JPH0898241A - Mobile communication system - Google Patents

Abstract

(57) [Abstract] [Purpose] When the same wave that is the characteristic of FM modulation is received, the signal with the lower electric field is suppressed, so it may not be possible to transmit an emergency signal in an emergency. It is difficult to secure safety. Therefore, it is an object of the present invention to enable reception of an emergency signal in an emergency by controlling the transmission time of the mobile station during a call. [Structure] A command station that performs call control and emergency interrupt display, one or more base stations that configure a wireless line with a mobile station and have a squelch delay circuit that prevents disconnection of the call line due to radio wave interruption, and It is composed of a plurality of mobile stations having a function of intermittently activating transmission during a call.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of emergency interrupt call operation in a mobile communication system.

[0002]

2. Description of the Related Art In a mobile communication system having a plurality of mobile stations, when a base station and one mobile station are in a call, other mobile stations in the base station zone of the base station other than the call are in progress. , For example, in the event of an emergency and the need to contact the command station connected to the base station urgently,
The mobile station sends an emergency interrupt signal or a voice call signal. However, depending on the positional relationship between the base station and the mobile station, the received signal strength of the radio wave of the mobile station that has received the emergency interruption operation and received by the base station is It may be weaker than the strength, and at this time, the communication of the mobile station that has performed the emergency interruption operation is not received by the base station side.

Therefore, conventionally, the communication system is generally a simplex or a semi-duplex system in which the base station side is a duplex system and the mobile station side is a simplex system, and an emergency interrupt signal is continued for an indefinite time. A mobile station that is currently in a call changes from transmitting to receiving state, and when the mobile station other than the mobile station performing the emergency interrupt operation enters a period in which it does not communicate, the interrupt signal can be received by the base station. I am trying.

For example, in the case of the simplex system, a base station,
Expect the time when all mobile stations other than the mobile station performing the emergency interruption operation are not transmitting, or wait for the end of the call.

Hereinafter, FIG. 3 showing an example of the configuration of the communication system of this prior art and FIG. 4 showing its schematic operation.
Will be explained.

A command station 1 is operated by a commander in order to communicate with the mobile station 16'-1 or 16'-2. 2 is a microphone for calling a mobile station, 3 is an amplifier for amplifying a transmission signal, 4 is a press switch, 5 is a reception signal amplifier, 6 is a monitor speaker, 7 is an emergency interruption signal detector, and 8 is an emergency interruption signal. It is an indicator. 9'is a base station,
The voice from the command station is FM-modulated and transmitted, and the received signal from the mobile station is demodulated into a voice signal, and the voice signal is output to the command station 1. The base station 9'has a simultaneous transmission / reception system. 10 is FM modulation transmitter, 11 is FM
Receiver, 13 is a receiver circuit switch, 14 is a duplexer, 15
Is an antenna.

This operation will be described. When the commander calls the mobile station 16'-1 or 16'-2, the press switch 4 is turned on and the microphone 2 is used for transmission. The transmitted voice signal is amplified by the amplifier 3 and sent to the base station 9 ', FM-modulated by the FM modulation transmitter 10, radiated from the antenna 15 through the duplexer 14, and the mobile station 16'-1 or 16'-.
Received at 2. At this time, if it is a selective call operation (select call operation), only the mobile station corresponding to the ID signal (identification signal) radiated together with the transmitted voice signal receives the command, and
If it is not a select call operation, all mobile stations will accept it.

On the other hand, for example, when transmission is performed by the mobile station 16'-1, the radio wave is received by the antenna 15 of the base station 9 ', demultiplexed by the duplexer 14 and demodulated by the FM receiver 11, and the receiving circuit. The switch 13 is closed and output to the command station 1. At the command station 1, the signal is amplified by the amplifier 5, and the speaker 6 is sounded.

This operation will be described with reference to FIG. In the base station 9 ′, when the mobile station 16′-2 transmits an emergency interrupt signal while receiving the call signal from the mobile station 16′-1, the received input voltage from the mobile station 16′-1 is Mobile station 16'-
If it is higher than the received input voltage from 2, the emergency interrupt signal is not received. The mobile station 16'-2 that has made the emergency interruption repeats the transmission automatically or manually, and the mobile station 16'-1 moves in the direction away from the base station 9 ', and the magnitude of the received input voltage is reversed. , Or when the call is ended and the transmission is stopped, the emergency interrupt signal from the mobile station 16′-2 is received by the base station 9 ′. Further, other communication systems may operate independently using an emergency frequency different from the call frequency.

[0010]

In the above-mentioned prior art,
For example, depending on the method of operating independently using the emergency frequency, the frequency allocation will decrease in the future and it will be difficult to realize it. In the simplex method and the semi-duplex method, D /
Un of U ratio (Desire / Undesire ratio)
Since the state in which the sire signal is large continues to be transmitted, and the urgent signal can be transmitted, the signal cannot be transmitted during the period until the Desire signal becomes large, so that a delay occurs until the signal arrives,
Therefore, there is a risk that the emergency response that can be taken by the operator of the command center will be delayed.

Similarly, when the communication system is the duplex system,
Since the communication radio wave continues to be emitted, there is a drawback that the emergency signal cannot be transmitted until the call ends and the radiation of the radio wave stops.

An object of the present invention is to eliminate these drawbacks and to enable quick emergency transmission even when a duplex system is used without adopting a system using a plurality of frequencies. To do.

[0013]

In order to achieve the above object, the present invention adopts a duplex system, in which the transmission time of a radio wave transmitted from a mobile station during a call is intermittent, and no radio wave exists. A radio wave carrying an emergency interrupt signal generated by a mobile station other than the one in communication is set for a period longer than twice the repetition period of the transmission time of the radio wave transmitted from the mobile station during the call, and Reach the station and extend the off-time of the receiving circuit due to the squelch of the base station so that the receiving circuit on the base station side operates continuously and the radio wave carrying the emergency interrupt signal is always at a constant interval in the intermittent period. , At least once with high D / U ratio.

[0014]

As a result, at the base station, the voltage received from one mobile station during a call disappears at regular intervals, and during this period, an emergency interrupt signal from another mobile station can be reliably received.
Further, on the side of the base station, since the receiving circuit is still connected due to the delay of the squelch operation, the emergency interrupt signal can be transmitted to the command station of the base station without delay.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIG. Here, the difference from the above-described configuration of the related art shown in FIG. 3 is that, in the internal configuration of the base station 9, partly different from that of the above-described base station 9 ′, the squelch signal for delaying the squelch signal for closing the switch 13 is delayed. Since the delay circuit 12 is added, the description of common parts will be omitted. In addition, the mobile stations 16′-1, 16′-2 of FIG.
1 will be described in detail. An internal configuration of the mobile stations 16-1 and 16-2 in FIG.
2 is a receiver, 18 is a press control circuit, 19 is a diode switch, and 20 is a terminating resistor.

When the commander calls, for example, the mobile station 16-1 or 16-2, the press switch 4 is turned on and the microphone 2 is used for transmission. The transmitted voice signal is amplified by the amplifier 3, sent to the base station 9, FM-modulated by the FM modulation transmitter 10, radiated from the antenna 15 through the duplexer 14, and received by the mobile station 16-1 or 16-2. . At this time, if there is a selective call (select call), only the mobile station with the matching ID code (identification code) accepts it, and if not, all mobile stations accept it. At this time, only mobile stations having the same ID code respond. On the other hand, for example, the mobile station 16-
When it is transmitted by 1, the signal is received by the antenna 15 of the base station 9, demultiplexed by the duplexer 14 and demodulated by the FM receiver 11, and the squelch delay circuit 12 closes the receiving circuit switch 13 and outputs it to the command station 1. At the command station 1, the speaker 5 is amplified by the amplifier 5.
Sound.

FIG. 2 shows the operation when the second mobile station 16-2 makes an emergency interrupt while the first mobile station 16-1 is in a normal call. In the voice transmission operation in a normal call, for example, the voice is transmitted during a period of T1 = 1000 ms, and is disconnected during a period of T2 = 100 ms to 200 ms (as short as possible so as not to be annoyed by the interruption of the voice, and an interrupt). The time is set so that the signal can be reliably received). Further, in the base station 9, the squelch-off time is delayed by, for example, T3 = 300 ms by the squelch delay circuit 12 in order to reduce squelch flapping.

At this time, the transmission time when the mobile station 16-2 makes an emergency interrupt is, for example, about 2500 ms, and at least two periods of the transmission and rest periods of the mobile station 16-1 are set, that is, (1000 ms + 200 ms). × 2 = 240
It should be output over a time of 0 ms or more. The emergency interrupt signal sent to the command station 1 is the emergency interrupt signal detector 7
And the emergency interrupt signal indicator 8 is turned on.

If a signal including an ID signal (identification signal) is repeatedly transmitted as an emergency interruption signal, the command station 1 can immediately find out which mobile station has issued the emergency interruption signal. The response to the emergency interrupt from the base station 9 is, for example,
The end of call is announced to the mobile station 16-1 during the call, and the call with the mobile station 16-2 that has made the emergency interruption is started.

If switching of the transmission output in each mobile station is performed by a press signal, the rise time until the transmission start of the transmitter 17-1 is, for example, several tens of ms, so the diode switch 19 is inserted in the transmission output. , To achieve that speedup.

[0021]

As described above, according to the present invention, in a mobile body such as a monol on an elevated track or a subway station that has no communication means other than radio between stations, in addition to the radio frequency used for normal operation. In addition, it does not require a radio frequency for emergency interruption, and it is possible to make quick contact in an emergency by using the duplex system, and it is possible to improve the efficiency of frequency use and the safety of train operation.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a diagram showing the operation of one embodiment of the present invention.

FIG. 3 is a configuration diagram of a mobile communication system according to a conventional technique.

FIG. 4 is a diagram showing an operation of a mobile communication system according to a conventional technique.

[Explanation of symbols]

 1 Command Center 2 Microphone 3 Amplifier 4 Press Switch 5 Amplifier 6 Monitor Speaker 7 Emergency Interrupt Signal Detector 8 Emergency Interrupt Signal Indicator 9 Base Station 10 Transmitter 11 Receiver 12 Squelch Delay Circuit 13 Receiving Circuit Switch 14 Duplexer 15 Antenna 16-1, 16-2, 16'-1, 16'-2 Mobile station 17-1 Transmitter 17-2 Receiver 18 Press control circuit 19 Diode switch 20 Termination resistor

Claims (2)

[Claims] 1. A command station, at least one duplex base station connected to the command office, and a plurality of duplex mobile stations capable of simultaneously existing in each of the base station zones. A mobile communication system comprising: a mobile communication system, wherein each mobile station has a call function that is normally performed between one mobile station and a base station at an assigned time, and an emergency call function performed by each mobile station. In a mobile communication system having an emergency call function to be performed with a base station by a call-in operation, the transmission control of each mobile station during the operation of the normal call function is continuous transmission for a predetermined time. And the transmission control of each mobile station at the time of the operation of the emergency call function by the above-mentioned emergency interruption, 2 which is the sum of the above and the short stop time A mobile communication system characterized by transmitting an emergency interrupt signal continuously for a time longer than twice. 2. The reception line is continuously connected in the base station by delaying the reception operation OFF timing by the squelch circuit of the receiver of the base station by the time of transmission stop during the operation of the normal call function. The mobile communication system according to claim 1, wherein: