Patent ID: 6456651
Filing Date: 2002-09-24
Classification: H04J,H04L

Abstract:
In a PCM modem system including an analog modem to which an input data stream is coupled, with the analog modem coupled to a digital modem through an analog loop and a central office, a method for optimizing a fractional sampling phase offset in an upstream direction from the analog modem to the digital modem to maximize the upstream data rate, comprising the steps of:generating a probing signal having at least two distinct phases of a pure tone; transmitting the probing signal in the upstream direction; measuring at least one of the phases of the probing signal; transmitting back to the analog modem a signal representing an amount to delay the input data stream, with the delay derived from the measuring the phase of at least one of the phases of the probing signal and being necessary to provide an optimal phase offset at the central office; and, delaying the input data stream by the derived delay.