JPS62225051A - Interface system - Google Patents

Abstract

PURPOSE:To transmit a signal to transmission lines of various system and various communication systems by providing plural interface functions corresponding to various transmission lines and various communication systems and switching them by plural relays. CONSTITUTION:In using a telephone line as the communication system connected to a DC current superimposing transmission line, the contact 3a of a relay 3 is disconnected from a signal line 4 by a switching signal 100 and connected to a constant current circuit 1 and a rectifier bridge circuit 2. Then the contact 9a of a relay 9 is disconnected from the position of an adder 7 by a switching signal 200. In desiring to connect the line to a transmission line not superimposed on a DC, the contact 3a of the relay 3 is switched to the position of the signal line 4 by the signal 100. Further, in desiring to use a radio line as the communication system, the contact 9a of the relay 9 is switched to the position of the adder 7. Thus, the DC current superimposing or non- superimposing as the line system and the telephone line and radio line as the communication system are used by switching the line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a system of an interface circuit installed in a terminal device of communication equipment.

[Technical Background of the Invention] Conventionally, the functions of the interface circuit of this type of terminal device are as follows.
It is determined solely by the method of the transmission line connected to this interface circuit and the communication method used (whether to use a telephone line or a wireless line, etc.). Therefore, the conventional interface circuit described above can only input and output signals to and from such a transmission line when the transmission line is of a direct current non-superimposed type.

[Problems with the Background Art] As mentioned above, conventionally, this type of interface circuit can only be used for a transmission line of a specific system, When a related device fails, there is a drawback that it is not possible to take emergency measures such as using a transmission path of a different system to bypass the failed related device and maintain communication.

[Object of the Invention] In view of the above-mentioned drawbacks, an object of the present invention is to provide an interface circuit capable of transmitting signals to various types of transmission paths and various communication systems.

[Summary of the Invention] The present invention provides an interface circuit with a plurality of interface functions that can support various transmission paths and various communication methods,
The above objective can be achieved by switching depending on the transmission path and communication method using these interface functions.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram showing one embodiment of the interface circuit of the present invention. Reference numeral 1 denotes a constant current circuit that, when a direct current is superimposed on the transmission audio output line connected to the transmission audio output terminal 10, is connected to related equipment (not shown) connected to the transmission audio output terminal 10. A DC loop is formed in the transmitting audio output terminal 10 to maintain a constant current regardless of voltage fluctuations across the transmitting audio output terminal 10. Reference numeral 2 denotes a rectifier bridge inserted in the transmission audio output line, which maintains the polarity of the DC voltage applied to the constant current circuit 1 constant even if the polarity of the transmission audio output terminal 10 is reversed, thereby preventing damage to the constant current circuit 1. It is necessary to prevent it. Reference numeral 3 denotes a relay, and its contact 3a switches between connecting the output terminal 10 and the transformer 6 via the constant current circuit 1 and the rectifier bridge 2 or via the signal line 4 using a switching signal 100. It is something.

5 is a capacitor that prevents direct current from flowing into the lances 1 to 6. 7 is an adder, and the transmission audio input terminal 11
Audio signal input from and keying tone generation circuit 8
The added signal is output to the transformer 6. However, when the contact 9a of the relay 9 is open, only the transmission fame signal is output to the transformer 6. A keying tone generating circuit 8 generates a keying tone signal, and is turned on and off by a keying control signal 300. Reference numeral 9 denotes a relay which turns on and off the contact 9a in response to the circuit switching signal 200. 12 is a received audio input terminal, and the received audio input line connected to this is connected to a received carrier removal circuit 14 via a transformer 13, and this received carrier removal circuit 14 is equipped with the interface shown in FIG. 3: When the terminal device is used as a wireless terminal, the received carrier superimposed on the received voice is removed.

15 is a receiving audio input terminal.

Next, the operation of this embodiment will be explained. First, when a terminal device equipped with the interface shown in FIG. 1 is connected to a direct current superimposed transmission line and a telephone line is used as the communication method, the contact 3a of the relay 3 is connected to the signal line by the switching signal 5q100. Constant current circuit separated from 4]
is connected to the rectifier bridge circuit 2 side, and the switching signal @2
00, the contact 9a of the relay 9 is separated from the adder 7 side.

When a transmission audio signal is input from the transmission audio input terminal 11 in such a state, this signal passes through the adder 7 as it is and is inputted to the transmission audio output line via the i-lance 6. The transmission audio signal is sent out from the transmission audio output terminal 10 via the constant current circuit 1 and the rectifier bridge 2 to a transmission path (not shown) in the form of a superimposed direct current. Next, the transmission path method is a direct current superimposition method, and if a wireless line is used as the communication method, the contact 9 of the relay 9 is
a to the adder 7 side, and outputs the keying control signal 300, which is generated in synchronization with the input of the audio signal inputted from the transmission audio input terminal 11, to the keying 1 to -n signal generation circuit 8. is turned on, and the keying 1 to -on signals are output to the adder 7. Therefore, in the adder 7, the keying 1 to -n signals are superimposed on the transmission audio signal, and a signal obtained by superimposing the keying tone signal on the transmission audio signal and a DC current is output from the transmission audio output terminal 10. The signal is sent to a transmission path (not shown). Note that the keying 1 to -on signals are control signals that turn on the radio, and if the radio is connected via the transmission path, the radio is turned on and the superimposed transmitted audio signal is switched on. It can be sent by.

Next, when it is desired to use the terminal device equipped with the interface shown in FIG. 1 by connecting it to a non-DC superimposed transmission line, the contact 3a of the relay 3 is switched to the signal line 4 side using the circuit switching signal 100. As a result, a transmission audio output line from which the constant current circuit 1 and the rectifier bridge 2 are separated is formed. In this case as well, when a telephone line is used as the communication method, the relay contact 9a of the relay 9 is disconnected from the adder 7 side and the transmitting audio signal is sent out from the transmitting audio output terminal 10 to a transmission path (not shown). . In addition, when a wireless line is used as the communication method, the contact 9a of the relay 9 is connected to the adder 7.
By switching to the side, the keying tone generation circuit 8 is turned on by the keying control signal 300 generated in synchronization with the input of the transmitted audio signal and output to the adder 7, so that the keying tone signal is superimposed on the transmitted audio signal. The transmitted signal is sent out from the transmission audio output terminal 10 to a transmission path (not shown). Note that when a telephone line is used as the communication method, the received audio signal input from the received audio input terminal 12 is sent to the received carrier removal circuit 1 via the transformer 13.
4, but since the received carrier is not superimposed, it is inputted as is to other circuits of the terminal device (not shown) via the received audio input terminal 15.

Furthermore, when a wireless circuit is used as the communication method, since the received carrier is superimposed on the received audio signal, the superimposed received carrier is removed by the received carrier removal circuit 14, leaving only the received audio signal. The received audio signal is output from the received audio input terminal 15 to other circuits of the terminal device (not shown). Also, since we assume here that the terminal device is connected to the terminal control device and the exchange via the transmission line, the transmission line is always non-DC superimposed on the reception line.
The only distinction is made between telephone and wireless communication methods.

In FIG. 2, a plurality of terminal devices 16 equipped with the above-mentioned interface are connected to a terminal control device 18 via a transmission line 17, and this terminal control device 18 is further connected to an exchange 20 via a transmission line 19. Further, it is assumed that the exchange 20 is connected to a telephone line 21 and a wireless line 22. In the case of the above system, the transmission line 17 is DC non-superimposed,
The transmission line 19 employs a DC superimposition method. Therefore, the terminal device 16 is normally switched to send and receive signals to and from the DC non-superimposed transmission line 17, and exchange is performed using the telephone line 21 connected to the DC non-superimposed transmission line 17 or the wireless line 22.
Depending on whether the keying tone signal is used or not, it is switched whether or not to superimpose the keying tone signal on the audio signal as described above.

If the terminal control device 18 breaks down in such a state,
As shown in FIG. 3, the terminal device 16 can be directly connected to the exchange 20 via the transmission line 23 to maintain communication. That is. In this case, since the transmission line 23 uses the same DC superposition method as the transmission line 19, the terminal device 16
is switched so that signals can be sent and received by connecting this DC superimposition type transmission line. Although not shown in FIG. 2, it is assumed that the terminal device 16 is connected in advance to the exchange a20 via the transmission line 23.

According to this embodiment, the transmission path method is direct current superimposition,
As a non-overlapping and communication method, the circuit can be switched and used for either a telephone line or a wireless line. Therefore, when a failure occurs in related equipment, communication can be maintained by using a transmission path of a different system and bypassing the failure-related equipment.

Further, since a terminal device equipped with the above-mentioned interface can connect to a plurality of transmission paths and employ a plurality of communication methods, the versatility of the terminal device can be improved.

[Effects of the Invention] As described above, the interface circuit of the present invention has the advantage of being able to transmit signals to various types of transmission paths and various communication systems.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, and Fig. 2 shows an example of a system in which a terminal device equipped with the interface circuit shown in Fig. 1 is connected to related TA devices via a transmission path. Block Diagram FIG. 3 is a block diagram showing an example of an emergency system when the terminal control I device fails in the system of FIG. 2. 1... Constant current circuit 2... Rectifier bridge 3.9.
...Relay 3a, 9a...Relay contact 4...
Signal lines 6, 13...Transformer 7...Adder 8...Keying tone generation circuit 14...Received carrier removal circuit Agent Patent attorney Noriyuki Ken Yudo Sanno - Figure 2 Figure 3

Claims (1)

[Claims] In an interface circuit that is interposed between a terminal device and a transmission path and transmits signals between the two, forming a signal transmission circuit that transmits signals suitable for the transmission path method and the communication method used by switching the circuit. An interface method featuring: