JPS597949B2 - Ultrasonic pulse width automatic control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic ultrasonic pulse width control device for a fish finder that automatically varies the pulse width of the ultrasonic waves in the fish finder according to the number of times the ultrasonic waves are emitted. .

In conventional fish finders, in order to increase the detection ability, it is common practice to reduce the number of ultrasonic waves emitted and widen the pulse width as the depth increases.

To change this pulse width, a switching system is used that uses a switch that is linked to a device that reduces the number of times the ultrasonic waves are emitted.

This switch method has the advantage of being able to determine any pulse width, but has the disadvantage of having to select each pulse width with a switch and adjusting each pulse width. .

In order to eliminate the drawbacks of the conventional example, the present invention counts the trigger interval of the oscillation trigger using pulses of a predetermined frequency, counts this count number at a frequency faster than this frequency, and calculates the unit from this count time. The present invention provides an automatic pulse width control device that automatically varies the emitted pulse width depending on the number of ultrasonic waves emitted per hour.

Hereinafter, actual examples will be explained in detail with reference to the drawings.

First, before describing embodiments of the present invention, the principle will be explained.

In a fish finder, an oscillation pulse is generated by an oscillation trigger, and the trigger interval T of this oscillation trigger is determined by the number of ultrasonic emission times per unit time.

At this trigger interval T, a predetermined frequency fu
When counting the pulses of
It becomes T.

Next, this count value is set to another predetermined frequency f.
Count down with the pulse of D (f D >> f u ), and if the time until the count value reaches O is t, the count value A' at this time is A' = t ÷ (pulse of fD interval) = 1÷1/fD-fDt.

This t becomes the oscillation pulse width. At this time, fD >> fu
is set to

Also, since A=A', fDt-fut,
The pulse width t is as follows.

Therefore, by appropriately setting the pulse frequencies fD and fu, an oscillation pulse t proportional to the oscillation trigger time interval T, that is, the number of ultrasonic emission times, can be obtained with a proportionality constant B (-fu/fD<1).

Next, FIG. 1 shows one actual case of the present invention.
2 is an oscillation trigger section, 2 is an automatic pulse width adjustment section, 3 is an oscillation section, 4 is an oscillation output section, 5 is a transducer, 6 is a reception section, and 7 is a recording section. The interval is set according to the depth.

In the pulse width automatic adjustment section 2, a pulse width is determined according to the interval between oscillation triggers, and a signal corresponding to this pulse width is output.

In response to this signal, the oscillator 3 also outputs a pulse signal,
The oscillation output unit 4 amplifies the ultrasonic wave, and the transducer 5 outputs the ultrasonic wave.

The reflected waves of the emitted ultrasonic waves are received by the transducer 5, amplified by the receiving section 6, and recorded by the recording section 7.

FIG. 2 shows one embodiment of the automatic pulse width adjustment section of the present invention, in which 8 is a down clock oscillator, 10 is an up clock oscillator, 9 is an oscillation trigger input terminal, and 11 to 14
is the NAI'Φ gate, 15 is the up-down counter, 1
6 is a pulse output terminal.

NAND gates 11 and 12 are cross-connected to form a two-state circuit.

Next, the operation of this automatic pulse width adjustment section will be explained.

First, when one negative trigger pulse is input from the oscillation trigger section 1 to the input terminal 9, the point a becomes It HIF, and the output from the output terminal 16 becomes ItH 93.

Therefore, the down clock from the down clock oscillation circuit 8 is transmitted through the NAND gate 13 to the up/down counter 1.
5 is input and is counted down.

When the down count reaches O, the up/down counter 1
The output of point 5 becomes "L", the output of point b becomes It H vp, the output of point a becomes "'L", and the output of output terminal 16 becomes at L ty.

Next, when point b becomes "H", an up clock is input through the NAND gate 14, and the up/down counter 15 counts up.

This up-counting continues until the next trigger pulse is input to the input terminal 9.

When the next trigger pulse is input to the input terminal 9, the down clock from the down clock 8 is again input to the up-down counter, and the up-down counter is counted down by the number of up-counts.

Therefore, by repeating this operation, the trigger interval of the trigger pulse is determined by the ratio of the count time t counted by the down clock and the count time T counted by the up clock, and is output from the oscillation trigger section 1. If the interval between trigger pulses becomes longer, the count time t counted by the down clock becomes longer, and the output terminal 16
Since the pulse width output from the oscillator 3 becomes wider, the pulse width output from the oscillation unit 3 becomes longer, and the pulse width of the ultrasonic wave automatically becomes longer.

It goes without saying that even if the down clock and up clock are reversed, the same operation is possible.

As explained above, according to the present invention, the pulse width of the ultrasonic pulse can be automatically varied according to the pulse interval of the trigger pulse, so the ultrasonic pulse width can be automatically changed by using one trigger pulse setting switch. It has the advantage of being able to be determined

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is a block diagram of an embodiment of the present invention.
FIG. 2 is a circuit diagram of an actual case of an automatic pulse width adjustment section of the present invention. 2... Pulse width automatic adjustment unit, 8... Down clock oscillator, 9... Input terminal, 10... Up clock oscillator, 11-14... NAND gate, 15...
Up counter, 16...output terminal.

Claims (1)

[Claims] 1. A first oscillator; a second oscillator that oscillates at a higher frequency than the oscillation frequency of the first oscillator; An up-down counter that counts down when the output of the oscillator is input, and an up-down counter that counts down when the output of the oscillator of
and a gate circuit that selectively connects the first and second oscillators to the up-down counter according to the state of the two-state circuit. An automatic ultrasonic pulse width control device for a fish finder, comprising: an output terminal for outputting the output of the two-state circuit as a signal for setting an ultrasonic pulse width.