JP3138796B2 - Communications system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system suitable for use in long-distance wired communication using a two-wire transmission line.

[0002]

2. Description of the Related Art Conventionally, in the construction and maintenance management of roads and railways, workers or site supervisors often communicate with each other using transceivers to confirm safety and exchange necessary information. .

[0003] At this time, if workers or site supervisors exchange erroneous information or if necessary information is not exchanged, this causes a serious accident or the like. There is a fear. Therefore, at the command center that manages the work, the transceiver communication status at the site is monitored, and if necessary, correct information and additional information are promptly transmitted to the worker or site supervisor through the transceiver used. If possible, accurate and accurate information transmission can be ensured, and work can be performed smoothly and safety can be improved.

On the other hand, when such a communication system is to be realized using an existing two-wire transmission line, a plurality of relay stations, specifically, a bidirectional amplifier circuit, are usually provided in the middle of the two-wire transmission line. Must be connected at predetermined distances to amplify the attenuated audio signal. However, conventional bidirectional amplifier circuits are interconnected using a hybrid transformer for two-wire / four-wire conversion, and audio signals transmitted in two directions are separated and amplified in one direction, respectively. Even if the separation performance is sufficient, in actual use, signal leakage to the opposite line becomes larger than the specified value due to the impedance of the two-wire transmission line, etc. When installed, there is a problem that remarkable deterioration of voice quality is caused.

The present invention has been made in response to such a demand of the prior art, and transmits accurate and accurate information to a work site or the like to ensure smooth progress of work and high safety, and to facilitate the work. Another object of the present invention is to provide a communication system that can be implemented at low cost and that can ensure high voice quality.

[0006]

A communication system according to the present invention comprises a plurality of relay stations connected to a two-wire transmission line.
., and each of the relay stations 3a... is connected to a pair of two-wire / four-wire conversion hybrid transformers 4x, 4y.
a pair of amplifiers 5 connected bidirectionally between the four lines y.
, and a pair of line open / close switches 6x, 6y connected in series to the output sides of the amplifiers 5x, 5y, respectively.
, An input / output unit 8 for inputting or outputting an audio signal Sv, a signal discriminating unit 9 for discriminating a signal in the two-wire transmission line 2, and an input / output unit 8 When there is no signal in any of the input / output unit 8 and the two-wire transmission line 2, the line open / close switches 6x, 6y are controlled to close. When the audio signal Sv is input from the
x, 6y ... and the line open / close switches 6x,
At least the destination information and / or
The control signals Sf and Sr including the transmission source information are converted into audio signals Sv.
Are transmitted to the two-wire transmission line 2, and further, when the signal discriminating unit 9 determines the transmission destination information of the own station from the transmission signal Sc in the two-wire transmission line 2, When the transmission signal Sc in the line transmission line 2 is taken in and the audio signal Sv is output to the input / output unit 8 and the transmission destination information of the other station is determined, And the line open / close switch 6x or 6y on the opposite side
And a control circuit unit 10 having a function of controlling the opening of the control circuit.

In this case, according to the most preferred embodiment, at least one of the relay stations has a control circuit unit 10 having a function of taking in the transmission signals Sc from all the other relay stations 3a from the two-wire transmission line 2. As a command station C3 having

On the other hand, the control circuit 10 adds a control signal Sf, Sr to the audio signal Sv input from the input / output unit 8 to generate a transmission signal Sc.
Is provided. Also, a pair of gate on / off switches 12x, 12y... Are connected between the output side of the transmission signal generation units 11 and the output sides of the line on / off switches 6x, 6y. As a result, when there is no signal in either the input / output unit 8 or the two-wire transmission line 2 or the signal discrimination unit 9 uses the signal in the two-wire transmission line 2 Is determined, the gate open / close switches 12x, 12y
, And transmits the transmission signal Sc to the two-wire transmission path 2.
Has a function of closing the gate opening / closing switches 12x, 12y... When transmitting the signal to or transmitting the transmission signal Sc in the two-wire transmission line 2. On the other hand, the control signals Sf and Sr are MS
It is desirable to use the K signal. Furthermore, the input / output units 8 are connected to the wireless transmission / reception units 14 which can input and output the audio signal Sv and can communicate with one or more transceivers 13p and 13q, or the microphone 15 and the speaker 16 are connected. .

[0009]

Next, the operation of the communication system 1 according to the present invention will be described. First, when no audio signal is input to the input / output unit 8 and the transmission signal Sc is not transmitted to the two-wire transmission line 2, since there is no signal, the line open / close switches 6x, 6y ... The two-wire transmission line 2 is controlled to be closed and is capable of bidirectional transmission.

Assume that communication is performed by the transceivers 13p and 13q. At this time, for example, installed at a location closest to the transceivers 13p and 13q, for example,
The wireless transmission / reception unit 14 provided in the relay station 3b can receive communication of each of the transceivers 13p and 13q. Thus, the audio signal Sv output from the wireless transmission / reception unit 14 is
Is provided to the control circuit unit 10 through On the other hand, the transmission signal generation unit 11 in the control circuit unit 10 generates the transmission signal Sc by adding control signals Sf and Sr including at least transmission destination information and / or transmission source information to the input audio signal Sv. I do. On the other hand, the line open / close switches 6x and 6y are controlled to be open by the control circuit unit 10, and the output side of the transmission signal generation unit 11 and the line open / close switches 6x and 6y are controlled.
a pair of gate open / close switches 12 connected between the output sides of y
x and 12y are controlled to be closed. As a result, the transmission signal Sc generated by the transmission signal generation unit 11 is applied to the output sides of the line open / close switches 6x and 6y, and the transmission signal Sc is transmitted bidirectionally on the two-wire transmission line 2. In this case, since the line open / close switches 6x and 6y are open, no signal leakage occurs.

On the other hand, each of the other relay stations 3a, 3c... Receives the transmission signal Sc from the relay station 3b.
The transmission signal Sc is determined by the signal determination units 9 of a, 3c,. At this time, when the transmission destination information of the other station is determined, the control circuit unit 10... Controls the line opening / closing switch 6x or 6y on the opposite side to the transmission direction of the transmission signal Sc.
Are controlled to open. As a result, the bidirectional amplifier circuits 7 become one-way amplifiers that can transmit only in the transmission direction, and signal leakage at each of the relay stations 3a is eliminated. Therefore, each relay station 3a, 3c... Has a sufficient gain,
High voice quality transmission is ensured. In addition, since an expensive noise filter or the like is not required, it can be realized easily and at low cost.

On the other hand, at least one of the relay stations transmits a transmission signal Sc from all the other relay stations 3a through the two-wire transmission line 2.
Are provided as a command station C3 having a control circuit unit 10 having a function of capturing the command signals. The command station C3 can receive the transmission signals Sc transmitted from all the other relay stations 3a. In this case, the command station C3 can directly input or output the audio signal Sv by the microphone 15 and the speaker 16 connected to the input / output unit 8, for example. This allows
The command station C3 can monitor the communication status of each of the transceivers 13p and 13q and can transmit the communication to the transceivers 13p and 13q via the relay station 3b that is the transmission source. Information can be transmitted. In addition, smooth progress of work and high safety are ensured.

The relay stations 3a can communicate with each other. In this case, for example, any of the relay stations 3a.
Determines the transmission destination information of its own station from the transmission signal Sc transmitted from the relay station 3b, thereby taking in the transmission signal Sc in the two-wire transmission line 2 and outputting the audio signal Sv to the input / output unit 8.
Output to Therefore, the received relay stations 3a can hear the voice transmitted from the relay station 3b via the speaker 16 or the wireless transmission / reception unit 14. Similarly, the received relay stations 3a can transmit to and communicate with the relay station 3b that is the transmission source.

[0014]

Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, the overall system configuration of the communication system 1 according to the present embodiment will be described with reference to FIG.

The communication system 1 includes a two-wire transmission line 2.
As the two-wire transmission line 2, for example, an existing two-wire cable provided along a railway line, a road, or the like can be used. Note that the length of the two-wire transmission line 2 can be assumed to be about 100 km. A plurality of relay stations 3a, 3b, 3c,... Are connected every 10 to 20 km in the middle of the two-wire transmission line 2. In this case, at least one of the base stations is the command station C3. 13p and 13q indicate a pair of transceivers that can communicate.

FIG. 1 shows a specific configuration of the relay stations 3a.
FIG. 3 clearly shows the configuration of the relay station 3b,
The configurations of b, 3c,... can be configured similarly to the relay station 3b.

In the relay station 3b, reference numeral 7 denotes a bidirectional amplifier circuit. The bidirectional amplifier circuit unit 7 includes a pair of two-wire / four-wire conversion hybrid transformers 4x and 4y connected in the middle of the two-wire transmission line 2. In addition, each hybrid transformer 4
A pair of amplifiers 5x and 5y are connected between the four lines x and 4y. The amplifiers 5x and 5y have opposite input and output directions, and perform bidirectional amplification. Furthermore, each amplifier 5
On the output side of x, 5y.
x and 6y are connected in series.

On the other hand, reference numeral 10 denotes a control circuit which has a computer function for controlling the entire system, and includes, as input circuits, a transmission signal generator 11, input on / off switches 23f and 23r, and an input delay circuit 24 shown in FIG. And output delay circuits 27 and 27 shown in FIG.
An output open / close switch 28 is provided. The transmission signal generation unit 11 includes a signal addition circuit 21 and an MSK (minimum cyst keying) signal generation circuit 22 that generates control signals Sf and Sr including destination information, source information, a channel number, and the like. . The output side of the signal addition circuit 21 is connected to the output sides of the line opening / closing switches 6x, 6y... Via a pair of gate opening / closing switches 12x, 12y. In this case, the line open / close switches 6x, 6y, the input open / close switches 23f, 23r, the gate open / close switch 1
The 2x, 12y, output open / close switch 28 is configured by, for example, an analog switch, and is controlled to open / close by a switch switching signal Ss provided from the control circuit unit 10.

The switching pattern of each switch by the control circuit unit 10 is as follows. First, the audio signal Sv is not input to the input / output unit 8 and the transmission signal Sv is input to the two-wire transmission path 2.
When there is no c, the line open / close switches 6x, 6y... are closed and the gate open / close switches 12x, 12y. When the audio signal Sv is input from the input / output unit 8, the line open / close switches 6x, 6y are controlled to open, and the gate open / close switches 12x, 12y are controlled to close. On the other hand, when the transmission signal Sc is taken in from the two-wire transmission line 2, the line opening / closing switch 6x (or 6y)... And the gate opening and closing switch 12x (or 12y). When the transmission destination information of the other station is determined for Sc, the line open / close switch 6x or 6y on the opposite side to the transmission direction of the two-wire transmission line 2
… Is provided with a function to control opening.

Reference numeral 8 denotes an input / output unit attached to the control circuit unit 10, and has an input unit 8i for inputting the audio signal Sv and an output unit 8o for outputting the audio signal Sv. In this case, the input unit 8i basically includes the microphone 1 shown in FIG.
5 and a transmission switch (press switch) 26, and a speaker 16 shown in FIG. 3 can be basically connected to the output unit 8o. Such a basic form is particularly applicable to the command section C3. On the other hand, the command section C
.. Except for the transceivers 13p and 13q to the input / output unit 8, as shown in FIG.
(Refer to FIG. 7). Each of the relay stations 3a can selectively connect the radio transmitting / receiving unit 14, the microphone 15, the press switch (transmission switch) 26, and the speaker 16 shown in FIGS. You may do so. The wireless transceiver 14 can be the same as the transceivers 13p..., The audio output signal (audio signal Sv) and the squelch signal Sk of the wireless transceiver 14 are applied to the input unit 8i, and the wireless communication from the output unit 8o is performed. An output based on the received audio signal Sv is provided to the transmission / reception unit 14.

On the other hand, reference numeral 9 denotes a signal discriminating section for discriminating a signal in the two-wire transmission line 2, which is connected to the output side of each of the amplifiers 5x and 5y, and outputs the signal discriminating section 9 to the control circuit section 1.
0 is added.

Next, the operation and function of the communication system 1 according to the present invention will be described with reference to FIGS.

First, when the audio signal Sv is not input to the input sections 8i and the transmission signal Sc is not transmitted to the two-wire transmission line 2, there is no signal, so that as shown in FIG. Are controlled to be closed by the control circuit unit 10, and the gate open / close switches 12x, 12y are controlled to be open, and the two-wire transmission line 2 is in a state where transmission is possible in both directions. .

On the other hand, as shown in FIG. 7, it is assumed that communication is performed by transceivers 13p and 13q near relay station 3b. At this time, the wireless transmission / reception unit 14 provided in the relay station 3b receives the communications of the transceivers 13p and 13q. As a result, the audio signal Sv (audio output signal) and the squelch signal Sk output from the wireless transmission / reception unit 14 are provided to the control circuit unit 10 via the input / output unit 8. In this case, as shown in FIG. 4A, the output of the squelch signal Sk is zero during the communication time Tt, and is output during the non-communication time. Therefore, the control circuit unit 10 determines the start and end of communication based on the falling point Pd and the rising point Pu of the squelch signal Sk.

The transmission signal generation unit 11 in the control circuit unit 10 applies a control signal S
A transmission signal Sc is generated by adding f and Sr, and transmitted to the two-wire transmission line 2. That is, the control circuit unit 10 determines the falling point Pd of the squelch signal Sk,
3f is closed, and the line open / close switches 6x, 6
y is controlled to open, and the gate open / close switch 12x,
12y is closed. Then, the time T is calculated by the delay timer.
1 (see FIG. 4 (B)) is performed, and after the elapse of the time T1, the control signal Sf shown in FIG. 4 (C) is output from the MSK signal generation circuit 22. The output time of the control signal Sf is 0.2 seconds. The control signal Sf uses the MSK signal. The control signal Sf includes transmission destination information (other station ID),
The information includes transmission source information (own station ID) and a channel number.
The setting of the time T1 by the delay timer is to adjust the priority at the time of simultaneous reception by the relay stations by making the adjacent relay stations different. And the control signal S
f is output from the signal addition circuit 21.

On the other hand, as shown in FIG. 4D, the audio signal Sv is input over a period substantially matching the period Tt of the squelch signal Sk. The input audio signal Sv is output by the delay circuit 24 to the output time of the control signal Sf (0.2
Second). Then, after a lapse of 0.2 seconds, the input opening / closing switch 23r is closed by the control circuit section 10, and the delayed audio signal Sv shown in FIG. This audio signal Sv is output from the signal addition circuit 21.

When the input of the audio signal Sv is completed, the time T2 (see FIG. 4B) is measured by the delay timer at the rising point of the squelch signal Sk. The switch 23r is controlled to open. Then, the control signal Sr indicating the end is output from the MSK signal generation circuit 22, and further output through the signal addition circuit 21. In this case, the time T2 is set by the delay timer.
The reason for delaying only is to adjust the fluctuation of the reception state. Note that a part of the front side of the delayed audio signal Sv is cut by the delay.

Therefore, before the audio signal Sv, the control signal Sf
Is added, and the control signal S is added after the audio signal Sv.
The transmission signal Sc shown in FIG. 4 (F) to which r is added is generated, and this transmission signal Sc passes through the path indicated by the dotted arrow in FIG. 5, that is, the gate opening / closing switches 12x and 12y and the hybrid transformers 4x and 4y. , Two-way transmission path 2. At this time, since the line open / close switches 6x and 6y are open, no signal leakage occurs.

On the other hand, each of the other relay stations 3a, 3c... Receives the transmission signal Sc from the relay station 3b.
a, 3c... by the signal discriminator 9.
The determination of c is performed. At this time, the other relay stations 3a, 3c ...
, When the transmission destination information of the other station is determined, as shown in FIG. 5, the control circuit units 10... Open / close the line opening / closing switches 6 y. As a result, the transmission signal Sc is transmitted along the path indicated by the dotted arrow shown in FIG. 6 and the line open / close switch 6y is open, so that the bidirectional amplifier circuit units 7... It becomes an amplifying circuit part, and signal leakage at each relay station 3a is eliminated. Therefore,
Each of the relay stations 3a, 3c... Secures a sufficient gain, and further, transmission of high voice quality. In addition, since an expensive noise filter or the like is not required, it can be implemented easily and at low cost.

On the other hand, the command station C3 is connected to all the other relay stations 3
a ... can be received. In this case, an output circuit (control circuit unit 1) extracted and shown in FIG.
0), the transmission signal Sc of the two-wire transmission line 2 is taken into the control circuit unit 10. That is, when the gate open / close switch 12x and the output open / close switch 28 of the line to which the transmission signal Sc is transmitted are controlled to be closed, the transmission signal Sc is sent to the control circuit unit 10 via the line open / close switch 6x and the gate open / close switch 12x. The audio is output from the speaker 16 via the output delay circuit 27 and the output open / close switch 28. By the control of the output delay circuit 27 and the output open / close switch 28, the control signals Sf and Sr added to the received audio signal Sv are canceled, and only the audio is output. Thereby, the command station C3 can monitor the communication status in each of the transceivers 13p and 13q. Also, the command station C3 can transmit to the transceivers 13p and 13q through the relay station 3b that is the transmission source. In this case, as shown in FIG. 2, the audio signal Sv is input from the input unit 8i by the microphone 15. In addition, the transmission switch 26
Generates a signal similar to the squelch signal Sk. Therefore, by operating the transmission switch 26, the falling point Pd and the rising point Pu in FIG. 4A can be obtained. Therefore, from the command station C3, the wireless transmitting / receiving unit 14,
Further, via the transceivers 13p and 13q, for example,
Accurate and accurate information can be transmitted to work sites. In addition, smooth progress of work and high safety are ensured.

The relay stations 3a can communicate with each other. In this case, for example, any of the relay stations 3a.
Determines the transmission destination information of its own station from the transmission signal Sc transmitted from the relay station 3b, thereby taking in the transmission signal Sc in the two-wire transmission line 2, and further outputting the audio signal Sv to the output unit 8o. . In this case, the gate opening / closing switch 12x may be closed as shown in FIG. 3, whereby the transmission signal Sc is taken into the control circuit unit 10 along a path indicated by a dotted arrow. Then, it is provided to the wireless transmission / reception unit 14 via the output unit 8o, so that sound can be output from the speaker 16. As a result, at the destination relay station,
The audio signal Sv transmitted from the relay station 3b can be received and heard by the attached wireless transmission / reception unit 14. Similarly, the received relay station can transmit to the source relay station 3b. Thus, the received relay stations 3a can hear the audio signal Sv transmitted from the relay station 3b by the speaker 16 or via the wireless transmission / reception unit 14. Similarly, the received relay station 3a can also transmit to the relay station 3b that is the transmission source, and communication can be performed between the two stations.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment.
For example, squelch signal and transmission switch operation
The detection results of the start point and the end point of the audio signal may be used. Also, the command station need not always be provided. Furthermore, the control signal can use a signal form other than the MSK signal. In addition, the details of the configuration can be arbitrarily changed without departing from the gist of the present invention.

[0034]

As described above, the communication system according to the present invention has a plurality of relay stations connected to a two-wire transmission line, and each relay station includes a pair of two-wire transmission lines connected in the middle of the two-wire transmission line. A bidirectional amplifying circuit unit having a hybrid transformer for four-wire conversion, a pair of amplifiers connected bidirectionally between the four wires of each hybrid transformer, and a pair of line open / close switches connected in series to the output side of each amplifier; An input / output unit for inputting or outputting signals, a signal discriminating unit for discriminating a signal in the two-wire transmission line, connected between the input / output unit and the bidirectional amplifier circuit unit, and connected to either the input / output unit or the two-wire transmission line. When there is no signal, the line open / close switch is controlled to be closed. On the other hand, when an audio signal is input from the input / output unit, the line open / close switch is controlled to be opened, and at least the destination information is output to the output side of the line open / close switch. And / or sends a transmission signal obtained by adding a control signal including transmission source information to the audio signal to the two-wire transmission path, and further, the signal discriminating unit converts the transmission destination information of the own station from the transmission signal in the two-wire transmission path. When it is determined, the transmission signal on the two-wire transmission line is fetched and the audio signal is output to the input / output unit, and when the destination information of the other station is determined, the transmission direction of the two-wire transmission line is reversed. Since the control circuit having the function of opening the line open / close switch is provided, the following remarkable effects can be obtained.

[0035] Since accurate and accurate information can be transmitted from another relay station (command station) for communication of a transceiver at a work site or the like, smooth work and high safety can be ensured.

Basically, since a bidirectional amplifier circuit is used, an expensive noise filter or the like is not required, and the present invention can be implemented easily and at low cost. In addition, high voice quality can be ensured by switch control of the bidirectional amplifier circuit. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main part of a communication system according to the present invention;

FIG. 2 is a block diagram showing an input system circuit of a control circuit unit in the communication system;

FIG. 3 is a block diagram showing an output system circuit of a control circuit unit in the communication system;

FIG. 4 is a time chart of signals of each unit in the communication system;

FIG. 5 is a block diagram showing a state at the time of transmitting a transmission signal in a bidirectional amplifier circuit unit of the communication system;

FIG. 6 is a block diagram showing a state when a transmission signal passes through a bidirectional amplifier circuit unit of the communication system;

FIG. 7 is an overall system configuration diagram of the communication system;

[Explanation of symbols]

 Reference Signs List 1 communication system 2 two-wire transmission line 3a relay station C3 command station 4x two-wire / four-wire conversion hybrid transformer 4y two-wire / four-wire conversion hybrid transformer 5x amplifier 5y amplifier 6x line open / close switch 6y line open / close switch 7 bidirectional Amplifying circuit section 8 input / output section 9 signal discriminating section 10 control circuit section 11 transmission signal generating section 12x gate opening / closing switch 12y gate opening / closing switch 13p transceiver 13q transceiver 14 wireless transmitting / receiving section 15 microphone 16 speaker Sv sound signal Sf control signal Sr control signal Sc Transmission signal

Claims (7)

(57) [Claims] 1. A relay system comprising: a plurality of relay stations connected to a two-wire transmission line; each relay station comprising a pair of two-wire / four-wire conversion hybrid transformers connected in the middle of the two-wire transmission line; A bidirectional amplifier circuit section having a pair of amplifiers connected bidirectionally between four wires and a pair of line open / close switches respectively connected in series to the output side of each amplifier; an input / output section for inputting or outputting an audio signal; A signal discriminator for discriminating signals in the line transmission line, connected between the input / output unit and the bidirectional amplifier circuit unit, and when there is no signal in either the input / output unit or the two-line transmission line, the line open / close switch is closed. Control and
On the other hand, when an audio signal is input from the input / output unit, the line open / close switch is controlled to open, and a control signal containing at least destination information and / or source information is output to the output side of the line open / close switch as an audio signal. The added transmission signal is transmitted to the two-wire transmission line, and when the destination information of the own station is determined from the transmission signal on the two-wire transmission line by the signal determination unit, the transmission signal on the two-wire transmission line is acquired. A control circuit unit having a function of outputting an audio signal to the input / output unit and, when determining destination information of another station, opening a line opening / closing switch on the opposite side with respect to the transmission direction of the two-wire transmission line. A communication system comprising: 2. The relay station according to claim 1, wherein at least one of the relay stations is a command station having a control circuit having a function of receiving transmission signals from all other relay stations from a two-wire transmission line. Item 2. The communication system according to Item 1. 3. The control circuit unit according to claim 1, further comprising a transmission signal generation unit configured to generate a transmission signal by adding a control signal to an audio signal input from the input / output unit.
A communication system as described. 4. A pair of gate on / off switches connected between an output side of a transmission signal generation unit and an output side of a line on / off switch, and the control circuit unit sends signals to both the input / output unit and the two-wire transmission line. When there is no such signal, or when the signal discriminating unit determines the destination information of the other station from the signal on the two-wire transmission line, the control unit opens the gate open / close switch and sends the transmission signal to the two-wire transmission line or transmits the transmission signal to the two-wire transmission line. 4. The communication system according to claim 1, wherein the gate opening / closing switch is controlled to be closed when the transmission signal is received. 5. The communication system according to claim 1, wherein the control signal uses an MSK signal. 6. The communication system according to claim 1, wherein the input / output unit is connected to a wireless transmission / reception unit capable of inputting / outputting a voice signal and communicating with one or more transceivers. 7. The communication system according to claim 1, wherein a microphone and a speaker are connected to the input / output unit.