JPH0288983A - Noise gate circuit - Google Patents

Abstract

PURPOSE:To remove impulse noise having periods longer than set time for limiting the re-trigger of a re-triggerable multivibrator by appropriately setting the set time. CONSTITUTION:This noise gate circuit is constituted of a receiving section 1 for receiving signals, target detecting section 2 for detecting a target signal, navigating section 3 which navigates an under-water navigating body by means of the target signal, and noise gate circuit 4 which remove a noise component. The circuit 4 is composed of a signal comparator 41, which controlling section 42, and switch 43, which are the constituents of a circuit for removing impulse noise having period longer than set time tau1. The switch 44 makes a turning off operation when a control signal 14 is high in level and turning on operation when the signal 14 is low in level. Therefore, the output signal of the circuit becomes a signal from which impulse noise is removed. The output signal is inputted to the target detecting section 2 and pulse signals corresponding to signals higher than a fixed level can be outputted as target detect signals 16.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a noise gate circuit for passive reception signals of an underwater vehicle, and in particular, the present invention relates to a noise gate circuit for receiving signals during passive operation of an underwater vehicle, and in particular, it is a noise gate circuit for noise gate circuits for receiving signals during passive operation of an underwater vehicle. The present invention relates to a noise gate circuit that removes impulse noise generated in cycles.

(Prior art) Conventionally, this type of signal processing unit is composed of a receiving unit and a target detection unit. After converting sound into an electrical signal from a wave receiver, the receiving unit amplifies and detects the received signal, This was used as the input signal for the detection unit. The target detection section outputs a detected signal of a certain set level or higher as a target detection signal to control the steering section.

(Problems to be Solved by the Invention) The conventional signal processing section described above multiplies the received signal by a time constant to blunt the leading edge of the impulse noise. If impulse noise of a certain large amplitude is added to the received signal, the impulse noise cannot be removed, and if the time constant is increased, the echo signal will also be dulled, so it is possible to completely eliminate the impulse noise without affecting the echo signal. The drawback is that it cannot be removed.

(Means for Solving the Problems) The noise gate circuit according to the present invention includes a detection section that detects a received signal, and a detection signal obtained by the detection section and a constant reference voltage, and a first gate signal is generated by comparing the detection signal obtained by the detection section with a constant reference voltage. A comparison section that outputs
a first retriggerable mono multivibrator that has a first retrigger setting time and is triggered by the first gate signal and outputs a second gate signal; It includes a second retriggerable mono multivibrator that is triggered by a second gate signal and outputs a control signal, and a switch that opens and closes the output of a detection signal in response to the control signal.

(Example) Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a system to which a noise gate circuit for an underwater vehicle according to the present invention is applied.

This system consists of a receiving section 1 for receiving received signals, a target detecting section 2 for detecting a target signal, a steering section 3 for steering an underwater vehicle based on the target signal, and a noise gate section 1 for removing noise components.
It consists of 4.

The noise gate circuit 4 is composed of a signal comparator 41, a switch control section 42, and a switch 43, which are configured to set τ1.
This is a circuit component that removes impulse noise that exceeds time.

FIG. 2 shows input/output signals of each part shown in FIG. 1.

Noise gate circuit 4 shown in FIG. 1 with reference to FIG.
The operation will be explained below.

A received signal 10 containing impulse noise with a period T is detected by a receiving section 1, and a detected signal 11 is obtained. Detection signal 1
1 is compared with a preset reference voltage by a signal comparison section 41, and outputs a gate signal 12 for a signal higher than this reference voltage. In response to this gate signal 12, the time τ
, and the triggerable multivibrator 42 outputs the gate signal 13. In addition, gate signal 13
In response to this, the retriggerable multivibrator 43, which is set to 2 in one hour, generates a control signal 14 to control the opening and closing of the switch 44. Here, time τ1 is a set time for a time limit for applying a retrigger, and time τ2 is a set time for a pulse width of impulse noise, which is set in advance. The switch 44 turns OFF when the control signal 14 is at a high level and turns ON when the control signal 14 is at a low level, and its output signal becomes a signal from which impulse noise has been removed, as shown in the detection output 15. The detection signal 15 is input to the target detection section 2, and a pulse signal corresponding to a signal of a certain level or higher is output as a target detection signal 16. Based on this target detection signal 16, the steering section 3 performs attitude control of the underwater vehicle.

(Effects of the Invention) As explained above, the present invention has the advantage that by appropriately setting the retrigger limit setting time of the retriggerable multivibrator that operates based on the detected signal of the received signal, the period can be set to be longer than or equal to the set time τ1. This has the effect of removing impulse noise with a pulse width τ2.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a noise gate circuit according to the present invention, and FIG. 2 is a diagram showing signal waveforms at various parts in FIG. 1. DESCRIPTION OF SYMBOLS 1... Receiving section, 2... Target detection section, 3... Steering section, 11... Noise gate circuit, 41... Signal comparison section, 4243... Retriggerable mono multivibrator, 44 ···switch.

Claims (1)

[Claims] It has a detection section that detects the received signal, a comparison section that compares the detection signal obtained by the detection section with a constant reference voltage and outputs a first gate signal, and a first re-trigger setting time,
a first retriggerable mono multivibrator that is triggered by the first gate signal and outputs a second gate signal; and a first retriggerable mono multivibrator that is triggered by the second gate signal and has a second retrigger setting time; A noise gate circuit comprising: a second retriggerable mono-multivibrator that outputs a signal; and a switch that opens and closes the output of a detection signal according to the control signal.