KR200410722Y1 - A circuit-loudness-rating improved electronic switching system - Google Patents

Abstract

The present invention relates to an electronic exchange having an improved connection volume rating, the subscriber line is connected to the subscriber line to the electronic switch; A switching circuit unit for setting a call path in response to a call request of the subscriber line; And a receiving pad which connects the subscriber matching unit and the switching circuit unit and removes sound and echo, wherein the receiving pad reduces the voice signal by 3 dB.

Connection volume rating, connection loss, transmission loss

Description

Electronic exchanger with improved connection volume rating {A CIRCUIT-LOUDNESS-RATING IMPROVED ELECTRONIC SWITCHING SYSTEM}

1 is a block diagram showing the internal configuration of the electronic exchanger according to the present invention.

2 is a diagram illustrating a connection state of a terminal to a terminal.

The present invention relates to an electronic exchange having an improved connection volume rating, and more particularly, to reduce the resistance value inserted into the receiving circuit of the electronic exchange so that the transmission loss of the subscriber line can be expanded.

An exchange is a key device that composes a telephone network with equipment used to provide public telephone service. The telephone network first establishes a line for signal transmission, and when the line setting is completed, a voice signal is transmitted through the established line. After the call is terminated, the line is terminated using the line termination procedure.

The exchanger uses a digital electronic exchanger that is currently used from a manual idle changer operated by a human. In the 1970s, digital exchangers began to commercialize digital exchangers using PCM (Pulse Code Modulation) due to the development of computer processing technology and semiconductor integrated circuit devices.

In addition to the digitalization of telecommunications, telephone networks are being replaced by analog-to-digital networks. Therefore, depending on the interval, the exchange performs conversion from analog to digital and digital to analog.

The digital electronic exchange unit has a resistance value called a receiving pad in the receiving circuit of the exchange to prevent the occurrence of echo and sound that may occur due to impedance mismatch of the high bridge circuit in the analog / digital conversion unit performing the analog / digital conversion. Insert

In Korea, in order to maintain constant call quality, the transmission loss on the subscriber line is set to 7dB or less and the transmission loss on the exchange-to-exchange section is set to 11dB or less. The transmission loss of the switch-to-switch section does not occur at all in the switch network section, and there is a problem that it is artificially generated by the insertion pad.

An object of the present invention for solving the above problems is to change the transmission loss of the switch-to-exchange section by changing the resistance value of the receiving pad of the digital electronic exchange, and to redistribute the reduced transmission loss to the subscriber line for transmission on the line. It is to expand the losses.

In order to achieve the above object, an electronic exchange having an improved connection volume rating includes: a subscriber matching unit having subscriber lines connected to the electronic exchange; A switching circuit unit for setting a call path in response to a call request of the subscriber line; And a receiving pad connecting the subscriber matching unit and the switching circuit unit and removing the sound and the echo, wherein the receiving pad reduces the voice signal by 3 dB.

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

Electronic exchanger according to the present invention will be described as an example of a digital electronic exchange using a PCM (Pulse Code Modulation) method.

1 is a block diagram showing the internal configuration of the electron exchanger according to the present invention.

The electronic exchange 10 includes a line interface 100, a hybrid circuit 200, a pad 300, a PCM modulation and demodulation unit 400, and a switching circuit 500.

The electronic exchange 10 is a device for setting and providing a corresponding call path when a telephone network subscriber such as a public telephone network requests a call, and the actual configuration further includes various functional units. In the preferred embodiment of the present invention will be described using only some components for convenience.

Typically, components including the line interface 100 and the hybrid circuit 200 of the electronic exchange 10 are referred to as subscriber matching units. Subscriber matching refers to the function of actually accepting the telephone subscriber line and entering the electronic switch 10.

The line interface 100 serves to receive a subscriber line, connects the subscriber line to the electronic switch 10, and transmits and receives a signal to and from the terminal 20 of the subscriber.

The hybrid circuit 200 serves to separate the transmitting signal and the receiving circuit for processing signals in the electronic exchange 10. The subscriber line is composed of two strands, and the transmission signal and the reception signal simultaneously use the same line. Therefore, in order to precisely process such a signal inside the exchange, the transmission signal and the reception signal are separated to serve to distinguish the transmission circuit and the reception circuit.

The pad 300 removes noise included in the received signal of the receiving circuit. The definition of noise means unwanted sounds. In the hybrid circuit 200, the transmission signal is finely induced in the reception signal due to the superposition of signals generated during the separation of the transmission signal and the reception signal, and environmental factors such as electromagnetic waves generated inside the electronic switch 10 circuit. Phenomenon occurs. Due to the finely induced transmission signal, a sound phenomenon and an echo phenomenon appear in the received signal. The pad 300 is inserted to remove such loud and echo phenomena. The inserted pad 300 causes a loss of the voice signal as a whole, and typically the pad 300 causes a loss of the voice signal of 7 dB. The pad 300 reduces the strength of the voice signal, but has an effect of improving the signal-to-noise ratio by removing noise.

The PCM modulation / demodulator 400 converts an analog voice signal into a signal of a pulse code modulation (PCM) method. When the analog voice signal is transmitted in the analog form, distortion of the signal occurs easily due to noise that may occur in a transmission environment. Therefore, when the voice signal is converted into a pulse code and transmitted, modulation and demodulation is performed by the PCM method for ease of original signal recovery even if it is affected by noise. In addition, the PCM scheme has higher subscriber capacity than analog.

The switching circuit 500 sets the path of the corresponding line by actually switching inside the electronic exchange 10. The switching circuit 500 checks a corresponding path according to the dialed number and provides a path by connecting a switch according to the corresponding path.

The operation of the electronic switch 10 using the PCM method is performed by a T-switch (Time-Switch), which is a switching network, and the signals of all voice channels to be exchanged are transmitted in 125 ms periods (8000 times a second). It is an 8-bit PCM code that is input in series at the exchange. In other words, the T switch sequentially records the PCM code of each channel at each cycle, sets the time-slot of the channels according to the sequence, and exchanges them according to the time arrangement.

Comprehensive transmission loss between the terminal 20 and the terminal 20 and connection loss of the electronic exchange 10, and transmission and reception volume ratings based on the overall loudness rating (OLR) technical standard, which is a criterion for determining communication quality. Receiving Loudness Rating (RLR) and transmission loss acceptance criteria in the line sector are as follows.

The standard of SLR (Sending Loudness Rating) according to international call is limited to 9dB for telephone service providers, and the national standard in Korea is based on 14dB and the ITU-T standard is based on 7 ~ 15dB. Doing.

The RLR is based on 5dB for telephone operators, 6dB for national standards, and 1-6dB for ITU-T.

The circuit loudness rating (CLR) for domestic calls is based on 11dB by the telephone service provider, and the recommended standard of ITU-T is 3 ~ 9dB.

In the domestic call, the OLR is based on 16dB by the telephone operator and 20dB by the national standard.

SLR refers to the volume loss between the talker and the end-switching exchange that is coupled to the talker. Sign language loudness rating (RLR) refers to the volume loss between the receiver and the end-switching exchange coupled with the receiver. Connection Volume Rating (CLR) is the volume loss between two end exchanges in a telecommunication network. Total Volume Rating (OLR) is the total volume loss on a line connected across the entire network.

The integrated volume rating (OLR) calculates the RLR of -3 dB and the SLR of 8 dB when the subscriber line loss is less than 7 dB, and the receiver volume is greater than 7 dB when the subscriber line loss exceeds 7 dB. The rated RLR is -7dB and the talk volume rating (SLR) is 3dB, and the connection volume rating (CLR) here is equal to 7dB, which is the insertion value of the exchange pad 300.

2 is a diagram illustrating a connection state of a terminal to a terminal.

The connection of the line between the terminals 20 is connected through the electronic switch 10, in which the transmission loss in the subscriber line is 3 dB and the connection loss of 7 dB occurs in the electronic switch 10, so that the total volume rating (OLR) is 10 dB. Becomes

The connection loss in the electronic exchange 10 depends on the network operation consisting of four tiers connected between the stations using the electronic exchange 10 from a single station to a central station, from a central station to a central station, and from a central station to a general office. Therefore, the connection loss in the network section, which is the exchange-switch section, operates up to 11 dB. The inter-station network begins to operate with the disappearance of the concept of the centralized station, which is currently connected from the single station to the central station and from the central station to the master station, and the connection loss of the current electronic exchange 10 can be changed from the existing 7 dB to 3 dB.

Therefore, the connection loss of the electronic exchange 10 can be improved by about 4 dB from 7 dB to 3 dB, and the reduced transmission loss corresponding to the improved 4 dB can be redistributed to the subscriber line field.

Therefore, even if the connection loss in the electronic switch 10 is set to 3 dB and the transmission loss in the subscriber line is revised to 11 dB, the integrated volume rating (OLR) can maintain the existing 14 dB.

Average Signal to Noise Ratio (SNR) Bit Error Rate (BER) When pad 7dB is applied 37 dB 6.09e-04 When pad 0dB is applied 39 dB 2.30e-04

Table 1 shows the transmission result according to the connection loss setting of the reception pad.

Table 1 shows that the transmission line of the subscriber line was set to 3dB and the connection loss value of the switch pad 300 of the switch was changed as a result of forming a line from the Namdaegu telephone station to the Jeju Island telephone station and again measuring the network quality. The result is when.

The connection loss of the pad 300 is reduced to improve the signal-to-noise ratio, and the improvement of the signal-to-noise ratio can be seen to improve the BER (Bit Error Rate).

As described above, the electronic exchange with improved connection volume rating according to the present invention is to improve the connection loss in the exchange and to redistribute it to the subscriber line section to extend the transmission loss of the subscriber line section, It has the effect of enabling the service of improved comprehensive loudness rating in the telecommunication cable of railway facilities.

In addition, by increasing the limit of subscriber line transmission loss from the existing 7dB to 11dB, it is possible to secure the existing comprehensive volume rating, and at the same time, it is possible to use the cable core wire of the same cable section more carefully than before, thereby reducing the cable investment cost and heterogeneous It is effective to prevent the loss caused by the use of wire diameter.

Claims (2)

A subscriber matching section to which subscriber lines are connected to the electronic switch; A switching circuit unit for setting a call path in response to a call request of the subscriber line; And And a receiving pad connecting the subscriber matching unit and the switching circuit unit and removing the sound and echo, wherein the receiving pad reduces the voice signal by 3 dB (decibel). Electronic exchanger. The method of claim 1, wherein the subscriber matching unit, And said subscriber line is separated into a transmitting circuit and a receiving circuit.

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