JP7032735B2 - Underwater positioning device - Google Patents

Description

The present invention relates to a technique for estimating the position of a source device by acoustic communication underwater.

Patent Document 1 describes an acoustic positioning system for positioning by acoustic communication underwater. In the acoustic positioning system described in Patent Document 1, the transmitter transmits a signal including a specific digital signal, and the receiver detects that the received signal contains a specific digital signal. Then, when it is detected that a specific digital signal is included, the receiver identifies the position of the transmitter from the time difference between the signals received by two or more different receiving hydrophones.

Patent Document 2 describes that the digital signal of Patent Document 1 is frequency-diffused by a known code and demodulated by a receiver using a known code. As a result, it is possible to perform positioning of a plurality of transmitters at the same time by using a unique code for a plurality of transmitters.

Patent Document 3 describes that transmission data is demodulated based on the Doppler shift amount caused by each of the plurality of relative velocities to generate a plurality of received data, and high-quality received data is selected from the plurality of received data. Has been done. It is described that the influence of multipath can be removed by this, and acoustic communication is performed underwater with good quality.

Japanese Unexamined Patent Publication No. 2008-128968 Japanese Unexamined Patent Publication No. 2011-252747 Japanese Unexamined Patent Publication No. 2016-25423

When the influence of multipath is remarkable, the signal transmitted from the transmitter is input to each receiver with a time delay due to the influence of multipath. The effect of multipath varies depending on the position of the transmission / reception hydrophone, the frequency used, and the time.

Therefore, in the acoustic positioning system described in Patent Document 1, when measuring the orientation of the transmitter from the time difference and the phase difference, multipath is obtained according to the position of the transmission / reception hydrophone, the frequency used, and the time. There is a problem that it is possible to obtain variable positioning results under the influence of.
It is also possible to detect positioning results that are not affected by multipath. However, temporal statistics need to be performed to detect positioning results that are not affected by multipath. Therefore, it is difficult to apply when at least one of the transmitter and the receiver moves.

Further, when the technique described in Patent Document 2 is applied, there is a problem similar to that of the acoustic positioning system described in Patent Document 1.

Further, when the technique described in Patent Document 3 is applied, data having no communication error is selected even if it is affected by multipath. Therefore, there is a problem that the positioning result may fluctuate.

An object of the present invention is to enable accurate positioning by underwater acoustic communication even when there is an influence of multipath.

The underwater positioning device according to the present invention is
A receiver that receives transmission data transmitted from the underwater transmitter,
A positioning calculation unit that calculates a plurality of positioning results indicating the positions of the underwater transmission device by inputting a plurality of reception data obtained from the transmission data received by the reception unit.
It includes a statistical analysis unit that estimates the position of the underwater transmission device based on the positioning results in a range corresponding to the variation of the plurality of positioning results among the plurality of positioning results calculated by the positioning calculation unit.

In the present invention, the position of the underwater transmitter is estimated based on the positioning result in the range corresponding to the variation of the positioning result among the plurality of positioning results.
Positioning results affected by multipath will fluctuate significantly. The magnitude of the effect of multipath can be estimated from the variation in positioning results. Therefore, it is possible to extract only the positioning results that are less affected by the multipath by extracting only the positioning results in the range corresponding to the variation in the positioning results. As a result, accurate positioning is possible even when there is an influence of multipath.

The block diagram of the underwater acoustic positioning system 1 which concerns on Embodiment 1. FIG. The flowchart which shows the operation of the underwater acoustic positioning system 1 which concerns on Embodiment 1. An explanatory diagram of a specific example of the calculation pattern of the positioning result 33 according to the first embodiment.

Embodiment 1.
*** Explanation of configuration ***
The configuration of the underwater acoustic positioning system 1 according to the first embodiment will be described with reference to FIG.
The underwater acoustic positioning system 1 includes an underwater transmission device 10 and an underwater positioning device 20. The underwater transmission device 10 is a device that transmits transmission data, and the underwater positioning device 20 is a device that receives transmission data and estimates the position of the underwater transmission device 10.

The underwater transmission device 10 includes a plurality of transmission units 11 from the transmission unit 11A to the transmission unit 11N. Each transmission unit 11 includes a carrier wave modulation unit 12, an analog amplifier 13, and a transmission hydrophone 14. The carrier wave modulation unit 12, the analog amplifier 13, and the transmission hydrophone 14 are realized by hardware such as a circuit or a device, or software.

The underwater positioning device 20 includes a plurality of receiving units 21 from the receiving unit 21A to the receiving unit 21M, a positioning calculation unit 22, and a statistical analysis unit 23. Each receiving unit 21 includes a receiving hydrophone 24, an analog amplifier 25, a carrier wave demodulation unit 26, and a division / separation unit 27. The positioning calculation unit 22, the statistical analysis unit 23, the receiving hydrophone 24, the analog amplifier 25, the carrier wave demodulation unit 26, and the division / separation unit 27 are realized by hardware such as a circuit or a device, or software. ..

*** Explanation of operation ***
The operation of the underwater acoustic positioning system 1 according to the first embodiment will be described with reference to FIG.
The operation of the underwater acoustic positioning system 1 according to the first embodiment corresponds to the underwater acoustic positioning method according to the first embodiment. Further, the operation of the underwater acoustic positioning system 1 according to the first embodiment corresponds to the processing of the underwater acoustic positioning program according to the first embodiment.

(Step S1: Transmission process)
Each transmission unit 11 of the underwater transmission device 10 transmits the transmission data 31 to the underwater positioning device 20.
Specifically, in each transmission unit 11, the carrier wave modulation unit 12 frequency-multiplexes the transmission data 31 and performs carrier wave modulation. The analog amplifier 13 amplifies the carrier-modulated transmission data 31. The transmission hydrophone 14 transmits the amplified transmission data 31 to the underwater positioning device 20 underwater. Although the transmission data 31 is different for each transmission unit 11, the carrier wave modulation is the same.

(Step S2: Reception processing)
Each receiving unit 21 of the underwater positioning device 20 receives the transmission data 31 transmitted from the underwater transmitting device 10 in step S1.
Specifically, in each receiving unit 21, the receiving hydrophone 24 receives the transmission data 31. The analog amplifier 25 amplifies the received transmission data 31. The carrier wave demodulation unit 26 demodulates the amplified transmission data 31. The division / separation unit 27 divides the carrier-demodulated transmission data 31 into frequency-multiplexed data for each frequency, and also performs MIMO (Multiple-Import and Multiple-Auto) separation to generate a plurality of received data 32. do. Each receiving unit 21 outputs the generated plurality of received data 32 to the positioning calculation unit 22. At this time, each receiving unit 21 outputs the carrier-to-noise ratio (hereinafter, C / N) for each received data 32 to the positioning calculation unit 22 in association with the received data 32.

(Step S3: Positioning calculation processing)
The positioning calculation unit 22 of the underwater positioning device 20 inputs a plurality of received data 32 output by each receiving unit 21 in step S2, and calculates a plurality of positioning results 33 indicating the position of the underwater transmitting device 10. The position of the underwater transmission device 10 includes at least the direction of the underwater transmission device 10 with respect to the underwater positioning device 20. The positioning calculation unit 22 outputs a plurality of positioning results 33 to the statistical analysis unit 23.
Specifically, the positioning calculation unit 22 is two reception data 32 obtained from the transmission data 31 transmitted by the same transmission unit 11, and is obtained from the transmission data received by different reception units 21. All combinations of the two received data 32 are targeted. The positioning calculation unit 22 calculates the positioning result 33 based on the time difference and the phase difference of the two received data 32 of the target combination. As a result, the positioning calculation unit 22 calculates a plurality of positioning results 33.
That is, the positioning calculation unit 22 targets the transmission data 31 transmitted from each transmission unit 11, and receives each combination of the two reception units 21 obtained from the plurality of reception units 21 by the target reception unit 21. The positioning result 33 is calculated from the two received data 32 obtained from the transmitted data 31 of the target. The positioning calculation unit 22 calculates the positioning result 33 from the reception data of the target frequency obtained by frequency-dividing the transmission data received by the reception unit 21 for each of the multiplexed frequencies.

The calculation pattern of the positioning result 33 will be specifically described with reference to FIG.
In FIG. 3, the number of transmitting hydrophones 14 (that is, transmitting unit 11) is two, and the number of receiving hydrophones 24 (that is, receiving unit 21) is four. Further, here, the frequency division multiplexing is set to 4.
In this case, the transmission data 31 transmitted from the transmission hydrophone 14A is received by the reception hydrophone 24A, the reception hydrophone 24B, the reception hydrophone 24C, and the reception hydrophone 24D. Therefore, regarding the transmission data 31 transmitted from the transmission hydrophone 14A, the positioning result 33 based on the reception data between the reception hydrophone 24A and the reception hydrophone 24B and the reception data between the reception hydrophone 24A and the reception hydrophone 24C are used. The positioning result 33, the positioning result 33 based on the reception data of the reception hydrophone 24A and the reception hydrophone 24D, the positioning result 33 based on the reception data of the reception hydrophone 24B and the reception hydrophone 24C, and the reception hydrophone 24B. Six types of positioning results 33 are obtained: a positioning result 33 based on the received data of the receiving hydrophone 24D and a positioning result 33 based on the received data of the receiving hydrophone 24C and the receiving hydrophone 24D. Similarly, for the transmission data 31 transmitted from the transmission hydrophone 14B, six types of positioning results 33 can be obtained. Therefore, a total of 12 positioning results 33 can be obtained.
In addition, 12 types of positioning results 33 can be obtained for each frequency obtained by frequency division. Here, since the frequency division multiplexing number is 4, 12 × 4 = 48 different positioning results 33 can be obtained.

In the above description, positioning between received data 32 at the same frequency is premised. However, positioning between received data 32 at different frequencies is also possible.
In this case, 12 types of positioning results 33 can be obtained for each combination of two frequencies of frequencies 1 to 4. The combinations of two frequencies of frequencies 1 to 4 are frequency 1-frequency 1, frequency 1-frequency 2, frequency 1-frequency 3, frequency 1-frequency 4, frequency 2-frequency 1, and frequency. 2-Frequency 2, Frequency 2-Frequency 3, Frequency 2-Frequency 4, Frequency 3-Frequency 1, Frequency 3-Frequency 2, Frequency 3-Frequency 3, Frequency 3-Frequency 4, Frequency 4 -Frequency 1, frequency 4-frequency 2, frequency 4-frequency 3, and frequency 4-frequency 4 are 16 ways. Therefore, 12 × 16 = 192 types of positioning results 33 can be obtained.

(Step S4: Statistical analysis processing)
The statistical analysis unit 23 of the underwater positioning device 20 determines the variation of the plurality of positioning results 33 among the plurality of positioning results 33 calculated in step S3 and the C / N of the plurality of received data output in step S2. The position of the underwater transmission device 10 is estimated based on the positioning result 33 in the range corresponding to at least one of the average value. The statistical analysis unit 23 outputs the positioning data 34 indicating the estimated position.
Specifically, the statistical analysis unit 23 compares the C / N of the target received data with the past C / N of the target received data for each of the plurality of received data output in step S2. It is determined whether or not the deterioration is equal to or more than the reference value (for example, 6 dB). The statistical analysis unit 23 excludes the received data that has deteriorated by more than the reference value from the plurality of received data, and calculates the average value of C / N for the remaining received data. The statistical analysis unit 23 uses the center value of the plurality of positioning results 33 calculated in step S3 as a reference, and positions the range according to at least one of the variation of the plurality of positioning results 33 and the average value of the C / N. The result 33 is extracted. Then, the statistical analysis unit 23 estimates the average position of the positions indicated by the extracted positioning result 33 as the position of the underwater transmission device 10.
Here, the range corresponding to the variation of the plurality of positioning results 33 is narrower as the variation is smaller. Further, the range corresponding to the average value of C / N is narrower as the average value of C / N is higher. For example, the range corresponding to the mean value of C / N is an error range of 5 degrees of the center value of statistical analysis when the mean value of C / N is 20 dB or more, and the mean value of C / N is 20 to 10 dB. In this case, the center value of statistical analysis is within an error range of 7 degrees, and when the mean value of C / N is 10 dB or less, the center value of statistical analysis is within an error range of 10 degrees. Here, the error range of the center value X degree means the range in which the deviation from the direction represented by the center value is X degree.

*** Effect of Embodiment 1 ***
As described above, in the underwater acoustic positioning system 1 according to the first embodiment, among the plurality of positioning results 33, the positioning result 33 is in the range corresponding to at least one of the variation of the positioning result 33 and the carrier-to-noise ratio. Based on this, the position of the underwater transmitter is estimated.
The positioning result 33 affected by the multipath fluctuates greatly and shows different positions. The magnitude of the effect of multipath can be estimated from the variation of the positioning result 33 and the C / N. Therefore, by extracting only the positioning result 33 in the range corresponding to at least one of the variation of the positioning result 33 and the C / N, it is possible to extract only the positioning result 33 which is less affected by the multipath. As a result, accurate positioning is possible even when there is an influence of multipath.

Here, in an environment where strong multipath is generated, frequency selective fading in which a specific frequency characteristic is deteriorated occurs, and C / N of a specific frequency is deteriorated. Therefore, it is considered that the signal whose C / N is deteriorated is affected by multipath. This effect changes depending on the arrangement of the antennas, and this effect also changes depending on the time of day.
Positioning results affected by multipath fluctuate greatly, and correct positioning results are concentrated within a certain error range. The stronger the influence of multipath, the narrower the error range is for correct positioning results. Therefore, the higher the average value of C / N, the more accurately the positioning can be performed by using only the positioning result 33 in a narrow range with respect to the center value.

In an environment where strong multipath is generated, frequency selective fading in which specific frequency characteristics deteriorate and signals with different routes are generated to change the positioning position. However, the underwater acoustic positioning system 1 according to the first embodiment frequency-multiplexes the transmission data and separates the transmission data on the receiver side. This makes it possible to reduce the influence of frequency selective fading and the influence of multipath.

*** Other configurations ***
<Modification 1>
In the first embodiment, the positioning calculation unit 22 is two reception data 32 obtained from the transmission data 31 transmitted by the same transmission unit 11, and is obtained from the transmission data received by different reception units 21. The positioning result 33 was calculated based on the time difference and the phase difference of the two received data 32. However, the positioning calculation unit 22 is two reception data 32 obtained from the transmission data 31 transmitted by different transmission units 11, and two receptions obtained from the transmission data received by the same reception unit 21. The positioning result 33 may be calculated based on the time difference and the phase difference of the data 32.

<Modification 2>
In the first embodiment, the carrier wave modulation unit 12 of the underwater transmitter 10 is frequency-multiplexed. However, the carrier wave modulation unit 12 performs only wideband modulation without multiplexing, and the division / separation unit 27 of the underwater positioning device 20 can use a plurality of band limiting filters to achieve the same effect as frequency multiplexing. Is.

1 Underwater acoustic positioning system, 10 Underwater transmitter, 11 Transmitter, 12 Carrier modulator, 13 Analog amplifier, 14 Transmit hydrophone, 20 Underwater positioning device, 21 Receiver, 22 Positioning calculation unit, 23 Statistical analysis unit, 24 Receive Hydrophone, 25 analog amplifier, 26 carrier wave demodulator, 27 division / separation unit, 31 transmission data, 32 reception data, 33 positioning result, 34 positioning data.

Claims (9)

A plurality of receivers having a receiving hydrophone for receiving transmission data transmitted by a transmitting hydrophone from an underwater transmitter, and
Using each combination of the two receiving units in the plurality of receiving units as the target combination, the positioning result indicating the position of the underwater transmitting device is calculated from the time difference in which the transmission data is received by each receiving unit in the target combination. With a positioning calculation unit that calculates a plurality of positioning results indicating the position of the underwater transmitter,
Underwater positioning including a statistical analysis unit that estimates the position of the underwater transmission device based on the positioning results in the range corresponding to the variation of the plurality of positioning results among the plurality of positioning results calculated by the positioning calculation unit. Device. A receiver having a receiving hydrophone that receives transmission data transmitted by the transmission hydrophone from a plurality of transmitters included in the underwater transmitter, and a receiver.
The underwater transmission device is based on the time difference between the time differences in which the transmission data transmitted from each transmission unit in the target combination received by the reception unit is received, with each combination of the two transmission units in the plurality of transmission units as the target combination. A positioning calculation unit that calculates a plurality of positioning results indicating the positions of the underwater transmitter by calculating the positioning results indicating the positions of
Underwater positioning including a statistical analysis unit that estimates the position of the underwater transmission device based on the positioning results in the range corresponding to the variation of the plurality of positioning results among the plurality of positioning results calculated by the positioning calculation unit. Device. The underwater positioning device according to claim 1 or 2 , wherein the statistical analysis unit estimates the position of the underwater transmission device based on the positioning results in the range based on the center value among the plurality of positioning results. The underwater positioning device according to any one of claims 1 to 3 , wherein the statistical analysis unit estimates the position of the underwater transmission device based on the positioning result in a narrower range as the variation is smaller. A claim that the statistical analysis unit estimates the position of the underwater transmission device based on the positioning result in the range corresponding to the carrier-to-noise ratio of the received data obtained from each transmission data among the plurality of positioning results. The underwater positioning device according to any one of 1 to 4 . The underwater positioning device according to claim 5 , wherein the statistical analysis unit estimates the position of the underwater transmission device based on the positioning result in a narrower range as the carrier-to-noise ratio is higher. The statistical analysis unit obtains positioning results in a range corresponding to the average value of the carrier-to-noise ratio for a plurality of received data excluding the received data whose carrier-to-noise ratio is deteriorated by a reference value or more compared to the past received data. The underwater positioning device according to claim 5 or 6 , which estimates the position of the underwater transmission device based on the above. Each of the plurality of receiving units receives transmission data transmitted from the plurality of transmitting units included in the underwater transmitting device.
The positioning calculation unit calculates the positioning result from the transmission data of the target received by each receiving unit in the combination of the targets, using the transmission data transmitted from each of the plurality of transmission units as the target transmission data. The underwater positioning device according to claim 1. The receiving unit receives frequency-multiplexed transmission data and receives the frequency-multiplexed transmission data.
The positioning calculation unit targets each of the multiplexed frequencies, and calculates the positioning result from the reception data of the target frequency obtained by frequency - dividing the transmission data received by the reception unit. The underwater positioning device according to any one of the above items.

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