JP7057639B2 - Underwater communication device - Google Patents

Description

The present invention relates to an underwater communication device in which a high frequency current is propagated in water using an electrode.

Conventionally, the following configurations are known as an underwater communication method.
(1) Ultrasonic communication (for short distance)
Carrier frequency: 40KHz, ultrasonic transmitter method (2) Extremely low frequency communication (submarine, etc.)
A configuration using an underwater antenna with a carrier frequency of about 400 KHZ is known.
(3) Laser light (visible light)
A configuration using a laser oscillator, a semiconductor laser, a visible light LED, and a condenser lens is known.

In the method (1), since the carrier frequency is 40 KHz at the maximum, the amount of data is about the voice "maximum 1 KHz" in the audible band.
Therefore, it is not suitable for image transmission and data communication.
The method (2) has a larger amount of data than the method (1), but the longer the wavelength, the larger the scale of the device.
Further, real-time image data communication requires a band of 6 MHz or more, and a carrier frequency of 60 MHz or more.
The method (3) can be expected to have a suitable communication speed depending on the data modulation method, but if the water quality is turbid or there is an obstacle, communication becomes impossible and the optical axis beam has a linearity. Supplement becomes a difficult point.
Further, in the communication device, the communication method, and the communication system of Japanese Patent Application Laid-Open No. 2010-21874, the electrode is arranged in water; However, there is no description about the antenna coupling that has directionality on the receiving side and the source of the coupled electromagnetic wave, and the transmission path of the electromagnetic wave of the modem signal is not clear, and it is a practical communication method or device. I can't say.

Japanese Unexamined Patent Publication No. 2010-21874

The problem to be solved by the present invention is an underwater communication device that generates a carrier wave using a pair of electrodes in water, seawater, or other liquid and propagates a high-frequency current, and the device can be miniaturized. It relates to a configuration capable of transmitting a large amount of data such as voice and image.

In the invention of claim 1, in order to achieve the above object, the present invention
In underwater communication equipment
The transmitter arranges two or two facing electrodes for transmission on the outside at separated positions, and applies a high-frequency AC voltage with an offset voltage of 0V between the terminal voltages to the facing electrodes for transmission to form a square wave-shaped carrier wave. Generated
The receiver is characterized in that two or two receiving facing electrodes are arranged externally at separated positions, and the voltage between the terminals of the receiving facing electrodes is received, amplified, and demodulated.
In the invention of claim 2,
The material of the counter electrode for transmission and the counter electrode for reception is titanium.
In the invention of claim 3,
The carrier wave of the transmitter has directivity along a line L connecting a pair of electrodes facing each other outside the pair of left and right side surfaces of the insulating housing.
The pair of counter electrodes on the receiving side are all arranged in a straight line so as to be aligned with the line connecting the pair of counter electrodes for transmission .

A carrier wave is generated using a pair of opposite electrodes for transmission, information is propagated through water, and received by the opposite electrode of the receiver, realizing underwater data communication with a simple configuration. ..

It is a schematic diagram of the verification experiment of underwater communication. (A) is a block diagram of a transmitter, and (b) is a diagram showing an output waveform between terminals A and B of a pair of opposite terminals for transmission. It is a schematic diagram which shows underwater communication. It is a perspective view of a transceiver.

Hereinafter, preferred embodiments of the underwater communication device of the present invention will be described with reference to the drawings.
The transmitter 1 and the receiver 10 which are communication devices are installed separately in the water.
The transmitter 1 is exposed to water by arranging two or two facing electrodes 2 and 3 for transmission outside the transmitter 1 as transmission terminals (antennas) at separated positions.

That is, in this embodiment, for example, the transmitter 1 has a communication (transmission) circuit built in the insulating housing C, and the communication is outside the pair of left and right side surfaces facing each other on the outside of the insulating housing C. A pair of electric wires 2a and 2b (for example, 45 mm long titanium electric wires) connected to the circuit are arranged in parallel (for example, at intervals of 12 mm) to form one electrode 2, and the pair of electric wires 3a and 3b have the same configuration. The other electrode 3 is formed at (see FIG. 4).

In the illustrated example, assuming that the left and right side surfaces C1 and C2 of the insulating housing C are separated by 100 mm, the electrodes 2 and 3 facing each other are connected to each other by 100 mm in the direction of an extension of a straight line from the electrodes 2 and 3. It has the directivity L of the generated radio wave.

Here, the water in water is not limited to water, but may be a solution such as seawater, but at least around the electrodes 2, 3, 12, and 13 that function as antennas, the closer to fresh water, the less the attenuation of radio waves.

In the housing C, as a transmission circuit, as shown in FIG. 2A, a step-up DC / DC converter 5 that oscillates a unique switch frequency and a pulse oscillator 6 are provided in a power supply unit 4 such as a rechargeable battery. Is connected.

Further, a gate driver circuit 7 is connected, and the gate driver circuit 7 is connected to a pair of n-channel MOSFETs 8 and 8, and switching control of the MOSFETs 8 and 8 is performed.

As a result, as shown in FIG. 2B, a high-frequency AC voltage having an offset voltage of 0V is applied between the terminal voltages A and B to the counter electrodes 2 and 3 to output a square wave-shaped carrier wave. I'm letting you.

Therefore, a signal wave for communication data (not shown) is placed on the carrier wave, modulated, and output into the water.
Here, as described above, the carrier wave has directivity along the line L connecting the facing electrodes 2 and 3, so that the carrier wave is aligned with the line connecting the facing electrodes 12 and 13 of the receiving device described later. It is preferable to set it.

Next, the receiver 10 is provided with two or two facing electrodes 12 and 13 for reception arranged at separated positions.
Here, the counter electrodes 12 and 13 of the receiver 10 correspond to the counter electrodes 2 and 3 of the transmitter, and FIG. 1 shows a diagram for verification in which only the counter electrodes 12 and 13 are submerged in water. However, the entire receiver may be submerged.

The communication (reception) circuit built in the receiver 10 has a known configuration in which the carrier wave received by the counter electrodes 12 and 13 serving as antennas is amplified and demodulated to extract a signal wave for communication data.

In the present invention, the materials of the counter electrodes 2, 3, 12, and 13 for transmission and reception may be any materials that can be used as electrodes, for example, carbon materials such as platinum, copper, and graphite, tungsten, and water resistance. A known conductive material having properties and durability in the sea may be used, but it is preferable to use a titanium rod or a titanium plate from the viewpoint of corrosion resistance.

Further, as described above, since the signal transmitted by the counter electrodes 2 and 3 has a directivity to travel straight, the counter electrodes 2 and 3 for transmission and the counter electrodes 12 and 13 on the receiving side are arranged. Have the maximum propagation efficiency by arranging them all in a straight line (see FIG. 1).

On the other hand, in the arrangement of the facing electrodes 2, 3 and 12, 13 even on one side, when the arrangement of the electrodes approaches a right angle, the gain drops even at an equidistant distance.
In this way, it was confirmed that signal propagation in water has the same directivity as radio wave propagation in the air.

Next, the AC frequency applied to the counter electrodes 2 and 3 for transmission was set to 2.6 MHz in the experiment, but from the value measured by the LCR meter (impedance analyzer), the capacitor returned from the counter electrode and water (aqueous solution). Since the value decreases as the frequency increases, it is advantageous to use a higher frequency.

As shown in FIG. 3, the transmitter 1 and the receiver 10 may be separate bodies, or the transmitter / receiver 40 having the same structure may be used for underwater bidirectional communication.
FIG. 4 is a perspective view showing the arrangement of counter electrodes serving as antennas for the transmitter 1 and the transceiver 40 of FIG.

[Verification experiment]
In order to verify the principle of the present invention, an electrode signal transmission experiment was conducted in a water tank 15 in a laboratory.
[Transmitter 1]
The case was a 100 x 85 x 63 (unit: mm) acrylic waterproof BOX.
Built-in internal transmitter, battery, booster circuit, and half-bridge power switch circuit.
Titanium wires having a diameter of 2 mmφ and a length of L = 45 mm are arranged in parallel on a side wall surface of 85 × 63 (mm) to form one counter electrode, which is provided on the left and right side wall surfaces of the housing C, respectively. It is set to 3 and fixed so as to be separated and exposed outside the housing C.

The transmitter 1 is submerged in a water tank 15 and set.
The potential difference of the signal between the peaks was set to 20VP-P.

[Receiver]
At a distance of 1050 mm from the transmitter 1, a pair of 2 mmφ titanium rods are submerged as receiving electrodes 12 and 13 to a depth of 200 mm from the water surface.
As shown in FIG. 1, both poles of the terminals of the counter electrodes 12 and 13 are connected to the matching unit 21, the bandpass filter 22, and the high frequency amplifier 23, and the amplified signal is AC with an AC voltmeter 24 and an oscilloscope 25. The voltage and waveform were measured (see FIG. 1).

[Measurement result]
Transmission output voltage: 20VP-P
Receiving terminal voltage: An electrode is placed at a distance of 1000 mm from the transmitting end. Transmission frequency Receiving terminal voltage 2.469MHz 11mV
1.2 MHz 9.5 mV
0.606MHz 6.2mV
Distance: Electrodes are placed at 500 mm 1.2 MHz 25 mV
0.606MHz 23mV
Make the direction of the electrode on the transmitting side a right angle. / Distance 500mm
1.2 MHz 3 mV
0.606 MHz 3 mV

Electrical characteristics between underwater electrodes (measured with LCR meter)
Water temperature 28 ° C
Titanium rods having a length of 2 mmφ and a length of 100 mm are opposed to each other in tap water in parallel at a separation distance of 70 mm.
C (F) R (Ω) Z (Ω)
100Hz, 29.34μF 719Ω 717Ω
1KHz, 23.7μF 708Ω 708Ω
10KHz, 8.7μF 706Ω 706Ω
100KHz, 147nF 706Ω 706Ω

NaCl is dissolved in the above aqueous solution at a concentration of 3% and measured. C (F) R (Ω) Z (Ω)
100Hz, 30.64μF 104Ω 710Ω
1KHz, 22.2μF 41Ω 40.54Ω
10KHz, 17.3μF 38.5Ω 38.45Ω
100KHz, -6.9nF 39.45Ω 39.32Ω

As a result, it was confirmed that the facing electrodes 2 and 3 for transmission and the facing electrodes 12 and 13 on the receiving side were all arranged in a straight line to have the maximum propagation efficiency.
On the other hand, in the arrangement of the facing electrodes 2, 3 and 12, 13, the gain drops even at an equal distance when the arrangement of the electrodes approaches a right angle even on one side.
It was confirmed that the AC frequency applied to the counter electrodes 2 and 3 for transmission and the capacitor value attributed to the counter electrode and water (aqueous solution) decreased as the frequency increased.

The above verification is a numerical value in the laboratory, but the communication distance can be dramatically extended by optimally setting the distance between the relative electrodes and the arrangement to resonate with the transmission frequency with respect to water or aqueous solution. be able to.
Further, although the verification is performed only on the carrier, it is preferable to appropriately select the optimum known structure for the carrier modulation method and the demodulation structure on the receiver side.

1 Transmitter 2, 3 Transmitter facing electrode 4 Power supply 5 Boost DC / DC converter 6 Pulse oscillator 7 Gate drive circuit 8 n-channel MOSFET
9 Diode 10 Receiver 12, 13 Counter electrode on the receiving side 15 Water tank 21 Matcher 22 Bandpass filter 23 High frequency amplifier 24 AC voltmeter 25 Oscilloscope

Claims (3)

In underwater communication equipment
The transmitter arranges two or two facing electrodes for transmission on the outside at separated positions, and applies a high-frequency AC voltage with an offset voltage of 0V between the terminal voltages to the facing electrodes for transmission to form a square wave-shaped carrier wave. Generated
A communication device in a liquid, wherein the receiver arranges two or two receiving counter electrodes on the outside at separated positions to receive, amplify, and demodulate the carrier wave. The communication device in a liquid according to claim 1, wherein the material of the counter electrode for transmission and the counter electrode for reception is titanium. The carrier wave of the transmitter has directivity along a line L connecting a pair of electrodes facing each other outside the pair of left and right side surfaces of the insulating housing.
The liquid according to claim 1 or 2, wherein the pair of counter electrodes on the receiving side are all arranged in a straight line so as to be aligned with the line connecting the pair of counter electrodes for transmission. Communication device inside.

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