KR0186030B1 - Trunk interface circuit - Google Patents

Abstract

In the trunk circuit of the exchange, the same trunk is partially changed according to the type of trunk to serve in the corresponding manner. To this end, an impedance matching means suitable for the NAT method and the CEPT method is provided by using the TX and RX transformers, respectively, and the clock reproducing unit is provided with each means to extract different clocks according to the corresponding method. Therefore, in the case of the CEPT method, the trunk interface unit and the equalizer are composed of the CEPT method circuit, and the impedance matching means and the clock reproducing unit of the CEPT method are selected. The impedance matching means and the clock reproducing unit may be selected.

Description

Trunk interface circuit of exchange

1 is a diagram showing a trunk circuit block configuration of an exchange.

FIG. 2 is a diagram showing a detailed configuration of the local process section in FIG.

FIG. 3 is a block diagram showing the block configuration of the line transmission unit of FIG.

4 is a diagram showing details of the trunk interface configuration of FIG.

The present invention relates to a trunk interface circuit of an exchange, and more particularly to a trunk interface circuit that can be commonly connected to CEPT trunks and NA trunks.

In general, a trunk line interface circuit of an exchange performs impedance matching and equalizing with the trunk, and performs clock recovery from received data. Trunk circuits performing the above functions include NA trunks (T1 structures) and CEPT trunks (E1 structures). Currently, exchange and transmission equipments in Korea are installed mainly on NA trunks, and are moving to CEPT trunk structure which is advantageous in terms of implementation of ISDN, transmission efficiency and management. That is, the NA trunk has a structure having 24 channels per line, and transmits 56 Kbps or less per channel due to the limitations of a signal transmission method, a method of maintaining an average signal of 1 signal per channel of 1/8 or more, and an alarm transmission method. Served at a speed. That is, in the NA trunk as described above, since the full channel is difficult to implement, the trend is to switch to the CEPT trunk.

However, eliminating NA trunks installed in large quantities and replacing them with CEPT trunks requires a lot of time and expense. Converters are emerging.

It is therefore an object of the present invention to provide a trunk interface circuit that can share NA trunk and CEPT trunk structures using NA trunks in an exchange.

Another object of the present invention is to provide a trunk interface circuit capable of performing impedance matching and equalization functions according to a trunk interface method of a method mounted in a trunk interface circuit of an exchange using a NA method and a CEPT method.

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 is a block diagram illustrating a trunk interface module for carrying out the present invention, which is connected to an S-bus interface unit 30, a T-bus interface unit 30, and a NAS / CEPT trunk. Line transmission unit 40, and a local control unit 10, CCS signal processing unit 50, CAS signal processing unit 60 and the like.

FIG. 2 is a block diagram showing the detailed block structure of the process unit including the local control unit 10, the CCS signal processing unit 50, the CAS signal processing unit 60, and the like. FIG. 4 is a diagram showing the detailed block configuration of the section 40, and FIG. 4 is a diagram showing the detailed circuit configuration of the line transfer section 40 of FIG.

The trunk interface operation of the exchange according to the embodiment of the present invention will be described in detail based on the configuration of FIGS.

First, the S-bus interface unit 20 performs a function of interfacing the communication module with the trunk module as shown in FIG. 1 at the master side (system control unit) and uses a 5 MHz clock. At this time, when the trunk accesses the trunk, the card ID is first read and then data is written to the DPM (Dual Port RAM) located in the S-bus interface unit 20. Then, the local controller 10 of the trunk module processes the control function requested by the master side, writes the result to the S-bus interface unit 20, and reads it from the master side. As described above, when the master side writes data for controlling the operation of the trunk module to the S-bus interface unit 20, the local control unit 10 reads it and processes the corresponding function, and then the result is again displayed. The operation of writing to the S-bus interface unit 20 is performed to interface a communication function between the master side and the local controller 10.

In the local processor including the local controller 10, the CCS signal processor 50, and the CCS signal processor 60, the local controller 10 is a CPU 200, a clock generator 201, and a memory. 202, RAM 203, and DP RAM 204. The clock generator 201 generates a clock of 16 MHz. In addition, the CCS processor 206 performs an HDLC control function for CCS signaling and may use SAB82525N. The first and second CAS processing units 207 and 208 perform an ST-bus interface function for CAS signaling and line management, and may use MT8920. The USART 209 may interface with a CRT monitor and use an Intel 8251N. The control / status 210 is an I / O buffer for performing trunk control, trunk status reads, LED control, and the like.

The T-interface unit 30 is connected to a highway connected to the trunk module, and selects the highway to form a passage with the NAT / CEPT line transmitter 40 to connect user data to the trunk. To perform. At this time, in the mode using the CCS signal channel, the CCS signal data may be inserted on the selected highway before outputting to the line transmitter 40, and the CCS signal data may be extracted from the highway received by the line transmitter 40. do. In this case, the CCS signal data to be inserted / extracted is processed by the CCS signal processor 50. The selection of the highway and the enable / disable of the T-bus are controlled by the local controller 10.

The line transmitter 40 is configured as shown in FIG. 3, and transmits user data and control information D3 / D4 (NAT) or ESF (CEPT), and inserts A and B bits / CCS. Select the signal. In the case of D3 / D4, an NBZS scheme is used to maintain 1/8 density during zero byte suppression.

First, let's look at NAT. Here, the equalizer 304 for impedance matching of 100Ω input / output may use MH89761 (equalizer). Since the high frequency has attenuates depending on the length of the cable (ie, the difference between the L and C components), the equalizer 304 adjusts the L and C components to pre-equalize the frequency response. -equalize). The trunk interface units 301 and 311 may set the equalization unit 304 in three steps. Secondly, in case of CEPT method, it has impedance matching of 70Ω / 120Ω input / output and uses coaxal cable or twisted cable.

In this case, since the line transmission unit 40 can serve two trunk interface units 301 and 311, the T-bus interface unit 30 can select and serve two sub highways among the 16 highways. In FIG. 40, two trunk interface units 301 and 311 are provided to perform an interface function between the trunk and the two highways.

Clock regeneration units 302 and 312 connected to the trunk interface units 301 and 311 regenerate a clock from data received and output from a counterpart system, and the regenerated clock is applied to the local controller 10 and used as a system clock. . The A / RO and A / R1 308 and 318 may control active / redundancy and loop for each line, and may have active / redundancy in pairs on one transmission line. . When all data received in the transmission line is all zero = no data, line control and clock regeneration are impossible. The zero detectors 307 and 317 detect the state in which there is no received data (NO Signals: All Zeros and T1 line off). When the zero detection unit detects the zero state, the zero detection unit 307 or 317 notifies the local control unit 10 to the user side (cell 1). To transmit the data.

In the line transmission unit 40 having the configuration as shown in FIG. 3, a concrete circuit for one trunk line may be represented as shown in FIG. 4 is a detailed circuit diagram of the trunk interface unit 301. In FIG. 4, the NA / CEPT trunk having the DS1-class interface structure converts unipolar data into bipolar data for long distance transmission and increases transmission efficiency. Impedance matching and call function, and a recovery clock (recovery clock) from the received data (recovery clock). In addition, the trunk module is a place where all calls (Data, Voice) are outgoing / incoming in the switching system and perform all functions accompanying it. As described above, the trunk module includes a NAT method and a CEPT method. In addition, the CEPT method has a CEPT function (CEPT facility), which is a European transmission path, and can be used in three modes (CTI mode, CTP mode, and transparent mode), and each mode can be changed by setting of software.

Here, the trunk module in the trunk module provides a circuit that can be interfaced in the corresponding trunk method according to the type of NAT method or CEPT method connected to the trunk line 40.

First, look at the interface circuit of NAT method.

The trunk interface unit 301 may use MH89760D manufactured and sold between MITELs. When the impedance is to be matched by the NAT method, the S1 switch and the S2 switch of the TX transformer 303 are positioned on the X terminal side, and the resistors R1 and R2 are set to 1.5 KΩ. The S3 switch and the S4 switch of the RX transformer 306 are positioned on the X terminal side. If set as above, it is matched with impedance for 100Ω input / output when using NAT type trunk.

In addition, in order to reproduce the clock received on the NAT line, the RIL coils connected to the LA and LB terminals of the trunk interface unit 301 are set to 43 μH-48.5 μH. The reproduction clock from the zero detector 307, the signal outputted from E20 terminal of the trunk interface unit ⁽³⁰¹⁾ is outputted as (RCK, RCK ^+), the clock under the control of the local control unit 10 of the reproducing Used as the reference clock for this system, synchronization between the two systems is achieved.

The trunk interface unit 301 outputs TTL level data to the / RXB and / RXA terminals. When the trunk interface unit 301 does not receive a signal for more than about 1 ms (8 frames), the trunk interface unit 301 receives the / RXA and / RXB signals. Output high signal to each terminal. Accordingly, when a high logic signal is generated at each of the / RXA and / RXB terminals, the gate G1 outputs a low signal, thereby triggering the multivibrator M1 to output a high logic signal. Therefore, since the buffer B1 is disabled, it alerts that no signal is received (NO Signal: All Zeros).

And when connected to the trunk of the NAT method, the equalization function can be set using the DIP switch and EQ equalizer of the equalizer 304. The EQ equalizer uses MH89761 manufactured and sold by Mytel, and sets the desired equalization value by manipulating the value of the DIP switch. At this time, switch S11 is on and switch S12-S14 is off. At this time, the DIP switch state is shown in Table 1 below.

Second, we will look at the CEPT interface circuit. In this case, the trunk interface unit 301 uses MH89790 manufactured and sold by Mytel. When the impedance is to be matched by the CEPT method, it is different depending on the 75Ω coaxial cable and the 120Ω twisted pair cable. First, in the case of the coaxial cable, the S1 switch and the S2 switch of the TX transformer 303 are positioned to the Y terminal side, and the resistors R1 and R2 are set to 887 Ω. The S3 switch and the S4 switch of the RX transformer 306 are positioned at the Y terminal. If it is set as above, it is matched with impedance for 75Ω input / output when using 75Ω coaxial cable. Secondly, when using a twisted pair cable of 120Ω, the S1 switch and the S2 switch of the TX transformer 303 are positioned on the Y terminal side, and the resistors R1 and R2 are set to 909Ω. The S3 switch and the S4 switch of the RX transformer 306 are positioned at the Y terminal, and when the twisted pair cable of 120Ω is used in the CEPT method, the S3 switch and the S4 switch are matched with impedance for 120Ω input / output.

In addition, the RIL coils connected to the LA and LB terminals of the trunk interface unit 301 are set to 32 µH to 39 µH to reproduce the clock received from the CEPT trunk. As a result, a signal output from the E20 terminal of the trunk interface unit 301 is reproduced through the zero detection unit 307 (RCK). , RCK The clock reproduced by the local controller 10 is used as a reference clock of the switching system to achieve synchronization between the two systems.

The operation of the zero detector 307 is the same as in the NAT method. When connected to the CEPT trunk, the equalization function can be set using the DIP switch and EQ equalizer of the equalizer 304. The EQ equalizer may use MH89791 manufactured and sold by Mytel, and set a desired equalization value by manipulating the value of the DIP switch. In this case, the S11 switch is turned on and the S12-S14 switch is turned off. The state of the DIP switch is set as shown in Table 2 below.

As described above, the trunk module can simultaneously service a NAT type or a CEPT type trunk, and thus, there is an advantage that the trunk of the NAT type currently in service can be easily replaced with a CEPT type trunk.

Claims (1)

In the trunk circuit of an exchanger, a local control unit for controlling the operation of the trunk circuit and interfacing a signal and voice data with a state exchanger is connected between a main control unit and the local control unit, and is connected between the main control unit and the local control unit. An S-bus interface unit for interfacing a control command and a processing result, a T-bus interface unit connected to a highway of a switch circuit and performing an interface function between a selected highway and a trunk circuit under the control of the local control unit, and the T- A signal processing unit for inserting and extracting signals under control of the local control unit, connected between a CEPT or NA trunk and the T-bus interface unit, and exchanging the trunk with the local station under control of the local control unit; To a line transmitter for interfacing signal and voice data And a trunk interface unit connected to the T-bus interface unit for processing voice data and signal data in a manner corresponding to the control of the local controller, NAT impedance matching means, and CEPT impedance matching means. And a TX transformer unit connected to the trunk interface unit, switched to an impedance matching unit corresponding to a control signal of the local control unit, to match impedance to voice and signal data output from the trunk interface unit, and NAT. An equalizing unit having equalizing means and CEPT equalizing means and connected between the TX transformer and the trunk, an equalizing means selected according to the selected trunk to adjust the gain of the signal and the voice transmitted to the trunk; NAT impedance matching means and CEPT impedance matching means A RX transformer connected to a trunk and connected to an impedance matching means corresponding to a control signal output from the local controller, the RX transformer configured to impedance match voice and signal data received by the trunk; And a clock reproducing unit configured to reproduce a clock of data received from the corresponding trunk and output the clock of the data as a system clock.