DEVICE FOR THE ELIMINATION OF THE ECHO

摘要

The echo elimination device can be used in the communicationsengineering, and in particular in the digital telephone systems.It increases the degree of dynamic neutralization of the echo(cross-talk) including in the connection of the digitalcommunication system to an analogue one, and in simultaneous callsfrom both sides of the line. The device contains a buffer (154)across which the speech signal from the remote end x(n) is fed tothree matching filters - initial filter (156), filter of the state(15) and echo elimination filter (160), and to a control unit(15) . The device also contains three adders (104, 108, 150), ahigh frequency filter (106) and two switches (162, 164). In thefirst adder (104) the speech signal from the near end v(n) isadded to the echosingal y(n) produced as a reflection of signalx(n) when crossing an unknown echo channel (102), for producingthe summation signal r(n). In the second adder (150) signal r(n)and first residual echo signal e(n) are produced for receiving thefirst residual echo signal e(n), and the r(n) signal and secondecho signal y(n) are added in the third adder (108) for producinga second residual echo signal e(n). Under the effect of signalsx(n), r(n), e(n) and e(n) the control unit (152) processes controlsignals based on a specific programme, to the three matchingfilters (156, 158, 160) and to the two switches (162, 164). Thedevice, by means of a noise analyzing unit (166) and noisesynthesis unit (168), also opens a facility for accurate speechdetection even in an environment having large noise background.8 claims, 14 figures