JPS5842985A - Fish detector with cathode-ray tube display - Google Patents

Abstract

PURPOSE:To prevent pictures from changing abruptly and to obtain easy-to-see display pictures by comparing a received signal stored in a memory with a received signal and updating storage contents only according to the variation. CONSTITUTION:A received ultrasonic-wave signal stored in a memory 9 is compared by a comparator 5 with a received ultrasonic-wave signal passed through an A/D converter 4, etc., and when they have no difference, the low-level output of the comparator 5 is applied through an inverter 6 to open an AND gate 8, thereby re-storing the readout contents of the memory 9 in a memory 8 through the gate 8. Therefore, a signal read out of the memory 8 through an AND gate 7 has only a varied part modified, and then the contents of the memory 9 are updated to prevent display pictures on a cathode-ray tube 10, which correspond to the contents of the memory 9, from changing abruptly. Consequently, a fish detector with easy-to-see picture display is obtained.

Description

[Detailed description of the invention] It is.

Conventional fish finders that use cathode ray tubes have had the disadvantage that the images change rapidly and are difficult to see because the signals received by the receiver and transmitted from the transducer are sequentially displayed on the cathode ray tube.

In order to eliminate the drawbacks of the conventional example, the present invention sequentially stores reflected signals from a transducer received by a receiver in a memory, sequentially reads them from the memory and displays them on a cathode ray tube, and also reads them from the memory. The emitted signal and the reflected wave signal received by the transducer are compared, and when they match, the signal read out from the memory is stored again, and when they do not match, the signal from the transducer is stored. The present invention provides a cathode ray tube display fish finder. Hereinafter, embodiments will be described in detail with reference to the drawings.

The figure shows a block diagram of an embodiment of the present invention.
1 is a transmitter, 2 is a transducer, 8 is a receiver, 4 is an AD converter, 5 is a comparison circuit, 6 is an inno (oneta, ?, 8 is an AND gate, 9 is a memory, 10 is a cathode ray tube) be.

Next, the operation of this embodiment will be explained. First, when an oscillation pulse output from a transmitter 1 enters a transducer 2, an ultrasonic wave is emitted from the transducer 2 into the water. This ultrasonic pulse is reflected by schools of fish in the water, the seabed, etc., and the reflected pulse is received by the receiver 8 via the transducer 2. The output of the receiver 8 is converted into a digital signal by the AD converter 4, and when inputted to the comparison circuit 5, the comparison circuit 5 compares it with the signal read out from the memory 9. Since the output of this memory 9 is zero at the initial stage, an output is output from the comparator circuit 5, and this output causes the signal from the receiver 8 to pass through the AND gate 7 and is stored in the memory 9. Here, the signal is read out from the memory 9 and compared with the signal from the receiver 8 in the comparator circuit 5. If there is no difference, the output of the comparator circuit 5 is zero, so the output of the inverter 6 becomes high level.
A signal read from memory 9 passes through AND gate 8 and is recorded in memory 9. Therefore, the signal read out from the memory 8 is displayed on the cathode ray tube 10 with only the changed portion changed, so that the image is fixed and becomes very easy to see.

It goes without saying that in the embodiment described above, changes in the signal read from the memory 9 and the signal output from the receiver can be detected using a comparison circuit, an inverter, and an AND gate.

As described above, according to the present invention, only the changed portion of the signal input from the receiver is displayed on the cathode ray tube, so there is an advantage that the image is very easy to see.

[Brief explanation of the drawing]

The figure is a block diagram of one embodiment of the present invention. l...Transmitter, 2...Transducer, 8...Receiver,
4...AD converter, 5...comparison circuit, 9...memory, lo...cathode ray tube. Patent applicant: Keisuke Honta

Claims (1)

[Claims] The emitted pulse from the transmitter is sent to a transducer, which converts it into an ultrasonic pulse and emits it into the water, and the reflected wave signal from the water is received by the transducer and amplified by the receiver. In a fish finder that stores reflected wave signals from the memory in a memory and displays reflected wave signals from the memory on a cathode ray tube, the signal read out from the memory is compared with the input from the receiver, and the signal from the receiver is determined. A cathode ray tube display fish finder characterized in that the signal stored in the memory is changed only for the part that is changing.