JPS61239725A - Removing method for click sound of radio equipment - Google Patents

Abstract

PURPOSE:To prevent noise which is generated during a break of a carrier from being sent out of a speaker, etc., and to obtain an easy-to-listen tone by employing a tone squelch system and stopping a tone for squelch control prior to the break of the carrier. CONSTITUTION:When the operator of a transmitter presses a press switch P.SW, the transmitter becomes ready to send through an OR circuit and a switch SW1 is turned on, so that the output of a transmit signal oscillator is superposed upon the output of a microphone M. Part of the press signal, on the other hand, is delayed by a specific time through a delay circuit D and actuates the transmitter through the OR circuit, so the transmission state is extended by the delay time, so that a transmit wave on which no transmit signal is superposed is sent out. When a receiver receives a radio wave, a speaker switch SW2 is turned on only while the transmit signal is contained therein and its demodulation output is outputted from a speaker SP, but the transmit signal stops before the transmit wave is ceased and the speaker output is cut off at the point of time, so that a click noise generated when the transmit wave is ceased is not outputted from the speaker.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a tone squelch circuit, and more particularly to a circuit for eliminating the click sound of a communication partner's receiver when a transmission wave is interrupted.

(Prior Art) Generally, a squelch circuit is provided in a wireless communication device in order to remove excessive noise output contained in a demodulated output signal when a desired wave is not received in the receiver.

However, conventional squelch circuits are designed to remove noise while the desired wave is not being received, and if the desired wave stops receiving the desired wave or the electric field strength decreases, the desired wave is not received by the receiver. The removal of the loud lick sound that occurs during the transitional period when the sound is no longer produced does not produce any sound.

In communication equipment that uses angle modulation, this click sound is generated by a demodulator that detects the amount of change in frequency and converts it into an audio signal, so when the rare 1st wave disappears, the amount of frequency change is the same. Because it is relatively large, it becomes a very loud noise that is output to the speaker or receiver, making it extremely difficult to hear.

(Object of the Invention) The present invention has been made in view of the problems in the conventional squelch circuit, and provides an easy-to-hear wireless communication system that eliminates the click sound when the squelch circuit is disconnected, especially a Nikoto 0-less telephone system. The purpose is to provide

(Summary of the Invention) In order to achieve this object, the present invention employs a tone squelch method, and when it is necessary to stop carrier transmission, the squelch control tone transmission pipe is stopped slightly in advance, and then the carrier is stopped. Configure it like this.

(Example) The present invention will be described in detail below based on an illustrated example.

FIGS. 1(a) and 1(b) show the transmission of the wireless device according to the present invention.
In a), l surrounded by a dotted line is a conventional wireless transmitter, and a modulator M for modulating the output of one oscillator osc.
The block configuration is represented by a microphone M as an OD and its auxiliary circuits, a low frequency amplifier AP@AMP, and power amplifiers T and AMP. In the present invention, a new addition to the above-mentioned block is that the make signal of the press switch P and 8W is inputted to the input OR via the delay circuit Dt, and the output signal is input to the input end of the circuit.
The make signals of the press switches p and sw are input to the other end of the R circuit, respectively, and the transmitter section is driven by the output signal of the R circuit.

Furthermore, a transmission signal generator @Te08C is provided, and its output is inputted to the modulating low frequency amplifiers AP and AMP via the switch 8Wz, and is controlled by the meter signal of the switch circuit 8W1t-the press switch p@sw during the press operation. The output of the transmission signal oscillator O8C is configured to be output to the t-modulation circuit.

On the other hand, the receiver of the wireless device that is the communication partner is connected by inserting a speaker switch 5Wzt between the demodulator DEM and the low frequency amplifier AP@AMP2, as shown in FIG. The speaker switch 5W2t is controlled by the signal extraction filter FIL L output, and the speaker switch is turned ON only while receiving the transmitted signal, and the demodulated sound is transmitted to the speaker SP.
Configure it to send from.

411 like this! The constructed wireless transceiver operates as follows.

In other words, in the same figure (al K), the operator only has to speak to Iiku M while pressing the press switches P and SW in the same way as operating a conventional transmitter, and by this press operation, the above-mentioned OR and circuit At the same time, the transmitter enters the transmitting state and the switch 8W1 is turned on, so that the output of the transmitting signal oscillator is superimposed on the output of the microphone M and the modulator MOD1 (
It is superimposed on the transmitted wave through the antenna A and sent out into space. When the operator releases the press switch, the switch SW1 is turned off, and the output component of the Renshin signal oscillator does not reach the modulator and is no longer superimposed on the transmitted wave.

However, a part of the press signal is delayed by a predetermined time, for example, about 0.5 sec to 1 sec, by the delay circuit, and then goes through the OR circuit to activate the transmitter, so the transmission state is extended by the delay time, and the transmission is delayed. A transmitted wave with no superimposed signals will be sent out.

On the other hand, in the receiver shown in FIG. 6(b), when the radio wave to be transmitted is received in the above-described procedure, the speaker switch 8Wz is conductive only while the transmitted signal is included in the radio wave, and its demodulated output is transmitted to the speaker 8. ' The signal is output from P to the outside, but the transmitted signal stops before the transmitted wave is cut off, and at that point the output power of the speaker is cut off. That is, the speaker output is cut off before the transmitted wave is cut off, so the click noise that occurs at that time does not come out of the speaker.

As explained above, the present invention uses 61 lines in the Breathtalk direction.

Sending stop thK destination □91 Ya. The receiver, which cuts off the superimposed transmission signal and uses this as the communication partner, only transmits the transmission signal while emitting the transmission signal.
Since the demodulated sound is transmitted to the outside through a speaker, etc., when the transmitted wave is interrupted, the operator who operates the receiver, which is the communication partner, has to listen to the clicking noise generated by the receiver. be freed from

In the above-described embodiment, a transmitting signal generator T.O20 in the transmitter and a filter FIL and a speaker switch 8W2 in the receiver were newly added, but the present invention adds to these. For example, if the present invention is applied to a radio device that employs the conventional tone/squeezing method, it is only necessary to add a delay gate, WlID, OR circuit to the transmitter, and the present invention can be implemented at an extremely low cost. can be carried out.

(Effects of the Invention) As explained above, the present invention is configured to stop the squelch control tone before the carrier is disconnected, so that the noise generated when the carrier is disconnected is prevented from being transmitted from the speaker, etc., making it easier to hear. This is effective in making it a received sound.

[Brief explanation of drawings]

FIG. 1 (at and (bl) are block diagrams of a wireless transmitter and receiver showing an embodiment of the present invention. T.O20...Tone oscillator. D...... ...Delay circuit.

Claims (2)

[Claims] (1) In a wireless system that employs a tone squelch system, the squelch control tone is stopped before the carrier output from the transmitter is stopped, and the receiver, which is the communication phase, makes demodulated sound only while detecting the squelch control tone. A method for removing a click sound from a wireless device, characterized in that the click sound is outputted to a speaker. (2) The click sound removal method for a radio device according to claim 1, wherein the radio system is a cordless telephone system.