Patent ID: 8089951
Filing Date: 2012-01-03
Classification: H04J

Abstract:
1. A method of transferring timing information over a network between a transmitter and receiver, comprising: generating a clock signals with a first digital controlled oscillator having a set center frequency at the transmitter based on a local oscillator at the transmitter; generating clock signals at the receiver with a digital controlled oscillator having a set center frequency based on a local oscillator at the receiver; sending time-stamped packets derived from the local transmitter clock to the receiver; creating time-stamped packets at the receiver containing timing information derived from the local receiver clock; processing said time-stamped packets to compute an estimate of the frequency deviation between the transmitter clock and the receiver clock; adjusting the center frequency of the digital controlled oscillator at the receiver so that it is synchronized with the digital controlled oscillator at the receiver, and wherein an overlapping multi-window approach is adopted wherein data adjustment blocks compute frequency adjustments from timing data accumulating during overlapping time intervals, and the data adjustment blocks take turns to output frequency adjustment data for the digital controlled oscillator at the receiver every T/M time intervals, where T is the time required to collect enough data to make an adjustment with a single adjustment block, and M is the number of adjustment blocks, and wherein an adjustment block is reset after outputting a frequency adjustment to update the local receiver clock, and variables stored in remaining adjustment blocks are adjusted to compensate for the updating of the local receiver clock, and wherein the compensation adjustments for variables S where T 1 is the time elapsed during the data collection of S y , S xy , S x and S 2x , and S x =Σ(x k ), S xy =Σ(x k y k ), S 2x =Σ(x k 2 ), and S y =Σ(y k ).