JPH08331065A - Acoustic communication equipment - Google Patents

Abstract

PURPOSE: To reduce the scale of the equipment and to facilitate the setting of a directivity beam by extracting a reflected wave component and reducing the component so as to attain the use of a wide directivity beam in the acoustic communication equipment making communication with an ultrasonic wave. CONSTITUTION: An acoustic communication equipment 10 uses a preamplifier 12 to amplify a reflecting wave training signal with a prescribed frequency and a prescribed pulse width from an acoustic communication equipment 20 and uses a phase shifter 13 to extract a narrow beam signal 101 directing a direction of a transmission source and calculates a direction of beam thereby calculating a direction of the transmission wave. A reflecting wave reduction circuit 15 receives the signal 101 and an omnidirectional reception signal 102 to calculate a delay time and an incident angle of a reflected wave and extracts a reflected wave component based on it and a reception level of the reflected wave component is estimated. Then sensor data sent from the communication equipment 20 are received and the reflected wave reduction circuit 15 subtracts a reflected wave level estimated through selection of the reflected wave to reduce the reflected wave and the result is fed to a demodulation circuit 16, in which the signal is demodulated to obtain sensor data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic communication device which uses ultrasonic waves for communication, and more particularly to an acoustic communication device which uses ultrasonic waves for communication in an environment where reflected waves interfere with each other, such as underwater. .

[0002]

2. Description of the Related Art An acoustic communication device using ultrasonic waves is used for communication between an observation station or an underwater moving body placed underwater and an observation ship or mother ship on the water.

Conventionally, an acoustic communication device using ultrasonic waves for the purpose of underwater communication of this type seems to exist within the beam range of a mutual transceiver even if the relative positions of the two communicating with each other move. In addition, the beam width of each transducer is widened. For this reason, the transmitter / receiver inputs noise from a wide range, resulting in deterioration of communication quality. It is also inconvenient when it is desired to keep the communication contents secret.

Therefore, in order to avoid such a problem,
An acoustic communication device has been proposed in which a narrow beam having a narrow beam directivity range is used to perform communication by directing beam patterns in mutually directing directions.

The communication between an observation station arranged underwater and an observation ship on the water will be described as an example. First, the observation ship is GPS (Global Positioning).
Use a navigation system such as System) to move to a position near the observation station. Then, the sensor data request command is transmitted as an ultrasonic signal from the observation ship in some directions in which the observation station is considered to exist.

Upon receiving the ultrasonic signal of the sensor data request command, the observation station first calculates the direction in which the signal was transmitted. Then, the sensor data as the observation result is converted into FSK (Frequency Shift).
t Keying) signal or PSK (Phase Shi)
ft Keying) signal, and transmits toward the calculated direction of the observation ship.

Upon receiving the ultrasonic signal of the sensor data, the observation ship calculates the direction in which the signal is transmitted. Subsequent communications will be directed toward the calculated observation station. Also, the received ultrasonic signal is
Demodulate and acquire as sensor data. Examples of this type of technology include the technology disclosed in Japanese Patent Laid-Open No. 3-245625.

[0008]

However, in the above-described conventional acoustic communication device, in order to reduce the data error caused by the interference between the signal directly received and the signal of the reflected wave reflected on the water surface or the like, the ultrasonic wave is generated. It is necessary to sufficiently suppress the side lobes of the signal transmitter / receiver and to make the directional beam as narrow as possible. For this reason, there is a drawback that the scale of communication hardware mounted on the observation ship or observation station becomes large.

Further, since a directional beam having a sufficiently narrow width is used, it is difficult to accurately cause the directional beams of the observation ship and the observation station to face each other.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional drawbacks, reduce a data error caused by a reflected wave, and provide an acoustic communication device in which the direction of a directional beam can be easily determined.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a transmission / reception in which an electric signal is converted into an ultrasonic signal for transmission and the received ultrasonic signal is converted into an electric signal. In an acoustic communication device provided with means, reflected wave reduction for reducing a reception level of a received signal by a reflected wave received after receiving at least one reflection after being transmitted from another acoustic communication device among received signals received Means are provided.

[0012] In another aspect, the reflected wave reducing means analyzes a signal having a known frequency and a pulse width among the received signals and detects the direct wave directly received from the other ultrasonic communication device. Means for calculating the delay time between the incident time and the incident time of the reflected wave and the incident angle of the reflected wave, and reception by the reflected wave of the received signal based on the calculated delay time of the reflected wave and the incident angle And a means for distinguishing and reducing signals.

According to another aspect, there is further provided a means for forming a received beam composed of a directional beam having directivity and an omnidirectional omnidirectional beam, and the reflected wave reducing means receives the wave. The delay time between the incident time of the direct wave and the incident time of the reflected wave received directly from the other ultrasonic communication device by analyzing the signal of known frequency and pulse width among the signals and the incidence of the reflected wave Means for calculating an angle, means for subtracting a received signal received by the directional beam from a received signal received by the omnidirectional beam to extract a reflected wave component in the received signal, and the calculated reflection And a means for calculating the reception level of the extracted reflected wave component based on the delay time of the wave and the incident angle and subtracting the reception level from the reception signal.

In another acoustic communication device that achieves the above object, a first unit having a wave transmitting means for converting an electric signal into an ultrasonic wave signal and transmitting the ultrasonic wave signal, and an ultrasonic wave transmitted from the first unit. An acoustic communication device comprising a second unit having a wave receiving means for receiving a signal and converting the signal into an electric signal,
The first unit includes a test signal transmitting unit that transmits a test signal having a preset frequency and a pulse width, and a data transmitting unit that transmits target data.
The reflected wave reducing means for reducing the reception level of the received signal by the reflected wave received by the second unit after having been transmitted at least once after being transmitted from the first unit among the received signals received by the second unit. And a data acquisition unit that acquires the target data from the received signal whose reflected wave is reduced by the reflected wave reducing unit, wherein the reflected wave reducing unit is the first
Analyzing the test signal transmitted from the unit of
Means for calculating the delay time between the incident time of the direct wave received directly from the unit and the incident time of the reflected wave and the incident angle of the reflected wave; and the calculated delay time and incident angle of the reflected wave. Based on the received signal of the data transmitted from the first unit, a means for distinguishing and reducing the received signal by the reflected wave is provided.

In another aspect, the second unit further includes means for forming a received beam including a directional beam having directivity and an omnidirectional beam having no directivity, and the reflected wave is provided. Reducing means subtracts the received signal received by the directional beam from the received signal received by the omnidirectional beam to extract a reflected wave component in the received signal of the data; and the calculated reflected wave Means for calculating the reception level of the reflected wave component in the received signal of the extracted data based on the delay time and the incident angle and subtracting it from the received signal of the data.

[0016]

[Operation] According to the present invention, the reflected wave reducing means calculates the delay time and the incident angle of reception of the reflected wave using signals of known frequency and pulse width, and based on this, The reception level of the reflected wave component can be reduced. Further, the reflected wave component can be easily extracted from the received signal by comparing the received signals of the omnidirectional beam and the directional beam.

[0017]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an acoustic communication device according to an embodiment of the present invention. In the present embodiment, as shown in FIG. 2, the acoustic communication device is mounted on an observation station placed underwater such as the seabed and an observation ship on the sea,
Observation data from the observation station (sensor data)
Will be described as an example.

As shown in the figure, the acoustic communication device of the present embodiment has an acoustic communication device 10 mainly for receiving data mounted on an observation ship and an acoustic communication device 10 mainly for transmitting data mounted on an observation station. And the acoustic communication device 20.

The acoustic communication device 10 mounted on the observation ship is
An N-channel transducer array 11 for transmitting and receiving ultrasonic signals, and an N-channel preamplifier 12 for receiving sensor data sent from the observation station,
The phase shifter 13, the beam direction calculator 14 for calculating the direction in which the received ultrasonic signal is transmitted, the reflected wave reduction circuit 15 for reducing the reception level of the reflected wave, and the demodulator 16, and the sensor data for the observation station. A phase adjuster 17 and an N-channel power amplifier 18 for transmitting a sensor data request command for requesting transmission are provided.

The N-channel transducer array 11 is formed by arranging transducers for transmitting and receiving ultrasonic signals, and transmits and receives electric signals as ultrasonic signals and receives ultrasonic signals. It is converted into an electric signal. The number of channels N is generally 4 (2 × 2), 9 (3 × 3), 16 (4 ×).
4), 25 (5 × 5), etc. It takes a large value to obtain a narrow and sharp beam, but in the present embodiment, a sharp beam, which is required in the technique for communicating by directing beam patterns in the conventional directions to each other, is used. No beam required. Therefore, the value of the number of channels may be a relatively small value.

The N-channel preamplifier 12 preamplifies the reception signal received by the N-channel transmitter / receiver array 11. The phase shifter 13 forms a received beam composed of a narrow beam having a certain directivity and an omnidirectional beam. Then, of the reception signals amplified by the N-channel preamplifier 12, a signal (narrow beam reception signal 101) received by a narrow beam directed in the direction of the transmission source of the ultrasonic signal is extracted. The beam direction calculator 14 calculates the direction in which the ultrasonic signal is transmitted based on the reception signal input via the N-channel preamplifier 12 and the phase adjuster 13. Since the relative position between the observation ship and the observation station is constantly changing, the feedback of the narrow beam reception signal 101 and the setting of the narrow beam direction by the phase shifter 13 and the beam direction calculator 14 are performed at any time.

The reflected wave reduction circuit 15 inputs the reception signal (omnidirectional beam reception signal 102) amplified by the N-channel preamplifier 12 and the narrow beam reception signal 101 extracted by the phase shifter 13, and receives the reception signal. Among them, the received signal by the direct wave directly received from the acoustic communication device 20 of the observation station and the received signal by the reflected wave received after being reflected by the sea surface etc. are distinguished and the received signal by the reflected wave is reduced. The operation of reducing the received signal by the reflected wave will be described later.

The demodulator 16 demodulates the signal whose reflected wave is reduced by the reflected wave reducing circuit 15. As a result, sensor data, which is the observation result at the observation station, can be acquired.

The phase adjuster 17 forms a transmission beam (narrow beam) having a certain directivity and performs beam forming for transmitting a sensor data request command for requesting transmission of sensor data to the observation station. In addition,
The direction of the beam forming by the phase adjuster 17 is controlled by feeding back the setting of the narrow beam direction of the received beam by the phase adjuster 13 and the beam direction calculator 14. The N-channel power amplifier 18 power-amplifies the signal of the sensor data request command beamformed by the phase adjuster 17 and sends it to the N-channel transducer array 11.

The acoustic communication device 20 mounted on the observation station includes an N-channel transducer array 21 for transmitting and receiving ultrasonic signals and an N-channel preamplifier for receiving a sensor data request command transmitted from the observation ship. 22, a phase shifter 23, a beam direction calculator 24 for calculating the direction in which the received ultrasonic signal is transmitted, a modulator 25 for transmitting sensor data to the observation ship, a phase shifter 26, and N channels A power amplifier 27 and a reflected wave training signal generation circuit 28 that generates a reflected wave training signal used to reduce the reflected wave in the acoustic communication device 10 of the observation ship are provided.

N-channel transmitter / receiver array 21, N-channel preamplifier 22, phasing device 23, beam direction calculator 24, phasing device 26, and N-channel power amplifier 2
Reference numeral 7 denotes an N-channel transmitter / receiver array 11, an N-channel preamplifier 12, and a phase adjuster 1 of the acoustic communication device 10, respectively.
3, the beam direction calculator 14, the phase adjuster 17, and the N-channel power amplifier 18 are the same.

The modulator 25 sends the sensor data to FSK.
(Frequency Shift Keying) signal or PSK (Phase Shift Keyin)
g) Modulate to signal. The modulated sensor data signal is beamformed by the phase adjuster 26, power-amplified by the N-channel power amplifier 27, and sent to the N-channel transceiver array 21.

The reflected wave training signal generation circuit 17 is
A reflected wave training signal used for executing the reflected wave reduction by the reflected wave reduction circuit 15 of the acoustic communication device 10 of the observation ship is generated. The reflected wave training signal is a pulse wave having a preset frequency and pulse width. This reflected wave training signal is similar to the sensor data in the phase adjuster 26 and the N channel power amplifier 27.
Is transmitted to the N-channel transducer array 21 via.

Here, the operation of reducing the reflected wave by the reflected wave reduction circuit 15 of the acoustic communication device 10 will be described.
When a reflected wave training signal is transmitted from the acoustic communication device 20 and received by the acoustic communication device 10, the reflected wave training signal is output from the N-channel preamplifier 12 as an omnidirectional beam reception signal 102 and from the phaser 13 to a narrow beam. The received signal 101 is input to the reflected wave reduction circuit 15.

The reflected wave reduction circuit 15 first analyzes the received signal of the input reflected wave training signal and calculates the delay time from the reception of the direct wave to the reception of the reflected wave. Since the reflected wave is received by the N-channel transmitter / receiver array 11 after passing a longer distance than the direct wave, it is received with a delay of a certain time as shown in FIG. Since the frequency and pulse width of the reflected wave training signal are preset, the delay time Td of the reflected wave can be easily calculated.

Next, the reception level value Rm of the reflected wave received by the omnidirectional beam, the reception level value Rm, n of the reflected wave received by the narrow beam, and the directivity function Dn of the narrow beam.
The incident angle θ of the reflected wave is calculated from the relationship with (θ) and Rm, n = Rm × Dn (θ).

Next, when the ultrasonic signal of the sensor data is transmitted from the acoustic communication device 20 and received by the acoustic communication device 10, the received signal of the sensor data is the omnidirectional beam reception signal 102 from the N-channel preamplifier 12. As
The narrow beam reception signal 101 is input from the phase shifter 13 to the reflected wave reduction circuit 15.

The reflected wave reduction circuit 15 first subtracts the reception signal Rl, n (t) of the narrow beam from the reception signal Rl (t) of the omnidirectional beam among the reception signals of the input sensor data. As shown in FIG. 5, the signals of the sensor data received by the omnidirectional beam and the narrow beam have the same phase between the direct waves and the reflected waves. In addition, in the direct wave reception signal, the reception level of the omnidirectional beam reception signal and the reception level of the narrow beam reception signal are theoretically the same, whereas in the reception signal of the reflected wave, the directivity function of the narrow beam is used. The reception level varies depending on Dn (θ). Therefore, if the reception signal Rl, n (t) of the narrow beam is subtracted from the reception signal Rl (t) of the omnidirectional beam, only the reflected wave component of the reception signal can be extracted as shown in FIG. .

Next, the reflected wave reduction circuit 15 refers to the extracted reflected wave component of the received signal, and receives the narrow beam received signal R after a delay time Td from the reception start time t.
Reception levels Rm, n of reflected wave components of l, n (t + Td)
Estimate (t + Td). The reception level Rm, n (t + Td) of the reflected wave component is Rm, n (t + Td) = {Rl (t + Td) -Rl, n
It can be calculated by (t + Td)} × Dn (θ) / {1-Dn (θ)}.

Then, the reflected wave reduction circuit 15 estimates the reflected wave component Rm, n from the narrow beam reception signal Rl, n (t).
The reception level of the reflected wave is reduced by subtracting n (t + Td).

Next, the operation of this embodiment will be described with reference to the time chart of FIG. First, the observation ship is GBS
(Global Positioning System
Use the navigation device such as m) to move to the sea near the observation station. Then, a sensor data request command for requesting the transmission of sensor data to the observation station is generated and sent to the N-channel transducer array 11 via the phase shifter 17 and the N-channel power amplifier 18 of the acoustic communication device 10 for observation. The station sends out an ultrasonic signal of a sensor data request command in several directions in which it is considered that the station is present.

When the N-channel transmitter / receiver array 21 of the acoustic communication device 20 receives the ultrasonic signal of the sensor data request command, the observation station amplifies the signal by the N-channel preamplifier 22, and the phase adjuster 23 and the beam. The direction calculator 24 calculates the direction of the N-channel transducer array 11 of the acoustic communication device 10 of the observation ship, which is the transmission source of the ultrasonic signal. Then, the phase adjuster 26 is adjusted based on the calculated direction of the acoustic communication device 10 to control the beamforming.

Next, in the observation station, the reflected wave training signal generation circuit 28 generates a reflected wave training signal and sends it to the N channel transmitter / receiver array 21 via the phase rectifier 26 and the N channel power amplifier 27, and the acoustic wave is transmitted. The signal is transmitted to the communication device 10. Then, after a lapse of a predetermined time, the sensor data is converted into an FSK signal or a PSK signal by the modulator 25, and the acoustic communication device is transmitted from the N-channel transmitter / receiver array 21 via the phase adjuster 26 and the N-channel power amplifier 27. Transmit to 10.

When the observation ship receives the reflected wave training signal at the N channel transmitter / receiver array 11 of the acoustic communication device 10, the received signal is sent to the reflected wave reduction circuit 15 via the N channel preamplifier 12 and the phase shifter 13. It is input, and the delay time of the reflected wave and the incident angle are calculated. Next, when the N channel transmitter / receiver array 11 receives the ultrasonic signal of the sensor data, the received signal is input to the reflected wave reduction circuit 15 via the N channel preamplifier 12 and the phase shifter 13 to reduce the reflected wave. After that, the demodulator 16 demodulates the received signal to obtain sensor data.

Although the present invention has been described above with reference to the preferred embodiments, the present invention is not necessarily limited to the above embodiments. For example, in the present embodiment, the acoustic communication device is described separately as an acoustic communication device whose main purpose is data transmission and an acoustic communication device whose main purpose is data reception. You may make it transmit and receive mutually. In this case, in any acoustic communication device, a modulator that modulates data to be transmitted, a reflected wave training signal generation circuit that generates a reflected wave training signal, and a reflected wave reduction circuit that reduces the reflected wave signal from the received signal And a demodulator for demodulating the received signal.

Further, the acoustic communication device of the present invention is used not only for transmitting and receiving predetermined data between two acoustic communication devices as in this embodiment, but also for making a call between three or more acoustic communication devices. Needless to say, it can be used in.

[0042]

As described above, the acoustic communication device of the present invention calculates the delay time of the reflected wave and the incident angle,
Based on this, it is possible to reduce the reception level of the reflected wave component from the reception signal, so that the directional beam (narrow beam)
Even if the width is relatively wide, the occurrence of data error due to the influence of interference of reflected waves is small. Therefore, it is possible to prevent the scale of communication hardware mounted on an observation ship, an observation station, or the like from increasing in order to form a directional beam having a sufficiently narrow width.

Since a directional beam having a relatively wide width can be used, it is not necessary to make the directional beams of the observation ship and the observation station face each other very accurately, and the direction of the directional beam can be easily set. .

Furthermore, since the reflected wave component can be easily extracted from the received signal by comparing the received signals of the omnidirectional beam and the directional beam, the reception level of the reflected wave in the received signal can be reduced. Can be done easily.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an acoustic communication device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a communication state according to the present embodiment.

FIG. 3 is a time chart showing the operation of this embodiment.

FIG. 4 is a chart showing a relationship between a transmission signal and a reception signal of a reflected wave training signal in the present embodiment.

FIG. 5 is a chart showing the relationship between transmission data and reception data in this embodiment.

FIG. 6 is a chart showing the relationship between the received data by reflected waves and the state in which the received data by reflected waves is reduced from the received data and the acquired data in the received data in the present embodiment.

[Explanation of symbols]

 10, 20 Acoustic communication device 11, 21 N-channel transducer array 12, 22 N-channel preamplifier 13, 17, 23, 26 Phaser 14, 24 Beam direction calculator 15 Reflected wave reduction circuit 16 Demodulator 18, 27 N Channel power amplifier 25 Modulator 28 Reflected wave training signal generation circuit

Claims (5)

[Claims] 1. An acoustic communication device comprising a wave transmitting / receiving means for converting an electric signal into an ultrasonic signal for transmission, and for converting the received ultrasonic signal into an electric signal. An acoustic communication device, comprising: a reflected wave reducing unit that reduces a reception level of a received signal by a reflected wave that has been transmitted from the acoustic communication device and then received through one or more reflections. 2. The reflected wave reducing means analyzes the signal having a known frequency and pulse width among the received signals to detect the incident time and reflection of the direct wave directly received from the other ultrasonic communication device. Means for calculating the delay time between the wave incident time and the incident angle of the reflected wave, and distinguishing the received signal of the reflected wave among the received signals based on the calculated delay time of the reflected wave and the incident angle The acoustic communication device according to claim 1, further comprising: a reducing unit. 3. A means for forming a received beam composed of a directional beam having directivity and an omnidirectional omnidirectional beam is further provided, and the reflected wave reducing means is a known signal among the received signals. The delay time between the incident time of the direct wave received directly from the other ultrasonic communication device and the incident time of the reflected wave and the incident angle of the reflected wave are calculated by analyzing the frequency and pulse width signals. Means, means for extracting a reflected wave component in the received signal by subtracting the received signal received by the directional beam from the received signal received by the omnidirectional beam, and delay of the calculated reflected wave The acoustic communication device according to claim 1, further comprising: a unit that calculates a reception level of the extracted reflected wave component based on time and an incident angle and subtracts the reception level from the reception signal. 4. A first unit having a wave transmitting means for converting an electric signal into an ultrasonic wave signal and transmitting the ultrasonic wave signal, and an ultrasonic wave signal transmitted from the first unit is received and converted into an electric signal. In an acoustic communication device including a second unit including a wave receiving unit, the first unit transmits a test signal transmitting unit that transmits a test signal having a preset frequency and pulse width, and transmits target data. The second unit receives a received signal by a reflected wave received by the second unit after having been transmitted at least once after being transmitted from the first unit in the received signal received by the second unit. A reflected wave reducing unit that reduces the level; and a data acquisition unit that acquires the target data from the received signal whose reflected wave is reduced by the reflected wave reducing unit. Uni Means for analyzing the test signal transmitted from the first unit to calculate the delay time between the incident time of the direct wave received directly from the first unit and the incident time of the reflected wave and the incident angle of the reflected wave. A means for distinguishing and reducing a received signal due to the reflected wave among the received signals of the data transmitted from the first unit based on the calculated delay time of the reflected wave and the incident angle. Acoustic communication device. 5. The second unit further comprises means for forming a received beam composed of a directional beam having directivity and an omnidirectional omnidirectional beam, and the reflected wave reducing means, Means for extracting a reflected wave component in the received signal of the data by subtracting the received signal received by the directional beam from the received signal received by the omnidirectional beam; delay time and incidence of the calculated reflected wave The acoustic communication device according to claim 4, further comprising means for calculating a reception level of a reflected wave component in the received signal of the extracted data based on the angle and subtracting the received level from the received signal of the data.