Patent ID: 6810025
Filing Date: 2004-10-26
Classification: H04B

Abstract:
In a DTMF transmission structure of a W-CDMA WLL system in which a DTMF signal is transmitted and received to and from a switching system through a terminal station and a base station controller, each of the terminal station and the base station controller comprising:an echo canceller for extracting an echo component from a received signal; a DTMF detector for discriminating whether a signal to be transmitted is a DTMF signal and controlling the operation of the echo canceller; an adder for adding the signal to be transmitted and the output of the echo canceller; a VOCODER for coding the output signal of the adder to a bit stream form or decoding the received signal in the bit stream form to an analog signal; an adjusted DTMF detector for detecting a digit component from the output of the VOCODER; a DTMF generator for reproducing a normal DTMF signal according to the detected digit component; and a silence generator for generating a silence for a predetermined time immediately after the DTMF signal is reproduced.