CN112882036B - Sonar audio speed and distance measuring device and method - Google Patents
Sonar audio speed and distance measuring device and method Download PDFInfo
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Abstract
The device comprises a signal conversion interface, an audio digital unit and a sonar digital audio speed and distance measuring unit, wherein the signal conversion interface is used for connecting the output end of an audio interface of a sonar system, receiving an audio signal output by the audio interface of the sonar system and carrying out signal conversion; the audio digitization unit is used for carrying out digitization processing on the audio signal; the sonar digital audio speed and distance measuring unit comprises an audio speed and distance measuring algorithm, and target motion element parameters are resolved by using audio signals subjected to digital processing through executing the algorithm. According to the method and the device, on the premise that the internal structure of the existing sonar system is not changed, the motion element parameters of the target are accurately calculated by using the audio output of the sonar system.
Description
Technical Field
The application relates to the technical field of sonar, in particular to a sonar audio speed and distance measuring device and method.
Background
Sonar needs to estimate the target distance and other motion parameters as soon as possible at the initial stage of finding the target. Passive distance measurement and speed measurement, that is, the motion factors of the target, such as distance, speed, course and other parameters, are solved by using the target motion information observed by passive sonar, which is one of the important directions of make internal disorder or usurp in sonar systems.
For many years, in the passive sonar technology, passive target motion analysis can be directly used for estimating motion parameters of a target, and relevant measurement parameters are used for fitting a motion track of the target, so that a powerful means is provided for more accurate positioning of the target. However, when a single base array is used for estimating the purely-oriented object motion elements, the base array platform is generally required to perform at least one maneuver during estimation, which brings certain limitation to detection. In many cases, it is difficult for the matrix to complete the solution of the target motion element by maneuvering in a short time. Meanwhile, the distance and the speed can be estimated by analyzing the data received by the towed array, but the algorithm performance is sharply reduced due to the unstable relative position of the array.
With the full development of computer technology and acoustic propagation theory, the operation amount of various algorithms does not become an obstacle to the development of sonar, so that a new theoretical model appears, the target motion elements can be solved without maneuvering, and the role of sonar is further highlighted. For example, when the sonar carrier platform is fixed and static or in a hovering state, the sonar detection distance is greatly increased due to much reduced self-noise. However, in the prior art, if other information is not considered, it is difficult to solve the target motion element only by the azimuth information.
Disclosure of Invention
According to the 1 st aspect of the application, a sonar audio speed and distance measuring device is provided, which comprises a signal conversion interface, an audio digitization unit and a sonar digitization audio speed and distance measuring unit, wherein the signal conversion interface is used for connecting the output end of the sonar system audio interface, receiving the audio signal output by the sonar system audio interface and performing signal conversion; the audio digitization unit is connected with the output end of the signal conversion interface and is used for carrying out digitization processing on audio signals; the sonar digital audio speed and distance measuring unit is connected with the output end of the audio digital unit, comprises an audio speed and distance measuring algorithm, and solves target motion element parameters by executing the algorithm and utilizing audio signals subjected to digital processing.
In some other examples, the signal conversion interface includes an input interface, a signal conditioning module, a path and connection conversion module, and an output interface, which are connected in sequence, where the input interface is used to connect the output end of the sonar system audio interface, and the output interface is connected to the input end of the audio digitization unit.
In other examples, the audio digitization unit comprises an audio input circuit, a program control amplifier, an anti-aliasing filter, an AD sample-and-hold circuit and a digitization audio processor which are connected in sequence, wherein the input end of the audio input circuit is connected with the output end of the signal conversion interface, and the output end of the digitization audio processor is connected with the sonar digitization audio speed and distance measurement unit.
In other some examples, still include speed measuring range finding parameter display control unit, with the digital audio frequency of sonar tests speed range finding unit and is connected, and it includes man-machine interaction interface for input digital audio frequency of sonar tests speed range finding unit and solves the required control parameter of target motion element parameter, and receive the digital audio frequency of sonar and test speed range finding unit and solve the target motion element parameter that obtains, and show.
In some other examples, the device further comprises a digitized audio storage unit connected with the audio digitization unit and used for storing the audio data output by the audio digitization unit through processing in a preset format.
In some other examples, the sonar system audio interface is a coaxial audio connector, and the input interface of the signal conversion interface is a coaxial audio connector adapted to the sonar system audio interface.
In other examples, the audio digitizing unit is implemented using a sound card of a computer.
According to the 2 nd aspect of this application, provide a sonar audio frequency range unit that tests speed, include:
the signal receiving module is used for acquiring audio signals output by the sonar system;
the line spectrum feature extraction module is used for extracting line spectrum features of the audio signal;
the relative radial velocity resolving module is used for resolving the target relative radial velocity according to the line spectrum characteristics; and
and the speed and distance measuring module is used for resolving the relative distance and the relative speed of the target according to the radial speed and the azimuth angle at two moments.
According to the 3 rd aspect of this application, a sonar audio frequency speed measuring range finding method includes following step:
receiving an audio signal output by a sonar system, and extracting line spectrum characteristics of the audio signal;
resolving the relative radial velocity of the target according to the line spectrum characteristics; and
and resolving the relative distance and the relative speed of the target according to the radial speed and the azimuth angle at two moments.
In other examples, median filtering is performed on the received audio signal, followed by line spectral feature extraction.
In addition, the line spectrum extraction at the current moment is adopted when the line spectrum feature extraction is carried out, so that the real-time calculation is conveniently realized. Or resolving the relative radial velocity according to the frequencies of the plurality of line spectrum signals, and combining the resolving results by taking the statistical values to effectively inhibit the influence of misjudgment and avoid depending on manual inspection.
Compared with the prior art, this application uses sonar system's audio output signal as the input, when sonar carrier platform is in fixed static or is in the state of hovering, can assist sonar user to carry out the parameter to the target motion factor and solve. Because the carrier platform is not needed to be maneuvered, the advantages of reduction of the self noise of the sonar system and increase of the detection distance are utilized, and more accurate target motion auxiliary data can be provided for sonar users.
Further features of the present application and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which is to be read in connection with the accompanying drawings.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:
FIG. 1 is a structural schematic diagram of a sonar audio speed and distance measuring device according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a signal conversion interface according to an embodiment of the present application;
FIG. 3 is a schematic diagram of an audio digitizing unit according to an embodiment of the present application;
FIG. 4 is a specific application example of a sonar audio speed and distance measuring device according to an embodiment of the present application;
FIG. 5 is an execution flow of a sonar audio speed and distance measuring method according to an embodiment of the present application;
FIG. 6 shows the FFT calculation results (sampling rate of 1.5KHz) of signals at all time points;
FIG. 7 shows the median filtering result at a certain time;
FIG. 8 shows the median filtering results for the signals at all times;
FIG. 9 shows a line spectrum extraction result at a certain time;
FIG. 10 shows the line spectrum extraction results at all time instants;
FIG. 11 is a sound pressure cross correlation result;
FIG. 12 shows the FFT computation of the sound field cross-correlation function at a certain time;
FIG. 13 is a radial velocity solution at a time;
FIG. 14 is a radial relative motion velocity calculation;
FIG. 15 shows radial velocity extraction results;
FIG. 16 is a graph of radial velocity results calculated from multiple line spectra based on Doppler effect;
FIG. 17 is a schematic diagram of a target motion factor solution;
FIG. 18 is a graph of radial velocity relationship at two times;
FIG. 19 is a target speed calculation result;
fig. 20 shows the target distance calculation result.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the application, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present application unless specifically stated otherwise. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.
Fig. 1 shows sonar audio frequency speed measuring and distance measuring device structure schematic diagram according to the embodiment of the application. As shown in FIG. 1, sonar audio frequency speed measuring and ranging device 10 is connected with sonar system audio interface 20, and includes signal conversion interface 11, audio frequency digitizing unit 12, sonar digitizing audio frequency speed measuring and ranging unit 13.
The signal conversion interface 11 is used for connecting the output end of the sonar system audio interface 20, receiving the audio signal output by the sonar system audio interface 20, and performing signal conversion. As shown in fig. 2, according to an example of the present application, the signal conversion interface 11 includes an input port interface 111, a signal conditioning module 112, a path and connection conversion module 113, and an output port interface 114, which are connected in sequence. Wherein, input interface 111 is used for connecting the 20 outputs of sonar system audio interface, and input interface 111 and sonar system audio interface 20 adaptation. The output interface 114 is connected to the input end of the audio digitizing unit 12, and the output interface 114 is adapted to the input end of the audio digitizing module 12.
It is understood that the signal conditioning module 112 may be omitted as needed, i.e. the input terminal interface 11 is directly connected to the path and connection converting module 113 to simplify the circuit structure.
The audio digitization unit 12 is connected to the output end of the signal conversion interface 11, and is configured to digitize the audio signal. As shown in fig. 3, according to an example of the present application, the audio digitizing unit 12 includes an audio input circuit 121, a programmable amplifier 122, an anti-aliasing filter 123, an AD sample-and-hold circuit 124, and a digitized audio processor 125, which are connected in sequence. Wherein, the input end of the audio input circuit 121 is connected to the output end of the signal conversion interface 11. The digitized audio processor 125 can be, for example, a DSP processor, and its output is connected to the sonar digitized audio speed and distance measuring unit 13.
The audio input circuit 121 receives the output signal of the signal conversion interface 11, controls the signal amplitude through the program control amplifier 122, filters out the frequency which may cause aliasing noise according to the sampling frequency through the anti-mixing filter 123, samples the signal through the a/D sample-and-hold circuit 124, inputs the processed audio data through the digital audio processor 125, and inputs the processed audio data through the sonar digital audio speed-measuring distance-measuring unit 13 to calculate the motion element.
The sonar digital audio speed and distance measuring unit 13 is connected with the output end of the audio digital unit 12 and comprises an audio speed and distance measuring algorithm library, and the algorithm library utilizes the audio data to measure speed and distance according to control parameters.
In another embodiment, the system further comprises a speed and distance measuring parameter display control unit 14 connected to the sonar digital audio speed and distance measuring unit 13, and the speed and distance measuring parameter display control unit comprises a human-computer interaction interface for inputting control parameters required for resolving by the sonar digital audio speed and distance measuring unit 13, receiving target motion element parameters obtained by resolving by the sonar digital audio speed and distance measuring unit 13, and displaying the parameters.
In another embodiment, the device further comprises a digitized audio storage unit 15, connected to the audio digitization unit 12, for storing audio data output by the audio digitization unit 12 in a predetermined format. As shown in fig. 3, the digitized audio storage unit 15 is connected to the digitized audio processor 125.
Fig. 4 is a specific implementation example of the sonar audio frequency speed and distance measuring device disclosed in the present application. As shown in the figure, the sonar system audio interface 20 is a coaxial audio connector female, the input interface 111 of the signal conversion interface 11 is a coaxial audio connector male, and the output interface 112 is adapted to the audio input circuit port of the audio digitizing unit 12. The input port interface 111 and the output port interface 112 are connected by a cable or by wireless communication. In this embodiment, the audio digitizing unit 12 is implemented by a sound card of the computer 100, and the output interface 112 may adopt an international standard (CTIA) connector or an international standard (OMTP) connector. As shown in fig. 4, taking CTIA connector as an example, after receiving an audio signal, the signal conversion interface 11 connects the left and right channel lines to the microphone paths of the two output ports 112 and 112 ', respectively, and after conversion, selects one of the output ports 112 or 112' to connect to the sound card microphone input port of the computer 100 as required.
In this embodiment, the sound card of the computer 100 serves as an audio digital unit of the sonar audio speed and distance measuring device, the hard disk (not shown) serves as a digital audio storage unit of the sonar audio speed and distance measuring device, the computer software system including the audio speed and distance measuring algorithm library and the CPU serve as the sonar digital audio speed and distance measuring unit of the sonar audio speed and distance measuring device, and the computer display serves as a speed and distance measuring parameter display control unit of the sonar audio speed and distance measuring device.
The computer sound card digitizes the input audio at a preset sampling rate (e.g., 44.1KHz) and a preset number of sampling bits (e.g., 16 bits), and stores the digitized input audio in a file format such as WAV, VOL, MID and the like in a computer hard disk through a bus. When storing, the data transmission mode can select direct transfer or Direct Memory Access (DMA). The bus may be selected from ISA bus or PCI bus.
According to control parameters input by a user through a human-computer interaction interface (such as a keyboard, a touch pad, a touch screen and the like), a CPU calls a corresponding algorithm to carry out calculation, sends target motion elements obtained through calculation to a display control unit, and displays the target motion elements through a computer display.
Alternatively, in order to increase flexibility, the output port of the signal conversion port in fig. 4 may be a female connector, and the female connector is connected to the input port of the computer microphone by an extension line having male connectors at both ends.
In some application, for example when being used for unmanned underwater vehicle, because high integration and the modularization of sonar system of unmanned underwater vehicle, adopt sonar system output audio signal after handling, sonar audio frequency speed measuring range unit need not to set up alone and measure the speed range parameter display control unit to measure the speed to the target and measure the distance and easily realize.
Aiming at the problems that the prior sonar system often requires a carrier platform to maneuver when resolving the moving elements of the target, the application utilizes the audio output of the sonar system to carry out audio digital processing on the premise of not changing the internal structure of the prior sonar system, and resolves the moving element parameters of the target such as relative radial velocity, relative distance and velocity under the assistance of methods such as signal feature extraction.
Fig. 5 is a schematic flow of a method for measuring speed and distance of a target by using the sonar audio speed and distance measuring device. As shown in fig. 5, the method includes the steps of:
the audio output signal of the sonar system is a time domain signal, and the signal is obtained by performing beam forming according to the sonar listening direction, namely the sonar system adds all channels and removes direct current to obtain a time domain audio signal. Meanwhile, the sonar listening direction for acquiring the signal is the target azimuth. And receiving a path of time domain audio signal output by an audio interface of the sonar system, and performing line spectrum feature extraction after the signal conversion interface and the audio digitization module process. For example, extracting frequency, doppler shift, etc. In practical application, line spectrum feature extraction is difficult due to possible background fluctuation. To solve this problem, background equalization, such as median filtering, may be performed first, followed by line spectral feature extraction.
Background equalization may employ, for example, TMP (two-pass mean) algorithm, ota (order locate average) algorithm, SP3PM (split third-pass mean) algorithm, TPSW (two-pass split window) algorithm, saxa (split average outside average) algorithm, and the like. The audio quality of the sonar can be effectively improved through background equalization processing, and the detection capability and the resolution of the sonar are improved.
Taking the audio signal of a certain experiment as an example, no large interferent appears during the experiment. The target navigates south of the sonar system and travels north at 5 knots (2.5 m/s). The majority of the target trajectory occurs in water at a depth of between 180 and 220 meters, with the latter half extending along the isophote 180 m.
According to an example process of the present application, a line spectrum feature of an audio signal is extracted by:
(1) and (3) segmenting an audio output signal of the sonar system, namely a path of time domain signal according to time intervals. For example, the interval of the segments is 1 s.
(2) A fourier transform (FFT) calculation is performed on each segment of the time domain signal. Further, the calculation result is saved after the calculation is finished.
Fig. 6 is a calculated FFT time-frequency diagram of 4500s time-domain signals, and it can be seen that although the target line spectrum is visible to the naked eye due to fluctuation of the background, it is still difficult to automatically extract the target line spectrum by a computer.
(3) The FFT computation result (amplitude) is converted to a decibel value.
In order to further improve the effect of automatically extracting the target line spectrum by the computer, after FFT calculation is carried out on each section of time domain signal, the FFT amplitude value is converted into a decibel value. The calculation formula is as follows: 20lg (FFT magnitude).
(4) Median filtering is performed to achieve spectral background whitening.
Fig. 7 shows the result of median filtering on a certain segment of the time domain signal. To demonstrate the median filtering effect, a time-frequency diagram is drawn by using the median filtering of signals at all time instants, as shown in fig. 8. Comparing with fig. 6, it can be seen from fig. 8 that the line spectrum is clearly visible, and the difficulty of extracting the line spectrum is greatly reduced.
During online real-time calculation, only line spectrum extraction at the current moment is generally performed, that is, line spectrum extraction needs to be performed on the median filtering result of each segment of signals in real time.
Here, the line spectrum extraction may be implemented by the following steps: calculating the slope of the frequency spectrum at each point, and removing points with slow change by setting a slope threshold; calculating the second-order slope of the frequency spectrum at each point, and selecting a spectral peak according to the characteristic that the spectral peak has a left boundary and a right boundary; setting a peak width threshold to remove spectral peaks with overlarge span; and setting a peak height threshold to remove spectral peaks with smaller amplitude.
The line spectrum extraction is performed on the median filtering result at a certain time shown in fig. 7, as shown in fig. 9. To show the line spectrum extraction effect, the line spectrum extraction results at all time instants are shown in fig. 10.
taking the target distance from the receiving point as r and r + Δ r (Δ r < r), the receiving point hydrophones receive sound pressures of p (r) and p (r + Δ r), respectively. Wherein, the sound pressure is expressed by a simple normal wave model as:
wherein,
is a constant number, zsIs the sound source depth and z is the receiving point depth.
The sound pressure difference between the two points is:
wherein,
krmis the mode depth modulus, #mIs the corresponding wave number.
Then there are:
wherein k ismn＝krm-krn。
For the case of the value of ar,
oscillation period ratio of
Much larger, IΔ(r, Δ r) during shaking
Dominate, so the above formula can be simplified as:
wherein,
average wave number of normal mode, IΔThe oscillating process of (r, delta r) mainly consists of
And (4) generating.
The differential field strength can be obtained by the following equation:
IΔ(r，Δr)＝Ir+Δr-p(r)p*(r+Δr)-p*(r)p(r+Δr)+Ir
in the above equation, the front term and the rear term on the right side of the equation are the sound intensities of two points, and are independent of vibration. The middle two terms are operated to only leave the real part of sound pressure cross correlation, namely IΔEquivalent to real (p (r) p x (r + Δ r)).
If order VrFor the speed of movement of the object at a distance r relative to the receiving point, Δ r ═ VrΔ t, then:
p(f，t)＝p(r)，p(f，t+Δt)＝p(r+Δr)
wherein,
is the average phase velocity at frequency f, e.g.
Take 1500 m/s.
If the cross-correlation result of sound pressures at different moments of a certain frequency is observed, namely f is a fixed value, and delta t is used as an independent variable, then the sound field cross-correlation function can be obtained:
IΔ(f；t，Δt)＝real(p(f，t)p*(f，t+Δt))
FFT is carried out on the sound field cross-correlation function at the moment t, and then the sound field cross-correlation function I is extracted according to the energyΔ(f; t, Δ t) oscillation frequency fIWherein the energy magnitude is determined by the magnitude of the FFT magnitude of the sound field cross correlation function.
And because:
frequency of oscillation f of sound field cross correlation functionIEquivalent to cosine function
Frequency of (2)
Then there are:
thus, it is possible to obtain:
exemplary specific solution flows include:
(1) selecting a certain frequency according to the target line spectrum extraction result, and performing cross-correlation calculation on the sound pressure at different moments under the selected frequency by using FFT calculation results of signals at all moments stored in the target line spectrum extraction process;
for example, according to the audio signal of a certain experiment in step 202, 201Hz is selected from the line spectrum extraction results, the calculation result shown in fig. 6 is calculated, that is, only the signal at 201Hz is retained at each time, Δ t is 1, 2, …,100s, and the 201Hz signal is subjected to cross-correlation calculation, so that the sound pressure cross-correlation calculation result is obtained as shown in fig. 11.
(2) Performing FFT calculation on the sound field cross-correlation function at the single moment obtained in the last step;
fig. 12 shows the result of FFT calculation of the sound field cross-correlation function at a certain time.
(3) According to the sound field cross-correlation function IΔ(f; t, Δ t) oscillation frequency fIAnd radial velocity VrThe relationship, that is,
each frequency value on the frequency spectrum is converted into a corresponding radial velocity.
Fig. 13 shows the conversion of the frequency of fig. 12 into the corresponding radial velocity, i.e. the radial velocity solution at that moment. To demonstrate the effect, the radial velocity solutions at all times are plotted together, as shown in fig. 14.
(4) And screening the energy value of each radial velocity, and taking the radial velocity containing the maximum energy value as the radial velocity of the target at the moment.
Based on the characteristic that one target only has one speed at the same time, the energy value of each radial speed is screened (because the FFT calculation result is bilaterally symmetrical, only half of the FFT calculation result can be used for calculation). And obtaining the radial speed of the target at the moment by selecting the radial speed containing the energy maximum value.
For example, in FIG. 13, the speed value with the largest energy is selected from the radial speeds 0-3.7129 m/s, and the radial movement speed of the target at the current moment is 2.376 m/s. To demonstrate the effect, the radial velocity extraction results at all times are plotted uniformly, as shown in fig. 15.
If the velocity resolution is performed for only one frequency, erroneous judgment due to noise fluctuation may occur in the radial motion velocity extraction. Therefore, on the basis of the current-time real-time radial velocity calculation through line spectrum extraction, the radial velocity can be calculated according to the frequencies of a plurality of line spectrum signals, the calculation results are combined, statistical values such as an average value and gross error elimination are obtained from the calculation results, the influence of misjudgment can be effectively inhibited, and the manual inspection of the target line spectrum is not relied on.
As shown in fig. 16, when the plurality of line spectrums calculate the radial motion velocity of the target according to the doppler shift, part of the results are obviously deviated from the normal results within 10min to 30min, but the trend of the radial motion velocity is about 2.5 m/s.
And step 206, resolving the relative distance and the relative speed of the target according to the radial speed and the azimuth angle at two moments.
It is understood that the motion trajectory of the target may be divided into a plurality of trajectory segments according to a time period, and when the time period is sufficiently small, the target may be regarded as performing a uniform linear motion on each trajectory segment, assuming that the target motion speed is V.
Suppose that at two moments in a certain time period, the corresponding target radial motion speeds are V respectivelyr1And Vr2The directions of the targets at the two moments are respectively theta1And theta2As shown in fig. 17.
As shown in FIG. 18, since the target moving speed is constant at two times, the radial velocity V is constantrCan be used for vector velocity
The orthogonal decomposition is carried out to obtain the following results:
wherein, theta3And theta4Respectively, the radial velocity directions at two moments and the target sailing direction, and theta4-θ3＝Δθ＝θ2-θ1。
Solving the above equation yields:
For example, at a known angle θ3And after the target movement speed V, OB is sin θ because the distance AB between two points A, B is V Δ t3AB/sin Δ θ, i.e., the distance of the target at the second instant. Similarly, the distance OA from the point A can also be obtained.
Therefore, knowing the relative radial velocity and orientation of the target at each time, the motion velocity at each time can be obtained according to the trigonometric formula, as shown in fig. 19.
As can be seen from the target velocity calculation results, the velocity results at the time points of 6min, 12min and 21min are abnormal, because the cross-correlation sampling period is long, which results in insufficient velocity resolution, so that the radial velocity at these several time points varies greatly.
Fig. 20 shows the calculated target distance, which is compared with the actual distance, and the calculated distance is about 500 meters away from the actual distance, which is still caused by the fact that the cross-correlation sampling period is long, the velocity resolution is large, and the resolving velocity is small.
The speed and distance measuring device and the method are particularly suitable for a sonar carrier platform to be in a fixed static state or a hovering state, and the detection distance of a sonar system is greatly increased due to the fact that self noise is greatly reduced.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present application and not for limiting the same; although the present application has been described in detail with reference to preferred embodiments, those of ordinary skill in the art will understand that: modifications to the specific embodiments of the application or equivalent replacements of some of the technical features may still be made; all of which are intended to be encompassed within the scope of the claims appended hereto without departing from the spirit and scope of the present disclosure.
Claims (4)
1. A sonar audio speed and distance measuring device is characterized by comprising a signal conversion interface, an audio digital unit and a sonar digital audio speed and distance measuring unit, wherein the signal conversion interface is used for connecting the output end of an audio interface of a sonar system, receiving an audio signal output by the audio interface of the sonar system and carrying out signal conversion; the audio digitization unit is connected with the output end of the signal conversion interface and is used for carrying out digitization processing on audio signals; the sonar digitized audio speed and distance measuring unit is connected with the output end of the audio digitized unit, comprises an audio speed and distance measuring algorithm, and solves target motion element parameters by executing the algorithm and utilizing digitized audio signals;
the sonar system audio interface is a coaxial audio connector, and the input end interface of the signal conversion interface is a coaxial audio connector matched with the sonar system audio interface;
the signal conversion interface comprises an input end interface, a signal conditioning module, a passage, a connection conversion module and an output end interface which are connected in sequence; the input end interface is used for connecting the output end of the audio interface of the sonar system, and the output end interface is connected with the input end of the audio digitization unit;
the audio digitization unit is realized by using a sound card of a computer, and the sound card of the computer digitizes input audio at a sampling rate of 44.1KHz and a preset sampling digit; a computer software system comprising an audio speed and distance measuring algorithm library and a CPU are used as the sonar digital audio speed and distance measuring unit;
the output end interface adopts a CTIA connector, after the signal conversion interface receives an audio signal, the left and right sound channel circuits are respectively connected to the microphone channels of the two output end interfaces, and one of the output end interfaces is selected to be connected to the microphone input interface of the computer sound card;
wherein, the resolving the target motion element parameter by using the audio signal after the digital processing comprises:
extracting line spectrum characteristics of the audio signal subjected to digital processing; when extracting the line spectrum characteristics of the audio signal, segmenting a path of time domain signal of the audio signal according to 1s time interval;
and resolving the relative radial velocity according to the line spectrum characteristics, wherein the method comprises the following steps: selecting a certain frequency according to the line spectrum feature extraction result, and performing cross-correlation calculation on the sound pressure at different moments under the selected frequency by using FFT calculation results of signals at all moments stored in the line spectrum feature extraction;
performing FFT calculation on the obtained sound field cross-correlation function at the single moment;
according to sound field cross-correlation function IΔ(f; t, Δ t) oscillation frequency fIAnd radial velocity VrRelation, each frequency value on the frequency spectrum is converted into a corresponding radial velocity; wherein the oscillation frequency fIPerforming FFT on the sound field cross-correlation function at the moment t, and extracting according to the energy;
screening the energy value of each radial speed, and taking the radial speed containing the maximum energy value as the radial speed of the target at the moment; and
and resolving the relative distance and the relative speed of the target according to the radial speed and the azimuth angle at two moments.
2. The sonar audio speed-measuring ranging device according to claim 1, wherein the audio digitizing unit comprises an audio input circuit, a programmable amplifier, an anti-aliasing filter, an AD sampling and holding circuit and a digitized audio processor which are connected in sequence, wherein the input end of the audio input circuit is connected with the output end of the signal conversion interface, and the output end of the digitized audio processor is connected with the sonar digitized audio speed-measuring ranging unit.
3. The sonar audio speed and distance measuring device according to claim 1, further comprising a speed and distance measuring parameter display control unit connected to the sonar digital audio speed and distance measuring unit, wherein the sonar audio speed and distance measuring device comprises a man-machine interaction interface for inputting control parameters required by the sonar digital audio speed and distance measuring unit to resolve the target motion element parameters, receiving the target motion element parameters resolved by the sonar digital audio speed and distance measuring unit, and displaying the target motion element parameters.
4. The sonar audio speed and distance measuring device according to claim 1, further comprising a digitized audio storage unit connected to the audio digitizing unit for storing the audio data output by the audio digitizing unit in a predetermined format.
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