JPH037295B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a selective calling system in wireless communications.

Conventional selective calling methods used in wireless communications include:
As shown in Fig. 1, when transmitting, first operate the selective call button switch etc. to send out a selective call signal according to the communication partner, and after receiving a response from the communication partner, make the call and end the call. In general, it was common practice to send a reset signal from the transmitter side or operate a reset switch on the receiver side to return to the original standby state.

However, in a communication device employing the conventional selective calling method as described above, not only is it necessary to perform a setting operation, but also the demodulated sound is continuously emitted to the outside from the time it receives the initially transmitted selective call signal until it is reset. However, there was a drawback in that it caused interference with unintended transmitted waves.

The present invention has been made in order to eliminate the drawbacks of the conventional selective call system, which is deceptive. A delay circuit that connects the signal to the modulator and a circuit that drives the transmitter based on the presence of the delayed microphone output are provided, and each time a press is pressed, a selective call signal is added to the beginning of the transmitted wave, and after the selective call signal is attached, the above-mentioned voice is transmitted. The signal is superimposed on the transmitted wave, and when the press switch is turned OFF, the transmitter is turned OFF only after the audio signal delayed by the delay circuit has been sent out, and on the receiver side, the selective call signal is It is an object of the present invention to provide a selective calling system in which a demodulated sound is outputted to the outside only when it belongs to the own station, and the state of the demodulated sound is always reset by a carrier squelch or noise squelch function.

The present invention will be explained in detail below with reference to illustrated embodiments.

FIG. 2 is a block diagram showing an embodiment of a radio device according to the present invention.

In the figure, M is a microphone whose output is input to the modulation circuit of the transmitter/receiver TR via a delay circuit D, a part of the signal is input to the audio detection circuit AF/DET, and the output drives the transmitter. A transmitting press switch provided on the microphone M, etc.
The output terminal of Pr SW is connected to the transmitter of the transceiver TR and the activation signal input terminal of the selective call oscillator MF OSC, and the selective call oscillator MF OSC is connected to the output terminal of the Pr SW.
The output of the OSC is connected to the modulation input terminal of the transceiver TR, and communication is performed via the antenna ANT.

Also, on the receiver side, the demodulated output DEM/OUT is sent to the speaker via the speaker switch SP/SW.
SP, and a part of it is input to the selective call detection circuit MF/DET, thereby generating the speaker open signal 1 and the squelch SQ/SQ of the transceiver TR.
OUT is input to the control terminal of the speaker switch SP/SW.

The operation when communicating with a plurality of deceptively configured transceivers is as follows.

In other words, when making a call, the operator
When the switch Pr/SW is pressed and directed toward the microphone M, while the audio signal is delayed in the delay circuit D, the selective call oscillator MF/OSC is first activated.
The output reaches the modulator of the transceiver TR and subsequently the audio signal is superimposed on the transmitted wave.

To end the transmission, press the press switch.
When Pr/SW is opened, while the microphone M output delayed by the delay circuit D remains, the operation of the transmitter is maintained by the output of the audio signal detection circuit AF/DET that detects a part of the signal. The transmission wave is sent out until the microphone M output signal disappears. On the other hand, when receiving radio waves sent out by a transmitter with a similar configuration, the selective call detection circuit MF/DET detects the selective call signal sent by the other party and identifies that the call is from the own station. Then, the speaker switch SP/SW is turned on with that output, and the demodulated output is outputted to the outside via the speaker SP. When the received wave disappears, noise squelch or carrier signal is generated.
The speaker switch SP/SW is turned off using the output signal SQ/OUT of the squelch circuit to stop external output of the demodulated signal.

The present invention deceptively sends out a selective calling signal each time the transmitter is activated and controls the external output of the demodulated output of the receiver of the communicating party, so it is not possible to end a call like in the conventional selective calling system. This not only eliminates the inconvenience of having to perform a reset operation to cancel the selective calling function each time, but also eliminates the inconvenience of having to perform a reset operation to cancel the selective calling function each time. Since it is possible to eliminate the disadvantages of the system, it is easy to operate and effective in ensuring reliable information transmission.

Various types of selective calling signals can be used in the present invention, such as DTMF (Dual Tone).
Multi Frequency) method or FSK (Fase Shift) method
By adopting the ``Keking'' system, you can make selective calls in a short time, so you don't have to worry about the delay time.Furthermore, you can omit the press switches Pr and SW, and the voice
It is easy to imagine that if the transmitter is driven by a control method, the operation will be even easier.

[Brief explanation of the drawing]

Figure 1 is a timing chart explaining the operation of the transceiver in the conventional selective calling system.
The figure is a block diagram of a transceiver according to the present invention. 1...Speaker open signal, D...Delay circuit, M...
...Microphone, AF/DET...Audio detection circuit, MF/
OSC...selective call originator, TR...transmitter/receiver,
MF/DET...Selective call detection circuit, SP/SW...
Speaker switch, SQ OUT...squelch signal, DEM OUT...demodulation output.

Claims (1)

[Claims] 1. A delay circuit that delays the microphone output of the transmitter for a predetermined period of time, a circuit that drives the transmitter based on the presence of the delayed microphone output signal, and a selective call oscillation circuit are provided, and a press switch is pressed, etc. Each time the transmitter is activated, a selective calling signal is added to the beginning of the transmission wave that it sends out, and the receiver is equipped with a selective calling signal detection circuit that detects the calling signal, and only when it matches the selective calling signal of the own station. A selective calling method characterized in that the demodulated output is outputted to the outside until the transmission wave is cut off.