JPS58184561A - Correlator for underwater detector - Google Patents

Abstract

PURPOSE:To enable the correlation of an underwater detection signal by using data of ship's velocity measured based on the detection signal of an underwater detedtor without providing a separate ship's velocity measuring device. CONSTITUTION:A microprocessor 4 computes the movement DELTAt of a ship itself based on ship velocity data fetched via an interface from frequency comparison circuit 9. The value thus obtained is sent to an addition circuit 27 from the interface 25 as numeral of an address displacement in a memory address of memory circuits 19 and 20 and as a switch 23 changeover the counts of an address counter 22 simultaneously, an added value of an addition circuit 27 is introduced to the memory circuit 20 when the counts of the address counter 22 are led to the memory circuit 19. As a result, a correlation circuit 24 performs the correlation with the memory data differentiated by the movement DELTAt of the ship among those memory data of the memory circuits 19 and 20.

Description

[Detailed Description of the Invention] The present invention aims to detect the speed of own ship using an underwater detection signal in an underwater detection device that detects underwater objects by transmitting and receiving ultrasonic pulses underwater. do.

When an underwater detection signal is very weak or needs to be clearly distinguished from noise, the correlation between the previous detection signal and the current detection signal is often dissipated.

As is well known, this method uses the fact that the reflected waves from the detected object are received periodically, whereas the noise signal appears non-periodically to identify the reflected waves from the detected object. . Therefore, it is very effective when the relative positional relationship between your ship and the detected object does not change between the previous detection pulse transmission and the current detection pulse transmission, or the change is small enough to be ignored. It is.

However, when the relative positional changes between the own ship and the detected object that occur between the transmission of a detection pulse and the transmission of the next detection pulse cannot be ignored, the above correlation cannot be performed. For example, when performing underwater detection by transmitting ultrasonic pulses in the forward direction of one's own ship, the direction of transmission and reception of the ultrasonic pulses and the direction of movement of one's own ship match, so the next detection pulse is transmitted after transmitting the detection pulse. The change in the position of own ship that occurs before the detection pulse is sent is relatively large. Therefore, as shown in Fig. 1, when the reflected pulses □ Rat, Rt are received by the detection pulse S1, when the next detection pulse St is transmitted, the reflected pulse is depressed, and Δ is set by the time as h. Waves are received quickly. This Δ time is caused by the movement of own ship.

In order to perform such a correlation between the received signals al and al, as is clear from FIG. 1, it is sufficient to shift the received signal a1 by Δ in time. This shift is performed, for example, by controlling the readout address when the received signal a1 is stored.

Therefore, when correlating the received signals a0 and al shown in FIG. 1, it is necessary to measure the displacement MΔt of the reflected pulse when the next detection pulse is transmitted, that is, the positional displacement of the own ship. In this case, the positional displacement of the own ship can be determined from the cruising speed.

The navigation speed of the ship can be measured using, for example, an electromagnetic log, but in this case, a device for measuring the ship speed must be provided separately from the underwater detection device.

This invention measures the ship's speed using the detection signal of the ice detection device at 111 degrees, without installing a separate ship speed measuring device as described above, and uses the ship speed data to correlate the underwater detection signal. It is something to do.

Examples of the present invention will be described below.

In FIG. 2, reference numeral 1 denotes an ultrasonic transducer which transmits ultrasonic pulses in the forward direction of the ship based on a transmitter 2. Transmitter 2
is controlled by the microprocessor-4 through the interface 3, and the output from the interface 3 is
Therefore, it sends out a transmission pulse every time it is activated. This transmission pulse is transmitted from the ultrasonic transducer 1 into the water via the switching circuit 5.

The reflected wave from the detected object is received by the ultrasonic transducer IK and then guided to the reception amplifier 6 via the switch 5. The received signal amplified by the reception amplifier 6 is detected by the detection circuit 7,
A received signal as shown in Fig. 1 al, 8% is transmitted.

The output of the reception amplifier 6 is sent to the detection circuit 7, while
It is also sent to the frequency comparison circuit 9 via the gate circuit 8.

The gate circuit 8 is conductive for the duration of the gate wave sent out from the gate wave generator 10 and guides the output of the receive amplifier 6 to the frequency comparator circuit 9.

Generally, when an ultrasonic pulse is transmitted underwater, as shown in Figure 3, a reflected underwater wave with a relatively high signal level called reverberation is received at time W immediately after the ultrasonic pulse S is transmitted. Ru. The gate wave generator 10 sends out a gate wave (FIG. 3C) that appears within the existence period W of the underwater reflected wave based on the transmission pulse of the transmitter 2. Therefore, the underwater reflected waves are selected from among the outputs of the reception amplifier 6 and guided to the frequency comparison circuit 9 as shown in FIG. 3d. Furthermore, a transmission frequency signal is introduced from the transmitter 2 to the frequency comparison circuit 9, and the frequencies of both signals are compared. As is well known, the frequency of underwater reflected waves changes depending on the speed of the ship relative to the water due to the Doppler effect. Therefore, when the frequency comparison circuit 9 detects the difference frequency between the underwater reflected wave and the transmitted signal, it is possible to obtain water speed data of the own ship from the difference frequency component. The difference frequency component detected by the frequency comparison circuit 9 is taken into the microprocessor 4 via the interface 3 and stored as ship speed data.

On the other hand, the detection output (FIG. 1) sent out from the detection circuit 7 is sent to the A/D converter 11, where the analog level of the received signal is converted into a digital value and guided to the buffer memory 12. The buffer memory 12 stores the converted data of the &D converter (7), and stores the received signal data at the storage address designated by the address counter 13. Address counter 13 is clock pulse generation circuit 1
Count the clock pulses sent from 4. The clock pulse generation circuit 14 is driven by the output of the interface 3, and sends out the same number of clocks as the memory addresses of the buffer memory 12 within the TR time after the transmission of the transmission pulses Sl and st. Note that this clock is guided to the address counter 13 via the OR circuit 15.

The stored data of the received signal stored in the backup memory 12 is read out when a clock is sent from the clock pulse generator 16. The clock pulse generator 16 is activated by the output of the interface 17, and the microprocessor-4 sends an output to the interface 17 after the buffer memory 12 has performed the above storage operation.

Based on this, the interface 17 drives the clock pulse generator 16 and at the same time causes the buffer memory 12 to perform a read operation. The clock pulses are guided to the address counter 13 via the clock pulse FioR circuit 15 of the clock pulse generator 16, and the buffer memory 12 detects all data at the memory address corresponding to the count value of the address counter 13 and sends it out. Note that the clock pulse generator 16 sends out the same number of clocks as the memory addresses of the buffer memory 12 every time it is activated by the interface 17, and after performing a storage operation during the TR time shown in FIG. The clock is sent out within a very short period of time until the clock is sent out.

The stored data read from the buffer memory 12 is led to either the storage circuit 19 or 2o via the switch 18. Memory circuits 19 and 20 are buffer memories 12
The stored data read from the memory is stored alternately for each transmission pulse S1, S. For example, the received signal obtained by the transmission pulse S1 is guided to the storage circuit 19, and the reception signal obtained by the transmission pulse S1 is
The received signal obtained by , is guided to the storage circuit 20. This switching operation 11 is performed by the microprocessor 4 controlling the switching device 18 via the interface 17. Also, when the data stored in the buffer memory 12 is read out, the clock pulse generator 16 simultaneously
The clock pulse is led to the address counter 22 via the OR circuit 21, and the memory circuit 19
Alternatively, 20 memory addresses are designated. The count value of the address counter 22 is switched to either the memory circuit 19 or 20 by a switch 23, and the switch 23 performs a switching operation in conjunction with the switch 18. Therefore, when the switch 18 directs the read data of the buffer memo 1/2 to the storage circuit 19, the switch 23 directs the read data of the buffer memo 1/2 to the memory circuit 19.
The count value of 2 is led to the storage circuit 19. As a result, the stored data read from the buffer memory 12 is transferred to the storage circuit 19.
are respectively stored at storage addresses designated by the address counter 22 of.

Although the memory circuit 19 has stored the data stored in the pack memory 12, when the next detection pulse is transmitted, the data stored in the buffer memory 12 is switched and guided to the storage circuit 20. Thereafter, memory circuits 19 and 20 alternately perform memory operations in the same manner. Therefore, while the storage circuit 19 is performing the above storage operation, the storage circuit 20 stores the previous detection signal.

The microprocessor 4 causes the memory circuits 19 and 20 to perform the above-mentioned memory operations, while simultaneously reading out the respective memory contents and sending them to the correlation circuit 24.

This reading is effected by the microprocessor-4 switching the memory circuits 19, 20 to read operation via the interface 25. At the same time, the interface 25 also activates the clock pulse generator 26 to send out clock pulses. Clock pulse is memory circuit 1
9. The same number of memory addresses as 20 are sent out, and the OR circuit 21
The address counter 22 is guided through the address counter 22. The count value of the address counter 22 is passed through the switching circuit 23 to the storage circuit 1.
9.20. Then, as described above, the data stored in the buffer memory 12 is transferred to the storage circuit 19.
Once transferred to the clock pulse generator 26, the clock count value of the clock pulse generator 26 is also guided to the memory circuit 19, and the memory circuit 19 transfers the stored data at the memory address corresponding to the count value to the correlation circuit 2.
Send to 4.

The count value of the address counter 22 is also led to an adder circuit 27 and added to the value sent from the interface 25.

Based on the ship speed data taken in from the frequency comparator circuit 9 via the interface 3, the microprocessor-4 calculates the own ship's speed data from when the transmission pulse S1 is transmitted until when the next transmission pulse S is transmitted. Calculate the movement amount Δt. The microprocessor 4 then sends the movement amount Δt to the adder circuit 27 from the interface 25 as a numerical value of the address displacement at the memory addresses of the memory circuits 19 and 20. The added value of the addition circuit 27 is then led to either the storage circuit 19 or 20 via the switch 23.

Therefore, since the switch 23 also switches the counted value of the address counter 22 at the same time, when the counted value of the address counter 22 is led to the memory circuit 19 as described above, the added value of the adder circuit 27 is Leads to 20.

As a result, the correlation circuit 24 correlates the data stored in the storage circuits 19 and 20 that differ by the amount of movement Δt of the own ship. Therefore, as is clear from FIG. 1, the correlation circuit 24 correlates the reflected waves R1u and R,1, and RtI and R3 from the same reflector.

The correlation result is taken into the microprocessor-4 via the interface 25, and then sent to the display device t28 for display. The display device 28 can display the received signal using any device such as a plastic display, a lamp tube display, a recording pen traveling type, or the like. Further, as the display format of the received signal, a conventionally known display format can be used.

[Brief explanation of the drawing]

FIG. 1 is a waveform diagram for explaining an underwater detection signal, FIG. 2 shows an embodiment of the invention, and FIG. 3 is a waveform diagram for explaining its operation. Patent applicant: Furuno Electric Co., Ltd.

Claims (1)

[Scope of Claims] An ultrasonic transceiver device that repeatedly transmits ultrasonic pulses substantially in front of the own ship and receives reflected waves from a detected object, and a received signal of the ultrasonic transceiver device. and a frequency comparison circuit that compares the frequencies of the transmitted ultrasonic pulses with each other, and calculation 1: c! that calculates ship speed data of own ship based on the comparison result of the frequencies. J path; a first storage circuit that stores the current received signal obtained by transmitting the ultrasonic pulse in time series; a second memory circuit that sequentially stores data; a second memory circuit that reads the memory contents of the second memory circuit in conjunction with the first memory circuit; and a readout signal that is read from the first memory circuit; a readout control circuit that performs readout control so that the relative positional relationship with the readout signal read out from the storage circuit is read out with an amount corresponding to the ship speed data calculated by the arithmetic circuit, and the readout control circuit A correlation device for an underwater detection device, comprising a correlation circuit that performs correlation between a readout signal of the first storage circuit and a readout signal of the second storage circuit.