Patent ID: 7385990

Claim:
A method of recovering timing information over multiple asynchronous packet networks, each having its own time grid, comprising: transmitting timestamped packets between a sender on a first said network and a receiver on a second said network; transporting timing information between the sender and receiver as a modulated signal comprising a modulation in the rate of sending out the timestamped packets transmitted between the sender and receiver; extracting said timing information from the packets arriving at the receiver; and using said timing information at the receiver to align the time grid at the receiver with the time grid at the sender; and wherein said modulated signal is manifested as an offset in the rate of transmission of packets from the sender, said offset being an odd fraction ƒ of a cycle of a clock signal such that the timing error at the receiver contains only high frequency components, and wherein the packet rate is offset by an amount equal to the ratio of the packet cycle and clock cycle multiplied by ƒ.