Patent ID: 6563863
Filing Date: 2003-05-13
Classification: H04B

Abstract:
A service chip for use with a computer, comprising:a CPU interface designed to receive a transmit sample sequence from a modem sample generator executing on a central processor of the computer, and presenting a receive sample sequence to a modem sample receiver executing on the central processor; a transceiver interface for presenting data to a line interface for conversion by a digital-to-analog converter to analog signals for transmission on a telephone line; an adaptive echo cancellation filter, designed to adapt in response to an echo correlation between data transmitted over a transmit channel of the modem and data received on a receive channel of the transceiver interface; a monitor designed to monitor the transmit sample sequence for a data starvation condition; and a first synthesizer designed to synthesize a transmit sample sequence for delivery to the-digital-to-analog converter over the transceiver interface when the monitor detects the data starvation condition, the synthesized transmit sample sequence being essentially free of timing information; and a second synthesizer designed to synthesize a received data sequence for delivery on the modem receive channel to the central processing unit through the CPU interface when the monitor detects the data starvation condition, the synthesized received data sequence imperfectly approximating an echo of the transmit channel, synthesis of the received data sequence being based on the adapted parameters of the echo cancellation filter.