JPH01161927A - Radio communication system - Google Patents

Abstract

PURPOSE:To prevent unpleasant squelch noise caused in a master station from reaching a talker of the master station by allowing a slave station to interrupt a transmission radio wave in a short time every prescribed time based on a reference of a control signal in common to the master station and the slave station and allowing the master station to interrupt a demodulation signal output synchronously therewith. CONSTITUTION:A master station sends a control signal to set a channel to a slave station. When a call to its own station is recognized, a radio wave is sent to set a channel to attain the communication. In this case, the slave station generates a timing of a prescribed period started by, the control signal to stop the transmission radio wave in a short time t1 for each prescribed time T based on the timing. On the other hand, the master station generates a timing of a prescribed period started by the control signal sent to the slave station, the output of a demodulation signal is interrupted before and after the interruption of the radio wave sent from the slave station in a short time t2 (<t1) based on the timing thereby preventing the output of squelch noise caused at the interruption of the transmission radio wave. Thus, unpleasant sense of the talker due to squelch noise is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a wireless communication system that performs communication between a master station and a plurality of slave stations using a set of radio waves.

(Prior art) Conventionally, in such wireless communication systems, when a master station and a slave station are talking, when another slave station needs to interrupt the master station due to an emergency situation, etc., the interruption radio waves are transmitted. Send. However, if the radio waves of this interrupt are weaker than the radio waves of the slave station during the call,
Since the frequencies of both radio waves are the same, due to the characteristics of the FM communication system, even if an interrupt radio wave is transmitted, it cannot be received by the master station, making it impossible to interrupt.

For this reason, a method is adopted in which the transmitted radio waves are stopped for a certain period of time at fixed intervals in the slave station during a call, and the slave station detects the voice transmitted by the slave station and the received voice from the master station, and the voice transmitted by the slave station is eliminated. , a control method in which the transmitting radio waves are cut off for a certain period of time when there is voice received by the master station, and the receiving circuit is cut off for a certain period of time when there is no voice received by the slave station and there is voice transmitted from the master station. Publication No. 179036/1983).

In all of these methods, the slave station that wishes to interrupt is not aware of the timing at which it can interrupt the master station, so it transmits interrupt radio waves continuously for a certain period of time.

(Problem to be Solved by the Invention) However, in the former method, during the response time of the squelch operation of the master station receiver when the slave station transmission radio wave is interrupted, approximately 50 to 10 Q
m SEC has the disadvantage that noise is generated during SEC, which makes the caller on the main station extremely uncomfortable.In addition, in the latter method, the discomfort caused to the caller on the main station due to the interruption of transmission radio waves from the slave station is synchronized between both stations. If it is perfect, this will not occur, but since audio level detection circuits and logic circuits are required for both the master station and the slave station, and the audio level detection means is an analog quantity, there will be a difference in the detected level values at the master station and slave stations. This has the drawback of making it difficult to achieve complete synchronization, and therefore squelch noise to the master station is unavoidable. Furthermore, since it is not known when the master station will be able to interrupt the slave station, it is necessary to transmit an interrupt radio wave for a certain period of time, which has the disadvantage of transmitting unnecessary radio waves.

It is an object of the present invention to eliminate these drawbacks and provide a wireless communication system that can reliably perform interruptions without causing discomfort to callers.

(Means for Solving the Problems) The present invention provides a wireless communication method in which communication is performed between a master station and a plurality of slave stations using a set of radio waves, in which a control signal transmitted from the master station to the slave stations is used. The master station is equipped with means for determining an interrupt signal to be activated and a means for detecting an interrupt signal from a slave station, and the master station is configured to activate the master station based on the timing of a constant cycle T of activation by the control signal transmitted from the master station. The slave station is provided with means for stopping the radio wave at a certain time during a call with the base station, and means for transmitting an interrupt signal radio wave in synchronization with the timing at which the transmitted radio wave is stopped when interrupting the master station, tl
is at least longer than the time t2.

(effect) The master station transmits a control signal for setting a communication path to the slave station.

The slave station identifies the received control signal, and when it learns that it has been called, it transmits radio waves, sets up a call path, and makes a call.

In this case, the slave station generates a timing with a fixed period of activation based on the control signal, and stops transmitting radio waves for a short time at fixed time intervals based on this timing. On the other hand, the master station also generates a timing with a fixed period of activation based on the control signal sent to the slave station, and based on this timing, outputs a demodulated signal before and after the radio waves transmitted from the slave station have a short interruption. As a result, the squelch noise generated when the transmission radio wave is cut off is not output. In addition, when a slave station that is not currently on a call sends an interrupt radio wave to the master station, the slave station that is currently on a call will transmit the interrupt radio wave during the short period of time when it stops transmitting radio waves for a short time. Send. When the master station detects an interrupt radio wave, it executes a predetermined interrupt operation.

Therefore, the aforementioned drawbacks can be eliminated.

(Embodiment) FIG. 2 is a conceptual diagram of the system of the present invention, in which the communication path between the master station side and the slave station side includes a master station control device 1, a transmitter 2, a receiver 3
, radio waves f1-fz, a receiver 4, a transmitter 5, and a slave station control device 6.

FIG. 1 shows an embodiment of the present invention, and is a block diagram of a master station control device 1 and a slave station control device 2 shown in FIG.

In FIG. 1, 101 is a master station control device corresponding to the master station control device 1 shown in FIG. 2, 102 is a modulation signal input terminal, 1
03 is a slave station originating/incoming call information signal terminal, and 104 is a demodulated signal output terminal. Each of the terminals is connected to a selective calling device (not shown), and the selective calling device is further connected to a PBX (not shown) or the like.

112 is a modulation signal output terminal, and 113 is a transmission activation output terminal, both of which are connected to the transmitter 2 shown in FIG.

114 is a demodulated signal input terminal, which is connected to the receiver 3 shown in FIG. Reference numeral 105 denotes a control unit controlled by the macroprocessor, which controls the entire master station control device 101.

106 is an analog switch that turns on and off the demodulated signal from the demodulated signal input terminal 114 based on the control signal 107 from the control unit 105 and sends it to the demodulated signal output terminal 104; 108 is a demodulated signal under the control of the control unit 105; A modem 111 that constantly monitors the demodulated signal inputted through the signal output terminal 104, detects call origination from the slave station, call end 1 interrupt, etc., and outputs a control signal 110 when the master station makes a call. is an analog switch that switches and outputs either the modulation signal input to the modulation signal input terminal 102 or the control signal 110 output from the island modem 108 based on the switching signal 109Vc output from the control section 105. On the other hand, 2
01 is a slave station control device corresponding to the slave station control device 6 shown in FIG. 2, and its basic configuration is the same as that of the master station control device 101.

202 is a modulation signal input terminal, 203 is an information signal terminal, 2
Reference numeral 04 denotes a demodulated signal output terminal, which is connected to, for example, a terminal control device having a telephone exchange function, both of which are not shown. 212 is a modulation signal output terminal, 213 is a transmission activation output terminal, both of which are connected to the transmitter 5 shown in FIG. 2, and 214 is a demodulation signal input terminal, which is connected to the receiver 4 shown in FIG. There is. 205 is a control unit, 206 is an analog switch, 208 is a modem, and 21 is an analog switch, each of which is connected to the control unit 10 of the master station control device 101.
5. It is the same except for the relationship between the analog switch 106-modem 108, the analog switch 111, the master station, and the slave station. However, the modem 208 in the slave station control device 201 does not have an interrupt signal detection function.

Next, the operations of the master station control device 101 and the slave station control device 201 shown in FIG. 1 will be explained using the waveform diagram shown in FIG. 3.

In the master station control device 101 , when a signal for calling a specific slave station from a selective calling device (not shown) is input to the slave station originating/receiving information signal terminal 103 , the control unit 105 sends a signal to the slave station via the transmission activation output terminal 113 A transmission activation signal is sent to the transmitter 2 shown in FIG. 2 to activate the transmitter 2, and a switching signal 109 is output to the analog switch 111,
The control signal 110 outputted to 0B is transferred to the analog switch 11.
1. Send the modulated signal to the transmitter 2 via the modulated signal output terminal 112. This control signal 110 is shown at A in FIG.

On the other hand, each slave station demodulates the control signal using the receiver 5 shown in FIG. 2, and inputs it to the demodulated signal input terminal 214 of the slave station control device 201 shown in FIG. Modem 208 and control unit 205
identifies the input control signal, and when it learns that its own station is being called, starts transmission, and a communication path is established between the master station and the slave station. As shown in FIG. 3, the control unit 205 of the slave station control device 201 controls
.

Timing measurement is started from , a transmission control timing signal shown in C is generated, and a corresponding transmission activation signal is sent to the transmitter 5 shown in FIG. 2 via the transmission activation output terminal 213. As a result, the transmitter 5 cuts off the double radio wave, and thereafter cuts off the transmitted radio wave for t2 seconds every T seconds. On the other hand, after transmitting the control signal 110, the control unit 105 of the master station control device 101 starts timing measurement from to shown in FIG. Generates a control timing signal and generates a corresponding control signal 1
07 to the analog switch 106.

The analog switch 106 is turned on and off based on the control signal 107, and the input terminal 1 shown in FIG.
The demodulated signal output terminal 104 disconnects the demodulated signal from 14.
I am trying not to output it from. Thereafter, the demodulated signal is turned off for t1 seconds every T seconds.

the values of t1 and t2 are set and found within a short time;
Therefore, despite the intermittent transmission of the radio waves and the intermittent output of the demodulated signal, the telephone conversation continues without any problem.

In order for a slave station other than the slave station that is currently on a call with the master station to send an interrupt signal to the base station that is currently on the phone due to the occurrence of an emergency, etc., the transmission control is generated in the same way as for the slave station that is currently on the phone. Using a timing signal, an interrupt signal is sent during a period of t2 seconds during which the slave station in the middle of a call cuts off its transmission radio waves. The modem 108 of the master station controller 1θ1 detects this interrupt signal and executes a predetermined interrupt operation.

If the interrupt signal is not received, the call continues between the master station and the slave station until the call ends;
By setting h>t2 to satisfy the condition h>t2 as shown in FIG. 3, the squelch noise generated at the master station due to the medical signal interruption of one slave station for t2 seconds can be suppressed by the master station control device 101.
It can be completely shut off using the analog switch 106. Therefore, the caller at the master station can make a call without being bothered by the unpleasant sound of the squelch noise.

Next, a case will be described in which, when the master station is talking with one slave station, another slave station interrupts the master station due to an emergency situation or the like.

When each slave station receives a control signal from the master station, it starts timing measurement using the control signal as a reference. Then, the master station turns on and off the analog switch at the timing shown in FIG. 3B, and the selected slave station intermittents transmission radio waves at the timing shown in FIG. 3C, and communication is performed between them.

If an interrupt instruction is given to the slave station control device at the time t3 shown in the third diagram due to button operation or the like in one slave station other than the slave station in use, the slave station control device
The interrupt signal is not immediately sent to the master station at the time of , but the interrupt signal is interrupted for t3 seconds from the time of t4, in line with the time when the selected slave station that is talking cuts off its transmission radio waves, as shown in Figure 3E. Send a signal. Thereafter, if necessary, transmission continues for a predetermined period of time every time the transmission radio waves of the slave station are cut off during a call. The master station constantly monitors the presence or absence of an interrupt signal using the modem of the master station control device, and when it detects an interrupt signal, executes a predetermined interrupt operation.

Therefore, it is possible to reliably interrupt the master station from a slave station that is not currently on a call.

Note that since the slave station can calculate the time from the interrupt operation time t3 to the time when the interrupt signal is sent, at the interrupt operation time t3,
If necessary, it is also possible to display the time during which an operator can interrupt the operation using a display or the like.

(Effects of the Invention) As described above in detail, according to the present invention, the slave station short-circuits the transmitted radio waves at regular intervals based on the control signal common to the master station and slave stations, and Since the output of the demodulated signal is cut off in synchronization with this, interrupts to the master station from a slave station that is not currently talking to the master station can be made reliably by using the short period of time, and the slave station can It is possible to prevent the unpleasant squelch noise generated in the master station due to the interruption of transmission radio waves from the station from reaching the caller of the master station.

In addition, since the slave station can know in advance the timing at which the interrupt signal will be sent, it is possible to display and notify the interrupt operator of the timing at which the interrupt will be possible, and to avoid sending invalid radio waves. be able to.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a conceptual diagram of the system of the present invention, and FIG. 3 is a waveform diagram for explaining the operation of FIG. 1. 101... Master station control device, 102.202... Modulation signal input terminal, 103... Slave station origination/reception information signal terminal,
104.204...Demodulated signal output terminal, 105°20
5... Control unit, 106, 206... Analog switch, switch, 108, 208... Modem, 111,
211... Analog switch, 112, 212... Modulation signal output terminal, 113, 213... Transmission start output terminal, 114.214... Demodulation signal input terminal, 201...
...Slave station control device, 203...information signal terminal. Patent applicant: Oki Electric Industry Co., Ltd.
Figure 1: Unexploded June's Shiiridem egg tip included □The movement of Figure 1 and the mechanism for the 3rd month of the month @Figure 3

Claims (1)

[Claims] In a wireless communication system in which communication is performed between a master station and a plurality of slave stations using a set of radio waves, at a timing of a constant period T activated by a control signal transmitted from the master station to the slave stations. Based on the time point t=nT−(t_1/2) to nT+(t_1/2)(
n=1, 2, 3...), the master station includes means for cutting off the output of the demodulated signal and means for detecting an interrupt signal from the slave station, and the control transmitted from the master station Based on the timing of a fixed cycle T activated by a signal, when talking with the master station, the time t=nT-(t_2/2) to nT+(t_
2/2) means for stopping the transmission radio waves for (n=1, 2, 3...), and transmitting an interrupt signal radio wave in synchronization with the timing of stopping the transmission radio waves when interrupting the master station; the slave station, wherein the time t_1 is longer than at least the time t_2.