JPH03211485A - Distance measuring instrument - Google Patents

Abstract

PURPOSE:To prevent mismeasurement due to an unnecessary signal and to simplify the hardware constitution by measuring the distance to a body which reflects an ultrasonic wave signal with a received signal which is received within the permissible time of reception interruption. CONSTITUTION:A ROM 11 is stored with a specific program and a microcomputer MPU 8 reads it in and executes its instructions. A burst wave electric signal which is sent out of a transmitter 7 by receiving a transmission command is applied to a transmitter receiver 1 and converted into an ultrasonic wave signal, which is sent into water 2. This signal is reflected by the sea bottom 3 and reconverted by the transmitter receiver 1 into the electric signal, which is amplified by an amplifier 5 to a constant level. When the amplifier output which is larger than the constant level is inputted, an interruption is initiated at time T1 and the MPU 8 obtains time T1 and allows an interruption in next measurement in only the time T1+ or -TG obtained by adding and subtracting time TG to and from last reception time T1. Subsequent measuring operation is performed similarly. Thus, the acceptance time is set to remove unnecessary signals which are not in this time, thereby preclude the mismeasurement.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a distance measuring device, and particularly to a distance measuring device suitable for a digital depth sounder used to measure the depth of the ocean floor or the like.

[Prior art]

Conventionally, as a technology in this kind of field, Japanese Patent Application Laid-Open No. 56-229
There was an ultrasonic distance measuring device disclosed in Publication No. 07.

FIG. 3 is a block diagram showing the configuration of the distance measuring device. In the figure, 31 is a pulse oscillator, 32 is a pulse modulator, 33 is a transmitter, 34 is a receiver, 35 is an amplifier, 36
is a level detector, 37 is a counter, 38 is a memory 39
．． 53 is a comparator, 46.52 is a buffer memory 41
is a gate, 47.50 is an average circuit, and 49.51 is a subtraction circuit. The averaging circuits 47 and 50 are composed of, for example, a shift register, an addition circuit, and a division circuit.

In the distance measuring device having the above configuration, the pulse oscillator 3
1 creates a transmission timing, a pulse modulator 32 modulates the transmission frequency, a transmitter 33 converts it into an ultrasonic signal, and sends this into the water. The ultrasonic signal propagates through the water for a distance, is reflected by the seabed 40, is received by the receiver 34, and is converted back into an electrical signal. This electrical signal is amplified to a constant level by an amplifier 35 and applied to a level detector 36.
When the reception level reaches a certain level or higher, a reception signal pulse 43 is sent out.

The averaging circuit 47 contains distance data measured in the past, and calculates a moving average of a plurality of the data. A subtraction circuit 49 subtracts 1 from the average output (average value) 48 of the averaging circuit 47 to a constant value. This result is stored in the buffer memory 46 and is ready for the next measurement.

On the other hand, the counter 37 starts counting by inputting the start pulse 42, and this output is sent to the comparator 39, which generates a comparison output until it matches the distance value stored in the buffer memory 46. Even if the received signal pulse 43 is input before this, the gate 41 is prohibited.

When the content of the counter 37 reaches a distance greater than the content of the buffer memory 46, the comparator 39 sends out a comparison output 44, and subsequent received signal pulses 43 pass through the gate 41 and are added to the memory 38 as a memory Hals 45. memory 3
8 stores the contents of the counter 37 at that time. This data is sent to the averaging circuit 47 in preparation for the next measurement.

Similarly, the averaging circuit 50, the subtraction circuit 51, the buffer memory 52, and the comparator 53 operate. In addition, 54 is the comparator 5
This is the comparison output of No. 3.

The averaging circuit 47 averages a relatively small amount of data and follows the measured value with a fast time constant, and the averaging circuit 50 averages a relatively large amount of data and follows the measured value slowly. It follows with a time constant. Further, the constant for the above-mentioned subtraction is always Kl<K2, and the normal prohibition gate is set so that the side generated by the averaging circuit 50 operates earlier in time. This allows temporally random noise to be removed.

[Problem to be solved by the invention]

The conventional distance measuring device described above has the advantage of being able to automatically set a prohibition gate for noise removal in response to changing measured values when measuring distance underwater using ultrasonic waves. , as shown in FIG. 3, has the disadvantage that the hardware configuration becomes large.

The present invention has been developed in view of the above points, and eliminates the drawback of the conventional hardware configuration being large, that is, the number of device components increases, and reduces the hardware configuration by using a microcomputer. The object of the present invention is to provide a distance measuring device that can be used easily.

[Means to solve the problem]

In a distance measuring device that receives the reflected signal of the ultrasonic wave signal with a transmitter and measures the distance to the object that reflected the ultrasonic wave signal based on the time from transmission to reception, the control unit A microcomputer is used in the process, and the microcomputer is provided with a means for permitting reception interrupts only during a predetermined time period set before and after the reception time of the previous reception, and when the reception is completed within the time period during which the reception interrupt is permitted. It is characterized by measuring distance using signals.

[Effect]

As mentioned above, a microcomputer is used in the control unit to allow reception interrupts only during a predetermined time period set before and after the reception time of the previous reception using software, and if the reception interrupt is received within the permitted time. Since the distance is measured based on the time from transmission to reception using the received signal, it is possible to prevent erroneous measurements due to unnecessary signals, and at the same time, the hardware circuit configuration for preventing erroneous measurements is extremely simple.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing an example in which the distance measuring device of the present invention is used in a depth sounder for measuring the depth of the seabed. In the figure, 1 is a transducer, 2 is underwater, 3 is on the ocean floor, 4 is a transceiver switch, 5 is an amplifier, 6 is a level detector, 7 is a transmitter, 8 is a microconverter, 9 is a timer 10 is RAM (
11 is a ROM (read-only memory), and 12 is a display. The operation of the sounder having the above configuration will be explained below.

A program for operating the microcomputer 8 is stored in the ROMII. The program is loaded,
Microcomputer 8 executes instructions.

First, a transmission command is sent to the transmitter 7. When the transmitter 7 receives a transmission command, it sends out a burst wave of a predetermined frequency to the transmitter/receiver switch 4 only during the pulse width. This burst wave is applied to the transducer 1 via the transceiver switch 4.

The transducer 1 converts the burst wave electrical signal into an ultrasonic signal and sends it into the water 2. This ultrasonic signal is reflected by the seabed 3, received by the transducer 1, and converted into an electrical signal again. This converted electric signal passes through a transmitter/receiver switch 4, is applied to an amplifier 5, and is amplified to a constant level. Furthermore, if the level detector 6 receives a wave of a certain level or higher, it sends out a pulse wave to the microcomputer 8. This pulse wave is input to the interrupt line of the microcomputer 8,
The microcomputer 8 is notified that the received wave has been received at a certain level or higher.

On the other hand, the timer 9 notifies the microcomputer 8 of the time using an interrupt line at regular intervals. Thereby, the microcomputer 8 can measure the time from the time of transmission until the output of the level detector 6 interrupts.

If this time is t (seC), the depth D (m) can be found as D=1/2ct. Here C is the speed at which the ultrasound signal propagates through water.

On the other hand, inside the microcomputer 8, gate software described in detail below performs processing to remove unnecessary signals other than signals reflected from the seabed.

FIG. 2 is a waveform diagram for explaining the operation of the gate. In the figure, A indicates the output level of the amplifier 5. Assume that when the output of the amplifier 5 of a certain level or higher is input at time T, an interrupt occurs at time T+ and the microcomputer 8 obtains time T1.

The next measurement will use the previous reception time T in software.

Interrupts are permitted only for a time T, ±TG, which is a predetermined time plus or minus a predetermined time. In other words, as shown in Figure B, reception interrupts are permitted only in the 2TG period. If a received wave as shown in C in the figure is received within this gate time peak, time T is obtained. T for the next measurement.
Saturday TG, that is, the previous reception time T2 as shown in the same figure.
The reception time can be set by adding or subtracting a predetermined time width TG.

If reception is not obtained for some reason in the next measurement, the gate at this time is set to a time width of T, ±TG and TE, and the gate is widened a little. In other words, the reception time is set as shown in E of the same figure. Assuming that the wave cannot be received the next time, T, ±TG ± 2TE as shown in F of the same figure.
Set a gate with a time span of

At this time, a wave is received inside the gate as shown in G in the same figure, and the time T
When the measurement time of , is obtained, the gates of T and ±TG are set for the next time. In other words, the reception time is set as shown in FIG. In other words, by setting the interrupt permission time around the time from the transmission command to the wave reception during the previous measurement, unnecessary signals outside this time can be removed and erroneous measurements can be prevented. In the above embodiment, a digital sounder that measures the depth of the ocean floor was used as an example, but the present invention is not limited to this. It can be used as a distance measuring device that measures the distance between this device and a reflecting object based on the time until reception.

〔Effect of the invention〕

As explained above, according to the present invention, the following excellent effects can be obtained.

(1) Since a microcomputer is used and the distance is measured by measuring the time from transmission to reception using a reception interrupt, the hardware part of the device can be miniaturized.

(2) In addition, a means is provided to enable reception interrupts only during a predetermined time period before and after the reception time of the previous reception using software, and measurement is performed using reception signals received within the time period during which this interrupt is permitted. Therefore, erroneous measurements due to unnecessary signals can be prevented.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of the distance measuring device of the present invention, Fig. 2 is a waveform diagram for explaining the operation of the gate of the distance measuring device of the present invention, and Fig. 3 is the configuration of the conventional distance measuring device. FIG. In the figure, 1... transducer, 2... underwater, 3...
・Undersea, 4...transmission/reception switch, 5...amplifier, 6
... Level detector, 7 ... Transmitter, 8 ...
Microcomputer, 9...Timer 10...
...RAM, 11...ROM, 12...Display.

Claims (1)

[Claims] In response to a transmission command from the control unit, the transmitter outputs an electrical transmission signal of a predetermined frequency to the wave transmitter, converts it into an ultrasonic signal and sends it out, and generates a reflected signal of the ultrasonic wave signal. In a distance measuring device that receives a wave with a wave transmitter, converts it into an electric signal, and measures a distance to an object that reflects the ultrasonic wave signal based on the time from transmission to reception in the control unit, the control unit A microcomputer is used in the microcomputer, and the microcomputer is provided with a means for permitting reception interrupts only during a predetermined time period set before and after the reception time of the previous reception, and the reception interrupt is received within the time period during which the reception interrupt is permitted. A distance measuring device characterized in that the distance to an object that reflects the ultrasonic wave signal is measured using a signal.