JPS63222279A - Underwater object measuring apparatus - Google Patents

Abstract

PURPOSE:To enable precision measurement with a simple construction, by transmitting an ultrasonic pulse signal under water from a transmitter based on a precision time signal outputted from a GPS to measure an arrival time thereof with an ultrasonic wave receiver. CONSTITUTION:A GPS receiver C is incorporated into an ultrasonic pulse transmitter B mounted on an underwater object A while a float E with a GPS antenna D mounted thereon is connected to the transmitter B mounted on the underwater object A with a cable F and an ultrasonic pulse signal is transmitted underwater from the transmitter B based on a precision time signal outputted from a GPS. A ship G under or on water is equipped with an ultrasonic wave receiver H, a GPS antenna J and a GPS receiver K and the arrival time of the ultrasonic pulse signal is measured with the receiver H to determine a linear distance R to the transmitter B.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides an ultrasonic transmitter (hereinafter referred to as an ultrasonic transmitter) attached to an underwater object.
It's called a transmitter. ) with a GPS receiver (hereinafter referred to as GPS), the transmitter position (as the transmitter is attached to the underwater object, the underwater object position) can be easily and accurately determined using the high precision time signal output by the GPS. The present invention relates to an underwater object position measuring device. Furthermore, the present invention attaches transmitters to a plurality of objects whose positions in the water have been measured in advance, and
The present invention relates to an underwater object position measuring device that easily and accurately measures the position of an underwater object.

(Prior art) In order to determine the straight-line distance, the depth meter used in this type of conventional device needs to transmit ultrasonic waves from the ship, and the depth meter must receive and respond to the ultrasonic waves. A transducer and an ultrasonic receiver were required for the depth meter. In addition, in order to identify the number of depth gauges, multiple receiving sonar units were required, as each depth gauge was transmitting ultrasonic pulses at different frequencies.

GPS, a recently proposed satellite navigation system, is a Global Positioning System.
m (abbreviation for universal positioning system), a satellite that uses a high-precision clock to passively measure the distance between the satellite and the user (without the user transmitting radio waves) It is a navigation system.

All NAVSTAR satellites, which are GPS satellites, have atomic clocks (2 cesium atomic clocks and 2 rubidium atomic clocks).
It is scheduled to be equipped with. The clocks on these satellites have been proven to have a stability of around 10-13 tons (nanoseconds, l O-”) per day.
), and most of the progress and lag can be predicted.

GPS consists of a space part, a control part, and a user part.The control part is a ground station facility that receives signals from the satellite at an unmanned monitoring station and monitors the status of the clock on the satellite and the orbit of the satellite. related data to the main control station.

The main control station predicts the future state of the satellite's clock and the satellite's position based on the data from the monitor stations at these various locations, and stores these predicted values in the memory on the satellite from one of the unmanned ground antennas. Send to. The ground antenna also receives telemetry signals from the satellite and transmits command signals for operation of the satellite.

The space part is a satellite, and the atomic clock on the satellite is 10.2
It oscillates at a frequency of 3MHz, and the transmission frequency is 1.
54 times 1572.42 MHz (Lυ and 120 times 12
27,6 MHz (L*). The reason why two frequencies are transmitted is to correct the propagation delay of radio waves in the ionosphere.

The ranging signal is a noise-like binary code, pseudo-noise (P N)
It is called a code, and is a code in which the same number of 0s and 1s appear irregularly. Two types of PN codes are transmitted from the satellite. One of them is a signal called the P code, which is a fast code of 10.23 megabits (Mb) per second, and is a long code with a length of one week. The other signal has a speed of 1.023 Mb/s and a length of 1 m5 (millisecond, one-tenth of a second), and is called the C/A code.

It is said that A is a signal that captures (AquisitLon) (the P signal). When using P code,
First, after receiving the C/A code, an operation is performed to move to the P code. It is said that this C/A code will be available for civilian use. However, since the C/A code beam is not transmitted at the same frequency, the ionospheric error is corrected by another method.

Broadcast data from a satellite in binary code is superimposed at a speed of b/s. This data is 30 seconds (1,500 bits)
This cycle is called one frame. This frame is further divided into 5 subframes every 6 seconds, subframe 1 is mainly correction data for predicting the satellite clock, and subframes 2 and 3 are prediction data for calculating the satellite orbit. Contains. The contents of subframes 4 and 5 change every frame, and return to the previous data at the 25th frame. Therefore, only these two subframes require 12.5 minutes to acquire all their data.

(Structure of the Invention) The present invention utilizes such GPS as an underwater object position measuring device by connecting a float equipped with a GPS antenna and a transmitter with a built-in GPS attached to an underwater object with a cable. The ultrasonic pulse signal based on the precise time signal output by the transmitter is transmitted underwater from the transmitter, while the receiver measures the time of arrival of the ultrasonic pulse signal in the water or in the water. This allows you to find the straight-line distance to.

In addition, when the above device transmits an ultrasonic signal from the transmitter based on the GPS time signal, the straight line distance from the receiver to the transmitter can be continuously transmitted by transmitting a continuous signal whose frequency changes with time. It is something that can be measured.

Further, in the above device, the present invention provides a plurality of transmitters, each of which is attached to a corresponding object whose position in the water has been confirmed in advance, and the ultrasonic signal transmitted by each of the transmitters is received by the receiver. The electric circuit means connected to the receiver measures the straight distance from each of the plurality of transmitters to the receiver, thereby making it possible to confirm the position of the ship.

(Effects of the Invention) In the present invention configured as described above, since the transmitter transmits ultrasonic waves at accurate times, the straight line distance to the transmitter can be easily determined. Conventionally, in order to determine the straight-line distance to a transmitter, it was necessary to transmit ultrasonic waves from the ship and have the transmitter receive and respond to them. For this purpose, the ship had a transmitting transducer and the transmitter had an ultrasonic receiver. However, this is not necessary with the device of the present invention.

Conventionally, when there are multiple transmitters, each transmitter has an identification code (for example,
(changing the frequency). However, the present invention has the advantage that by shifting the transmission timing from each transmitter in advance, there is no need to include an identification code or to identify means on the receiving side.

Furthermore, the present invention allows a transmitter to transmit a continuous signal whose frequency changes with time, so that the position of an object in or on the water can be continuously measured even if the object moves. The position of an object in or on water can be accurately measured two-dimensionally or three-dimensionally by installing two transmitters at positions whose positions have been confirmed in advance and transmitting signals.

(Example) As an example of the underwater object position measuring device according to the present invention, a GPS receiver is incorporated into a depth gauge attached to an underwater object, and the depth gauge position is measured using a high-precision time signal output by the GPS. The following describes the device that does this.

As shown in Figure 1, a GPS receiver is connected to an ultrasonic pulse transmitter B attached to an underwater object A, and a float E with a GPS antenna D attached to the transmitter B attached to the underwater object is connected with a cable F. Then, an ultrasonic pulse signal based on the precise time signal outputted by the GPS is transmitted underwater from the transmitting DB, while an ultrasonic receiver I, a GPS antenna J, and a GPS receiver K are installed in the boat G underwater or on the water. is installed, and the straight line distance R to the transmitter B is determined by measuring the arrival time of the ultrasonic pulse signal with the receiver H.

Figure 2 shows an example of the timing when there is only one transmitter. When the digit changes, a pulse is output), (C) shows the input pulse of the ultrasonic receiver. Note that R=td-c, c: underwater sound speed.

The transmitter shown in FIG. 2 transmits pulses based on a time signal.

Fig. 3(a) shows the electric circuit on the transmitter side, Fig. 3(b) shows the electric circuit on the receiver side, and Fig. 4 shows the signal waveform of each electric signal in the electric circuit of Fig. 3. .

In Fig. 3(a), 1 is the GPS antenna, 2 is the G
3 is an integrator, 4 is a V/F converter, 5 is an amplifier, and 6 is an ultrasonic transmitter. The antenna l constantly receives the GPS time signal shown in Fig. 4(a), and the GPS receiver 2
outputs the pulse signal shown in FIG. 4(b) from the integrator 3.
A signal whose frequency increases linearly with time as shown in FIG. 4(C) is generated through the V/F converter 4, and an ultrasonic signal is transmitted from the transmitter 6 to the receiver side through the amplifier 5. In FIG. 3(b), 11 is a receiver, 12 is an amplifier, 1
3 is a multiplier, 14 is a GPS antenna, 15 is a GPS receiver, 16 is an integrator, 17 is a V/F converter, 18 is a low-pass filter, 19 is a period measuring device, 20 is a latch, 2
1 is a ROM, and 23 is a display.

The antenna 14 always receives the GPS time signal shown in FIG. 4(a), the GPS receiver 15 outputs the pulse signal shown in FIG. 4(b), and the integrator 16 and V/F converter 17
The waveform signal shown in FIG. 4(c) is sent to the multiplier 13 through the multiplier 13.

The receiver 11 receives the ultrasonic signal from the transmitter 6, passes it through the amplifier I2, and transmits the waveform signal shown in FIG. 4(d) to the multiplier 13.
send to The multiplier 13 calculates two types of waveform signals as shown in FIG. 4(c) and (d), and passes them through the low-pass filter 18 and the period measuring device 19 to produce the signals as shown in FIG. 4(e). The period of the frequency signal of the difference between the two signals, signal (c) and signal (d), is sent to the latch 20. The latch 20 latches the period of the frequency signal shown in FIG. 4(e) sent from the period measuring device 9 at the timing of the pulse signal shown in FIG. 4(b) sent from the GPS receiver. The period of the frequency signal in the water and the corresponding distance value are stored in the ROM 21 in advance, and when the period of the frequency signal from the latch 20 enters the ROM 21, the distance value corresponding to the period of the frequency signal is stored in the ROM 21. is output to the display 23. Therefore, the position of the transmitter, that is, the position of the underwater object to which the transmitter is attached, can be easily and accurately measured using the high-precision time signal output by the GPS.

Further, in the underwater object position measuring device as shown in the above embodiment, if the transmitter is made to transmit a continuous signal whose frequency changes with time, the receiver and the electric circuit means can continuously receive signals from the transmitter. It is now possible to sequentially measure the straight-line distance to the aircraft, making it possible to continuously measure the position of moving objects such as ships. moreover,
As a modification of Fig. 1, Fig. 5 shows two underwater objects A (
Figure 8 shows one equipped with three underwater objects (A , , A t , A3). Each underwater object A is equipped with an ultrasonic pulse transmitter B and a GPS receiver C, and a cable F connects the GPS antenna D attached to the corresponding float E to the receiver C.

On the other hand, the ship G is equipped with an ultrasonic receiver (G), a GPS antenna (J), and a GPS receiver (K) in the same way as the one in Figure 1.
It is equipped with The electric circuit on the transmitter side when equipped with the two underwater objects A, A, shown in FIG.
b) and the corresponding electrical circuit on the receiver side
FIG. 7 shows the signal waveform of each electric signal in the electric circuit shown in FIG. 6. 6 and 7 are the same as those in FIGS. 3 and 4, the same numbers are given to each component, and the explanation thereof will be omitted. Figures 6 and 7
The difference between the modified example in the figure and the one in FIGS. 3 and 4 is that on the transmitter side in FIGS. The changeover switches 7a and 7b are provided between the converter 4 and switched by the time signal from the GPS receiver 2. On the other hand, on the receiver side in FIG. latch 20
ROMs 21a and 20b are provided in each latch.
On the other hand, the latches 20a, 20b and the GPS receiver 15 are connected to the latches 20a, 20b and the GPS receiver 15.
5 and the GPS receiver 15 is provided with a delay circuit 24. Antenna of each float E,,E,! and ship G
The anti-+''I4 of the GPS receivers 2 and 15 constantly receive the GPS time signal shown in FIG. 7(a), respectively.
Outputs the pulse signal shown in Figure (b), and integrators 3 and 16
The waveform signal of FIG. 7(C) is selected through the switch 7a,
7b and multiplier 13. On the transmitter side of FIG. 6(a), by switching the changeover switch 7a, the waveform signal of FIG. 7(d) is transmitted from the transmitter 6 through the V/F converter 4 and the amplifier 5 to the receiver. While transmitting to the side, Fig. 6 (
On the transmitter side of b), the seventh
The waveform signal in FIG. 7(e) whose timing is shifted from that in FIG.
transmits the ultrasonic signal to the receiver side. On the receiver side in FIG. 6(c), the receiver If receives the ultrasonic signals from the two transmitters 6.6 and passes them through an amplifier 12, corresponding to the ultrasonic signals from the transmitters 6.6, respectively. Then, the waveform signals shown in FIGS. 7(r) and 7(g) are sent to the multiplier 13, respectively. The multiplier 13 calculates the waveform signal of FIG. 7(C) and FIGS. 7(f) and (g), respectively, and sends the output as shown in FIG. 7(h) to the low-pass filter I8 and By switching the changeover switch 25 via the period measuring device 19, the period of the frequency signal is latched into the corresponding latches 20a, 20b at different timings. R.O.
M21a, 2 lb are loaded and stored in advance with the period of the frequency signal underwater and the corresponding distance value, and when the period of the frequency signal from the corresponding latch 20a, 20b is entered, the corresponding frequency is input from the ROM 21a, 2 lb. A distance value corresponding to the period of the signal, that is, a pair of transmitters 6
．． 6 to the receiver 11 are outputted to the displays 23a and 23b. Therefore, by attaching transmitters to a plurality of objects whose positions in the water have been measured in advance, it is possible to more easily and accurately measure the positions of objects in or on the water (ships, submersibles, etc.).

In addition, the three underwater objects A r , A t , and
Figure 9 shows the electrical circuit on the transmitter side when equipped with A3.
a).

9(b) and (c), and the corresponding electric circuit on the receiver side is shown in FIG. 9(d), and further, the signal waveform of each electric signal in the electric circuit of FIG. 9 is shown in FIG. The modifications shown in FIGS. 9 and 10 are approximately the same as those shown in FIGS. 6 and 7, except that the changeover switches 7a, 7
b, 7c and 25° are respectively of the three-point switching type, and latches 20a, 20b, 20c and 110M21a, 2 correspond to the three-point switching contacts of the changeover switch 25゛.
lb, 21c, and the 110M21
a, 2 l b, and 21c, and the arithmetic circuit 26 is newly equipped with a transmitter position circuit 27. Each float E I, E t ,
The antenna 1 of E3 and the antenna I4 of ship G always receive the GPS time signal shown in Fig. 1O(a), and
The pulse signals shown in FIG. 10(b) are output from the S receivers 2 and 15, and the pulse signals shown in FIG. 10(C) are outputted through the integrator 3 and I6.
The waveform signal is output to the changeover switches 7a, 7b, 7c and the multiplier 13. Part i.

On the transmitter side in Figure (a), by switching the changeover switch 7a,
The waveform signal shown in FIG. 1O(d) is transmitted from the transmitter 6 to the receiver side through the V/F converter 4 and the amplifier 5. On the other hand, on the transmitter side of FIGS. 10(b) and (c), the timings of FIGS. 10(e) and (r) are shifted from that of FIG. The waveform signal is passed through the v/F converter 4 and the amplifier 5, and an ultrasonic pulse signal is transmitted from the transmitter 6 to the receiver side. 9th
On the receiver side in FIG. Correspondingly, waveform signals as shown in FIGS. 10(g), (h), and (i) are sent to the multiplier 13, respectively. In the multiplier 13, the waveform signal of Fig. 1O (c) and Fig. 1θ (g), (h) and (
i) respectively, and each output is passed through a low-pass filter 1.
8 and the period measuring device 19, the corresponding latches 20a, 20h, 20 are set by switching the changeover switch 25°.
c, f and J in Fig. 10 (1) at different timings, respectively.
, , f, respectively.
a, 20b.

Latch to 20c. ROM21a, 2lb, 21
The period of the frequency signal in water and the corresponding distance value are input and stored in each of c, and when the frequency signal from the corresponding latch 20a, 20b, 20c is input, the corresponding frequency is input from the ROM 21a, 2lb, 21c. A distance value corresponding to the period of the signal, that is, a pair of transmitters 6,
6. Straight distance from 6 to receiver 11 R1, Rt, R
a is output to the position calculation circuit 26. Position calculation circuit 26
is the position (x+, Ytr Z1
1Xt+Ytr Ztl and
Z) is calculated and displayed on the display 23'.

Therefore, as described above, three transmitters are attached to three corresponding objects whose positions in the water have been confirmed in advance, and the ultrasonic pulse signals transmitted by each of the transmitters are received by the receiver to detect the target object. The electric circuit means connected to the receiver measures the linear distances from each of the three transmitters to the receiver, thereby making it possible to reliably confirm the position of the ship.

Note that, as a method of outputting the GPS time signal, it is processed by the CPU control circuit shown in FIG. 11, for example. That is, in FIG. 11, the GPS receiver can know the distance to each satellite and the rate of change in distance by measuring the reception timing of the PN code from the four GPS satellites and the Doppler frequency of the transmission frequency. However, since this measured value is obtained based on the clock signal within the receiver, it includes errors such as offset. Therefore, these obtained distances are called pseudo distances, and the rate of change in distance is called a pseudo distance change rate.

If the pseudo distance to the satellite is Rn, then Rn=RN+CXΔt +CΔt, (1) xi, yi, zi: Position of satellite i Xo * Yo, Zo: Position of receiver antenna C:
Speed of light Δt: The clock errors xi, yi, and zi in the receiver are known by knowing the transmission time from the satellite, and are unknown or the four of X1lJO+ZO+Δt.

Therefore, equation (+) can be solved by knowing xi, yi, and zi for the four satellites.

The pseudo distance change rate can also be determined as a three-dimensional velocity using a similar method.

In this way, X. The three-dimensional positions of +yo and Zo, the offset value of Δt, and the own speed can be determined.

By knowing the offset value of Δt, the deviation from the GPS time can be known, so it is possible to adjust the clock in the receiver to match the GPS time (the difference is kept within 160 μs in Coordinated Universal Time).

In this way, a GPS receiver can obtain accurate latitude, longitude, and altitude, as well as its own moving speed and accurate time.

After the GPS signal received by the antenna is amplified, it is
The frequency is converted by the l mixer.

Since the GPS signal is subjected to spectrum spreading using a PN code, this demodulation is performed first.

Since the PN code is unique to each satellite, the CP
Use U to select the code. Next, since the PN code is a pulse train of 1 chip (976 ns) and 1023 chips (] ms), it is necessary to align the start point of this code with the start point of the code from the satellite.

The CPU checks the code match signal while changing the PN code start point and determines whether the code matches.

Next, the phase of the PN code clock (the phase with a period of 976 ns per chip) is adjusted to determine the phase amount that maximizes the A/D conversion output of the code matching signal. A/D conversion input is PN
After the code and the signal multiplied by m of the PSC output are mixed at M3, they are mixed with the GPS signal at M2, and the spread spectrum signal is despread (demodulated) to determine the existence of the received signal.

By detecting the maximum value of A/D conversion at the start point and phase adjustment of the PN code, the delay time of the code from the satellite (l
(within ms). Next, the received signal squared by the M4 mixer is a PL composed of vCO and M5.
Carrier demodulation is performed in the L circuit.

By demodulating the carrier, it is possible to measure the Doppler frequency from the difference in the position of each satellite, which becomes the basis for measuring its own three-dimensional velocity. On the other hand, the output of the VCO is 172
By mixing the carrier with the multiplied 90° phase shift using M6, information from each satellite (time, satellite position, satellite orbit information, parameters, etc.) that is phase modulated at 50 Hz can be obtained.

The time can be determined by knowing the time information from the satellite (in 1.5S units every 6S) and the timing of this time information within 1m5 (PN code pulse train) to determine the position of each satellite. Become.

This series of operations is performed for the four satellites, and the measurement is completed by knowing each satellite's information, Doppler frequency, and time information. It is not necessary to know satellite information all the time, and it is sufficient to know it every 30 minutes. The latter two need to be measured each time.

The Is correction value can be determined by knowing Δt for outputting the time pulse and knowing the offset error of the clock in the receiver. Next, as shown in FIG. 12, a major correction of the rise of Is is made by first knowing the time after the next 6S in units of 1.5S with an error within Ims from the time information from each satellite.

In Figure 12, at the rise of IS at the satellite time, the CPU
If you interrupt manually, it is possible to judge the difference from the GPS time with an error within Ims, so set the correct time after the next 6S (adjust the advance using a shift register and counter, etc.) Generally, GPS reception With this machine, it is possible to synchronize the rise of the Is pulse with the GPS time with an error within ±1 oans.

In addition, as shown in Fig. 13, the pulse position of IS obtained on the receiver side as the timing on the receiver side corresponding to the output timing on the satellite side, the values of B and D are fixed, and the value of A is fixed on the satellite side. The value of B is (preamble + α), which is approximately 180m5°D, which is the delay time due to the length of the cable from the antenna to the receiver.

By setting a delay amount of toout=1s-A-B-D, it is possible to synchronize with the true Is pulse.

Since a GPS receiver requires O20 stability of about 10-9, synchronization of about ±100 ns is possible by measuring and correcting the amount of delay every 10 seconds.

The time information itself needs to be output to IS Moe in consideration of delays.

If you only want to output a time pulse, if you know the satellite's position that can be determined from the received signal from any one satellite and your own exact position, you can find out the amount of delay in the time pulse from the satellite. , the time pulse can be corrected. By demodulating the received PN code, the timing pulse and its time can be determined. This situation is shown by comparing the time timing on the satellite side and the received timing.

As described above, the underwater object position measuring device according to the present invention has a simple configuration and can achieve the intended purpose.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the underwater object position measuring device according to the present invention, Fig. 2, (a) to (C) are time charts of each transmitter, and Fig. 3, (a) and (b). is an electrical circuit diagram of the device shown in FIG. 1, FIG. 4, (a) to (e) are electrical signal waveform diagrams related to the circuit shown in FIG. 3, and FIGS.
6, (a) to (C) are explanatory diagrams showing modified examples of FIG. 1, and FIG. 7, (a) is an electric circuit diagram of the device in FIG.
) to (h) are electrical signal waveform diagrams related to the circuit in FIG. 6, FIG. 9, (a) to (d) are electrical circuit diagrams of the device in FIG. 8, and FIG. 1O (a) to (i) and (1) are electric signal waveform diagrams related to the circuit of FIG. 9, and FIG.
The control block diagrams of the PU, FIGS. 12 and 13, are timing diagrams of the satellite and receiver, respectively. A...Underwater object, B...Ultrasonic transmitter signal,
C...GPS receiver, D...GPS antenna, E
...Float, F...Cable, G...Ship, G...Ultrasonic receiver, J...GP
S antenna, K...GPS receiver.

Claims (3)

[Claims] (1) While installing an ultrasonic receiver and a GPS on a boat underwater or on the surface, the GPS antenna installed on a float on the water and the ultrasonic transmitter attached to an underwater object are connected by a cable, and the above float or object is connected by a cable. Or GP to cable
S, and an electric circuit means for measuring the arrival time of the ultrasonic pulse signal transmitted by the transmitter underwater to the receiver based on the precise time signal output by the GPS, and the output of the means An underwater object position measuring device characterized in that the straight-line distance from the transmitter to the receiver is determined by: (2) In the device according to claim 1 above,
The transmitter is configured to transmit a continuous signal whose frequency changes with time, and the receiver and electric circuit means continuously measure the linear distance from the transmitter to the receiver. Underwater object position measuring device. (3) In the device according to claim 1 or 2, a plurality of the transmitters are each attached to a corresponding object whose position in the water has been confirmed in advance, and each of the transmitters is The ultrasonic signal to be transmitted is received by the receiver, and the electric circuit means connected to the receiver measures the straight distance from each of the plurality of transmitters to the receiver to confirm the position of the ship. An underwater object position measuring device characterized by being able to measure the position of an underwater object.