A method for estimating channel parameters of acoustic Doppler velocity measurement

Abstract

The present invention belongs to the field of underwater acoustics, and in particular relates to a method for estimating parameters of an acoustic Doppler velocity measurement channel. Current methods for measuring sound attenuation and sound scattering coefficients are greatly affected by changes in water scatterers and bottom changes, resulting in strong uncertainty, which leads to the problem of low accuracy in the measured sound attenuation and sound scattering coefficients. The present invention corrects the echo level measured by a transducer based on the equivalent plane wave reverberation level formula for volume reverberation and seabed reverberation, combined with known sound expansion attenuation and pure water absorption attenuation, to obtain volume backscattering correction curves and bottom backscattering correction curves, then derivates the distance to obtain the sound absorption coefficient, and then obtains the volume and bottom scattering coefficients, thereby solving the problem of low accuracy in the measured sound attenuation and sound scattering coefficients.

Description

Technical Field

[0001] The present 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 the Doppler effect, a Doppler current profiler (ADCP) and Doppler velocity log (DVL) were developed. The ADCP estimates velocity by extracting Doppler information from the echo signals of tiny scatterers moving with the water flow in the beam-illuminated area. The DVL estimates velocity by extracting Doppler information from the echo signals scattered by the beam-illuminated river or seabed. Acoustic Doppler velocity measurement channel parameters include the sound absorption coefficient and sound scattering coefficient of water scatterers, as well as the sound scattering coefficient of the river or seabed. Acoustic Doppler velocity measurement channel parameters are used to determine the precise measurement range of the device and optimize the device frequency selection and power setting to meet measurement requirements at different depths and complex hydrological environments, thereby improving velocity measurement accuracy.

[0003] However, the current methods for measuring sound attenuation and sound scattering coefficients are relatively complex. Theoretical formulas are usually obtained through model simulation and numerical simulation. They are greatly affected by changes in water scatterers and bottom changes, and have strong uncertainty. 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 present invention aims to address the problem that current methods for measuring sound attenuation and sound scattering coefficients are significantly affected by variations in water scatterers and bottom variations, resulting in high uncertainty and low accuracy in the measured sound attenuation and sound scattering coefficients. A method for estimating acoustic Doppler velocity channel parameters is proposed, including:

[0005] Step 1: The transceiver of the shipborne Doppler velocimeter 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 shipborne Doppler velocimeter also serves as a receiving end, which receives the reverberation echo signal of the scattered transmitted sound wave signal;

[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 measured;

[0009] Step 2: intercepting the volume reverberation echo signal from 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 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 based on the temperature of the sea area to be measured, the seabed reverberation echo signal and the seabed reverberation echo level equation.

[0011] In the second step, 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 2.1: According to the temperature of the sea area to be measured, the volume reverberation echo signal reception 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 sea area to be measured 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 sea area to be measured 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 step 3, the seabed reverberation echo signal is intercepted from the reverberation echo signal, and the seabed sound scattering coefficient of the seabed to be measured is estimated according to the temperature of the seabed 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 reception 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 signal RL BC ;

[0017] Step 32: The compensated seabed reverberation echo signal RL obtained in step 31 BC And the sound absorption coefficient α of the scattering particles in the sea area to be measured 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 a method for estimating acoustic Doppler velocity measurement channel parameters. Based on the measured echo levels of body reverberation and bottom reverberation, the method compensates for acoustic expansion and pure water sound absorption to correct the echo level curve, and then derivates the distance to achieve estimation of scatterer sound attenuation, body scattering, and bottom scattering coefficients. This 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 This is a schematic diagram of the principle flow of a method for estimating acoustic Doppler velocity measurement channel parameters 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] This paper proposes a method for estimating acoustic Doppler velocity channel parameters, including acoustic absorption, volume scattering, and bottom scattering coefficients. Current methods for measuring acoustic attenuation and scattering coefficients are significantly affected by variations in water scatterers and the seafloor, resulting in high uncertainty and low accuracy in the measured acoustic attenuation and scattering coefficients. This paper uses the equivalent plane wave reverberation level formulas for volume reverberation and seafloor reverberation, combined with known acoustic expansion attenuation and pure water absorption attenuation, to correct the echo level measured by the transducer. This method generates volume backscattering correction curves and bottom backscattering correction curves. The sound absorption coefficient is then derived with respect to distance, and subsequently the volume and bottom scattering coefficients are calculated.

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

[0024] Step 1: The transceiver of the shipborne Doppler velocimeter is used as the transmitter, which transmits the acoustic wave signal obliquely toward the seabed of the sea area to be measured.

[0025] The transceiver of the shipborne Doppler velocimeter also serves as a receiving end, which receives the reverberation echo signal of the scattered transmitted sound wave signal;

[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 measured;

[0028] Step 2: intercepting the volume reverberation echo signal from 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 signal and the volume reverberation echo level equation;

[0029] 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 based on the temperature of the sea area to be measured, the seabed reverberation echo signal, and the seabed reverberation echo level equation.

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

[0031] In the step 1, the shipborne Doppler velocimeter is installed on the bottom of the hull;

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

[0033] When sound waves are projected onto an inhomogeneous medium in the ocean, scattered waves are generated. At this time, part of the sound energy continues to propagate in the original direction, while the other part of the sound energy scatters 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 scattering of sound waves by the unevenness of the seabed, the surface roughness, and the scatterers nearby 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] Transmitting and receiving are synchronized, and the curve data of the reverberation echo signal changing with distance is collected. Other steps and parameters are the same as those in the first embodiment.

[0036] Specific embodiment three: This embodiment differs from specific embodiment one in that:

[0037] In the second step, 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 2.1: According to the temperature of the sea area to be measured, the volume reverberation echo signal reception 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 sea area to be measured 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 sea area to be measured 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 and second embodiments.

[0042] Specific embodiment 4: The difference between this embodiment and specific embodiments 1 to 4 is that in step 21, the temperature of the sea area to be measured, the volume reverberation 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 reception 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 reception time of the volume reverberation echo signal, the half-acoustic spread 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 measured and the half sound expansion attenuation TL of the sea area to be measured 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, a compensation method 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 embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that:

[0050] In the step 2-11, 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; S v is the volume scattering coefficient of the scattering particles per unit volume in the water area illuminated 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 measured; 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 transmitted 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 reception time of the volume reverberation echo echo signal are used to obtain the pure water sound absorption coefficient of the sea area to be measured in the volume reverberation echo level equation, 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, and 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 the static pressure, in atm, which can be converted from the water depth; the water depth is calculated based on the reception time and emission angle of the volume reverberation 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 of 8.0.

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

[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 based on the interference phenomenon of the emitted sound waves in the sound field. The near field refers to the area closer to the transducer, where 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 farther from the transducer, where 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 dividing 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 signal RL after compensation in step 214 VC The volume-corrected echo level equation is expanded as follows:

[0069]

[0070] The other steps and parameters are the same as those in the first to fourth embodiments.

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

[0072] dRL VC =-2(α s +α υ )dr

[0073]

[0074] d represents the derivative;

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

[0076]

[0077] ; Other steps and parameters are the same as those in one of the specific implementation methods one to five.

[0078] Specific embodiment seven: This embodiment differs from specific embodiments one to six in that, in step three, the seabed reverberation echo signal in the reverberation echo signal is intercepted; based on 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 reception 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 signal RL BC ;

[0080] Step 32: The compensated seabed reverberation echo signal RL obtained in step 31 BC And the sound absorption coefficient α of the scattering particles in the sea area to be measured 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 the first to sixth embodiments.

[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 signal RL are calculated based on 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 signal RL BC ; The specific process is:

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

[0084] Step 3-12: According to the receiving time of the seabed reverberation echo signal, the three-quarter sound expansion attenuation TL of the sea area to be measured is obtained 1B ;

[0085] Step 313: Based on the pure water sound absorption coefficient of the sea area to be measured and the three-quarter sound expansion attenuation TL of the sea area to be measured 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 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, a compensation method 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, only one compensation is performed, and the compensated signal is analyzed according to the compensated formula.

[0087] The other steps and parameters are the same as those in the first to seventh embodiments.

[0088] Specific embodiment nine: The difference between this embodiment and specific embodiments one to eight is that in step three, the seabed reverberation 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-quarters acoustic spread attenuation TL of the sea area to be measured is obtained according to the receiving time of the seabed reverberation echo signal. 1B ; expressed as:

[0092] TL 1B =30lgr

[0093] Among them, r represents the distance between the scattering particles and the transducer, which is calculated based on the reception time of the echo signal of the reverberation echo of the seabed. Calculating the distance between the scattering particles and the transducer based on the reception 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 transmitted 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-field and far-field dividing distance is calculated using the transducer radius and the emission center frequency. This 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 measured and the three-quarter sound expansion attenuation TL of the sea area to be measured 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 signal RL BC , which can be expressed as:

[0095]

[0096] The other steps and parameters are the same as those in the first to eighth embodiments.

[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 sea area to be measured obtained in step 2 sυ , calculate the seabed scattering coefficient S of the scattering particles in the sea area to be measured b , which can be expressed as:

[0098]

[0099] The other steps and parameters are the same as those in the first to ninth embodiments.

[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-mentioned specific implementation methods. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent replacements and improvements 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 scope of protection 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 shipborne Doppler velocimeter is used as the transmitter, which transmits sound wave signals to the seabed of the sea area to be measured. The transceiver of the shipborne Doppler velocimeter also serves as a receiving end, which receives the reverberation echo signal of the scattered transmitted sound wave signal; 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 measured; Step 2: intercepting the volume reverberation echo signal from 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 signal and the volume reverberation echo level equation; Step 3: intercepting the seabed reverberation echo signal from the reverberation echo signal; estimating the seabed sound scattering coefficient of the sea area to be measured based on the temperature of the sea area to be measured, the seabed reverberation echo signal, and the seabed reverberation echo level equation; In the step 1, the shipborne Doppler velocimeter is installed on the bottom of the hull; The parameters of the transceiver transducer of the shipborne Doppler velocimeter include: the combined directional beam width of the transceiver transducer is Ψ; the sound source level of the transceiver 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; and the center frequency of the transmitted sound wave signal is f; 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; In the second step, 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 2.1: According to the temperature of the sea area to be measured, the volume reverberation echo signal reception 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 sea area to be measured 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 sea area to be measured obtained in step 2 sυ , calculate the volume scattering coefficient S of the scattering particles in the sea area to be measured v ; In the step 21, the temperature of the sea area to be measured, the volume reverberation echo signal 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 reception 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 reception time of the volume reverberation echo signal, the half-acoustic spread 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 measured and the half sound expansion attenuation TL of the sea area to be measured 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 ; In the step 3, the seabed reverberation echo signal is intercepted from the reverberation echo signal; and the seabed sound scattering coefficient of the seabed to be measured is estimated according to the temperature of the seabed to be measured, the seabed reverberation echo signal and the seabed reverberation echo level equation. The specific process includes: Step 3. According to the temperature of the sea area to be measured, the reception 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 signal RL BC ; Step 32: The compensated seabed reverberation echo signal RL obtained in step 31 BC And the sound absorption coefficient α of the scattering particles in the sea area to be measured obtained in step 2 sυ , calculate the seabed scattering coefficient S of the scattering particles in the sea area to be measured b ; In the step 3, the seabed reverberation echo level equation and the seabed reverberation echo signal RL are calculated based on 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 signal RL BC ; The specific process is: Step 3: Transform 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 spread attenuation TL of the sea area to be measured is obtained 1B ; Step 313: Based on 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 signal RL BC .

2. The method for estimating acoustic Doppler velocity channel parameters according to claim 1, wherein: In the step 2-11, 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; S v is the volume scattering coefficient of the scattering particles per unit volume in the water area illuminated 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 measured; 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 transmitted 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 reception time of the volume reverberation echo echo signal are used to obtain the pure water sound absorption coefficient of the sea area to be measured in the volume reverberation echo level equation, 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 reception time and emission angle of the volume reverberation echo echo signal; f represents the center frequency of the transmitted signal, In the step 213, the half acoustic spread attenuation TL of the sea area to be measured is obtained according to the receiving time of the volume reverberation echo echo signal. 1V It can be expressed as: 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 reception time of the volume reverberation echo signal; The volume reverberation echo signal RL after compensation in step 214 VC The volume-corrected echo level equation is expanded as follows:

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

4. The method for estimating acoustic Doppler velocity channel parameters according to claim 3, wherein: In the 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 spread attenuation TL of the sea area to be measured is obtained according to the receiving time of the seabed reverberation 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 reception 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 measured and the three-quarter sound expansion attenuation TL of the sea area to be measured 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 signal RL BC , which can be expressed as:

5. The method for estimating acoustic Doppler velocity channel parameters according to claim 4, wherein: 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 sea area to be measured obtained in step 2 sυ , calculate the seabed scattering coefficient S of the scattering particles in the sea area to be measured b , which can be expressed as:

Images