JPH0342531B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a communication system, and more particularly, to a communication system having a plurality of communication channels.

Amateur radio in the VHF and UHF bands and the US
A communication device such as a CB radio has a system having one call channel and a plurality of call channels. When making a call, there is a method in which an empty channel is manually searched, and if an empty channel is found, this channel is designated and the other party is called from the call channel, and thereafter the designated channel is used to make a call.

Such a system has the disadvantage that the manual channel search makes the operation complicated, makes it difficult to perform a reliable search operation, and also tends to monopolize a certain channel.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a communication system that can reliably automatically search for idle communication channels without making the operation complicated.

The communication system of the first invention of the present application searches for one empty call channel from the plurality of call channels in a calling operation of a wireless communication system having one call channel and a plurality of call channels, and makes the searched free call channel. This is a communication method that calls a channel as data and sends it to the channel.When searching for an empty call channel, it sequentially switches between multiple call channels in the receiving state, detects the presence or absence of a received carrier signal for each of these call channels, and When a communication channel in which no signal exists is detected for a first predetermined period of time, a predetermined audio frequency signal is sent as a transmitting state for a second predetermined period of time, and then the presence or absence of a received carrier signal is detected as a receiving state again, and the presence or absence of a received carrier signal is detected. The present invention is characterized in that the communication channel is set as the searched idle communication channel only when the absence of the signal is detected for a third predetermined period of time. Further, the communication method of the second invention of the present application sequentially switches a plurality of communication channels in the receiving state, detects the presence or absence of a carrier signal for each of these communication channels, and detects the presence or absence of a carrier signal for each communication channel in which the received carrier signal does not exist. When a predetermined period of time is detected, the communication channel is set to a transmitting state and a predetermined audio frequency signal is transmitted for a second predetermined period of time, and then the receiving state is set again and when the absence of a received carrier signal is detected for a third predetermined period of time, the corresponding communication channel is set to an idle communication channel. This is a communication system that has an idle call channel search method that is set as . It is characterized by receiving and demodulating frequency signals.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a circuit block diagram of an embodiment of the present invention. Reception input from a transmitting/receiving antenna 1 is introduced into a demodulator 3 via a transmitting/receiving switch 2. In FIG. This demodulated output is applied to the system controller 4 to drive the speaker 5, and is also applied to the code detector 6 to detect the digital code signal (see Figure 2) sent from the other station (other communication device). It will be done. The system controller 4 variously controls other circuit blocks in accordance with this detection output. In addition, a carrier detector 7 is provided to detect the received signal.
The presence or absence of an IF (intermediate frequency) carrier is detected, and the system controller similarly controls other circuit blocks based on this detection signal.

On the other hand, the audio input from the microphone 8 is applied to the modulator 9 via the system controller 4, but in this case, the outputs of the code generator 10 and the audible tone signal generator 11 are applied to the modulator 9 as necessary. and will be modulated. The code generated by the code generator 10 is information (lower column) of the number of bits (upper column) as shown in FIG. 2, and is a digital code signal of 120 bits in total. That is, the start bit consists of 15 bits and serves as information for notifying in advance the transmission of each subsequent digital information. The 32-bit ATIS (Automatic
The Transmitter Identification Signal (Transmitter Identification Signal) code is the call sign data information of the own station, and the 2-bit type code indicates the type of paging mode and is information for distinguishing between simultaneous paging and individual paging. The 32-bit partner station code is call sign data information of the partner station with which you wish to make a call when making an individual call, and the 6-bit S-CH code indicates call channel data. The final 33-bit parity code is digital data for parity checking.

The signal from the audible tone generator 11 may be e.g.
It is a 1KHz monotone sine wave and is generated for about 1 second when necessary under the control of the system controller 4. The signal emitted from this audible tone generator 11 is a predetermined audible frequency signal.

The output of the modulator 9 is sent to the antenna 1 via the switch 2.
Sent from. This switching device 2 is also controlled by the controller 4. Further, a channel controller 12 is provided, which sets the channel (frequency) of the communication device based on output control data from the controller 4, and when folded down, it has a PLL (phase locked loop) configuration. . this
By varying the frequency division ratio of the programmable divider of the PLL circuit in accordance with control data from the controller 4, the oscillation frequency of the VCO (voltage controlled oscillator) in the PLL is controlled. By using this VCO output as a local signal in the demodulator 3, it becomes possible to receive the channel specified by the controller 4. Furthermore, by using this VCO output as a modulation carrier in the modulator 9, it becomes possible to transmit the channel specified by the controller 4 in the same way.

The timer 13 is activated by a trigger signal from the controller 4 to count time, and the controller 4 performs a timed operation based on the timer output. Reference numeral 14 denotes a memory, which has a RAM (random access memory) configuration and stores communication channels, ATIS codes of communication partner stations, and the like. Also, 1
5 is ROM (read-on memory),
ATIS codes, etc. are stored.

Reference numeral 16 denotes a PTT (Push to Talk) switch, and when this switch is pressed, it becomes a transmitting state. 17
is a call code setting switch, which allows selection of individual and simultaneous call modes and setting of the ATIS code of the other station. 18 is a call termination switch, which is used to notify the system of the end of communication;
Reference numeral 9 is an interrupt switch for specifying an interrupt to a busy channel.

3A and 3B are flowcharts for explaining the operation of the embodiment of the present invention, in which the connectors indicated by A are connected to each other, and the connectors indicated by B are also connected to each other. Note that C-CH in the figure is a call channel, and is a single channel that transmits only the code signal shown in FIG. 2 for calling the other station. S-CH is a speech channel, and indicates a channel for transmitting and receiving speech, codes, and audible tones.
Indicates a channel.

When the power is turned on, random initial setting is first performed as a communication channel. After that, it was made into a call channel and the first reception was completed. In this standby state, the system is configured to call or determine whether or not it has been called before proceeding to each operation.

First, the case of calling, that is, calling will be explained. Manual call sign setting switch 17
Set the operation mode and the other station (individual call mode only), and store each code in RAM14.
memorize to. Subsequently, by pressing the PTT switch 16, a free call channel search is automatically performed. With this PTT switch 16,
The transmitting call switching function during a call and the empty channel search start function as described above are used together, but in order to distinguish between them, if you press the PTT switch during a call mode, a call mode setting flag is displayed, and even if you are on a call, Configure the tobacco flag so that it is not output,
The controller 4 determines the presence or absence of this flag and automatically selects the mode.

The automatic search for a free call channel is performed in the following steps. The channel controller 12 is controlled by the controller 4 and set to a randomly initialized communication channel (previously stored in the RAM 14 at the time of initial setting), and at the same time, the switch 2 introduces the output of the antenna 1 to the demodulator 3. The receiver will operate as shown below and enter the receiving state. Here, if a carrier is detected by the carrier detector 7, that channel is a busy (used) channel, and therefore a shift to the next channel is performed. If there is no carrier, the receiving state is maintained for another 3 seconds, and if a carrier is detected during that time, the channel is advanced again. If no carrier is detected during the three seconds, the transmitting state is switched and the audible tone generator 11 is controlled to send out a 1 KHz signal for one second. These, 3
Timer 13 is used to determine the time elapsed, such as seconds and 1 second.
The determination of the passage of time in each operation described below is also performed under the control of the timer 13.

After 1 second has elapsed, the device returns to the receiving state of the communication channel, and determines whether there is a receiving carrier for 3 seconds. If there is a carrier, the channel is switched to another call channel again, and if there is no carrier, this call channel is judged to be an empty channel.
Store this channel in RAM14. This operation is sequentially performed for each of a plurality of communication channels, making it possible to search for an empty channel. 1KHz for 1 second
The reason for transmitting the signal is that if the communication channel is busy, this 1KHz monotone signal will be received by the user of the busy channel, and as a result, the receiver who received this monotone signal will be However, if the PTT switch 16 is pressed to send out the carrier, the caller who is searching for an empty channel will be informed that the channel is in use, making it possible to reliably search for an empty channel. It will become.

When the idle call channel is searched for and stored in the memory in this way, switching to the call channel is automatically set. Here, it is determined whether or not the call channel is in use in the receiving state by detecting the output of the carrier detector 6. If it is in use, it waits until the end of use, and when the carrier runs out, it is controlled so that a digital code containing the local ATIS code is sent. This digital code is of the type shown in Figure 2.
Empty call channel stored in RAM14,
Includes ATIS code of the other station, call type code, etc.
It also includes the local ATIS code in ROM15. Thereafter, the communication channel is switched to a reception state, and in the case of an individual call, a confirmation operation with the other party is started.

In this confirmation operation, the following things are automatically done. That is, in the receiving state, the presence or absence of the detection output of the code detector 7 is checked for one second, and the
If the ATIS code etc. can be confirmed, it is the ATIS code of the other party.
It is stored in RAM14. A match with the ATIS code is determined. Once the two match, it is possible to shift to a conversation state.

If the ATIS code of the other station cannot be received, or if this ATIS code does not match the requested ATIS code, the communication channel in the memory 14 is erased and the system automatically returns to the initial waiting state.

All of the above operations are shown in the flowchart of FIG. 3A. Since all of the above operations are performed automatically, the complexity of the user's operability is eliminated, and reliability is significantly improved by making it possible to accurately search for idle channels and accurately confirm the other party's station. It becomes.

The operation in the call state will be explained based on the flowchart shown on the left side of FIG. 3B. If there is no operation of the PTT switch 16 or carrier detection output within the past three minutes, the controller 4 assumes that the call has ended, erases the memory 14, and returns the system to the initial expected state. If the PTT switch is pressed within 3 minutes, it will enter the transmitting state. PTT
When the switch is released, it enters the receiving state. If a 1KHz audible tone is received in this state,
This means that a tone signal is being sent for confirmation when searching for an empty channel at another station.
The PTT switch 16 is held down for a while to send out a carrier signal, thereby informing other third party stations that the communication channel is currently in use, thereby eliminating interruptions to this channel.

During a call, an ATIS code is sent every minute, and this is an operation that satisfies the standards required for personal radios. If the call is over, the switch 18 is operated and the system returns to the initial expectant state.

Next, the operation when called will be explained using the flowchart in the center of FIG. 3B. When a code is detected by the code detector 6 in the standby state, that is, in the call channel setting state, the start bit is judged, the data code is read, the parity is checked, and the calling mode is determined.
The ATIS code and the ATIS code stored in the ROM 15 are compared. If the two match and it is an individual call, the designated call channel is set.
If the ATIS codes do not match, the system automatically returns to the initial expect state.

Simultaneously with the setting of the communication channel, the channel is controlled to be in the receiving state, and the presence or absence of a carrier is detected. If a carrier is detected here, it is determined that it is a busy channel, and the channel returns to the initial state again. If there is no carrier, an ATIS code or the like is sent out, and after a certain period of time, the call state is entered.

If the calling mode is all-at-once calling, the system immediately shifts to the designated calling channel and enters into a talking state. At this time, if a switch for rejecting all calls is provided separately, it is possible to prevent the users from responding to all calls.

Next, using the flowchart shown on the right side of FIG. 3B, the operation when searching for a busy channel and making an interrupt call will be described. When the interrupt command switch 19 is operated, the communication channel becomes a randomly initialized communication channel and is switched to a receiving state. Here, the presence or absence of a carrier is determined based on the detection output of the carrier detector 7, and if there is no carrier, the communication channel is advanced to another and the presence or absence of a carrier is checked again. The channel with the carrier is stored in the memory 14, the system is set to this channel, and the communication operation begins thereafter. At this time, if you do not send or receive calls, the channel will simply be monitored. If all channels are searched and there is no signal, it will automatically return to the initial state.

Note that the numerical examples of the times shown above are not limited to these, and can be determined as appropriate in consideration of the followable range of the device and various other conditions. Determining the presence or absence of a carrier requires a certain amount of time so as not to be sensitive to pulsed nozzles such as ignition noise. For example, if you also consider the PLL lockup time (50ms), it will be 100m.
It is conceivable to set it to about s. In addition, the system controller 4 and timer 1 in the circuit shown in FIG.
3 and RAM 14 can of course be constructed using a so-called microcomputer.

As described above, according to the present invention, since the search for empty channels is automatically and reliably performed, there are advantages in that the operation is simplified and the confirmation of empty channels is reliable.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram of an embodiment of the present invention, FIG. 2 is a diagram of a transmission data signal format including an ATIS code, and FIG. 3 is a flowchart of an embodiment of the present invention. Explanation of symbols of main parts, 4... System controller, 6... Code detector, 7... Carrier detector, 12... Channel controller, 14, 15...
memory.

Claims (1)

[Claims] 1. In a calling operation of a wireless communication system having one paging channel and a plurality of call channels, one free call channel is searched from the plurality of call channels, and the searched free call channel is used. A communication method in which data is sent to the paging channel, and when searching for the empty call channel, the plurality of call channels are sequentially switched in the receiving state, and the presence or absence of a received carrier signal is detected for each of these call channels. When a communication channel in which no received carrier signal is present is detected for a first predetermined period of time, a predetermined audio frequency signal is sent as a transmitting state for a second predetermined period of time, and then the presence or absence of a received carrier signal is detected again as a receiving state; A communication system characterized in that the communication channel is set as the searched idle communication channel only when the absence of a received carrier signal is detected for a third predetermined period of time. 2. In the receiving state, the plurality of call channels are sequentially switched and the presence or absence of a received carrier signal is detected for each of these call channels, and when a call channel in which the received carrier signal does not exist is detected for a first predetermined time, a second predetermined time is detected. A free call channel in which a predetermined audio frequency signal is sent in a transmitting state, and then the call channel is set as a free call channel when the absence of the received carrier signal is detected for a third predetermined period of time in a receiving state. A communication method having a search method, wherein the predetermined audio frequency signal is received when the predetermined audio frequency signal arrives during a call in any one of the plurality of call channels. A communication method characterized by demodulation.