JPH10197633A - Marine acoustic tomographic data analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and accurately track the peak of acoustic wave receiving signal data by shifting acoustic wave reception starting time so that the difference between reference time and the propagating time of acoustic waves transmitted at another time may become zero. SOLUTION: Acoustic wave receiving signal data Ri outputted from a data inputting section 11 at every periodical observation are inputted to a memory 1. An arithmetic processing section 12 calculates the signal density of sequential data Si(t) of the acoustic wave receiving signals read out from the data Ri at certain acoustic wave receiving time and detects the maximum signal level value by using the generated signal density sequence. Then the section 12 finds the difference between this propagating time and the propagating time of the maximum level value of a reference acoustic wave receiving signal written in a memory 4 as a variation VTi . Then the section 12 finds the difference between the acoustic wave reception starting time in the data Ri and the variation VTi as acoustic wave reception starting time data NTSi for tracking and generates acoustic wave receiving signal sequence data NRi for tracking by shifting the data NTSi so that the variation VTi may becomes zero. Therefore, the correlation between the reference acoustic wave receiving signal data and single peaks of other acoustic wave receiving signal data become definite.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a received signal peak tracking technique used for data analysis in a marine acoustic tomography data analyzer.

[0002]

2. Description of the Related Art First, transmission and reception of underwater sound waves in a marine acoustic tomography system will be described. FIG. 7 is a diagram illustrating transmission and reception of underwater sound waves in the marine acoustic tomography system. In the example of the marine acoustic tomography system in FIG. 7, a predetermined sound pulse is sequentially transmitted from a single seawater sound source at predetermined intervals (for example, every three hours). Each of the periodic transmission waves is received by a single acoustic receiver installed in the sea, for example, about 1000 km away from the sea.

[0003] On the receiving side, the received signal data in reception time of the transmission wave of (AM0.00 in the example of FIG. 7) is the reference time transmitted from the sea source periodically with the reference reception signal data R _a , And other times (AM3.
00, AM 6.00,...) For each reception time of the transmission wave, the data R ₁ , R
_2, ... and R _i, performs tracking of each received signal data. As described later with reference to FIG. 5, the sound waves in the ocean propagate through a plurality of propagation paths having different water depths.
Since the propagation speed changes due to the difference in water temperature and water pressure depending on the water depth of each propagation path, the propagation path propagates through different propagation paths at different propagation times to reach the underwater receiver. The received wave in FIG. 7 shows this state.

Conventionally, the received signal data R _a observed in reception time at which the received signal data of the tracking (some reference used for data analysis in ocean acoustic tomography data analyzer, is observed for other reception time Between the received signal data groups (R ₁ , R ₂ ,... R _i ) and the signal peaks that would have passed through the same propagation path, and a signal tracking process for associating the signal peaks. ) Is the “fluctuation” (arrangement of several hours) of arbitrary received signal data with respect to reference received signal data using a single received signal peak sequence that frequently appears in received signal data. The received signal sequence observed in the above is mainly affected by ocean phenomena due to tides, and the arrival time fluctuates periodically). Shift the wave start time Later, it was to implement the tracking of the received signal peak.

FIG. 6 is a conceptual diagram of a conventional variation calculation using a single peak. In FIG. 6, _a plurality of single peaks appearing in the received signal data Ra at the reference reception time are shown. , as shown by a broken line in FIG., received signal data R ₁ in the other reception time, R _2, ... for performing mapping of a plurality of the single peak appears in the R _i each arrival of the single peak The concept of calculating the time variation is shown.

[0006]

However, in the conventional tracking technique of received signal data used for data analysis in a marine acoustic tomography system, the marine state that changes with time (exactly, the water temperature, salinity, and pressure of the ocean) Density structure), it has been difficult to constantly calculate the amount of change in propagation time with only a single peak series. In addition, single peaks have the problem that signal interference and peak splitting occur due to ocean fluctuations, and the accurate propagation time of the received signal peak (the time required for the acoustic signal to reach the receiver from the sound source) cannot be determined. there were. In ocean acoustic tomography, it is required to accurately identify received signal data calculated in a reference field and observed received signal data (correspondence between the former and latter signal peaks). Therefore, it was necessary to accurately track the received signal data that was observed at the stage prior to the identification by some method.

[0007]

A marine acoustic tomography data analyzing apparatus according to the present invention transmits a sound wave transmitted at a predetermined interval from a single underwater sound source to a single receiver at a predetermined distance from the sound source. In the marine acoustic tomography data analysis device having a function of performing peak tracking of the received signal data, the sound wave transmitted from the underwater sound source at a reference time at a predetermined cycle and at other times is received by the receiver. Each signal is received, and the signal density of the received signal data obtained at each reception time is sequentially calculated, and the propagation time from the start time of each reception until the maximum value of the signal density of the received signal data is obtained is calculated. The difference between the propagation time at the reception time of the transmission wave at the reference time and the propagation time at the reception time of the transmission wave at the other time is calculated by the amount of change in the reception time. And determined, and has a means for shifting the reception start time of the received signal data at each reception time of the transmission wave of the other time so as to zero the variation in the respective reception time. As a result, the correspondence between the peak appearing in the received signal data at the reception time of the transmitted wave at the reference time and the peak appearing in the received signal data at each reception time of the transmitted wave at other times becomes clear, Peak tracking of wave signal data is easy and accurate.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 5 is an explanatory diagram showing that the received signal data of a sound wave radiated from an underwater sound source always includes a signal that arrives latest at the shortest distance between the sound source and the receiving point. is there. FIG. 5A shows the relationship between depth and sound speed. In the ocean, when the depth increases from the sea surface, the sound speed decreases due to a decrease in water temperature, but at a depth of about 1000 m, the sound speed becomes minimum, and when the depth further increases, the sound speed decreases. As the water pressure increases, the sound speed increases.

FIG. 5B shows a state in which a plurality of propagation paths passing through different water depths exist between a single underwater sound source and a single receiving point. Then, a signal group passing through a propagation path having a small propagation depth amplitude (difference between the maximum value and the minimum value of the depth) indicated by the tip of the arrow in FIG. 5B is the signal that reaches the shortest distance the latest. This signal group has a characteristic that the signal level is high. Each received signal data R in FIG.
Signal groups indicated by arrows near the right ends of ₁ to R _i are the signal peak groups that propagate the slowest in the shortest distance.

The present invention calculates the signal peak density of a group of signal peaks which are always present in the received signal data and which propagates the shortest at the shortest distance, and uses the propagation time at which the signal density becomes the maximum to calculate the reference reception time. By generating a variation between the received signal data and the received signal data at an arbitrary reception time, and by shifting the reception start time at an arbitrary reception time so that the variation is zero, The aim is to make tracking accurate and simple.

FIG. 1 is a block diagram of a received signal tracking system of a marine acoustic tomography data analyzing apparatus according to the present invention. In FIG. 1, 1 is a received signal data memory capable of writing and reading data, 2 is a data memory for signal density calculation, 3 is a signal density sequence data memory, 4 is a maximum level signal time data memory, and 5 is a data memory. A fluctuation amount data memory, 6 is a tracking received signal sequence data memory, 11 is a data input / output unit for inputting / outputting data to / from the outside of the system, and 12 is an arithmetic processing unit. The memory, the data input / output unit 11 and the arithmetic processing unit 12 are connected to the bus 13.

FIG. 2 is a flowchart showing the processing sequence of the received signal tracking processing according to the present invention, and the numeral following S in FIG. 2 indicates a step number. FIG. 3 is a conceptual diagram of the received signal data in the present invention. In the figure, the received signal data R _i is the received signal start time data Ts _i and the received signal sequence data S.
_i (t) (for each peak of the received signal, the propagation time (msec) and the sound pressure level are constituted by numerical data). FIG. 4 is a conceptual diagram of tracking of received signal data after being shifted by the fluctuation amount generated according to the present invention.

The operation of the system of FIG. 1 will be described with reference to FIGS. 3 and 4 based on the flowchart of FIG. In S1 of FIG. 2, the received signal data is stored. From the data output unit 11 of FIG. 1, regular observation time interval (e.g. 3 hour intervals) at ocean acoustic tomography received signal data measured by the system R _i is, received signal data in sequence for each observation Input to the memory 1. The received signal data R _i is
As shown in FIG. 3, this is a data set including reception start time data Ts _i and reception signal sequence data S _i (t).

The received signal series data S _i (t) is time series data in which the propagation time and the sound pressure level of each peak of the received signal are constituted by numerical values.
T in the S _i of (t) (), instead of the propagation time between the sound source and the receivers, and the relative time from reception start time Ts _i to peak (msec). Here, the suffix i is a serial number (1 to n) given to the received signal data R when the received signal data is input to the received signal data memory 1 in order for each observation.

In S2 of FIG. 2, a signal density calculation process is performed. Here, calculates the signal density of the received signal data R _i. The arithmetic processing unit 12 of FIG. 1, first reads the received signal data R _i of reception time from reception signal data memory 1, and writes the signal density calculation data memory 2. The received signal sequence data S _i (t) is selected from the received signal data R _i written in the signal density calculation data memory 2.
Is read. Next, as shown in the following equation (1), the signal density of the received signal sequence data S _i (t) is calculated to generate a signal density sequence Z _i (t).

[0016]

(Equation 1)

In the equation (1), L represents the length of time during which the density calculation is performed. Then, Z _i (t) generated by the equation (1) is written to the signal density sequence data memory 3.

At S3 in FIG. 2, a process of determining the maximum density time is performed. The arithmetic processing unit 12 in FIG. 1 reads out the signal density sequence Z _i (t) written in the signal density sequence data memory 3 and determines the maximum signal level value of Z _i (t) using these. The signal level maximum value Z _i (tm) is detected. Then, the propagation time t of the signal level maximum value Z _i (tm)
Let m be tm _i and write this tm _i to the maximum level signal time data memory 4.

In step S4 of FIG. 2, a process for generating a fluctuation fluctuation amount is performed. Arithmetic processing unit 12 of FIG. 1, the maximum level signal propagation time of the time level maximum value of the data memory 4 in the written serving as a reference signal (see reference reception signal data R _a in FIG. 4) tm _a, optionally the signal propagation time of the level maximum (see received signal data R ₁ to R _i, except for R _a in FIG. 4) t
read a m _i. Here, the subscript a indicates reference received signal data. Next, as shown in the following equation (2), tm _i
And it obtains the difference tm _a, this as variation VT _i, writes the change amount data memory 5.

[0020]

(Equation 2)

At S5 in FIG. 2, the reception start time data is shifted. The arithmetic processing unit 12 reads the received signal data R _i written in the received signal data memory 1 and the variation VT _i written in the variation data memory 5. Next, a difference between the reception start time data Ts _i and the variation VT _i is obtained from the read reception signal data R _i , and this difference is set as tracking reception start time data NTs _i . Then, by shifting the reception start time data Ts _i to the tracking reception start time data NTs _i (i.e. the variation amount V
T _i was shifted reception start time data Ts _i to zero) to generate a tracking received signal series data NR _i, writes the tracking received signal series data memory 6. FIG. 4 shows the received signal data after such a shift. As shown by the broken line in FIG. 4, _a single peak appearing in the reference received signal data Ra and the other received signal data R ₁ to R _{1 are shown} . The correspondence with a single peak appearing in R _i becomes clear, and tracking of received signal data becomes easy and accurate.

As described above, according to the present embodiment, in the marine acoustic tomography data analyzer, the received signal peak tracking for identifying the received signal data used for sound ray identification has a maximum signal density of the received signal data. Using the propagation time of the value, generate a variation between the propagation time of the reference received signal data and the propagation time of any received signal data,
By shifting the reception start time data of the reception signal data so that the fluctuation amount becomes zero, tracking can be performed more accurately and simply than in the past, and it is possible to contribute to improvement in the accuracy of data analysis.

[0023]

As described above, according to the present invention, a sound wave transmitted from a single underwater sound source at predetermined intervals is received by a single receiver at a predetermined distance from the sound source. In a marine acoustic tomography data analyzer having a function of performing peak tracking of signal data, sound waves transmitted from the underwater sound source at a reference time and other times according to a predetermined cycle are received by the receivers, respectively. The signal density of the received signal data obtained for each wave time is sequentially calculated, and the propagation time until the maximum value of the signal density of the received signal data is obtained from each reception start time is obtained. The difference between the propagation time at the reception time of the transmission wave and the propagation time at each reception time of the transmission wave at the other time is obtained as a variation amount at each reception time, and the variation at each reception time is calculated. Since to have a means for shifting the reception start time of the received signal data at each reception time of the transmission wave of the other time to the amount to zero,
The correspondence between the peak appearing in the received signal data at the reception time of the transmission wave at the reference time and the peak appearing at the reception signal data at each reception time of the transmission wave at other times becomes clear, and the reception signal data Is easy and accurate.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a received signal tracking system of a marine acoustic tomography data analysis device according to the present invention.

FIG. 2 is a flowchart showing a processing order of a received signal tracking process according to the present invention.

FIG. 3 is a conceptual diagram of received signal data in the present invention.

FIG. 4 is a conceptual diagram of tracking of received signal data after shifting by a variation amount according to the present invention.

FIG. 5 is an explanatory diagram of a signal that is always present in received signal data and that propagates at the shortest distance and the latest.

FIG. 6 is a conceptual diagram of a conventional variation calculation using a single peak.

FIG. 7 is a diagram illustrating transmission and reception of underwater sound waves in the marine acoustic tomography system.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 received signal data memory 2 signal density calculation data memory 3 signal density sequence data memory 4 maximum level signal time data memory 5 fluctuation data memory 6 tracking received signal sequence data memory 11 data input / output unit 12 arithmetic processing unit 13 bus

Claims (1)

[Claims] 1. A function of receiving a sound wave transmitted from a single underwater sound source at predetermined intervals by a single receiver at a predetermined distance from the sound source and performing peak tracking of the received signal data. In the marine acoustic tomography data analyzer, sound waves transmitted from the underwater sound source at a reference time according to a predetermined cycle and at other times are respectively received by the receiver,
The signal density of the received signal data obtained for each reception time is sequentially calculated, and the propagation time from the start time of each reception until the maximum value of the signal density of the received signal data is obtained is obtained. The difference between the propagation time at the reception time of the transmission wave at the time and the propagation time at the reception time of the transmission wave at the other time is obtained as a variation amount at the respective reception time, and the variation at each reception time is obtained. An ocean acoustic tomography data analysis device, comprising means for shifting a reception start time of reception signal data in each reception time of the transmission wave at the other time so that the amount becomes zero.