JP3232354B2 - Trunk line device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a trunk line device to which a signaling system between exchanges based on an LP monitoring signal system is applied.

[Conventional technology]

As shown in FIG. 3, a conventional trunk line device of this type connects three signal paths of a transmission drive signal, an incoming call signal, a dial pulse, and a response signal to an exchange control unit, and
It is converted into a monitoring signal and transmitted and received between the other trunk line devices via a two-wire transmission line.

FIG. 3 is a functional block diagram showing an example of the related art. In FIG. 3, the trunk line device uses the LP monitoring signal system described in the Electronic Information and Communication Handbook (edited by the Institute of Electronics, Information and Communication Engineers, 1988 edition, PP2046-2047).

According to FIG. 3, the relay device is a DC blocking capacitor 1,
The two-line transmission lines A and B are connected to the four-line switching device communication line via the relay ring 2 and the hybrid circuit 3. Further, the trunk line device has a transmission switching circuit 4, a loop disconnection detection circuit 5, and a polarity detection circuit 6.

The transmission switching circuit 4 connects the transmission lines A and B with the DC blocking capacitor 1
, And is always in an incoming call state, and is connected to the transmission lines A and B by switching to the polarity detection circuit 6 when receiving the transmission drive signal. The loop disconnection detecting circuit 5 connects the loop circuit of the relay device connected to the transmission line to the -48V and the ground power supply E via the transmission switching circuit 4, detects the current, and receives the incoming call signal. Also, it detects the current of the intermittent loop circuit, receives the dial pulse, converts the dial pulse into an on / off signal, and sends it to the exchange control unit. The polarity detection circuit 6 detects the polarity reversal of the transmission lines A and B when starting the transmission line device connected to the transmission lines A and B via the transmission switching circuit 4 driven by the transmission driving signal, and responds. A signal is received, and the exchange control unit is notified.

The monitoring signal described in the electronic information and communication handbook mentioned above is LP
There are SR expressions in addition to expressions. The SR monitoring signal system is ON for the SR line.
According to the OFF signal, the monitor signal and the dial pulse are transferred.

FIG. 2 is a time chart showing an example of an SR line reception signal of the SR monitoring signal system. As will be described in detail later, the SR line received signal is in an on / off format. The monitoring signal indicates whether the transmission path is empty or closed, but also transfers the dial pulse received from the transmitting side.

[Problems to be solved by the invention]

As described above, the conventional trunk line device is configured separately for each of the LP system and the SR system of the monitoring signal. Therefore, particularly in a small-scale switching device such as a key telephone device, there are few trunk lines between the switching devices and a single function. Regardless of whether or not a trunk line device is provided, there is a problem in that a processor for executing the trunk line processing needs programs and circuits corresponding to various signal systems.

An object of the present invention is to provide a trunk line device that solves the above-mentioned problem by controlling two signal systems from a processor using one signal system.

[Means for solving the problem]

The trunk line device of the present invention detects a loop of a two-wire loop circuit of the transmission line of the LP-type monitoring signal system at the time of an incoming call, and detects a loop of the loop circuit as a dial pulse. A polarity detection circuit connected to the two lines of the transmission line to detect the reversal of the polarity as a response signal, and the two lines of the transmission line to the input of the loop intermittent detection circuit and to exchange control of the transmission switching drive signal during transmission. And a transmission switching circuit that receives and outputs the output of the polarity detection circuit, and outputs a logical sum of the output of the polarity detection circuit. It has a logical sum circuit for outputting to the exchange control unit as an SR line reception signal.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a functional block diagram showing an embodiment of the present invention, and FIG. 2 is a time chart showing an example of a signal state of a main part of FIG.

In FIG. 1, the same components as those in FIG. 3 described above are denoted by the same reference numerals, and description thereof will be omitted. The trunk line device according to FIG.
It has an OR circuit 7 in addition to the hybrid circuit 3, the transmission switching circuit 4, the loop disconnection detection circuit 5, and the polarity detection circuit 6, and is connected to the transmission lines A and B by the LP monitoring signal system. However, the signal between the trunk line device and the exchange control unit (not shown) of the other exchange connected to the trunk line device is an SR type monitoring signal type SR.
Line received signal.

The OR circuit 7 receives the outputs of the loop disconnection detection circuit 5 and the polarity detection circuit 6 and outputs the SR line reception signal.
An incoming call signal and a dial pulse are input to the output of the loop disconnection detection circuit 5, and a response signal is input to the OR circuit 7 as an ON signal (code “1”) at the output of the polarity detection circuit 6.

Next, the received signal will be described with reference to FIG. 2 and FIG. First, FIG. 2A shows an example of a received signal at the time of an incoming call. The transmission lines A and B are normally connected to the transmission switching circuits 4 and connected to the loop disconnection detection circuit 5 at the time of incoming. When the transmission path, that is, the trunk line device is empty, the loop disconnection detection circuit 5 detects the loop disconnection and is outputting the OFF signal. When a call is received, the loop disconnection detection circuit 5 detects the formation of the loop from the supplied current value, changes the signal to an ON signal as a call reception signal, and outputs the signal. This on signal changes to an off signal as a disconnection signal when loop disconnection is detected. Detection of loop interruption during transmission of the ON signal is processed as transmission of a dial pulse.

Next, FIG. 2 (B) shows an example of a received signal at the time of transmission. At the time of transmission, the transmission switching drive signal drives the transmission switching circuit 4 to switch the transmission lines A and B to the polarity detection circuit 6, so that the current of -48V and the ground E of the opposite trunk line device of the transmission lines A and B is supplied. Current is being supplied from the power supply. The SB line monitoring signal can faithfully receive the SS line monitoring signal of the connected device. Therefore, at the time of transmission, after detecting a polarity inversion pulse called a wink delay pulse transferred at the time of transmission switching, the polarity detection circuit 6 detects the polarity inversion, and converts the off signal into an on signal only during the polarity inversion as a response signal. And outputs the result to the OR circuit 7. When the polarity is restored, the polarity detection circuit 6 changes the ON signal to the OFF signal as reception of the disconnection signal. The output of the loop disconnection detection circuit 5 and the polarity detection circuit 6 is selected by the transmission switching circuit 4 in the case of a relay line device operating normally, so that the output of the OR circuit 7 is output from the SR line in FIG. The received signal is output to the exchange control unit as it is.

[Effects of the Invention] As described above, the present invention provides a trunk line device connected to a transmission line of the LP monitoring signal system, in which a logical signal of a detection signal of a loop circuit of the transmission line and a response signal of polarity inversion of the transmission line is provided. The addition of the sum circuit allows the switching control unit to control the SR monitoring signal system, so the processor of the switching control unit and its peripheral circuits have been simplified by removing some of the LP monitoring signal system. , The effect of being able to be shared.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing an embodiment of the present invention.
FIG. 3 is a time chart showing an example of a signal state at a main portion in FIG. 1, and FIG. 3 is a functional block diagram showing an example of a conventional example. 4 ... transmission switching circuit, 5 ... loop interruption detection circuit, 6 ...
... Polarity detection circuit, 7 ... OR circuit.

Claims (1)

(57) [Claims] 1. A loop disconnection detecting circuit for detecting a loop of a two-wire loop circuit of a transmission line of an LP-type monitoring signal system at the time of an incoming call and detecting a disconnection of the loop circuit as a dial pulse. A polarity detection circuit connected to the two wires to detect the reversal of the polarity as a response signal, and the two wires of the transmission line to the input of the loop intermittent detection circuit, and to receive the transmission switching drive signal from the exchange control unit during transmission. And a transmission switching circuit for switching connection to the input of the polarity detection circuit, wherein the output of the loop discontinuity detection circuit and the output of the polarity detection circuit are input, and the logical sum of the results is input to the SR line. A trunk line device comprising: an OR circuit that outputs a received signal to the switching control unit.