JP5757303B2 - Underwater acoustic positioning system - Google Patents

Description

  The present invention relates to an underwater acoustic positioning system and an underwater acoustic positioning method for observing crustal movement of the seabed using acoustic signals. The present invention is an underwater acoustic positioning system capable of observing seafloor crustal deformation between a shipboard station and a seafloor station and calculating the degree of seafloor crustal movement by processing the observed data on the shipboard station or on land. And an underwater acoustic positioning method.

  Since GPS radio waves or light do not reach the ocean floor, it has been difficult to observe crustal deformations at the ocean floor. The observation of the crustal movement can be measured by determining the position of the shipboard station by GPS and receiving the acoustic signal emitted from the shipboard station toward the seabed station. However, since the sound speed of the acoustic signal in the sea changes every moment depending on the seawater temperature, salinity concentration, etc., it is difficult to accurately grasp in time and space. On the other hand, the observation device installed in the shipboard station accurately determines the position of the acoustic transducer of the shipboard station that emits an acoustic signal because the ship itself moves in at least three directions of rolling, pitching, and yawing. It was difficult.

  A conventional example will be described with reference to FIGS. FIG. 6 is a schematic diagram for explaining an example of transmitting and receiving a predetermined ID code and ranging signal with respect to each maritime station with a time difference in the conventional example. FIG. 7 shows a conventional example, and is a schematic diagram showing the example of FIG. 6 in time series. 6 and 7, the shipboard station 611 transmits the ID code S1 and the ranging signal M toward (m1) which is one of the submarine stations 612. Submarine station 612 (m1) transmits ID code S6 and ranging signal M to shipboard station 611 as response signals. Next, the shipboard station 611 transmits the ID code S2 and the ranging signal M toward (m2) which is one of the submarine stations 612. Submarine station 612 (m2) transmits ID code S6 and ranging signal M to shipboard station 611 as response signals. Similarly, the shipboard station 611 performs transmission / reception sequentially with the submarine stations 612 (m3, m4,...).

  The ID code S6 and the ranging signal M are transmitted from each submarine station 612 to the shipboard station 611 with a time difference of 10 seconds, for example. The transmission and reception of ranging signals shown in FIGS. 7 and 8 not only takes time, but the data obtained at the first submarine station 612 (m1) and the data obtained at the last submarine station 612 (m4) Since it is in a different state depending on the temperature and salinity, the position and inclination of the ship (pitching, etc.), it has a drawback of lacking accuracy.

  FIG. 8 is a diagram illustrating a distortion state in a phase inversion section of a bit signal in a conventional example. (A) is an example in which one bit is composed of four waves, and (B) is a state when the phase changes. (C) is a figure for demonstrating the distortion in a phase inversion area. In FIG. 8, the acoustic signal transmitted and received between the shipboard station 611 and the submarine station 612 is composed of, for example, four waves per bit. As shown in FIG. 8B, the phase when the bit changes from “1” to “0” is inverted. However, since it is actually an acoustic signal, the phase inversion section is distorted and cannot be clearly distinguished as shown in FIG. Such a bit signal has a problem in the reliability of the ID codes and ranging signals of the shipboard station 611 and the submarine station 612.

  As another conventional example, for example, in an underwater position measurement system using a transponder described in Japanese Patent Laid-Open No. 8-189969, the reception signal reading unit within a reading time when a call signal is emitted. Read the pulse signal from the connected signal conversion means. The control calculation unit stores the pulse signal read by the reception signal reading unit in the memory unit corresponding to each reading time, and compares a predetermined number of latest pulse signals for the reading time among the stored pulse signals. The pulse signals present at the same timing in the pulse signals to be compared are regarded as pulse signals based on the true response signal, and the gate switch unit receives the control signal in an appropriate period including the period in which the pulse signal exists. When the pulse signals from the detection unit are allowed to pass and the plurality of timers stop time integration, the integration time accumulated by each timer is taken in, and the underwater position is calculated from the taken integration time.

JP-A-8-189969

  In recent years (after the Great Tohoku Earthquake), the probability of a large earthquake occurring has increased. It is possible to predict the earthquake in the near future by accurately observing the crustal deformation of the seabed. The crustal movement of the sea floor cannot be observed by radio waves or light, so there was no means other than using acoustic signals. However, the speed of the acoustic signal not only changes depending on the seawater temperature, salinity, and the state of the shipboard station, but also tends to pick up various temporally and spatially derived noises.

  In order to solve the problems as described above, the present invention transmits the ID code and ranging signal from the shipboard station all at once to each submarine station, and after receiving these received signals at the shipboard station, It is an object of the present invention to provide an underwater acoustic positioning system and an underwater acoustic positioning method capable of examining crustal deformation with little error by analyzing. In addition, the present invention transmits the ID code and ranging signal from the shipboard station all at once to the submarine station, and after receiving the received signal at the shipboard station in two times, these are analyzed, It is an object of the present invention to provide an underwater acoustic positioning system and an underwater acoustic positioning method capable of examining crustal movements with less errors.

(First invention)
The underwater acoustic positioning system according to the first aspect of the present invention receives acoustic signals transmitted simultaneously from shipboard stations equipped with GPS based on GPS observation data on land, at a plurality of submarine stations installed on the seabed. By transmitting the acoustic signal from the submarine station to the shipboard station, the position data of the submarine station can be collected, and comprises the ID code (S0) and the ranging signal (M) from the shipboard station. An onboard station transmitter that transmits acoustic signals to each of the submarine stations and an acoustic signal from the onboard station transmitter, respectively, and different ID codes (S1, S2, S3, S4) for each submarine station. , ...) of the attached said ranging signal (M), respectively performs the first transmission from the seafloor with a time difference, the first time and the first 2nd Reversing the signal sequence, the ID code (S4, S3, S2, S1 , ···) and the total time required for each of the transmission of the ranging signal (M) is with a time difference that is substantially been averaged same The submarine station transmission / reception unit that performs the second transmission from the submarine station, the shipboard station reception unit that receives the first and second transmission signals from the respective submarine stations with a time difference, and the received It is at least comprised from the data processing apparatus which performs the calculation which determines the position of the said submarine station based on the received signal of the 1st time and the 2nd time, and the position signal from GPS.

( Second invention)
In the underwater acoustic positioning system according to the second aspect of the invention, the ID code (B sequence code) and ranging signal (M sequence code) change from “0” to “1” or “1” to “0”. , And the same bit continues as “0”, “0”, “0”... And “1”, “1”, “1”,. It is characterized by having time to stop.

(Third invention)
The underwater acoustic positioning method according to the third aspect of the present invention is to receive acoustic signals simultaneously transmitted from a shipboard station equipped with GPS based on GPS observation data on land by a plurality of submarine stations installed on the seabed, By transmitting the acoustic signals from the submarine station all at once to the shipboard station, the position data of the submarine station can be collected, and the ID code (S0) and ranging signal (M) from the shipboard station are collected. Are simultaneously transmitted to each of the submarine stations, and each of the submarine stations receives the acoustic signal, and an ID code and a ranging signal (S1, M), (S2) that are different depending on each submarine station. , M), (S3, M), (S4, M),..., And the first transmission is performed with a predetermined time difference with respect to each of the ID code and the ID code. And ranging signals (S4, M), (S3, M), (S2, M), (S1, M),... Are transmitted for the second time with a time difference from the submarine station. The transmission order of the first time and the second time is reversed, and the total time required for each transmission is averaged so as to be approximately the same, and transmitted from each submarine station. An operation for determining the position of the submarine station is performed on the basis of the first and second received signals and the position signal from the GPS.

  According to the present invention, since the ID code and ranging signal from the shipboard station are simultaneously transmitted to the respective submarine stations, they are simultaneously returned as a reply signal. Accurate data to know crustal deformation can be obtained. Even when the shipboard station exists at the center of each observation point, the crustal movement can be sufficiently analyzed by using FFT (Fast Fourier Transform).

  According to the present invention, the ID code and ranging signal from the shipboard station are transmitted to the submarine station all at once, and then the reply signal from the submarine station is divided into two times with respective time differences. Since it can be received by a station, data for knowing crustal deformation can be obtained more accurately from many observation points even though the shipboard station is at the center position of a plurality of submarine stations. In addition, the reply signals from the submarine stations that are sent in two steps are each averaged in delay time.

  According to the present invention, the ID code (B-sequence code) and the distance measurement signal (M-sequence code) are provided with a time during which output is stopped between bits, and thus are not easily affected by waveform distortion. The distinction becomes clear, and high-quality data can be obtained as the ID code and the distance measurement signal.

FIG. 1 is a schematic diagram for explaining an example in which ranging signals with the same ID code are simultaneously transmitted to a submarine station in the first embodiment of the present invention. FIG. 2 is a schematic diagram for explaining an example in which ranging signals with different ID codes attached to the respective submarine stations are simultaneously returned to the shipboard station in the first embodiment of the present invention. FIG. 3 is a diagram for explaining an example in which the distance measurement signal transmitted from the maritime station is received twice in the shipboard station in the second embodiment of the present invention. FIG. 4 is a diagram for explaining an example in which a pause period is inserted between a bit transmission period and a transmission period in the third embodiment of the present invention. FIG. 5 is a diagram for explaining an example of a waveform that actually appears in the third embodiment of the present invention. FIG. 6 is a schematic diagram for explaining an example of transmitting and receiving a predetermined ID code and ranging signal with respect to each maritime station with a time difference in the conventional example. FIG. 7 shows a conventional example, and is a schematic diagram showing the example of FIG. 6 in time series. FIG. 8 is a diagram illustrating a distortion state in a phase inversion section of a bit signal in a conventional example. (A) is an example in which one bit is composed of four waves, and (B) is a state when the phase changes. (C) is a figure for demonstrating the distortion in a phase inversion area.

  In the underwater acoustic positioning system of the present invention, after the acoustic signal oscillated from the acoustic transducer of the shipboard station is received by the submarine station, the acoustic signal is returned almost simultaneously from the submarine station to the shipboard station. The returned acoustic signal calculates the correct position of the submarine station by, for example, GPS provided in the shipboard station. The GPS is based on GPS observation data on land. The calculated result can determine how the position of the submarine station has changed on the ground.

  In the underwater acoustic positioning system of the present invention, acoustic signals (ID code S0, ranging signal M) are simultaneously transmitted from the acoustic transducer toward a plurality of submarine stations installed on the sea floor from the onboard station equipped with the GPS. Send. After that, the submarine station that has received the acoustic signal from the acoustic transducer sends a reply signal (ID code S1, S2, S3, S4,..., And ranging signal M) to the shipboard station. The acoustic signals of each submarine station received by the shipboard station are collected and processed by a data processing device, whereby the position information of the submarine station can be obtained accurately. In the underwater acoustic positioning system of the present invention, the measurement results return almost simultaneously with a single call, so it is less affected by changes in seawater temperature and salinity, etc., and is accurate and has good data collection efficiency. .

  The acoustic signal includes an ID code (B series code) attached to each submarine station and a ranging signal (M series code) for determining the positions of the shipboard station and the submarine station. The shipboard station transmitter transmits an acoustic signal including the ID code (B sequence code) and the ranging signal (M sequence code) to each of the submarine stations. The acoustic signals are respectively received by the submarine station transmission / reception unit. The submarine station transmitting / receiving unit transmits a reply signal (S1, S2, S3, S4,..., And M) to the shipboard station according to the respective positions.

  The shipboard station receiver receives the reply signals (S1, S2, S3, S4,..., And M) sent from the submarine station transceiver. The shipboard station receiver stores the return signal (S1, S2, S3, S4,..., And M) and the position signal from the GPS as data. The reply signal is received by the shipboard station reception unit with a time difference depending on the position of each submarine station, so that the position of each submarine station can be determined. The data is carried back to the ground at the shipboard station or as data, and the data processor performs an operation to determine the position of the submarine station. Since the underwater acoustic positioning system of the first invention sends acoustic signals all at once and processes the data returned almost all at once, it collects a large amount of data efficiently in a short time with little change in seawater temperature and salinity, etc. be able to. In general, the onboard station transmitting unit and the onboard station receiving unit are integrated transmission / reception devices provided in the onboard station, and are described separately for convenience of explanation.

  Since the ID code (B sequence code -256 bit) and ranging signal (M sequence code -512 bit) of the present invention are composed of different numbers of bits determined in advance, the ID code and ranging received by the shipboard station Many accurate data can be obtained without signal interference. In addition, the underwater acoustic positioning system of the present invention can reduce noise from signal transmission to reception even though the propagation speed of the acoustic signal is slow (1500 m / sec in the sea).

(The first aspect of the present invention)
The underwater acoustic positioning system according to the first aspect of the present invention divides transmission and reception when performing between a shipboard station equipped with GPS and a plurality of submarine stations installed on the seabed into two times, and each has a time difference. Transmitting from multiple maritime stations to the shipboard station. Since the first data and the second data in the first invention are such that the delay time of the data transmitted from the submarine station is the same in total, the error of each data can be reduced. it can. In addition, since the first invention has few errors in data, more accurate data can be obtained in data analysis even if a shipboard station exists on the center of a plurality of submarine stations.

The transmitting unit of the shipboard station transmits acoustic signals (ID code S0, ranging signal M) all at once from the acoustic transducers. Each of the submarine stations is transmitted as a reply signal with a predetermined time difference (S1, M), (S2, M), (S3, M), (S4, M),. Next, each submarine station is transmitted as a reply signal with a predetermined time difference (S4, M), (S3, M), (S2, M), (S1, M). Divided into two times, data of each submarine stations to have a time difference, it was possible to obtain accurate data Ri good. This is particularly advantageous when the shipboard station is at the center of the submarine station. The time difference can be arbitrarily set.

( Second invention)
The underwater acoustic positioning system of the second invention is for obtaining excellent data in the first invention. Since the acoustic signal is mechanical vibration, it takes time until the vibration becomes zero. The mechanical vibration may be difficult to detect between successive vibrations and when it changes to vibrations of different phases. Therefore, in the second invention, when the bit changes from “0” to “1”, or from “1” to “0”, and when the same bit changes to “0”, “0”, “0”. ”,“ 1 ”,“ 1 ”,..., There is a time during which output stops between each bit. The stop time of each bit can be made accurate because the boundary between the bits can be clearly identified. The number of waves forming the bit can be 2 to 4 waves or more.

( Third invention)
In the underwater acoustic positioning method of the third invention, the acoustic signal received by the submarine station is divided into two parts and transmitted. In the first transmission signal, a predetermined time difference is given to the submarine stations m1 to m4. Next, the second transmission signal is sent back in reverse with a predetermined time difference from the submarine stations m4 to m1. Since the first transmission signal and the second transmission signal have the average delay time from each submarine station to the shipboard station, the overall error can be reduced.

  FIG. 1 is a schematic diagram for explaining an example in which ranging signals with the same ID code are simultaneously transmitted to a submarine station in the first embodiment of the present invention. FIG. 2 is a schematic diagram for explaining an example in which ranging signals with different ID codes from the respective submarine stations are simultaneously returned to the shipboard station in the first embodiment of the present invention. 1 and 2, the underwater acoustic positioning system is provided with a transducer 111 on the bottom of an onboard station 11 equipped with GPS, and a plurality of submarine stations 12 (m1, m2, m3, m4,.・) Is laid. The shipboard station 11 includes at least a GPS for accurately knowing the position of the ship and a transducer 111 that receives signals toward the submarine station 12 (m1, m2, m3, m4,...). The shipboard station 11 is a system in which the shipboard station 11 receives the sound signal from the seabed station 12 after transmitting the sound signal oscillated from the transducer 111 to the seabed station 12.

  The returned acoustic signal from the submarine station 12 (m1, m2, m3, m4,...) Is received by the acoustic transducer 111, and then transmitted to the submarine by the GPS provided in the shipboard station 11. The position of the station 12 is calculated. The GPS is based on GPS observation data on land. For example, the observation can be performed every several months to determine how the position of the submarine station 12 has changed.

  The underwater acoustic positioning system according to the present embodiment is configured to simultaneously transmit acoustic signals (ID code S0 and ranging) from the acoustic transducer 111 toward the plurality of submarine stations 12 installed on the seabed from the onboard station 11 equipped with the GPS. Signal M). Thereafter, the submarine station 12 that has received the acoustic signal from the transducer 111 sends response data almost simultaneously toward the shipboard station 11. The acoustic signals (S1, S2, S3, S4,..., And M) of the submarine stations 12 (m1, m2, m3, m4,...) Received by the shipboard station 11 are the respective positions (distances). Are collected with slightly different time differences. Each data is processed by a data processor (not shown), so that the position information of the submarine station 12 can be obtained accurately. In the underwater acoustic positioning system of the present embodiment, the measurement results return almost simultaneously from each submarine station 12 (m1, m2, m3, m4,...) With a single call from the shipboard station 11, Accurate data can be efficiently obtained before conditions such as seawater temperature and salinity concentration change every moment.

  The acoustic signal includes an ID code (B series code) attached to each submarine station 12 and a ranging signal (M series code) for determining the positions of the shipboard station 11 and the submarine station 12. The transmitting unit of the shipboard station 11 transmits an acoustic signal including the ID code (B sequence code) and the ranging signal (M sequence code) to each of the submarine stations 12 at the same time. The acoustic signals are received by the submarine station transceiver unit (not shown). The submarine station transmitting / receiving unit transmits a reply signal (S1, S2, S3, S4,..., And M) according to the respective positions.

  The B sequence code and the M sequence code are pseudo-random signals generated based on an artificial rule. These signals have the property that the autocorrelation value shows a sharp peak and at the same time the correlation value with other than itself is extremely low. Therefore, the signal has an advantage that the propagation time can be determined by correlation processing even when the received signal is unclear due to ambient noise or the like.

  The receiving unit (not shown) of the shipboard station 11 is a reply signal sent from the transmitting / receiving unit (not shown) of the submarine station 12 (m1, m2, m3, m4,...). (S1, S2, S3, S4,..., And M) are received. The receiving unit of the shipboard station 11 stores the return signal (S1, S2, S3, S4,..., And M) and the position signal from the GPS as data. The data is brought back to the ground at the shipboard station 11 or as data, and a calculation process for determining the position of the submarine station 12 is performed by a data processing device (not shown). Since the underwater acoustic positioning system of the first embodiment sends acoustic signals all at once and processes the data returned almost all at once, it is efficient in a short time when the seawater temperature and salinity concentration do not change, and a lot of accurate data Can be collected. In general, the transmitting unit in the onboard station and the receiving unit in the onboard station of this embodiment are an integral transmitting / receiving device provided in the onboard station, and are described separately for convenience of explanation.

  Since the ID code (S0, B sequence code -256 bits) and ranging signal (M, M sequence code -512 bits) in the present embodiment are composed of different predetermined sequences and bit numbers, the shipboard station 11 A lot of accurate data can be obtained without interference between the received ID code and ranging signal. In addition, the underwater acoustic positioning system of the present embodiment can reduce noise entering from signal transmission to reception despite the low propagation speed of the acoustic signal in the sea (1500 m / sec in the sea). .

  FIG. 3 is a diagram for explaining an example in which the distance measurement signal transmitted from the maritime station is received twice in the shipboard station in the second embodiment of the present invention. The submarine station 12 of the second embodiment receives the acoustic signals (ID code S0 and ranging signal M) transmitted all at once from the underwater acoustic positioning system of the shipboard station 11. The submarine station 12 that has received the acoustic signals (ID code S0 and ranging signal M) receives acoustic signals (S1, M), (S2, M), (S3) having time differences as the first transmission signals. , M), (S4, M) are returned. Next, each of the submarine stations 12 returns a time difference acoustic signal (S4, M), (S3, M), (S2, M), (S1, M) as a second transmission signal. Is done.

  Acoustic signals (S1, M) and (S4, M), (S2, M) and (S3, M), (S3, M) and (S2, M), (S4, M) and (S1, M), since the delay time of the clock time is averaged in total, the measurement error can be reduced, and more accurate data than the first invention can be obtained by dividing into the first time and the second time. it can. This is particularly advantageous when the shipboard station is at the center of the submarine station. The time difference can be arbitrarily set.

  FIG. 4 is a diagram for explaining an example in which a pause period is inserted between a bit transmission period and a transmission period in the third embodiment of the present invention. FIG. 5 is a diagram for explaining an example of a waveform that actually appears in the third embodiment of the present invention. In FIG. 4 (a), in the portion where the phase changes between the “1” bit and the “0” bit, conventionally, it is not clearly distinguishable as shown in FIG. 4 (a) due to distortion of the acoustic device. was there. However, by providing a waveform pause period as shown in FIG. 4 (b), it is easy to distinguish the waveforms even if there is some distortion in the phase inversion period as shown in FIG. 4 (c). become.

  FIG. 5A shows a case where the same bits are continuous with “0”, “0”, “0”..., Or “1”, “1”, “1”,. . In such a case, the present invention provides a time during which output stops between bits. As shown in FIG. 5B, the stop time of each bit can be accurately determined because the boundary between the bits can be clearly identified. Since the acoustic signal is mechanical vibration, it takes time until the vibration becomes zero, but the bits are continuously from “0” to “1”, “1” to “0”, “1”, and “0”. ”Can be clearly identified by receiving a period in which the output is paused. 4 and 5, an example in which one bit is four waves is shown, but it is not related to the number of waves and can be four waves or more, not two waves.

  As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example. The present invention can be modified in various ways without departing from the scope of the claims. The shipboard and submarine stations, transmission / reception apparatus, data processing apparatus, etc. of the present invention are composed of known communication engineering and acoustic engineering techniques, and can be modified without departing from the scope of the claims. .

11 ... Shipboard 111 ... Transducer 12 ... Maritime

Claims (3)

A plurality of submarine stations installed on the seabed receive acoustic signals transmitted simultaneously from the shipboard stations equipped with GPS based on GPS observation data on land, and the sound signals are received from the respective submarine stations. In the underwater acoustic positioning system that can collect the position data of the submarine station by transmitting to
An onboard station transmitter for simultaneously transmitting an acoustic signal comprising an ID code (S0) and a ranging signal (M) from each of the aboveboard stations to each of the submarine stations;
The acoustic signals from the shipboard station transmitters are received, and the ranging signals (M) with different ID codes (S1, S2, S3, S4,. The first transmission is performed with a time difference from the station, the transmission order of the first and second transmissions is reversed, and the ID code (S4, S3, S2, S1,...) And the ranging signal A submarine station transmission / reception unit that performs a second transmission from the submarine station with a time difference in which the total time required for each transmission of (M) is averaged and substantially the same;
An onboard station receiver that receives the first and second transmission signals from the respective submarine stations with a time difference;
A data processing device that performs an operation for determining the position of the submarine station based on the received first and second received signals and a position signal from GPS;
An underwater acoustic positioning system characterized by comprising at least.   The ID code (B-sequence code) and ranging signal (M-sequence code) have a bit changed from “0” to “1”, or “1” to “0”, and the same bit is “0”, “ When “0”, “0”..., And “1”, “1”, “1”,... Are consecutive, there is provided a time during which output stops between each bit. The underwater acoustic positioning system according to claim 1. Acoustic signals transmitted simultaneously from shipboard stations equipped with GPS based on GPS observation data on land are received by a plurality of submarine stations installed on the sea floor, and the acoustic signals are simultaneously transmitted from the respective submarine stations. In the underwater acoustic positioning method capable of collecting the position data of the submarine station by transmitting to the shipboard station,
An acoustic signal composed of an ID code (S0) and a ranging signal (M) is transmitted from the shipboard station to each of the submarine stations,
In the submarine station, the acoustic signal is received, and the ID code and ranging signal (S1, M), (S2, M), (S3, M), (S4, M), which are different depending on each submarine station, .., And the first transmission is performed with a predetermined time difference for each, and the ID code and ranging signals (S4, M), (S3, M), (S2, M), (S1, M),... Are transmitted for the second time with a time difference from the submarine station, the first and second transmission sequences are reversed, and the total time required for each transmission is averaged. and so as to be substantially the same is of, and transmitted from each of seafloor,
An underwater acoustic positioning method, wherein a data processor performs an operation for determining a position of the submarine station based on the received first and second received signals and a position signal from GPS.

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