JPS6094539A - Squelch control circuit - Google Patents

Abstract

PURPOSE:To prevent the deterioration of talking quality by utilizing a period where no modulation signal exists to superimpose a required signal on a transmission wave, thereby controlling squelch of an opposite receiver. CONSTITUTION:A mark timer circuit M.TIM of a transmitter 1 starts a squelch open signal generator SQ.S and transmits a squelch open signal when no microphone M output exists, at an initial short time inputting a press signal PTT, and at the intermission with a prescribed period while the microphone M output is consecutive for a prescribed time or over. The receiver circuit is connected to a time counter T.C via a filter circuit FIL detecting the squelch open signal at a receiver 3. The output of an amplifier AMP is outputted to a speaker while the squelch open signal is detected via an output of an AND circuit AND through the output of the T.C and the output of a noise squelch N.SQ and for only a prescribed time after the open signal is lost.

Description

[Detailed description of the invention] The present invention relates to a squelch control method for a wireless communication device.

Conventional squelch methods for wireless communication devices, especially FM mobile communication devices, include a carrier squelch method that detects the presence or absence of a carrier, or a noise squelch method that detects the noise that occurs at the demodulator output end when a carrier is not present. The squelch method is common, but both methods do not have the ability to identify interference waves of the same wavelength received from other radios, and will output audio for communications other than the intended purpose.To prevent this, This is a so-called tone squelch method in which a specific continuous tone signal is always superimposed on the transmitted wave and the sound is output externally only when the receiver detects it.However, in the conventional tone squelch method as described above, the continuous tone signal is constantly modulated into a signal Since the transmission is mixed into the Hz transmission, a portion of the limited frequency deviation, for example 0.5 of 5K I-1z, must be ceded, reducing the amount of information that can be transmitted and deteriorating the quality of speech. It had the disadvantage of being forced to do so.

The present invention has been made in order to eliminate all the drawbacks of the conventional tone squelch method as described above. When the modulated signal continues for a certain period of time or more, the squelch open signal is superimposed on the transmitted wave at a required period, and the squelch is released while the receiver detects the squelch open signal and for a predetermined time after the detection signal disappears. It is an object of the present invention to provide a squelch control system in which the squelch function of the receiver is controlled by the squelch function (No. 8) sequentially transmitted by the transmitter.

The present invention will be described in detail below based on embodiments shown in the drawings.

FIG. 1 is a block diagram showing an embodiment of the squelch control method according to the present invention.

In this figure] is a transmitting section, 2 is an oscillator O8C, an f modulator M (month), a high frequency section R, pAMp, a modulation pre-circuit 11
) A general transmitter consists of a microphone M and a mark timer circuit M and T through a voice controller VOK to detect the presence or absence of part of the output of the microphone M.
Connect to IM and use its output to connect the squelch open signal generator SQ.
・The signal generated by controlling S is connected to the IDC circuit, and the mark timer circuit M and TIM are connected to the output PTTf of a press switch (not shown) and the mark timer circuit. M and TIM are the case where there is no output of the microphone M and the press signal PTT-i
The squelch open signal generator 5Q-8 in the next stage is activated to generate the squelch open signal at the initial short time when the microphone output is input, and at intermittent intervals with a certain period if the microphone output continues for a predetermined period or more. This is input to the IDC circuit. Also 3
4 is a receiving section of a communication device whose communication partner is the above-mentioned transmitting section 1, and 4 is a high frequency section RF, a demodulator DISC, and a noise squelch N.

8Q, a general receiver consisting of a low frequency amplifier AMP and a speaker SP, and a filter circuit FIL that detects the squelch open signal by converting a part of the output of the demodulator DISC into a general receiver.
While detecting the squelch open signal through an AND circuit AND which is connected to the time counter T-C via l and whose output and the output of the noise squelch N and 8Q are input, and after this signal disappears. The configuration is such that the output of the low frequency amplifier AMP is output to the speaker for a predetermined period of time.

Next, what is the operation of the squelch control circuit of the present invention configured as described above? [This will be explained with reference to the time chart shown in Figure 2.]

Now, when the operator activates the transmitter as shown in Figure 2 Cat by pressing the press switch (not shown) of the transmitter 1, a part of the signal is input to the mark timer circuit and the squelch is activated in the next stage. Start the signal generator to generate a squelch open signal for a short time and superimpose it on the transmitted wave. Furthermore, if the microphone output is intermittent as shown in Fig. 2, it is detected by the voice controller VOK, and as shown in Fig. The squelch open signal is sent out intermittently.

On the other hand, the squelch open signal thus sent out is received by the full receiver 3, detected by the filter circuit FIL, and its output is input to the time counter TC. At this time, while the squelch open signal is present before the time counter T-CVi and for a predetermined period of time after it disappears, the signal indicating that the squelch should be opened is fully output, so that this and the output of the noise squelch circuit N-8Q are combined. The logic p is taken, and only when both of the above signals are present, the low frequency amplifier AMP 2 is operated and the output thereof is outputted to the outside from all the speakers SP.

Therefore, if the squelch open signal is continuously superimposed on the transmitted wave at a predetermined time interval, the receiver that detects this can keep the squelch open continuously during that time, or it can either completely stop transmitting or Figure 2 (
As shown in cl and (d), the receiver can close the squelch and stop the external output of the audio by the time counter's output or the function of the conventional noise squelch N-8Q.

The squelch opening signal used in the present invention may be a single tone signal like the conventional tone squelch, or a plurality of parallel tones or other digital signals such as frequency shift keying system 1.
The squelch open signal transmission interval time T on the transmitting side is slightly longer than the squelch open time 'r1 after the squelch open signal disappears in the time counter T・C on the receiving side. In addition, if an audible tone is used as the squelch opening signal, a filter may be provided in front of the low frequency amplifier AMI'.Also, if the present invention is applied to a communication device equipped with a transmitter/receiver, the transmitter It would also be possible to share the mark timers M and TIM on the side and the time counters T and C on the receiver side.

Since the present invention is configured and operates as described above, the required signal is superimposed on the transmitted wave using the period in which there is no modulation signal, and the squelch of the other party's receiver is controlled. Not only does it not cause deterioration, but if the squelch opening signal is specifically encoded, an individual selection function can be added, which is extremely effective in improving both the quality and functionality of wireless communication.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a transmitter and receiver showing an embodiment of the present invention, and FIGS. 2(a) to 2(d) are timing charts showing the operation timing of each part of the whistle. 1...Transmitter, 2...Conventional general transmitter, 3...Receiver, 4
...... Conventional general reception 99. VOK
・・・・・・・・・Voice controller, M, 'L"
IM・・・・・・Mark timer circuit, SQ,
8...Squelch open signal generator, N/SQ
...Noise squelch circuit, FIL...
・・・・・・Filter circuit, T・C・・・・・・・
・Time counter, AND......Logical product circuit patent applicant Toyo Tsushinki Co., Ltd.

Claims (1)

[Claims] During a short period when the transmitter is started up and when there is no modulated signal such as an audio signal, the squelch signal is activated in a predetermined pattern, and when the modulated signal continues for a certain period of time, the squelch signal is activated at the required period. The signal is superimposed on all transmitted waves, and the squelch of the receiver is released while the squelch open signal is detected by the receiver that is the communication partner, and for a predetermined time after the detection signal disappears, and the reception output is output to the outside. A squelch control method characterized in that the squelch function of a receiver is controlled so as to.