METHOD AND APPARATUS FOR TRANSMIT TIMING ADJUSTMENT IN A HOST-PROCESSOR-BASED MODEM

摘要

During operation a transmitter and receiver of a central site termination unit (TU-C) (101) are driven by a sample clock derived from a network clock source (103). A remote termination unit (TU-R) (102) operates with a free running sampling clock and acquires and tracks the network clock (103) from a downstream signal (104). The regenerated network clock is then used to drive both the receiver (107) and the transmitter (108) of the TU-R (102). In particular, the transmit samples are generated on a block by block basis using fast algorithms. To avoid glitches during data transmission caused by block processing, the data sample at the boundary of blocks of data is replaced by an interpolated value. In particular, a first order approximation to the correct value of the boundary sample is made, and the first order approximation is substituted in place of the boundary data sample of the block.