Acoustic Doppler velocity measurement channel parameter estimation method

Abstract

The invention belongs to the field of underwater sound, particularly relates to an acoustic Doppler velocity measurement channel parameter estimation method, and aims to solve the problem that the accuracy of measured sound attenuation and sound scattering coefficients is low due to the fact that an existing method for measuring the sound attenuation and sound scattering coefficients is greatly influenced by water body scatterer changes and bottom changes and is high in uncertainty. According to an equivalent plane wave reverberation level formula of volume reverberation and seabed reverberation, in combination with known sound expansion attenuation and pure water absorption attenuation, an echo level measured by a transducer is corrected to obtain a volume backscatter correction curve and a bottom backscatter correction curve, then distance derivation is performed to obtain a sound absorption coefficient, and the sound absorption coefficient is calculated. Therefore, the problem of low accuracy of the measured sound attenuation and sound scattering coefficient is solved.

Description

Technical Field

[0001] The invention belongs to the field of underwater acoustics, and in particular relates to a method for estimating acoustic Doppler velocity measurement channel parameters. Background Art

[0002] Based on the principle of Doppler effect, Doppler current profiler (ADCP) and Doppler velocity log (DVL) were developed. ADCP estimates velocity by extracting Doppler information of echo signals of tiny scatterers moving with the water flow in the beam irradiation area. DVL estimates velocity by extracting Doppler information of scattered echo signals of rivers or seabeds irradiated by the beam. Acoustic Doppler velocity measurement channel parameters include the sound absorption coefficient and sound scattering coefficient of water scatterers and the sound scattering coefficient of rivers or seabeds. Acoustic Doppler velocity measurement channel parameters are used to determine the precise measurement range of the equipment, optimize the frequency selection and power setting of the equipment, so as to meet the measurement requirements at different depths and complex hydrological environments, thereby improving the velocity measurement accuracy.

[0003] However, the current methods for measuring sound attenuation and sound scattering coefficients are relatively complicated. The theoretical formulas are usually obtained by model simulation and numerical simulation. They are greatly affected by changes in water scatterers and bottom changes, and have strong uncertainties. As a result, the existing technology has the problem of low accuracy in measuring sound attenuation and sound scattering coefficients. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the current method for measuring sound attenuation and sound scattering coefficient is greatly affected by the change of water scatterers and bottom changes, and has strong uncertainty, resulting in low accuracy of the measured sound attenuation and sound scattering coefficient. A method for estimating channel parameters of acoustic Doppler velocity measurement is proposed, including:

[0005] Step 1: The transceiver of the ship-borne Doppler speed meter is used as the transmitter, which transmits sound wave signals to the seabed of the sea area to be measured.

[0006] The transceiver of the ship-borne Doppler speed meter also serves as a receiving end, which receives the reverberation echo signal of the transmitted sound wave signal after scattering;

[0007] The reverberation echo signal includes: a volume reverberation echo signal and a seabed reverberation echo signal;

[0008] The ship-borne temperature sensor measures the temperature of the sea area to be tested;

[0009] Step 2: intercepting the volume reverberation echo signal in the reverberation echo signal, and estimating the water body sound absorption coefficient and the water body sound scattering coefficient of the sea area to be measured according to the temperature of the sea area to be measured, the volume reverberation echo echo signal and the volume reverberation echo level equation;

[0010] Step 3: intercept the seabed reverberation echo signal from the reverberation echo signal, and estimate the seabed sound scattering coefficient of the sea area to be measured according to the temperature of the sea area to be measured, the seabed reverberation echo signal and the seabed reverberation echo level equation.

[0011] In the step 2, the water body sound absorption coefficient and the water body sound scattering coefficient of the sea area to be measured are estimated according to the temperature of the sea area to be measured, the volume reverberation echo echo signal and the volume reverberation echo level equation. The specific process includes:

[0012] Step 2: According to the temperature of the sea area to be measured, the volume reverberation echo signal receiving time and the volume reverberation echo level equation, the volume reverberation echo level equation and the volume reverberation echo signal RL are calculated. V Compensation is performed to obtain the volume correction echo level equation and the compensated volume reverberation echo echo signal RL VC ;

[0013] Step 22: Obtain the compensated volume reverberation echo signal RL according to step 21 VC , calculate the sound absorption coefficient α of the scattering particles in the measured sea area sυ ;

[0014] Step 23: The compensated volume reverberation echo signal RL obtained in step 21 VC and the sound absorption coefficient α of the scattering particles in the tested sea area obtained in step 2 sυ , calculate the volume scattering coefficient S of the scattering particles in the sea area to be measured v ;

[0015] In the step 3, the seabed reverberation echo signal is intercepted from the reverberation echo signal, and the seabed sound scattering coefficient of the sea area to be measured is estimated according to the temperature of the sea area to be measured, the seabed reverberation echo signal and the seabed reverberation echo level equation. The specific process includes:

[0016] Step 3: According to the temperature of the sea area to be measured, the receiving time of the seabed reverberation echo signal and the seabed reverberation echo level equation, the seabed reverberation echo level equation and the seabed reverberation echo signal RL are calculated. B Compensation is performed to obtain the seabed correction echo level equation and the compensated seabed reverberation echo echo signal RL BC ;

[0017] Step 32: The compensated seafloor reverberation echo signal RL obtained in step 31 BC and the sound absorption coefficient α of the scattering particles in the tested sea area obtained in step 2 sυ , calculate the seabed scattering coefficient S of the scattering particles in the sea area to be measured b .

[0018] The beneficial effects of the present invention are:

[0019] The present invention proposes an acoustic Doppler velocity measurement channel parameter estimation method, which is based on the measured body reverberation and bottom reverberation echo levels, compensates for sound expansion and pure water sound absorption to correct the echo level curve, and then derives the distance to achieve the estimation of scatterer sound attenuation, body scattering and bottom scattering coefficients. The method is efficient and simple, and solves the problem of low accuracy of measured sound attenuation and sound scattering coefficients in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the principle flow of an acoustic Doppler velocity measurement channel parameter estimation method of the present invention;

[0021] Figure 2 It is a schematic diagram of a measurement scenario of an acoustic Doppler velocity measurement channel parameter estimation method of the present invention. DETAILED DESCRIPTION

[0022] The present invention proposes an acoustic Doppler velocity measurement channel parameter estimation method, including acoustic absorption, body scattering and bottom scattering coefficients. In view of the current method for measuring acoustic attenuation and acoustic scattering coefficients, which is greatly affected by changes in water scattering bodies and seabed changes, has strong uncertainty, and leads to the problem of low accuracy of measured acoustic attenuation and acoustic scattering coefficients, the present invention corrects the echo level measured by the transducer based on the equivalent plane wave reverberation level formula of volume reverberation and seabed reverberation, combined with the known acoustic expansion attenuation and pure water absorption attenuation, obtains body backscattering correction curves and bottom backscattering correction curves, then obtains the acoustic absorption coefficient by derivation of the distance, and then obtains the body and bottom scattering coefficients.

[0023] Specific implementation method 1: Combination Figure 1 The invention is described, comprising:

[0024] Step 1: The transceiver of the ship-borne Doppler speed meter is used as the transmitter, and the transmitter transmits the sound wave signal obliquely to the seabed of the sea area to be measured.

[0025] The transceiver of the ship-borne Doppler speed meter also serves as a receiving end, which receives the reverberation echo signal of the transmitted sound wave signal after scattering;

[0026] The reverberation echo signal includes: a volume reverberation echo signal and a seabed reverberation echo signal;

[0027] The ship-borne temperature sensor measures the temperature of the sea area to be tested;

[0028] Step 2: intercepting the volume reverberation echo signal in the reverberation echo signal, and estimating the water body sound absorption coefficient and the water body sound scattering coefficient of the sea area to be measured according to the temperature of the sea area to be measured, the volume reverberation echo echo signal and the volume reverberation echo level equation;

[0029] Step three, intercepting the seabed reverberation echo signal from the reverberation echo signal; estimating the seabed sound scattering coefficient of the sea area to be measured according to the temperature of the sea area to be measured, the seabed reverberation echo signal and the seabed reverberation echo level equation.

[0030] Specific implementation method 2: The difference between this implementation method and specific implementation method 1 is that:

[0031] In the step 1, the ship-borne Doppler velocimeter is installed at the bottom of the hull;

[0032] The transceiver and transducer equipment parameters of the shipborne Doppler speed meter include: the combined directional beam width of the transceiver and transducer is Ψ; the sound source level of the transceiver and transducer is SL; the pulse width of the transmitted sound wave signal is τ; the transmission angle of the transmitted sound wave signal is θ; the center frequency of the transmitted sound wave signal is f; and the bandwidth of the transmitted sound wave signal is B. The above parameters are all equipment parameters, which are parameters known and set by the implementer.

[0033] When sound waves are projected onto an uneven medium in the ocean, scattered waves are generated. At this time, part of the sound energy continues to propagate in the original direction, and the other part of the sound energy is scattered around to form a scattered sound field. The scattering of sound waves by scatterers in the seawater medium, such as mud and sand particles, marine organisms, and water masses with uneven temperatures, is superimposed at the receiving point to form a volume reverberation signal. The unevenness of the seabed, the surface roughness, and the scatterers nearby scatter sound waves, which are superimposed at the receiving point to form a seabed reverberation signal. The seabed reverberation signal follows the volume reverberation. The volume reverberation echo signal is the reverberation echo signal before the first seabed scattering reaches the receiving end;

[0034] The seabed reverberation echo signal is the reverberation echo signal t time after the first seabed scattering reaches the receiving end; t is a positive number; the transmission angle is the angle between the beam axis and the horizontal plane; the beam axis is a parameter definition well known to those skilled in the art;

[0035] The transmission and reception are synchronized, and the curve data of the reverberation echo signal changing with the distance is collected. The other steps and parameters are the same as those of the first specific implementation method.

[0036] Specific implementation method three: This implementation method is different from the specific implementation method one in that:

[0037] In the step 2, the water body sound absorption coefficient and the water body sound scattering coefficient of the sea area to be measured are estimated according to the temperature of the sea area to be measured, the volume reverberation echo echo signal and the volume reverberation echo level equation. The specific process includes:

[0038] Step 2: According to the temperature of the sea area to be measured, the volume reverberation echo signal receiving time and the volume reverberation echo level equation, the volume reverberation echo level equation and the volume reverberation echo signal RL are calculated. VCompensation is performed to obtain the volume correction echo level equation and the compensated volume reverberation echo echo signal RL VC ;

[0039] Step 22: Obtain the compensated volume reverberation echo signal RL according to step 21 VC , calculate the sound absorption coefficient α of the scattering particles in the measured sea area sυ ;

[0040] Step 23: The compensated volume reverberation echo signal RL obtained in step 21 VC and the sound absorption coefficient α of the scattering particles in the tested sea area obtained in step 2 sυ , calculate the volume scattering coefficient S of the scattering particles in the sea area to be measured v

[0041] The other steps and parameters are the same as those in the first to second embodiments.

[0042] Specific implementation method 4: The difference between this implementation method and specific implementation methods 1 to 4 is that in step 21, according to the temperature of the sea area to be measured, the volume reverberation echo echo signal and the volume reverberation echo level equation RL V , and obtain the volume-corrected echo level RL VC The specific process is:

[0043] Step 2: Convert the volume reverberation echo signal RL V Expand according to the volume reverberation echo level equation formula;

[0044] Step 212: using the temperature of the sea area to be measured and the volume reverberation echo echo signal receiving time, obtain the pure water sound absorption coefficient of the sea area to be measured in the volume reverberation echo level equation formula;

[0045] Step 213: According to the receiving time of the volume reverberation echo echo signal, the half acoustic expansion attenuation TL of the measured sea area is obtained. 1V ;

[0046] Step 214: According to the pure water sound absorption coefficient of the sea area to be tested and the half sound expansion attenuation TL of the sea area to be tested 1V , the volume reverberation echo level equation and the volume reverberation echo echo signal RL V Compensation is performed to obtain the volume correction echo level equation and the compensated volume reverberation echo echo signal RL VC .

[0047] The volume reverberation echo echo signal RL VThe volume reverberation echo level equation is an expansion equation that theoretically analyzes the received signal according to sound propagation and scattering, which is a well-known content in the field of underwater acoustics. In practical applications, the sound absorption and sound scattering coefficients in the expansion equation are generally empirical values, which deviate from the actual sea conditions. Therefore, compensation is used to specifically solve the sound absorption and sound scattering coefficients. The compensated volume reverberation echo level equation is named the volume correction echo level equation. Since the volume reverberation echo echo signal RL V The only difference from the volume reverberation echo level equation is the way of expression. In fact, only one compensation is performed, and the compensated signal is analyzed according to the compensated formula.

[0048] The other steps and parameters are the same as those in the first to third embodiments.

[0049] Specific implementation method 5: This implementation method is different from specific implementation methods 1 to 4 in that:

[0050] In step 2-1, the volume reverberation echo signal RL V According to the volume reverberation echo level equation formula, it can be expressed as follows:

[0051]

[0052] Among them, SL is the sound source level of the transceiver and transducer; S v is the volume scattering coefficient of the scattering particles per unit volume in the water area irradiated by the transducer beam; r is the distance between the scattering particles and the transducer; α ω is the sound absorption coefficient of pure water in the sea area to be tested; α s is the acoustic scattering attenuation coefficient of the scattering particles; α υ is the viscous absorption coefficient of the scattering particles; c is the speed of sound in water; τ is the pulse width of the acoustic wave signal emitted by the transducer; Ψ is the combined directional beam width of the transducer;

[0053] In step 212, the temperature of the sea area to be measured and the volume reverberation echo echo signal reception time are used to obtain the pure water sound absorption coefficient of the sea area to be measured in the volume reverberation echo level equation formula, which is expressed as follows:

[0054]

[0055] f1=1.32×10 3 (T+273.1)e (-1700 / (T+273.1))

[0056] f2=1.55×10 7 (T+273.1)e (-3052 / (T+273.1))

[0057] A1=1.03×10-8 +2.36×10 -10 T-5.22×10 -12 T 2

[0058] A2=5.62×10 -8 +7.52×10 -10 T

[0059] A3=(55.9-2.37T+4.77×10 -2 T 2 -3.48×10 -4 T 3 )×10 -15

[0060] P2=1-10.3×10 -4 P+3.7×10 -7 P 2

[0061] P3=1-3.84×10 -4 P+7.57×10 -8 P 2

[0062] Wherein, e represents an exponential function, A1, A2 and A3 are parameters affecting temperature on sound absorption, P2 and P3 are parameters affecting pressure on sound absorption, f1 and f2 are relaxation frequencies; T represents the temperature of the sea area to be measured, in °C, which can be measured by a temperature sensor; P represents static pressure, in atm, which can be converted from water depth; the water depth is calculated based on the receiving time and emission angle of the volume reverberation echo echo signal; the calculation formula is well known to those skilled in the art;

[0063] f represents the center frequency of the transmitted signal, in Hz. This pure water sound absorption formula is applicable to seawater with a salinity of 35‰ and a pH value of 8.0.

[0064] In step 213, the half acoustic spread attenuation TL of the measured sea area is obtained according to the receiving time of the volume reverberation echo echo signal. 1V The formula is:

[0065] TL 1V =20lgr

[0066] Where r represents the distance between the scattering particle and the transducer.

[0067] The distance r between the scattering particles and the transducer is calculated based on the reception time of the volume reverberation echo echo signal; the calculation of the distance between the scattering particles and the transducer based on the echo signal reception time requires consideration of the near and far fields of the sound wave. The near field and far field of the sound wave are divided according to the interference phenomenon of the emitted sound wave in the sound field. The near field refers to the area close to the transducer, and the interference result is affected by the phase and amplitude of the sound wave, and the sound field fluctuates. The far field refers to the area far from the transducer, and the interference result is only affected by the phase of the sound wave, the sound field no longer fluctuates, and the amplitude of the sound pressure decays according to the law of spherical waves. When applied under far-field conditions, the sound wave expands according to the law of spherical waves, and the near-far field boundary distance is calculated using the transducer radius and the emission center frequency. This is well known to those skilled in the art.

[0068] The volume reverberation echo echo signal RL after compensation in step 214 VC The volume-corrected echo level equation is expanded to:

[0069]

[0070] The other steps and parameters are the same as those in Specific Embodiments 1 to 4.

[0071] Specific implementation method 6: The difference between this implementation method and specific implementation methods 1 to 5 is that in step 22, the compensated volume reverberation echo echo signal RL is obtained according to step 21. VC , calculate the sound absorption coefficient α of the scattering particles in the measured sea area sυ , the specific calculation process is:

[0072] dL VC =-2(α s +α υ )dr

[0073]

[0074] d represents the derivative;

[0075] The volume reverberation echo echo signal RL after compensation in step 21 in step 23 VC and the sound absorption coefficient α of the scattering particles in the tested sea area in step 2 sυ , calculate the volume scattering coefficient S of the scattering particles in the sea area to be measured v , expressed as:

[0076]

[0077] ; Other steps and parameters are the same as those in Specific Implementation Methods 1 to 5.

[0078] Specific implementation method seven: The difference between this implementation method and specific implementation methods one to six is ​​that in step three, the seabed reverberation echo signal in the reverberation echo signal is intercepted; according to the temperature of the sea area to be measured, the seabed reverberation echo signal and the seabed reverberation echo level equation, the seabed sound scattering coefficient of the sea area to be measured is estimated. The specific process includes:

[0079] Step 3: According to the temperature of the sea area to be measured, the receiving time of the seabed reverberation echo signal and the seabed reverberation echo level equation, the seabed reverberation echo level equation and the seabed reverberation echo signal RL are calculated. B Compensation is performed to obtain the seabed correction echo level equation and the compensated seabed reverberation echo echo signal RL BC ;

[0080] Step 32: The compensated seafloor reverberation echo signal RL obtained in step 31 BC and the sound absorption coefficient α of the scattering particles in the tested sea area obtained in step 2 sυ , calculate the seabed scattering coefficient S of the scattering particles in the sea area to be measured b

[0081] The other steps and parameters are the same as those in Specific Embodiments 1 to 6.

[0082] Specific embodiment eight: The difference between this embodiment and specific embodiments one to seven is that in step three, the seabed reverberation echo level equation and the seabed reverberation echo echo signal RL are calculated according to the temperature of the sea area to be measured, the receiving time of the seabed reverberation echo signal, and the seabed reverberation echo level equation. B Compensation is performed to obtain the seabed correction echo level equation and the compensated seabed reverberation echo echo signal RL BC ; The specific process is:

[0083] Step 3: Convert the seabed reverberation echo signal RL B Expand according to the volume reverberation echo level equation formula;

[0084] Step 312: According to the receiving time of the seabed reverberation echo signal, the three-quarter sound expansion attenuation TL of the sea area to be tested is obtained 1B ;

[0085] Step 313: According to the pure water sound absorption coefficient of the sea area to be tested and the three-quarter sound expansion attenuation TL of the sea area to be tested 1B , the seabed reverberation echo level equation and the seabed reverberation echo echo signal RL B Compensation is performed to obtain the seabed correction echo level equation and the compensated seabed reverberation echo echo signal RL BC

[0086] The seabed reverberation echo signal RL BThe seabed reverberation echo level equation is an expansion equation that theoretically analyzes the received signal according to sound propagation and scattering, which is a well-known content in the field of underwater acoustics. In practical applications, the sound absorption and sound scattering coefficients in the expansion equation are generally empirical values, which deviate from the actual sea conditions. Therefore, compensation is used to specifically solve the sound absorption and sound scattering coefficients. The compensated seabed reverberation echo level equation is named the seabed correction echo level equation. Since the seabed reverberation echo echo signal RL B The only difference from the seabed reverberation echo level equation is the way of expression. In fact, it only performs one compensation, and the compensated signal is analyzed according to the compensated formula.

[0087] The other steps and parameters are the same as those in Specific Embodiments 1 to 7.

[0088] Specific embodiment 9: The difference between this embodiment and specific embodiments 1 to 8 is that in step 3-1, the seabed reverberation echo echo signal RL B According to the volume reverberation echo level equation formula, it can be expressed as follows:

[0089]

[0090] Among them, S b is the seabed scattering coefficient of scattering particles per unit area of ​​the seabed area illuminated by the transducer beam;

[0091] In step 312, the three-quarter sound expansion attenuation TL of the sea area to be measured is obtained according to the receiving time of the seabed reverberation echo echo signal. 1B ; expressed as:

[0092] TL 1B =30lgr

[0093] Among them, r represents the distance of the scattering particles from the transducer, which is calculated based on the receiving time of the echo signal of the reverberation echo of the seabed. Calculating the distance of the scattering particles from the transducer based on the receiving time of the echo signal requires considering the near and far fields of the sound wave. The near field and far field of the sound wave are divided according to the interference phenomenon of the emitted sound waves in the sound field. The near field refers to the area close to the transducer. The interference result is affected by the phase and amplitude of the sound wave, and the sound field fluctuates. The far field refers to the area far away from the transducer. The interference result is only affected by the phase of the sound wave. The sound field no longer fluctuates, and the amplitude of the sound pressure decays according to the law of spherical waves. When applied under far-field conditions, the sound wave expands according to the law of spherical waves, and the near-far field boundary distance is calculated using the transducer radius and the emission center frequency. It is well known to people in this field.

[0094] Step 313: According to the pure water sound absorption coefficient of the sea area to be tested and the three-quarter sound expansion attenuation TL of the sea area to be tested 1B, the seabed reverberation echo level equation and the seabed reverberation echo echo signal RL B Compensation is performed to obtain the seabed correction echo level equation and the compensated volume reverberation echo echo signal RL BC , expressed as:

[0095]

[0096] The other steps and parameters are the same as those in Specific Embodiments 1 to 8.

[0097] Specific embodiment 10: The difference between this embodiment and specific embodiments 1 to 9 is that the compensated seabed reverberation echo signal RL obtained in step 32 according to step 31 BC and the sound absorption coefficient α of the scattering particles in the tested sea area obtained in step 2 sυ , calculate the seabed scattering coefficient S of the scattering particles in the sea area to be measured b , expressed as:

[0098]

[0099] The other steps and parameters are the same as those in Specific Implementations 1 to 9.

[0100] The above only describes the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the above specific implementation methods. Although the present invention has been disclosed as above in the preferred embodiments, it is not used to limit the present invention. Any technician familiar with the profession can make some changes or modify the technical contents disclosed above into equivalent embodiments with equivalent changes without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for estimating acoustic Doppler velocity channel parameters, characterized in that: The following steps are involved: Step 1: The transceiver of the ship-borne Doppler speed meter is used as the transmitter, which transmits sound wave signals to the seabed of the sea area to be measured. The transceiver of the ship-borne Doppler speed meter also serves as a receiving end, which receives the reverberation echo signal of the transmitted sound wave signal after scattering; The reverberation echo signal includes: a volume reverberation echo signal and a seabed reverberation echo signal; The ship-borne temperature sensor measures the temperature of the sea area to be tested; Step 2: intercepting the volume reverberation echo signal in the reverberation echo signal, and estimating the water body sound absorption coefficient and the water body sound scattering coefficient of the sea area to be measured according to the temperature of the sea area to be measured, the volume reverberation echo echo signal and the volume reverberation echo level equation; Step three, intercepting the seabed reverberation echo signal from the reverberation echo signal; estimating the seabed sound scattering coefficient of the sea area to be measured according to the temperature of the sea area to be measured, the seabed reverberation echo signal and the seabed reverberation echo level equation.

2. The method for estimating acoustic Doppler velocity channel parameters according to claim 1, characterized in that: In the step 1, the shipborne Doppler velocimeter is installed at the bottom of the hull; The parameters of the transceiver and transducer device of the ship-borne Doppler speed meter include: the combined directional beam width of the transceiver and transducer is Ψ; the sound source level of the transceiver and transducer is SL; the pulse width of the transmitted sound wave signal is τ; the transmission angle of the transmitted sound wave signal is θ; the center frequency of the transmitted sound wave signal is f; The seabed reverberation echo signal is a reverberation echo signal t time after the first seabed scattering reaches the receiving end; t is a positive number.

3. The method for estimating acoustic Doppler velocity channel parameters according to claim 2, characterized in that: In the step 2, the water body sound absorption coefficient and the water body sound scattering coefficient of the sea area to be measured are estimated according to the temperature of the sea area to be measured, the volume reverberation echo echo signal and the volume reverberation echo level equation. The specific process includes: Step 2: According to the temperature of the sea area to be measured, the volume reverberation echo signal receiving time and the volume reverberation echo level equation, the volume reverberation echo level equation and the volume reverberation echo signal RL are calculated. V Compensation is performed to obtain the volume correction echo level equation and the compensated volume reverberation echo echo signal RL VC ; Step 22: Obtain the compensated volume reverberation echo signal RL according to step 21 VC , calculate the sound absorption coefficient α of the scattering particles in the measured sea area sυ ; Step 23: The compensated volume reverberation echo signal RL obtained in step 21 VC and the sound absorption coefficient α of the scattering particles in the tested sea area obtained in step 2 sυ , calculate the volume scattering coefficient S of the scattering particles in the sea area to be measured v .

4. The method for estimating acoustic Doppler velocity channel parameters according to claim 3, characterized in that: In the step 21, the temperature of the sea area to be measured, the echo signal of the volume reverberation echo and the volume reverberation echo level equation RL are calculated. V , and obtain the volume-corrected echo level RL VC The specific process is: Step 2: Convert the volume reverberation echo signal RL V Expand according to the volume reverberation echo level equation formula; Step 212: using the temperature of the sea area to be measured and the volume reverberation echo echo signal receiving time, obtain the pure water sound absorption coefficient of the sea area to be measured in the volume reverberation echo level equation formula; Step 213: According to the receiving time of the volume reverberation echo echo signal, the half acoustic expansion attenuation TL of the measured sea area is obtained. 1V ; Step 214: According to the pure water sound absorption coefficient of the sea area to be tested and the half sound expansion attenuation TL of the sea area to be tested 1V , the volume reverberation echo level equation and the volume reverberation echo echo signal RL V Compensation is performed to obtain the volume correction echo level equation and the compensated volume reverberation echo echo signal RL VC .

5. The method for estimating acoustic Doppler velocity channel parameters according to claim 4, characterized in that: In step 2-1, the volume reverberation echo signal RL V According to the volume reverberation echo level equation formula, it can be expressed as follows: Among them, SL is the sound source level of the transceiver and transducer; S v is the volume scattering coefficient of the scattering particles per unit volume in the water area irradiated by the transducer beam; r is the distance between the scattering particles and the transducer; α ω is the sound absorption coefficient of pure water in the sea area to be tested; α s is the acoustic scattering attenuation coefficient of the scattering particles; α υ is the viscous absorption coefficient of the scattering particles; c is the speed of sound in water; τ is the pulse width of the acoustic wave signal emitted by the transducer; Ψ is the combined directional beam width of the transducer; In step 212, the temperature of the sea area to be measured and the volume reverberation echo echo signal reception time are used to obtain the pure water sound absorption coefficient of the sea area to be measured in the volume reverberation echo level equation formula, which is expressed as follows: f1=1.32×10 3 (T+273.1)e (-1700 / (T+273.1)) f2=1.55×10 7 (T+273.1)e (-3052 / (T+273.1)) A1=1.03×10 -8 +2.36×10 -10 T-5.22×10 -12 T 2 A2=5.62×10 -8 +7.52×10 -10 T A3=(55.9-2.37T+4.77×10 -2 T 2 -3.48×10 -4 T 3 )×10 -15 P2=1-10.3×10 -4 P+3.7×10 -7 P 2 P3=1-3.84×10 -4 P+7.57×10 -8 P 2 Wherein, e represents an exponential function, A1, A2 and A3 are the parameters affecting temperature on sound absorption, P2 and P3 are the parameters affecting pressure on sound absorption, f1 and f2 are relaxation frequencies; T represents the temperature value of the sea area to be measured, P represents the static pressure, in atm, which can be converted from the water depth; the water depth is calculated based on the receiving time and the transmitting angle of the volume reverberation echo echo signal; f represents the center frequency of the transmitting signal, In step 213, the half acoustic spread attenuation TL of the measured sea area is obtained according to the receiving time of the volume reverberation echo echo signal. 1V The formula is: TL 1V =20lgr Where r represents the distance between the scattering particle and the transducer. The distance r between the scattering particles and the transducer is calculated based on the receiving time of the volume reverberation echo signal; The volume reverberation echo echo signal RL after compensation in step 214 VC The volume-corrected echo level equation is expanded to:

6. The method for estimating acoustic Doppler velocity measurement channel parameters according to claim 5, characterized in that: In the step 22, the compensated volume reverberation echo signal RL is obtained according to the step 21. VC , calculate the sound absorption coefficient α of the scattering particles in the measured sea area sυ , the specific calculation process is: dRL VC =-2(a s +a υ )dr d represents the derivative; The volume reverberation echo echo signal RL after compensation in step 21 in step 23 VC and the sound absorption coefficient α of the scattering particles in the tested sea area in step 2 sυ , calculate the volume scattering coefficient S of the scattering particles in the sea area to be measured v , expressed as:

7. The method for estimating acoustic Doppler velocity channel parameters according to claim 6, characterized in that: In the step 3, the seabed reverberation echo signal is intercepted from the reverberation echo signal; according to the temperature of the sea area to be measured, the seabed reverberation echo signal and the seabed reverberation echo level equation, the seabed sound scattering coefficient of the sea area to be measured is estimated. The specific process includes: Step 3: According to the temperature of the sea area to be measured, the receiving time of the seabed reverberation echo signal and the seabed reverberation echo level equation, the seabed reverberation echo level equation and the seabed reverberation echo signal RL are calculated. B Compensation is performed to obtain the seabed correction echo level equation and the compensated seabed reverberation echo echo signal RL BC ; Step 32: The compensated seafloor reverberation echo signal RL obtained in step 31 BC and the sound absorption coefficient α of the scattering particles in the tested sea area obtained in step 2 sυ , calculate the seabed scattering coefficient S of the scattering particles in the sea area to be measured b .

8. The method for estimating acoustic Doppler velocity measurement channel parameters according to claim 7, characterized in that: In the step 31, the seabed reverberation echo level equation and the seabed reverberation echo signal RL are calculated according to the temperature of the sea area to be measured, the receiving time of the seabed reverberation echo signal and the seabed reverberation echo level equation. B Compensation is performed to obtain the seabed correction echo level equation and the compensated seabed reverberation echo echo signal RL BC ; The specific process is: Step 3: Convert the seabed reverberation echo signal RL B Expand according to the volume reverberation echo level equation formula; Step 312: According to the receiving time of the seabed reverberation echo signal, the three-quarter sound expansion attenuation TL of the sea area to be tested is obtained 1B ; Step 313: According to the pure water sound absorption coefficient of the sea area to be tested and the three-quarter sound expansion attenuation TL of the sea area to be tested 1B , the seabed reverberation echo level equation and the seabed reverberation echo echo signal RL B Compensation is performed to obtain the seabed correction echo level equation and the compensated seabed reverberation echo echo signal RL BC .

9. The method for estimating acoustic Doppler velocity measurement channel parameters according to claim 8, characterized in that: In step 3, the seabed reverberation echo signal RL B According to the volume reverberation echo level equation formula, it can be expressed as follows: Among them, S b is the seabed scattering coefficient of scattering particles per unit area of ​​the seabed area illuminated by the transducer beam; In step 312, the three-quarters acoustic expansion attenuation TL of the sea area to be measured is obtained according to the receiving time of the seabed reverberation echo echo signal. 1B ; expressed as: TL 1B =30lgr Where r represents the distance between the scattering particles and the transducer, which is calculated based on the receiving time of the echo signal of the seabed reverberation echo; Step 313: According to the pure water sound absorption coefficient of the sea area to be tested and the three-quarter sound expansion attenuation TL of the sea area to be tested 1B , the seabed reverberation echo level equation and the seabed reverberation echo echo signal RL B Compensation is performed to obtain the seabed correction echo level equation and the compensated volume reverberation echo echo signal RL BC , expressed as:

10. The method for estimating acoustic Doppler velocity measurement channel parameters according to claim 9, characterized in that: The compensated seabed reverberation echo signal RL obtained in step 31 in step 32 BC and the sound absorption coefficient α of the scattering particles in the tested sea area obtained in step 2 sυ , calculate the seabed scattering coefficient S of the scattering particles in the sea area to be measured b , expressed as:

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