SU1389001A1 - Two-line duplex data transmission system - Google Patents

Abstract

This invention relates to telecommunications and increases noise immunity by increasing the speed of tuning an echo canceller (EC). The system contains two stations 1 and 2, each of which contains a transmitter 3, an uncoupling unit 4, a readout switch 5, a subtraction unit (WB) 6, a receiver 7, EC 8. An adaptation configuration step node 17 has been added that contains BB 9 and 13, multipliers (P) 10 and 11, a roll-up adder 12, a divider 14, a block 15 for the formation of a reference voltage. a half-pair rectifier 16. The error signal received at the output of WB 9 is fed to P 10. At the output of P 10, a signal is received with a voltage equal to the square of the error. This signal in the adder 12 is averaged over the length of K iterations, then goes to divider 14 and to WB 13. The 2nd input of WB 13 receives a signal from block 15. Block 15 produces a signal with a voltage (L1, equal to the minimum acceptable value error square, the output of WB 13 is a signal equal to the difference of the square of the error and the reference voltage, the output of divider 14 is a signal of voltage equal to the value of the tuning step.Then this signal after rectifier 16 goes to P 11, where the product error signal and tuning step. This signal comes a control input 8. 1 EC yl. i (L

Description

sh.

00 00

1The invention relates to telecommunications and can be used to build duplex digital subscriber lines.

The purpose of the invention is to increase noise immunity by increasing the speed of adjustment of the echo canceller.

The drawing shows the structures

on the two-wire Q electrical circuit formed by the echo canceller 8, the Subuplex data transmission system. The two-wire duplex data transmission system contains two stations 1 and 2, each of which contains a transmitter 3, a decoupling unit 4, a counting key 5, a first subtraction unit 6, a receiver 7, echo canceller, a torus 8, a second subtraction unit 9, the first multiplier 10 , the second multiplier 11, the accumulator adder 12, the third subtraction unit 13, the divider 14, the reference voltage generation unit 15, the full-wave rectifier 16, the echo-compensator adjustment step unit 17.

Two-wire duplex data transmission system operates as follows.

15

20

25

Since the recognition of the code symbols in the receiver 7 is performed by a single-counting method at the clock interval, it is sufficient to compensate for the signal at the reference points in time.

The difference signal from the output of the first subtraction unit 6 is fed to the input of the receiver 7, where the transmitted symbols are recognized.

The error signal received at the output of the second subtractive unit 9 is fed to the input of the first multiplier 10. At the output of the first multiplier bodies 10, a signal is obtained with a voltage equal to the square of the error (square error signal). This signal in the accumulating adder 12 is averaged over the length of K iterations. The signal is then fed to the input of the divider 14 and to the input of the third subtractive unit 13. The second input of the third subtractive unit 13 receives a signal from the unit 15 for the formation of the reference voltage. The unit 15 is abacted with a voltage signal whose value is equal to the minimum allowable value of the square of the error to achieve the specified probability of error.

Stations 1 and 2 simultaneously transmit and receive along a common path (via a two-wire physical line).

A stream of zeros and ones (data stream) is fed to the input of transmitter 3 of station 1, where it is converted into a linear signal whose spectrum is matched to the spectrum of the path.

The signal from the output of transmitter 3 is fed to the input of the decoupling unit 4. But the direction of transmission the signal is fed to the input of the two-wire line and is transmitted to the station 2 side.

The signal received from the line from station 2, distorted due to cable losses, irregularity of the amplitude-frequency characteristics (AFC) of the line between stations, the impact of inherent noise and crosstalk from neighboring cable pairs, enters the input of the reference switch 5. Simultaneously the input of the readout key 5 receives an echo signal from the own transmitter 3 of station 1, caused by the unbalance of the decoupling unit 4. The readout key KLUCH 5 is a device strobe the input signal at the clock time and memorize ayuschee its value to

the duration of the clock interval.

The discrete signal having an echo component, from the output of the reading key 5, is fed to the first input of the first subtractive unit 6. The second input of the first subtractive unit 6 receives a counter-current signal.

five

0

five

0

five

0

5 0 5

Since the recognition of the code symbols in the receiver 7 is performed by a single-counting method at the clock interval, it is sufficient to compensate for the signal at the reference points in time.

The difference signal from the output of the first subtraction unit 6 is fed to the input of the receiver 7, where the transmitted symbols are recognized.

The error signal received at the output of the second subtraction unit 9 is fed to the input of the first multiplier 10. At the output of the first multiplier 10, a signal is obtained with a voltage equal to the square of the error (square error signal). This signal in the accumulating adder 12 is averaged over the length of K iterations. The signal is then fed to the input of the divider 14 and to the input of the third subtractive unit 13. The second input of the third subtractive unit 13 receives a signal from the unit 15 for the formation of the reference voltage. Block 15 produces a voltage signal whose value is equal to the minimum permissible square error value in order to achieve a given error probability.

The output of the third subtraction unit 13 receives a signal equal to the difference of the square of the error and the reference. tension The output divider 14. a signal is received with a voltage equal to the step size. This signal is then rectified using a full-wave rectifier 16 and is fed to the second input of the second multiplier 11, where the product of the error signal and the tuning step is determined. This signal is fed to the control input of the echo canceller 8.

Thus, input of node 17 allows adaptively changing the step of tuning the echo canceller 8 depending on the ratio of the magnitude of the quadrature error signal at the current time interval and the reference value, which increases the speed of tuning the echo canceller 8.

Claims (1)

Invention Formula four A two-wire duplex data transmission system comprising two stations, each of which contains a serially connected transmitter, a decoupling unit, the first output of which is connected to the communication line, a second output of the decoupling unit through the read key is connected to the first input of the first readout unit, the second the input of which is connected to the output of the echo canceller, the first input of which is connected to the input of the transmitter, and the output of the first subtractive unit is connected to the input of the receiver, characterized in that, in order to increase the interference Resistant by increasing the speed adjustment ehokom- compensator, the adaptation step introduced node tuned echo canceller containing the second subtraction unit, the first and second inputs of which are connected respectively to the input and output of the receiver, the output of the second subtraction unit is connected to the first and second inputs of the first multiplier and the first input of the second multiplier, the output of the first multiplier is connected through the accumulating adder the first input of the divider and the first input of the third subtractive unit, the second input of the second one is connected to the unit of formation of the reference voltage, the output of the third subtractive unit is connected to volts The first input is a divider, the output of which is connected to the second input of the second multiplier, the output of which is connected to the control (via the echo canceller input) through a two-loop periodical coupler.