JPS63217892A - Artificial line inserting method for private branch exchange - Google Patents

Abstract

PURPOSE:To simplify the constitution of its own artificial line by inserting the artificial line into a primary side of a transformer, which is a part to which a high voltage from a trunk line is not applied, and also, a part which is not influenced by a hybrid circuit, etc. CONSTITUTION:An artificial line 20 is inserted into a primary side of a transformer 15, that is, an output side interposing a DC cut capacitor 14 of a DC bias circuit 13. As a result, a DC component of power which is fed from a station exchange through input terminals T, R from a trunk line is bypassed by a DC bypass circuit 13, therefore, only an AC component of a signal applied from the office exchange is applied to the artificial line 20. Accordingly, since only an AC signal component of a low voltage and a low power is applied to the artificial line 20, the parts specification required for the artificial line 20 goes to very lenient. In such a way, the artificial line 20 can be constituted simply and at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for inserting a pseudo line in a private branch exchange, which can simplify the pseudo line.

(Prior Art) When constructing a telephone system by connecting a private branch exchange to a central office exchange and accommodating a plurality of telephone terminals in the private branch exchange, for example, when the connection distance between the central office exchange and the private branch exchange is short, Generally, a pseudo line is inserted into a private branch exchange in order to match the line (office line).

That is, in this type of telephone system, as shown in the schematic configuration in FIG. It is configured by connecting the telephone terminal 5 via the terminal. When the line length of the central office line connecting the trunk circuit 2 and the central office exchange 1113 is short, a pseudo line is generally inserted into the trunk circuit 2 in order to match the central office line (line).

That is, the trunk circuit 2 basically operates as shown in FIGS. 3 and 4.
As shown in the figure, a station signal detection circuit 112 and a station signal 9 are connected to the line input terminals T and R connected to the station exchange @3 via the station line.
The sending circuits 12 are connected to each other, and the line input terminal T
, R are connected to the primary side of a transformer 15 via a DC bypass circuit 13 and a DC cut capacitor 14, and a hybrid circuit 16 is connected to the secondary side of this transformer 15.

The station signal detection circuit 11 is used to detect a bell signal and ground from the exchange 3, and the station signal transmission circuit 12 is used to send dial pulses to the exchange 3. be. Further, the DC bypass circuit 13 constitutes a DC circuit for the central office exchange 3, and works with the DC cut capacitor 14 to cut the DC component, and cuts the DC component from the voice signal and various signals (ring back) from the central office exchange 3.・Tone, busy tone, etc.) are added to the transformer 15.

The hybrid circuit 16 receives and receives the audio signal and various signals via the transformer 15, and transfers these signals to the two.
This is a 4-line conversion. This hybrid circuit 16
The line circuit 4 is connected via a switch circuit (not shown) to form a communication path between the central office exchange 3 and the telephone terminal 5.

Here, the pseudo line 20 for matching with the office line is generally inserted immediately after the line input terminals T and H, as illustrated in FIG. 3, to directly match the office line. It is now possible to As a result, the matching is effectively achieved and the operations of the station signal detection circuit 11 and the station signal transmission circuit 12 are compensated.

However, in this way, the pseudo line 20 is connected to the line input terminal T,
When inserted immediately after H, a high voltage is applied to the pseudo line 20 due to the power supply from the central office exchange ta3 via the central line, so the rated voltage is high as a circuit component making up the pseudo line 20, and the rated voltage is high. It was necessary to select parts with a large amount of power. For this reason, it was undeniable that the price of the dummy line 20 would inevitably increase.

On the other hand, it has been considered to insert a pseudo line 20 between the secondary side of the transformer 15 and the hybrid circuit 16 as illustrated in FIG. If the pseudo line 20 is inserted in such a part, the power supply from the office line is blocked via the transformer 15, so the pseudo line 20
can be constructed using circuit components with low rated voltage and low rated power.

However, since the line characteristics of the pseudo line 20 change under the influence of the transformer 15 and the hybrid circuit 16, for example, the circuit constants of the pseudo line 20 may be changed to maintain predetermined line characteristics, or the circuit constants of the hybrid circuit 16 may be changed. will need to be changed. Therefore, there was a problem in that the pseudo line 20 could not be easily inserted depending on the connection relationship between the private branch exchange 1 and the central office exchange 113.

(Problem to be solved by the invention) In this way, in the past, the pseudo line was inserted immediately after the input end of the trunk circuit or on the secondary side of the transformer, so it was difficult to make the pseudo line high withstand voltage. However, there is a problem in that it is not possible to simply insert a pseudo line depending on the equipment condition of the private branch exchange.

The present invention was made in consideration of these circumstances, and its purpose is to simplify the configuration of a pseudo line for matching with the central office line, and to connect the pseudo line to a private branch exchange. An object of the present invention is to provide a method for inserting a pseudo line in a private branch exchange, which can be easily inserted into a trunk circuit.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a pseudo line for matching lines connecting a central office exchange and a private branch exchange to the main body of the exchange in the trunk circuit of the private branch exchange. The pseudo line is inserted into the primary side of a transformer that separates and connects the connected hybrid circuit and the DC bypass circuit connected to the line, to the primary side to which the DC bypass circuit is connected. It is something to do.

(Function) According to the present invention, since the pseudo line is inserted on the primary side of the transformer, the line characteristics are not affected by the transformer or hybrid circuit, and it is connected to the station line via the DC bypass circuit. Therefore, high voltage due to power supply from the central office exchange via the central office line is not applied. Then, through the DC bypass circuit, a matching effect is exerted on the station line in an AC manner.

Therefore, it is possible to configure a pseudo line with the same circuit constants as the pseudo line inserted at the input end of a conventional trunk circuit, and since high DC voltage from the office line is not applied, the rated voltage and rated power It becomes possible to construct a pseudo line easily and inexpensively using small circuit components.

Furthermore, since the hybrid circuit is separated via the transformer, there is an effect that the circuit constants do not need to be changed at all.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of inserting a pseudo line into a trunk circuit according to an embodiment method, and the same parts as in the conventional system are denoted by the same reference numerals.

The feature of this method is that the pseudo line 20 is inserted on the primary side of the transformer 15, that is, on the output side of the DC bypass circuit 13 via the DC cut capacitor 14.

Therefore, a station signal detection circuit 111 and a station signal input/output circuit 12 are connected to the line input terminals T and H of the trunk circuit 2, respectively.
Further, a DC bypass circuit 13 is connected to the line input terminals T and R. A pseudo line 20 inserted into the trunk circuit 2 is connected to the output end of this DC bypass circuit 13 via a DC cut capacitor 14, and the primary side of a transformer 15 is connected via this pseudo line 20. Further, a hybrid circuit 16 is connected to the secondary side of the transformer 15.

The pseudo line 20 has a resistor r1. inserted in series with one of the lines. r2, and resistance r1. It consists of a capacitor C connected in parallel between the connection point of r2 and the other line. These resistances r1. r2 and the capacitor C constitute a pseudo line 20 having a predetermined attenuation characteristic.

Thus, according to the pseudo line 20 inserted between the DC bypass circuit 13 and the primary side of the transformer 15, the power supplied from the central office line through the input terminals T and R from the central office exchange tl13 is controlled. Since the DC component is bypassed by the DC bypass circuit 13, only the AC component of the signal provided from the central office exchange 3 is applied to the pseudo line 20. Therefore, only low-voltage, low-power AC signal components are applied to the pseudo-line 20, so the component specifications required for the pseudo-line 20 are very loose. As a result, it becomes possible to construct the pseudo line 20 simply and inexpensively using general-purpose circuit components with low rated voltage and low rated power.

Further, since the pseudo line 20 is inserted before the transformer 15 with respect to the office line, its circuit characteristics are not influenced by the transformer 15 or the hybrid circuit 16. As a result, the conventional input terminal T.

Compared to the pseudo line 20 inserted immediately after R, there is no need to particularly change the circuit constants of the pseudo line 20, and there is no need to change the circuit constants of the hybrid circuit 16.

Therefore, the pseudo line 20 can be inserted very easily depending on the line length of the central office line connecting the private branch exchange 1 and the central office exchange@3.

It should be noted that the present invention is not limited to the above embodiments, but the configuration of the pseudo line 20, its circuit constants, etc. may be determined according to the specifications of the switching system. Various modifications can be made without departing from the gist of the invention.

[Effects of the Invention] As explained above, according to the present invention, the pseudo line is connected to one part of the transformer, which is a part to which high voltage from the central line is not applied and which is not affected by a hybrid circuit or the like.
Since it is inserted on the next side, it is possible to simplify the configuration of the pseudo-line itself, and it has great practical effects such as maintaining versatility and simplifying the insertion procedure.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of inserting a pseudo line into a trunk circuit according to an embodiment method of the present invention, Fig. 2 is a schematic configuration diagram of a switching system, and Figs. 3 and 4 are diagrams showing a conventional pseudo line, respectively. It is a figure which shows the insertion example of. 1... Private branch exchange, 2... Trunk circuit, 3...
Central office exchange, 4... Line circuit, 5... Telephone terminal, 1
1... Station signal detection circuit, 12... Station signal sending circuit,
13...DC bypass circuit, 14...DC cut
Capacitor, 15...Transformer, 16...Hybrid circuit, 20...Pseudo line.

Claims (1)

[Scope of Claims] When inserting into the private branch exchange a pseudo line that matches the lines connecting the central office exchange and the private branch exchange, A method for inserting a pseudo line in a private branch exchange, characterized in that the pseudo line is inserted into the primary side of a transformer that connects the DC bypass circuit connected to the DC bypass circuit in a DC-separated manner.