In a PCM modem system, a method and apparatus for optimizing the fractional sampling phase offset in the upstream direction to maximize the upstream data rate utilizes a probing signal from the analog modem generated during startup and having at least two distinct phases of a pure tone, with the probing...http://www.google.ca/patents/US6456651?utm_source=gb-gplus-sharePatent US6456651 - Method and apparatus for adjustment of the sampling phase in a PCM modem system using a dual-phase probing signal
