Patent ID: 8401092

Claim:
An apparatus for use at a cable provider facility, the apparatus comprising: first and second modulators receiving data from respective first and second data sources and generating respective first and second symbol streams, the first and second data sources being characterized by respective different first and second source reference clocks; an input for receiving a system clock that is independent of said first and second reference clocks and is characterized by a system clock period; and first and second phase synchronizers coupled to said first and second modulators, respectively, each phase synchronizer having a source reference clock input, a system clock input, and an output coupled to the modulator; said first and second phase synchronizers and said first and second modulators operating in response to said system clock; each phase synchronizer responding to signals at its respective source reference clock and system clock inputs to provide symbol phase information to the respective modulator to synchronize the respective modulator to the reference clock while the modulator operates in response to said system clock.