency modulation waveform frame data and a second segment of hyperbolic frequency modulation waveform frame data; calculating a first sliding correlation value by sliding the first segment of hyperbolic frequency modulation waveform frame data according to a preset detection window, and calculating a first page detection decision value corresponding to the first sliding correlation value based on a preset page test recursive formula during the sliding process; and comparing the first page detection decision value with a first page detection decision value threshold. If the first pagination detection decision value is greater than the first pagination detection decision value threshold for the first time, the time domain position corresponding to the current hyperbolic frequency FM waveform frame data point is recorded. Based on the time domain position corresponding to the current hyperbolic frequency FM waveform frame data point, the target time domain position is determined. At the target time domain position, the second sliding correlation value is calculated based on the detection window sliding through the second segment of hyperbolic frequency FM waveform frame data. During the sliding process, the second pagination detection decision value corresponding to the second sliding correlation value is calculated based on the preset pagination test recursive formula. The second pagination detection decision value is compared with the second pagination detection decision value threshold. If the second pagination detection decision value is greater than the second pagination detection decision value threshold, the composite beacon signal is determined to be valid.

[0144] In one embodiment, the plurality of surface base stations 202 are respectively used to estimate the Doppler scaling factor of the cyclic prefix orthogonal frequency division multiplexing (CFD) symbols to obtain a Doppler scaling factor, including: performing a set of resampling processes on the CFD symbols to obtain a resampled signal; performing a fast Fourier transform on the resampled signal to obtain a frequency domain resampled signal, and extracting data from the frequency domain resampled signal to obtain first empty subcarrier data; searching the frequency domain resampled signal with minimizing the energy of the first empty subcarrier as the first objective function to determine an optimized resampling factor; and based on the optimized resampling factor, estimating the Doppler scaling factor of the cyclic prefix orthogonal frequency division multiplexing (CFD) symbols to obtain a Doppler scaling factor. The cyclic prefix orthogonal frequency division multiplexing symbols are resampled to obtain the optimal resampled signal; the optimal resampled signal is then subjected to frequency offset compensation to obtain the compensated optimal resampled signal; the compensated optimal resampled signal is then subjected to a fast Fourier transform to obtain the frequency domain compensated optimal resampled signal, and data is extracted from the frequency domain compensated optimal resampled signal to obtain the second empty subcarrier data; the frequency domain compensated optimal resampled signal is searched with minimizing the energy of the second empty subcarrier as the second objective function to determine the optimized frequency offset; and a Doppler scaling factor is synthesized based on the optimized resampled factor and the optimized frequency offset.

[0145] In one embodiment, the plurality of surface base stations 202 are respectively used to estimate the arrival time of the composite hyperbolic frequency modulation waveform to obtain the target arrival time, including: constructing a matched filter, performing matched filtering processing on the composite hyperbolic frequency modulation waveform based on the matched filter to obtain a filtered composite hyperbolic frequency modulation waveform, and determining the peak position of the filtered composite hyperbolic frequency modulation waveform; performing local fitting processing on the peak position of the waveform using a parabolic interpolation method to obtain a fitted parabolic equation, and determining the target arrival time based on the fitted parabolic equation.

[0146] In one embodiment, the data center 203 is used to estimate the target position of the moving target based on the target arrival time, the base station coordinate information, and the target depth value, including: based on the target arrival time corresponding to each of the plurality of surface base stations, arbitrarily selecting one surface base station from the plurality of surface base stations as a reference surface base station, calculating the relative arrival time difference between the remaining surface base stations and the reference surface base station, and converting the relative arrival time difference into a distance difference; constructing a nonlinear equation system about the target position based on the base station coordinate information corresponding to each of the plurality of surface base stations and the distance difference, wherein the nonlinear equation system includes a target depth value constraint; and solving the nonlinear equation system using a least squares iterative algorithm to obtain the target position of the moving target.

[0147] The buoy system described above can implement the moving target measurement method of the buoy system in the above method embodiment. The options in the above method embodiment are also applicable to this embodiment, and will not be described in detail here.

[0148] like Figure 3 As shown, Figure 3 This is a schematic diagram of the structure of a computer device provided in this application; it includes a processor 111, a communication interface 112, a memory 113 and a communication bus 114, wherein the processor 111, the communication interface 112 and the memory 113 communicate with each other through the communication bus 114, and the memory 113 is used to store computer programs.

[0149] In one embodiment of this application, the processor 111, when executing the program stored in the memory 113, implements a moving target measurement method for a buoy system provided in any of the foregoing method embodiments.

[0150] It will be understood by those skilled in the art that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program may be stored in a storage medium, which is a computer-readable storage medium. The computer program is executed by at least one processor in the computer system to implement the process steps of the embodiments of the above methods.

[0151] Therefore, embodiments of this application also provide a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the moving target measurement method of the buoy system provided in any of the foregoing method embodiments.

[0152] The storage medium is a physical, non-transitory storage medium, such as a USB flash drive, external hard drive, read-only memory (ROM), magnetic disk, or optical disk, or any other physical storage medium capable of storing program code. The computer-readable storage medium can be non-volatile or volatile.

[0153] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this application.

[0154] In the embodiments provided in this application, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the system embodiments described above are merely illustrative. For example, the division of each unit is only a logical functional division, and there may be other division methods in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed.

[0155] The steps in the methods of this application embodiment can be adjusted, merged, or deleted according to actual needs. The units in the system of this application embodiment can be merged, divided, or deleted according to actual needs. Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0156] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, a terminal, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application.

[0157] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0158] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Since these modifications and variations fall within the scope of the claims and their equivalents, this application also intends to include these modifications and variations.

[0159] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for measuring moving targets in a buoy system, characterized in that, include: The system receives target arrival time, Doppler scaling factor, target depth value, and base station coordinate information from multiple surface base stations. The target arrival time, Doppler scaling factor, target depth value, and base station coordinate information are obtained by the surface base station receiving a composite beacon signal from a moving target and processing the composite beacon signal. The composite beacon signal includes a composite hyperbolic frequency modulated waveform and a cyclic prefix orthogonal frequency division multiplexing symbol. The target position of the moving target is estimated based on the target arrival time, the base station coordinate information, and the target depth value, and the target velocity of the moving target is estimated based on the Doppler scaling factor.

2. The method as described in claim 1 above, characterized in that, The surface base station receives composite beacon signals transmitted by moving targets and performs signal processing on the composite beacon signals, including: Receive a composite beacon signal sent by a moving target, wherein the composite beacon signal includes a composite hyperbolic frequency modulated waveform and a cyclic prefix orthogonal frequency division multiplexing symbol; The arrival time of the target is estimated by performing an arrival time estimation on the composite hyperbolic frequency modulated waveform; The Doppler scaling factor is estimated by performing Doppler scaling factor estimation on the cyclic prefix orthogonal frequency division multiplexing symbol; The cyclic prefix orthogonal frequency division multiplexing symbol is then adjusted to obtain the target depth value of the moving target.

3. The method as described in claim 2 above, characterized in that, The generation process of the composite beacon signal includes: Set the parameters for the first hyperbolic frequency modulation waveform and the second hyperbolic frequency modulation waveform; Based on the parameters of the first hyperbolic frequency modulation waveform, a first hyperbolic frequency modulation waveform is generated, and based on the parameters of the second hyperbolic frequency modulation waveform, a second hyperbolic frequency modulation waveform is generated. Based on the preset hyperbolic frequency modulation waveform interval, the first hyperbolic frequency modulation waveform and the second hyperbolic frequency modulation waveform are spliced ​​together to obtain a composite hyperbolic frequency modulation waveform. Set the cyclic prefix orthogonal frequency division multiplexing symbol parameters, construct a frequency domain signal based on the cyclic prefix orthogonal frequency division multiplexing symbol parameters, and perform inverse Fourier transform processing on the frequency domain signal to obtain orthogonal frequency division multiplexing symbols; Add a cyclic prefix to the orthogonal frequency division multiplexing symbol to obtain a cyclic prefix orthogonal frequency division multiplexing symbol; The composite hyperbolic frequency modulated waveform and the cyclic prefix orthogonal frequency division multiplexing symbol are spliced ​​together to obtain the composite beacon signal.

4. The method as described in claim 3 above, characterized in that, Before estimating the arrival time of the composite hyperbolic frequency modulated waveform to obtain the target arrival time, the method further includes: Discretize the composite hyperbolic frequency modulated waveform to obtain a composite hyperbolic frequency modulated waveform sequence; The composite hyperbolic frequency modulated waveform sequence is framed to obtain the first hyperbolic frequency modulated waveform frame data and the second hyperbolic frequency modulated waveform frame data. The first sliding correlation value is calculated by sliding the first hyperbolic frequency FM waveform frame data according to the preset detection window, and the first page detection decision value corresponding to the first sliding correlation value is calculated based on the preset page test recursive formula during the sliding process. The first pagination detection decision quantity is compared with the first pagination detection decision quantity threshold. If the first pagination detection decision quantity is greater than the first pagination detection decision quantity threshold for the first time, the time domain position corresponding to the current hyperbolic frequency FM waveform frame data point is recorded. Determine the target time domain location based on the time domain location corresponding to the current hyperbolic frequency modulated waveform frame data point; At the target time domain location, the second sliding correlation value is calculated based on the detection window for the second segment of hyperbolic frequency FM waveform frame data. During the sliding process, the second page detection decision value corresponding to the second sliding correlation value is calculated based on the preset page test recursive formula. The second pagination detection decision value is compared with the second pagination detection decision value threshold. If the second pagination detection decision value is greater than the second pagination detection decision value threshold, the composite beacon signal is determined to be valid.

5. The method as described in claim 2 above, characterized in that, The step of estimating the Doppler scaling factor of the cyclic prefix orthogonal frequency division multiplexing symbols to obtain the Doppler scaling factor includes: The cyclic prefix orthogonal frequency division multiplexing symbol is subjected to a set of resampling processes to obtain a resampled signal; The resampled signal is subjected to a fast Fourier transform to obtain a frequency domain resampled signal, and data is extracted from the frequency domain resampled signal to obtain the first empty subcarrier data. Using minimizing the energy of the first empty subcarrier as the first objective function, the frequency domain resampled signal is searched to determine the optimal resampling factor; Based on the optimized resampling factor, the cyclic prefix orthogonal frequency division multiplexing symbol is resampled to obtain the optimal resampled signal; The optimal resampled signal is subjected to frequency offset compensation processing to obtain the compensated optimal resampled signal; The optimal resampled compensation signal is subjected to a fast Fourier transform to obtain the optimal resampled frequency domain compensation signal, and the optimal resampled frequency domain compensation signal is used to extract data to obtain the second empty subcarrier data. Using minimizing the energy of the second empty subcarrier as the second objective function, the optimal resampled signal for frequency domain compensation is searched to determine the optimal frequency offset. Based on the optimized resampling factor and the optimized frequency offset, a Doppler scaling factor is synthesized.

6. The method as described in claim 2 above, characterized in that, The step of estimating the arrival time of the composite hyperbolic frequency modulated waveform to obtain the target arrival time includes: A matched filter is constructed, and the composite hyperbolic frequency modulation waveform is subjected to matched filtering processing based on the matched filter to obtain a filtered composite hyperbolic frequency modulation waveform, and the peak position of the filtered composite hyperbolic frequency modulation waveform is determined. The peak position of the waveform is locally fitted using a parabolic interpolation method to obtain a fitted parabolic equation, and the target arrival time is determined based on the fitted parabolic equation.

7. The method as described in claim 1, characterized in that, The step of estimating the target position of the moving target based on the target arrival time, the base station coordinate information, and the target depth value includes: Based on the target arrival time corresponding to each of the plurality of water surface base stations, one water surface base station is randomly selected from the plurality of water surface base stations as a reference water surface base station. The relative arrival time difference between the other water surface base stations and the reference water surface base station is calculated, and the relative arrival time difference is converted into a distance difference. Based on the coordinate information of the base stations corresponding to the plurality of surface base stations and the distance difference, a set of nonlinear equations about the target location is constructed, wherein the set of nonlinear equations includes a target depth value constraint. The target position of the moving target is obtained by solving the nonlinear equations using the least squares iterative algorithm.

8. A buoy system, characterized in that, include: Cooperative beacons installed on moving targets, multiple surface base stations deployed on the water, and data centers; The cooperative beacon is used to generate and broadcast a composite beacon signal, wherein the composite beacon signal includes a composite hyperbolic frequency modulated waveform and a cyclic prefix orthogonal frequency division multiplexing symbol; The plurality of surface base stations are respectively used to receive composite beacon signals sent by moving targets, and to process the composite beacon signals to obtain target arrival time, Doppler scaling factor, target depth value and base station coordinate information; The data center is configured to receive target arrival time, Doppler scaling factor, target depth value and base station coordinate information sent by the plurality of surface base stations, estimate the target position of the moving target based on the target arrival time, the current coordinate information and the target depth value, and estimate the target velocity of the moving target based on the Doppler scaling factor.

9. A computer device, characterized in that, The computer device includes a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The storage medium stores a computer program that, when executed by a processor, can implement the method as described in any one of claims 1-7.

Images