JPH0195695A - Digital exchange - Google Patents

Abstract

PURPOSE:To easily set the constant of an optimum balance connection network conforming to respective subscriber lines by automatically selecting the constant of the balance connection network based on the detected value of a hybrid return loss. CONSTITUTION:A subscriber circuit 2 has the plural constants of balance connection networks 3. The return loss of the subscriber line is measured by using a PCM digital pattern generating circuit 8 for test signal generation and a PCM level detecting circuit 9, and the optimum constant of the balance connection network 3 of the subscriber lines is determined from the measured value. Thus, the optimum constant of the balance connection network 3 conforming to the setting condition of the subscriber line can be set, and it can be easily reset.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to means for optimally setting a balanced connection network of a digital exchange having a two-wire/four-wire conversion circuit.

〔overview〕

The present invention is a means for optimally setting a balanced network for a digital exchange having a two-wire/four-wire conversion circuit, by measuring the reflection of subscriber lines and automatically setting constants for the balanced network based on the measured values. , it is possible to easily set the constants of the balanced wiring network.

[Conventional technology]

In traditional digital exchanges, the subscriber line is two-wire;
Since the digital switch network is a four-wire system, a hybrid circuit that performs two-wire to four-wire conversion is required. In this hybrid circuit, a signal on the transmitting side passes through a circuit on the receiving side and returns to the transmitting side. Therefore, a balanced wiring network, which is a balanced circuit that cancels this signal, is required. Conventionally, the constants of a plurality of balanced wiring networks were manually switched and set according to the line-side impedance.

[Problem that the invention seeks to solve]

In this way, in the conventional constant setting for a balanced wiring network, for example, the constants were set by conducting a call test and switching to manual settings based on hearing sensation, which made it difficult to set the constants for a balanced wiring network that was optimal for each subscriber's line. However, there was a drawback that changing the constants was quite complicated.

The present invention aims to eliminate such drawbacks, and aims to provide a digital exchange having means for automatically setting constants.

[Means for solving problems]

The present invention includes a PCM digital pattern generation circuit that is housed in a time division switch circuit and generates a test signal, and a PCM digital pattern generation circuit that is housed in the time division switch circuit and measures reflection from a subscriber line in accordance with the level of the test signal. The present invention is characterized by comprising a PCM, a level detection circuit, and a control means for automatically setting the constant of the balanced wiring network based on the measured reflection.

[Operation] The subscriber circuit is provided with constants of a plurality of balanced wiring networks, and the return loss of the subscriber line is measured using a PCM digital pattern generation circuit for test signal generation and a PCM level detection circuit. From this measured value, the constants of the optimal balanced network of subscriber lines are determined. This makes it possible to optimally set the constants of the balanced network in accordance with the installation conditions of the subscriber lines, and also to easily re-set them.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings. 1st
The figure is a block configuration diagram showing the configuration of an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of the subscriber circuit shown in FIG. 1. FIG. 3 is a diagram showing the relationship between line resistance and return loss corresponding to a plurality of balanced wiring networks,
A plurality of constant circuits of a balanced wiring network are set to correspond to a wide range of changes in line resistance.

First, the configuration of this embodiment will be explained based on FIG. This embodiment includes a subscriber circuit 2 which is an analog subscriber circuit having a hybrid circuit 2-1 to which a balanced connection network 3 whose constants can be adjusted is connected, and a time division switch circuit 5 that accommodates this subscriber circuit 2. , a hybrid of a PCM digital pattern generation circuit 8 which is housed in the time division switch circuit 5 and generates a test signal, and a subscriber line which is housed in the time division switch circuit 5 and from which this signal is sent out based on the level value of the test signal. It includes a PCM level detection circuit 9 that measures a return loss value, and a CPU 6 and a control circuit 4 that are control means that set constants of the balanced wiring network based on the measured hybrid return loss value.

Here, the special number "00" is assigned to the PCM digital pattern generation circuit 8 for generating test signals and the PCM digital pattern generation circuit 8 for detecting the PCM level.
It is assumed that the signal connects the hybrid return loss detection circuit 7 having the level detection circuit 9 and the subscriber circuit 2. When you dial special number "00" from analog telephone 1,
The CPU 6 detects the special number "00" and connects the digital communication paths 11 and 12 and the hybrid return loss detection circuit 7 via the time division switch circuit 5. The CPU 6 sends a command to start measurement to the hybrid return loss detection circuit 7 via the control line 16. The hybrid return loss detection circuit 7 prompts the subscriber to confirm the start of measurement by emitting a measurement start sound to the analog telephone 1 via the digital communication path 13, the digital communication path 12, and the analog communication path IO. A test signal is output from a PCM digital pattern generation circuit 8, and a PCM level detection circuit 9 detects the level of a backflow signal from an analog terminal. The result is judged by the CPU 6 via the control line 17, and the select switch circuit 3-1 of the balanced wiring network 3 selects constants of a plurality of balanced wiring networks in the constant circuit 3-2 of the balanced wiring network. The return loss is detected and the constants of the optimal balanced wiring network are set. When the setting is completed, the hybrid return loss detection circuit 7 outputs a constant setting completion sound for the balanced connection network to the analog telephone 1 via the digital communication path 13, digital communication path 12, and analog communication path 10, and confirms the subscriber's confirmation. prompt. In the manner described above, constants for an optimal balanced wiring network can be set.

〔Effect of the invention〕

As explained above, the present invention automatically selects the constants of the balanced connection network based on the detected value of the hybrid return loss, so it is possible to easily set the constants of the balanced connection network that are optimal for each subscriber line. There is an effect that can be done.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram showing the configuration of an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of the subscriber circuit shown in FIG. 1. FIG. 3 is a diagram showing the relationship between line resistance and hybrid IJ turn loss corresponding to each balanced wiring network. 1...Analog telephone set, 2...Subscriber circuit, 3...
- Balanced wiring network, 4... Control circuit, 5... Time division switch circuit, 6... CPU, 7... Hybrid return loss detection circuit, 8... PCM digital pattern generation circuit, 9...・PCM level detection circuit, 10...Analog communication path, 11.12.13.14...Digital communication path, 15.16.17.18...Control line, 2-1
...Hybrid circuit (HYB), 3-1...Select switch circuit, 3-2...Constant circuit. Patent applicant NEC Corporation,. Agent: Patent Attorney Nao Takashi IdeExample configuration Figure 1 Subscriber circuit configuration Figure 2

Claims (1)

[Claims] (1) In a digital exchange equipped with an analog subscriber circuit having a two-wire/four-wire conversion circuit connected to a balanced connection network whose constants can be adjusted, and a time division switch circuit accommodating this analog subscriber circuit, A PCM digital pattern generation circuit housed in the division switch circuit and generating a test signal; and a PCM level detection circuit housed in the time division switch circuit and measuring reflection from the subscriber line in accordance with the level of the test signal. and control means for automatically setting the constant of the balanced wiring network based on the measured reflection.