| 摘要 |
<P>PROBLEM TO BE SOLVED: To achieve stable frequency-time synchronization even under a network environment having fluctuation in transmission delay and path switching. <P>SOLUTION: An RTT (round trip time) is filtered to remove packets largely deviated from a mean value of a delay time, client time is controlled by using only the data approximate to the mean value of the delay time. Alternatively, an RTT is filtered, and the client time is controlled by using only the data within an error range estimated from the previous RTT. Alternatively, when an RTT or a one-side delay time suddenly changes, it is considered that path switching is caused, and the process shifts to a hold-over operation. Further, an offset value is donated so as to cancel a change amount at that time. <P>COPYRIGHT: (C)2009,JPO&INPIT |
