KR100805602B1 - Device for automatically configuring impedance of balancing network in subscriber interfacing circuit of exchange - Google Patents

Abstract

The present invention provides a device for automatically setting impedance of a subscriber matching circuit balanced network of a switching system that measures a characteristic impedance of a subscriber line and automatically sets a balanced network of a subscriber matching circuit according to a characteristic impedance of a subscriber line when a new subscriber is registered. It is about. According to an aspect of the present invention, there is provided a switching system including a subscriber matching circuit for matching impedance of a line with a hybrid balanced network, comprising: a characteristic impedance measuring unit measuring a characteristic impedance of a corresponding subscriber line when an initial line is installed; As a control unit for transmitting the value of the characteristic impedance measured by the characteristic impedance measuring unit, there is an effect to automatically set the characteristic impedance of the subscriber line and reduce the echo.

Description

Device for automatically configuring impedance of balancing network in subscriber interfacing circuit of exchange

1 is a block diagram of an impedance automatic setting apparatus of a subscriber matching circuit balanced network according to the present invention.

2 is a graph showing characteristic impedance curves of a typical subscriber line.

The present invention relates to a device for automatically setting impedance of a subscriber matching circuit balanced network of an exchange system. More particularly, the present invention relates to a balanced circuit network of a subscriber matching circuit by measuring a characteristic impedance of a subscriber line when a new subscriber is registered. The present invention relates to a device for automatically setting impedance of a balanced circuit network of a subscriber matching circuit of an exchange system that is automatically set according to a characteristic impedance.

Until recently, due to the small area of the country, the transmission interval was short, so echo on the line did not pose any problem in terms of communication quality.                         

Types of echo include Talker Echo, where the talker hears his voice, and Listener Echo, where the talker hears the same content over and over again with a slight time difference. It will have a greater impact.

Caller reverberation has a great impact on call quality because it gives the caller the feeling of talking in a water bottle, while caller reverberation occurs at the same time, with a slight lag. Since it comes back and is heard more than once, the voice signal level is attenuated a lot and has no significant effect.

The effect of echo on the call quality of service has a bad effect in proportion to the magnitude of the delay time proportional to the distance of the end-to-end transmission interval and the level of the echo signal.

That is, since the call voice signal is returned and affects, the degree of affecting the call quality is proportional to the magnitude of the level of the call voice being echoed to the magnitude of the delay.

In recent years, reverberation has been raised as a problem in terms of improving call quality since signal processing in communication systems used in communication networks has increased and delays have increased.

In particular, in the next-generation communication network that packetizes voice and integrates with various other media, delay is likely to increase, so controlling echo is an important challenge.                         

In addition, since the maximum transmission distance is only a few 100km in Korea, the echo did not cause any problems.

In addition, since transmission control devices for controlling or suppressing echoes are included in transmission sections via international communication lines or satellites having a long transmission distance, they do not affect the call.

However, in Korea, digital cellular mobile phones are introduced to form a call line in conjunction with a wired telephone network, and in recent years, the reverberation greatly affects the call quality because an internet telephone through the Internet provides a telephone service in conjunction with a wired telephone network. As a result, the need for echo control is increasing.

When a wired telephone network provides a telephone call service by interworking with a cellular mobile telephone network or an internet network, echo is a problem because the delay required for transmission of a call voice is increased, which is caused by an analog subscriber matching circuit of a digital exchange. It can be said.

In other words, the digital call line does not have a path for generating echo signals because the call lines of the sender and receiver are completely separated, whereas in the analog subscriber line part, the digital call line and the analog call use the same line. If the impedance matching is not perfect in the hybrid where the line is interfaced, it can cause echo.

The subscriber matching circuit of the digital switchboard is generally engineered to 600Ω, the rated impedance of the domestic subscriber line.                         

The reason is that it is technically possible to match the impedance on a per subscriber line basis, but it is difficult to apply on the actual site due to excessive engineering cost burden.

In addition, since the analog exchange is a two-wire analog call line with the internal exchange of the exchange, the impedance mismatch in the hybrid of the channel unit of a device in which analog / digital conversion is performed while the digital network and the relay line of the analog exchange are interfaced. The impedance mismatch of this part is more difficult to solve than the mismatch on the analog matching circuit of the digital exchanger.

The reason is that the subscriber line connected to the analog telephone subscriber matching circuit of the digital switchboard is fixed, whereas the two-wire call relay line connected to the channel unit of the device to which the analog / digital conversion is performed by the relay line of the analog switchboard is fixed. This is because engineering for perfect impedance matching on a per-line basis is fundamentally impossible because it is continuously variable by switching.

In order to solve the above problems, an object of the present invention is to automatically set the matching of the balanced network included in the subscriber matching circuit.

Another object of the present invention is to minimize the factors of echo that may occur in the telephone subscriber matching circuit.

To this end, the present invention, in the switching system comprising a subscriber matching circuit for matching the impedance of the line with a hybrid balanced network, a characteristic impedance measuring unit for measuring the characteristic impedance of the subscriber line when the initial line is installed And a control unit which transmits a value of the characteristic impedance measured by the characteristic impedance measuring unit to the balanced network.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 1 shows an impedance automatic setting device of a subscriber matching circuit balanced network of a switching system, wherein the hybrid coil 10 and subscriber line of the subscriber matching circuit 50 convert between analog two-wire lines and digital four-wire lines. The balanced circuit 20 for setting the characteristic impedance, the characteristic impedance measuring unit 30 for automatically measuring the characteristic impedance of the corresponding subscriber line, and the controller 40 for transmitting the value of the characteristic impedance measured by the balanced network 20 Equipped.

Here, the balanced network 20 is composed of a bridge composed of a resistor (R) component and a capacitance (C) component.

This is because, as shown in FIG. 2, the characteristic impedance of the subscriber line is composed of a resistance component and an inductance (L) component, and therefore, conjugate matching must be performed to achieve impedance matching.

In Korea, a loaded cable is not used as a subscriber line, and a cable composed of core wires of various diameters is used mainly for unloaded cables. configuration have the step of 50Ω, and the capacitance components in the range is configured to have a value of 0.001μ F in the range of 0.1 ~ 0.01μ F.

First, the characteristic impedance measuring unit 30 measures the resistance and the capacitance which are the characteristic impedance of the subscriber line.

The characteristic impedance measuring unit 30 is built in the exchanger or utilized as a separate line characteristic measuring device. When the characteristic impedance is measured at the initial line installation and the value is input to the control unit 40, the control unit 40 The balance circuit 20 is commanded to form a bridge having a resistance and a capacitance value corresponding to the value.

The impedance measurement of the characteristic impedance measuring unit 30 and the connection between the control unit 40 and the bridge of the balanced circuit network 20 of each subscriber matching circuit 50 include a test bus for testing the subscriber matching circuit 50. Bus) eliminates the need for a separate access network.

As described above, the present invention has the effect of reducing the reverberation factor by setting the impedance of the balanced network of the telephone subscriber matching circuit to the characteristic impedance of the subscriber line.

In addition, the call quality is maintained to be good by minimizing the reverberation factor, and the call quality is maintained when interworking with the existing network in the next generation network environment.

Claims (6)

A switching system comprising a subscriber matching circuit having a hybrid balanced network for matching impedance of a line, Characteristic impedance measuring unit for measuring the characteristic impedance of the subscriber line when the initial line is installed, And a control unit for transmitting a value of the characteristic impedance measured by the characteristic impedance measuring unit to a balanced network. The method of claim 1, And said impedance is a resistor and an electrostatic capacitance, wherein the impedance matching device of the subscriber matching circuit balanced network of the switching system. The method of claim 2, The resistor is composed of a value having an interval of 50 Ω in the range of 500 to 700 Ω, the capacitance is configured to a value having an interval of 0.001 μ F in the range of 0.1 to 0.01 μ F Automatic impedance setting device of balanced network. The method of claim 1, The impedance measurement of the characteristic impedance measuring unit and the connection between the control unit and the balanced network of each subscriber matching circuit use a test bus for testing the subscriber matching circuit. Impedance automatic setting device. The method of claim 1, And the characteristic impedance measuring unit and the control unit are built in the exchanger. The method of claim 1, The characteristic impedance measuring unit and the control unit is an impedance automatic setting device of the subscriber matching circuit balanced network of the switching system, characterized in that provided as a separate device outside the exchange.

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