Patent ID: 8483244

Claim:
A method of recovering timing information over packet networks, comprising: measuring raw network time delays from timing packets of a single stream sent between a transmitter and a receiver over a packet network; predicting a current delay estimate using a minimum statistics adaptive filter to track local minima of the measured raw network time delays over a series of successive smoothing windows of L received timing packets of the single stream, by: maintaining a first variable tracking a local minimum measured raw network time delay within a smoothing window, maintaining a second variable representing the current delay estimate, said second variable being regularly updated within each smoothing window and being set equal to a minimum between the current value thereof and the measured raw network time delay for the current timing packet, after L received timing packets at the start of a new smoothing window setting said second variable equal to the current value of said first variable and subsequently updating the value of said first variable, and adaptively varying the value of L based on estimated delay variations between the transmitter and the receiver to change the tracking characteristics of the minimum statistics adaptive filter; selecting those incoming timing packets of the single stream within the smoothing window which meet a particular criterion relative to the current delay estimate; and making frequency adjustments determined from the measured raw network time delays of the selected timing packets of the single stream for a local clock at the receiver.