JPH10221444A - Method and device for measuring seabed acoustic characteristic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate a wide depth range with a thin depth resolution. SOLUTION: Measurement data obtained by receiving a sound wave from a wide bandwidth sound source and a plurality of processing frequencies of the received sound wave are used. A depth range corresponding to each of a plurality of processing frequencies is obtained by a transmission depth calculation part 5. After that, analyses are successively executed from the analysis of a shallow depth range by a high processing frequency to the analysis of a deep depth range, and the estimation value of acoustic characteristics of one split depth range that is a previous analysis result is utilized as information that is known to the analysis of the depth range. An estimation accumulation part 14 successively accumulates seabed acoustic characteristic estimation value up to depth ranges Zn-1-Zn being outputted from an end judgment part 13 and outputs the estimation value of all accumulated depth ranges as the seabed acoustic characteristic estimation value of depth 0-ZN under the seabed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for measuring seafloor acoustic characteristics, and more particularly to a method for estimating submarine acoustic characteristics based on correlation between measured data of sound waves propagating in the sea and replica data obtained by propagation calculation. The present invention relates to a measuring method and a measuring device.

[0002]

2. Description of the Related Art A conventional undersea acoustic characteristic measuring apparatus accurately and efficiently estimates multidimensional unknown parameters relating to undersea acoustic characteristics based on correlation values between measurement data of sound waves propagating in the sea and replica data. (IEEE Journal of Oceanic Engineering, Vol. 18, Issue 3 (IEEE J
OURNAL OF OCEANIC ENGINEERING, VOL.18, NO.3) 224
Pp. 231).

FIG. 5 is a block diagram showing an example of a main part of the conventional submarine acoustic characteristic measuring apparatus. In the figure, first, the parameter setting unit 21 sets a multidimensional parameter set relating to the seafloor acoustic characteristics. Here, the multi-dimensional parameter set includes, for example, a sound velocity profile, density, attenuation rate, layer structure, and the like under the seabed indicating acoustic characteristics under the seabed. The replica calculator 22 calculates the replica data corresponding to the set parameter set using a predetermined propagation model, and outputs the replica data to the correlation calculator 23.

The correlation calculator 23 calculates a correlation value between the measurement data obtained by each receiver and the above-mentioned replica data. At this time, input measurement data and replica data corresponding to an arbitrary single processing frequency fN are used. The measurement data input to the correlation calculation unit 23 in the first iteration loop is also used in the correlation calculation in the subsequent iteration loop.

The correlation change calculator 24 calculates the difference between the correlation value calculated by the correlation calculator 23 and the correlation value obtained in the previous loop of the repetitive processing, that is, the amount of change in the correlation value. The correlation change evaluation unit 25 evaluates this change amount. Specifically, the correlation change evaluation unit 25 determines whether or not the correlation value has changed so as to increase based on the amount of change in the correlation value. Further, when it is determined that the correlation value has decreased, it is determined whether or not the value obtained by the random number calculation satisfies a probability distribution that determines an allowable probability of allowing the decrease of the correlation value.

[0006] The moving average calculation unit 26 includes a correlation change evaluator 2.
According to 5, when it is determined that the correlation value has increased, or when the above value satisfies the probability distribution that determines the allowable probability of allowing the correlation value to decrease even when the correlation value decreases, the correlation value Calculate the moving average of the change. The parameter update unit 27 receives the moving average value calculated by the moving average calculation unit 26, and updates the value of the parameter set to a value newly set in the current loop. The end determination unit 28 determines whether or not a preset end condition is satisfied. If the end condition is satisfied, the end determination unit 28 updates the updated parameter set value up to the submarine depth ZN to be analyzed. Output as sea floor acoustic characteristics. If the termination condition is not satisfied, the parameter setting unit 21 repeats the processing of the next loop.

The magnitude of the probability distribution is proportional to the moving average of the change in the correlation value.
Then, the moving average of the change in the correlation value is calculated and the update of the probability distribution is set, and the probability distribution is used in the next loop. On the other hand, when the correlation change evaluation unit 25 determines that the correlation value is reduced and does not satisfy the probability distribution, the parameter setting unit 21 does not update the value of the parameter set and repeats the next loop process from the parameter setting unit 21.

[0008]

However, in the above-mentioned conventional seafloor acoustic characteristic measuring apparatus, only one processing frequency fN is used for the analysis of the entire depth range. Average value for
When performing analysis over a wide depth range, the resolution in the depth direction becomes coarse, and therefore, it is difficult to analyze a wide depth range with a fine depth resolution.

The present invention has been made in view of the above points,
It is an object of the present invention to provide a method and a device for measuring a seafloor acoustic characteristic that can estimate and acquire a submarine acoustic characteristic in a wide depth range with a fine depth resolution.

[0010]

In order to achieve the above object, a method of the present invention comprises transmitting a plurality of sound waves, including a plurality of processing frequencies, transmitted through the sea and transmitted through an entire underwater sound field including below the sea floor. Received by the receiver, the correlation between the measurement data obtained by each of the plurality of receivers and the replica data by propagation calculation obtained in the order of the frequencies for each of the plurality of processing frequencies, The estimated values of the seafloor acoustic characteristics in the depth range are calculated, and these estimated values are sequentially accumulated to measure the estimated values of the seafloor acoustic characteristics in the entire depth range to be analyzed.

Further, in order to achieve the above object, the present invention provides a broadband sound source for transmitting a wideband sound wave including a plurality of processing frequencies into the sea, and a transmitting device which transmits the whole undersea sound field including under the seabed. A wave array, a receiver array consisting of a plurality of receivers each receiving a wave, measurement data from a plurality of receivers constituting the receiver array, and a plurality of processing frequencies for each of the frequency order An analysis unit for obtaining an estimated value of the seafloor acoustic characteristic in the entire depth range of the analysis target from the correlation with the replica data obtained by the propagation calculation.

According to the present invention, a wideband sound wave is transmitted / received, and the seafloor sound in a depth range at each processing frequency is obtained from a correlation between the measurement data and replica data obtained by propagation calculation obtained in order of each of a plurality of processing frequencies. The estimated values of the characteristics are calculated, and the estimated values of the seafloor acoustic characteristics in the entire depth range of the analysis object are measured based on the accumulated and estimated values.

Here, as shown in FIG. 4, the sound wave transmitted from the sound source 16 below the sea surface, propagates below the sea floor and returns to the receiving point 17 underwater again has a lower frequency among the frequencies f1, f2 and f3. Sound waves with higher frequencies penetrate deeper into the ocean floor, and sound waves with higher frequencies stop at lower depths. For this reason, the measurement data of the high-frequency sound wave includes only shallow undersea information, and the analysis using this measurement data is limited to a narrow depth range. That is, for sound waves having a frequency relationship of f1>f2> f3, the penetration depth is Z1 <Z2 <
Z3.

Therefore, in the present invention, the analysis using the measurement data of the high-frequency sound wave is started, and the analysis using the measurement data of the low-frequency sound wave is repeated. Underwater acoustic characteristics can be estimated.

[0015]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration diagram of one embodiment of a method and apparatus for measuring a seafloor acoustic characteristic according to the present invention. In this figure, this embodiment has a broadband sound source 1 installed in the sea, a receiver array 2 in which a plurality of receivers are arranged in the sea, and a plurality of receivers constituting the receiver array 2. It comprises an analyzer 3 having an analyzer 4 for obtaining seafloor acoustic characteristics based on measurement data from the wave device. Underwater broadband sound source 1
The broadband sound wave transmitted from is transmitted through the entire underwater sound field including under the sea floor, and is received by a plurality of receivers constituting the receiver array 2. The analysis device 3 analyzes the measurement data obtained by each of the plurality of receivers constituting the receiver array 2 by the analysis unit 4 and outputs the seafloor acoustic characteristics.

In this embodiment, a sound wave in a frequency band including at least the frequencies f1 to fN is transmitted from the broadband sound source 1, and a plurality of processing frequencies f1 to fN
Is performed in order from the analysis of the shallow depth range by the high frequency, and the estimated seafloor acoustic characteristics are used as known information in the analysis of the deep depth range by the next frequency, and this is used for all processing frequencies. Is to be repeated.

Next, the analysis unit 4 will be described.
FIG. 2 is a block diagram showing an embodiment of a main part of the submarine acoustic characteristic measuring apparatus according to the present invention. The block diagram of FIG. 2 is a block diagram showing the configuration of the analysis unit 4 of FIG. 1, and includes a parameter setting unit 6, a replica calculation unit 7, a correlation calculation unit 8, a correlation change calculation unit 9, a correlation change evaluation unit 10, moving Average calculator 1
1. In addition to the same configuration as the analysis unit of the conventional seafloor acoustic characteristic measuring device including the parameter updating unit 12 and the end determining unit 13, an estimated value accumulating unit 14 for accumulating the pitch acoustic characteristic estimated value from the end determining unit 13. And a transmission depth calculation unit 5 to which the estimated value is input, and further controls the parameter setting unit 6, the replica calculation unit 7, and the correlation calculation unit 8 with the transmission depth calculated by the transmission depth calculation unit 5. It is.

In this embodiment, first, the penetration depth calculation
In the part 5, the transmission depths Z1 to ZN of the frequencies f1 to fN are
Is calculated. This penetration depth Z1 to Z N propagates below the ocean floor
After receiving, the frequencies f1 to f that can be received by the receiver array 2
This is the maximum subseafloor depth reached by N sound waves. Also,
1 to N in wave numbers f1 to fN are estimation processes of this embodiment.
Is the number of the processing frequency used in
> F2>. . . > FN. Where the sound
Waves penetrate deeper at lower frequencies, so
The depth is Z1 <Z2 <. . . <ZN.

The processing after the calculation of the transmission depth by the transmission calculation section 5 in the analysis section 4 is divided into processing by a total of two stages of processing loops of a first loop and a second loop. In the first loop, the processing frequency and the depth range to be analyzed are updated sequentially,
The estimated value of the seafloor acoustic characteristics in the depth range is accumulated, and in the subsequent loop, the processing of estimating the multi-dimensional parameter with respect to the processing frequency and the analysis depth range set in the first loop is performed.

In order to perform the above-described processing in the two-stage processing loop, the transmission depth calculating unit 5 calculates the processing frequency fn of the first-stage n-th loop by using the replica calculating unit 7 and the correlation calculating unit 8.
And the depth range below the seabed to be analyzed, Zn-1 to Zn
Is output to the parameter setting unit 6, and further, the estimated values of the seafloor acoustic characteristics at the depths of 0 to Zn−1 below the seabed accumulated in the loop completed so far are output to the replica calculation unit 7.

The parameter setting unit 6 determines the depth range Zn-1 to
A multidimensional parameter set relating to the sea floor acoustic characteristics of Zn is set. Here, the multidimensional parameter set is, for example, a sound velocity profile under the seabed showing the acoustic characteristics under the seabed,
The density, the attenuation rate, the layer structure and the like are factors. The replica calculator 7 calculates replica data of the frequency fN corresponding to the set parameter set using a predetermined propagation model, and outputs the replica data to the correlation calculator 8. In this calculation, the estimated values of the seafloor acoustic characteristics in the depth range of 0 to Zn-1 are interpolated into the calculation parameters as known information.

The correlation calculator 8 calculates a correlation value between the measured data of the frequency fN obtained by each receiver and the replica data input from the replica calculator 7. Note that the measurement data input to the correlation calculation unit 8 in the first loop in the subsequent stage is continuously used in the correlation calculation in the subsequent loop. The correlation change calculator 9 calculates the difference between the correlation value supplied from the correlation calculator 8 and the correlation value obtained in the previous loop, that is, the amount of change in the correlation value.

The correlation change evaluator 10 evaluates the amount of change in the correlation value calculated by the correlation change calculator 9. Specifically, the correlation change evaluation unit 10 determines whether or not the correlation value has changed so as to increase based on the amount of change in the correlation value. Further, when it is determined that the correlation value has decreased, the correlation change evaluation unit 10 determines whether or not the value obtained by the random number calculation satisfies a probability distribution that determines an allowable probability of allowing the decrease of the correlation value. judge. The moving average calculation unit 11 determines whether or not the above value allows the correlation value to decrease even when the correlation change evaluation unit 10 determines that the correlation value has increased or when the correlation value has decreased. Satisfies the probability distribution which determines the moving average of the correlation values.

The parameter updating unit 12 updates the value of the parameter set to a value newly set in the current loop, based on the moving average value calculated by the moving average calculation unit 11. The end determination unit 13 determines whether or not a preset end condition is satisfied, and when the end condition is satisfied, the value of the parameter set updated by the parameter update unit 12 is set in the depth range Zn-1 to Zn. The estimated value is output to the estimated value storage unit 14 as the estimated value of the seafloor acoustic characteristic. If the end condition is not satisfied, the parameter setting unit 6 starts the processing of the next subsequent loop.

The magnitude of the probability distribution is proportional to the moving average of the change in the correlation value. Moving average calculator 11
Then, the moving average of the change in the correlation value is calculated, the update of the probability distribution is performed, and the probability distribution is used in the next loop processing. On the other hand, when the correlation change evaluating unit 10 determines that the correlation value is reduced and the probability distribution is not satisfied, the parameter setting unit 6 does not update the value of the parameter set, and repeats the processing of the next subsequent loop from the parameter setting unit 6.

The estimated value accumulating section 14 sequentially accumulates the seafloor acoustic characteristic estimated values in the depth range Zn-1 to Zn output from the end judging section 13 and accumulates them after completing the first-stage N-time loop processing. The estimated values of all depth ranges are output as estimated values of the seafloor acoustic characteristics at the depths below the seafloor 0 to ZN. If all loops of the first stage have not been completed, the estimated value accumulating unit 14
Outputs the stored seafloor acoustic characteristic estimation values of depths 0 to Zn to the penetration depth calculation unit 5 and repeats the processing of the next initial stage loop.

Next, the operation of the embodiment of FIG. 2 will be described with reference to the flow of processing of the first-stage loop and the flowchart showing the relationship between the first-stage loop and the second-stage loop of FIG. As described above, the processing algorithm of this embodiment is divided into a two-stage processing loop. In the first-stage loop, the processing frequency and the depth range to be analyzed are sequentially updated, and the estimated value of the seafloor acoustic characteristics in the depth range is updated. Is stored, and in the subsequent loop, a process of estimating parameters for the processing frequency and the analysis depth range set in the first loop is performed.

First, in the first-stage loop, data having the lowest processing frequency fN is sequentially processed from the data having the highest processing frequency f1.
, The processing loop is repeated a total of N times for each of the N processing frequencies until the processing frequency fn (where n =
1, 2,. . . , N) are sequentially accumulated, and finally the estimated values of the seafloor acoustic characteristics of all the depth ranges 0 to ZN to be analyzed are known in the next loop. Given as information.

Specifically, first, the transmission depths Z1 to ZN of the sound waves having the frequencies f1 to fN are calculated by the transmission depth calculator 5 (step S1 in FIG. 3). Subsequently, a first-stage loop starts (step S2 in FIG. 3), and first, depth ranges 0 to Z1 based on the measurement data and the replica data of the frequency f1.
The estimation process of the seafloor acoustic characteristics is performed in a subsequent loop (see FIG. 3).
Step S3), the estimation result is accumulated in the estimation value accumulating unit 14 as the seafloor acoustic characteristic estimation value of the depth range 0 to Z1, and the accumulated estimation value is used as known information of the second loop processing of the first-stage loop. (Step S4 in FIG. 3).

Hereinafter, in the same manner as above, the frequencies f2 and f2
3,. . . , FN−1, the estimation processing of the seafloor acoustic characteristics in the depth range Zn−1 to Zn by the replica data is performed in the subsequent loop, and the estimated value at that time is obtained in the submarine sound in the depth range Zn−1 to Zn. The estimated value is stored in the estimated value accumulating unit 14 as the characteristic estimated value, and the accumulated estimated value is given as known information of the next first-stage loop processing. , And the resulting estimate is used in the depth range ZN-
When the estimated values are stored in the estimated value storage unit 14 as the estimated values of the seafloor acoustic characteristics of 1 to ZN (step S5 in FIG. 3),
From 4, the estimated values of the seafloor acoustic characteristics at all the analysis depths 0 to ZN are output, and the process ends.

Next, the operation of the subsequent loop will be described with reference to FIG.
Will be described in more detail. The subsequent loop is based on the first loop.
Multi-dimensional parameters for the set processing frequency and depth range.
It is a loop of a repetitive process for estimating a meter.
Every time the processing loop is repeated, the parameter setting unit 6
N-dimensional parameters related to seafloor acoustic characteristics by random number calculation
Meter set {X (1)-X (N)} is used for penetration depth calculation
Set according to the analysis depth range Zn-1 to Zn input from the section 5.
Is determined. Replicate the set parameter set.
The calculator 7 transmits the replica data of each receiver in a predetermined
Calculate by model. At this time, the replica calculation unit 7
Are the depths 0 to Z input from the penetration depth calculation unit 5 n-1
Interpolation of acoustic characteristic estimation values into calculation parameters as known information
I do.

The correlation value R between the replica data and the measurement data input from each receiver is calculated by the correlation calculator 8. The measurement data from each receiver is input in the first loop processing of the subsequent loop, and the measurement data is continuously used in the subsequent loop processing of the subsequent loop. The replica data corresponding to the processing frequency fn input from the penetration depth calculation unit 5 is calculated by the replica calculation unit 7, and the measurement data corresponds to the processing frequency fn input from the penetration depth calculation unit 5. These are selected by the correlation calculator 8 and used for the correlation calculation.

As a method of calculating the correlation value R, for example, a Bartlett correlation equation can be used. The measurement data vector of each receiver is defined as a vector M =
{M (1),. . . , M (N)}, and the replica data vector of each receiver is defined as a vector X = {X
(1),. . . , X (N)}, the correlation value R is calculated by the following equation.

R = M ^T [XX ^T ] M (1) where T is an operator of complex conjugate transpose, and [] is a time average of measured values. The calculated correlation value R is normalized, and becomes the maximum correlation value 1 when the vector M and the vector X completely match. Note that the calculation of the correlation value R is not limited to this method, and another calculation method such as a method using an MV correlation equation may be applied.

Next, the correlation value R (i) obtained by the correlation calculator 8 and the correlation value R calculated during the previous loop processing are calculated.
The difference (i-1) is calculated as the correlation value change ΔR by the correlation change calculator 9 based on the following equation.

ΔR = R (i) −R (i−1) (2) The correlation change evaluation unit 10 determines whether or not the correlation value R has increased based on the correlation value change ΔR. ,
That is, when it is determined that the correlation value R has increased, the moving average of the correlation value change is calculated by the moving average calculation unit 11, and the value of the parameter set set in the previous loop processing is newly updated by the parameter update unit 12. Update the value of the set parameter set.

On the other hand, when ΔR <0, that is, when the correlation value R decreases, the correlation change evaluating unit 10 further determines whether or not the value φ obtained by the random number calculation satisfies the probability distribution P (ΔR). You. Here, the probability distribution P (ΔR) is represented by ΔR
It is calculated when <0, and 0 <P (ΔR) <１ ／, and the value φ is an arbitrary number selected with equal probability in the range [0, 1]. When P (ΔR) ≧ φ, that is, when the value φ obtained by the random number calculation satisfies the probability distribution P (ΔR), the moving average of the correlation value change is calculated by the moving average calculation unit 11, and then the parameter is calculated. The updating unit 12 replaces the value of the parameter set set in the previous loop processing with the value of the newly set parameter set.

The probability distribution P (ΔR) is obtained by calculating the correlation value change Δ
It is proportional to the moving average value of R and is obtained by the following equation.

P (ΔR) = 1 / [1 + exp {−ΔR / (<T> / ln (K))}] (3) where <T> is a moving average value of ΔR, and K is It is a large constant. The moving average <T> of ΔR is calculated every time the value of the parameter set is updated. In the next loop processing, the moving average value newly calculated is used as the value of <T> in the calculation formula of the probability distribution P (ΔR). By doing so, it is possible to gradually allow the parameter values to converge while stochastically allowing the case where the correlation value R decreases, that is, the situation worsens.

When the parameter set is replaced (updated), the convergence of each parameter, that is, the variation range of the parameter value with respect to the number of repetitions is determined by the end determination unit 13.
When the fluctuations of all parameters are stabilized below a predetermined value, the repetition processing of the subsequent loop ends, and the value of the newly replaced parameter set is changed to the seafloor acoustic characteristics of the depth range Zn-1 to Zn. Is output to the estimated value accumulating unit 14 as the estimated value of. If the fluctuations of all parameters do not fall below the predetermined values, the parameter setting unit 6 newly sets a parameter set, and starts the processing of the next subsequent loop.

On the other hand, in the correlation change evaluation section 10, ΔR
<0, that is, when it is determined that the correlation value R decreases and the value φ obtained by the random number calculation does not satisfy the probability distribution P (ΔR), the value of the set parameter set is excluded, and The parameter set value set at the time of the loop processing remains. Then, the parameter setting unit 6
Thus, the parameter set is newly set, and the processing of the next subsequent loop is repeated.

[0042]

As described above, according to the present invention,
A wideband sound wave is transmitted and received, and the estimated value of the seafloor acoustic characteristic in the depth range at each processing frequency is calculated from the correlation between the measured data and the replica data obtained by propagation calculation obtained for each of the plurality of processing frequencies in order of frequency. Since the estimated values of the seafloor acoustic characteristics in the entire depth range of the analysis target are measured using the estimated values obtained by accumulating and synthesizing them, the estimated values of the seafloor acoustic characteristics in the entire depth range of the analysis target in a wide range of depths are calculated at a fine depth. It is possible to obtain at a resolution, and it is possible to improve the measurement accuracy and reliability of the submarine acoustic characteristic measuring device.

[Brief description of the drawings]

FIG. 1 is a schematic overall configuration diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of an embodiment of a main part of the present invention.

FIG. 3 is a flowchart for explaining the operation of FIG. 2;

FIG. 4 is a diagram showing a difference in penetration depth below the seabed according to frequency.

FIG. 5 is a block diagram of an example of a main part of a conventional device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 broadband sound source 2 receiver array 3 analyzer 4 analyzer 5 penetration depth calculator 6 parameter setting unit 7 replica calculator 8 correlation calculator 9 correlation change calculator 10 correlation change evaluation unit 11 moving average calculator 12 parameter update unit 13 End determination unit 14 Estimated value storage unit

Claims (9)

[Claims] 1. A sound wave having a plurality of processing frequencies transmitted in the sea and propagated in the entire underwater sound field including under the sea floor is received by a plurality of receivers, and each of the plurality of receivers receives the sound wave. From the correlation between the obtained measurement data and the replica data obtained by the propagation calculation obtained in the order of frequency for each of the plurality of processing frequencies, an estimated value of the seafloor acoustic characteristic in a depth range at each processing frequency is calculated, and these estimations are performed. A seafloor acoustic characteristic measuring method characterized by sequentially accumulating values and measuring an estimated value of the submarine acoustic characteristic over the entire depth range to be analyzed. 2. A broadband sound source for transmitting a wideband sound wave including a plurality of processing frequencies into the sea, and a plurality of reception units for receiving the transmitted sound wave transmitted through the entire underwater sound field including under the seabed. A receiver array comprising receivers, a correlation between measurement data from a plurality of receivers constituting the receiver array, and replica data by propagation calculation obtained in order of frequency for each of the plurality of processing frequencies. An analysis unit for obtaining an estimated value of the seafloor acoustic characteristic over the entire depth range of the analysis target from the apparatus. 3. The analysis unit divides the entire depth range to be analyzed into a plurality of transmission depths corresponding to the plurality of processing frequencies, and obtains replica data by propagation calculation for each of the divided transmission depth ranges. In addition, the estimated value of the seafloor acoustic characteristic of the entire depth range to be analyzed is calculated based on the estimated value of the submarine sound propagation characteristic for each of the penetration depth ranges obtained by dividing the estimated value of the submarine sound propagation characteristic from the correlation with the measurement data of the receiver. The seafloor acoustic characteristic measuring apparatus according to claim 2, wherein: 4. A transmission depth calculation unit for dividing the entire depth range of the analysis target into a plurality of transmission depths corresponding to the plurality of processing frequencies, and a plurality of transmission depth calculation units obtained by the transmission depth calculation unit. A parameter setting unit that sets a multidimensional parameter relating to seafloor acoustic characteristics by random number calculation for each of the transmission depths of the seafloor; a replica calculation unit that performs propagation calculation of replica data of a processing frequency corresponding to the set parameter; A correlation calculation unit for calculating a correlation value between the measurement data of the processing frequency and the replica data from the processing unit, and a correlation value at the transmission depth input this time from the correlation value calculation unit and a different transmission depth previously input. A correlation change calculator for calculating a change with a correlation value, and evaluating the correlation change obtained by the correlation change calculator to determine whether the parameter set is updated. A correlation change evaluation unit for selecting whether to exclude, a moving average calculation unit for calculating a moving average of a change in the correlation value when the update is selected, and a parameter set value when the update is selected. A parameter update unit for updating to a value set by a parameter setting unit, and an end condition of the iterative processing by the correlation change calculation unit, the correlation change evaluation unit, the moving average calculation unit, and the parameter update unit after the parameter update is performed. It is determined whether or not the condition is satisfied, and if the condition is satisfied, the repetition processing is terminated,
An end determination unit that outputs the updated value of the parameter set as an estimated value of the seafloor acoustic characteristic related to the depth range, and an estimated value storage unit that stores the estimated value output from the end determination unit. In the case where the termination condition is not satisfied, the processing from the parameter setting unit is repeated. The seafloor acoustic characteristic measuring apparatus according to claim 2, wherein an estimated value of the submarine acoustic characteristic over the entire depth range of the analysis target is output from a value accumulating unit. 5. The correlation change evaluation unit, wherein the correlation value increases or the correlation value decreases, and a value obtained by random number calculation satisfies a probability distribution that allows the correlation value to decrease. The apparatus according to claim 4, wherein the updating is selected in the case. 6. The moving average calculating section calculates a moving average of a change in the correlation value, updates a probability distribution proportional to the magnitude of the moving average, and executes the correlation change evaluating section at the next processing. The seafloor acoustic characteristic measuring apparatus according to claim 4, wherein the probability distribution is used according to: 7. The end determination unit evaluates a variation width of each parameter value with respect to the number of repetitions, and when the variation of all parameters is stabilized to a set value or less, the correlation change calculation unit, the correlation change evaluation The apparatus according to claim 4, wherein the processing by the unit, the moving average calculating unit, and the parameter updating unit is terminated. 8. The propagation calculation parameter as a known information, wherein the replica calculation unit interpolates, as known information, an estimated value of a seafloor acoustic characteristic in an already estimated depth range corresponding to another processing frequency. Item 4. A submarine acoustic characteristic measuring apparatus according to item 4. 9. The analysis unit may calculate a seafloor acoustic characteristic estimation value of a transmission depth range for each of the plurality of processing frequencies in order from a highest processing frequency to a lowest processing frequency, from a higher frequency to a lower frequency. 9. The method according to claim 2, wherein the estimated value of the seafloor acoustic characteristic in the previous depth range is used as known information in the calculation of the estimated value of the submarine acoustic characteristic in the depth range by the next processing frequency. The seafloor acoustic characteristic measuring device according to the item.