| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce the influence of delay fluctuation received by a sync packet when correcting the time of a clock unit utilizing the sync packet. <P>SOLUTION: A jitter amount calculation unit 105 calculates a jitter amount on the basis of the receiving times and transmitting times of two adjoining sync packets, and a delay time estimation unit 110 estimates the delay time Td of the sync packet on the basis of the jitter amount. For instance, the delay time Td of each sample of the sync packet is obtained by shifting the cumulative jitter amount so that the minimum value of the cumulative jitter amount may become the minimum value of the delay time which is measured and determined beforehand. A time correction unit 111 obtains the correction time by correcting the transmitting time of the sync packet on the basis of the delay time Td, and rewrites and corrects the time of a clock unit 109 with the correction time. Since the estimated delay time Td includes the fluctuating delay of the sync packet, the influence of the delay fluctuation is reduced for the time of the clock unit corrected with the correction time. <P>COPYRIGHT: (C)2011,JPO&INPIT |
