Patent ID: 8291105

Claim:
A method for identifying inaccurate time measurements when running time synchronization on a local area network, the local area network comprising a sending device, a destination device and a switching device and/or a store-and-forward device arranged on a path between the sending device and the destination device, the method comprising: storing a value for an estimated relative local frequency deviation (dfR) and a confidence comparison value for a local time-of-day clock in a memory in the sending device; obtaining a time value (tP) of the local time-of-day clock at a previous time adjustment; obtaining an estimated local frequency accuracy (d2fR) at the previous time adjustment; obtaining an estimated local time precision (dtP) at the previous time adjustment; receiving time stamps; calculating a new time adjustment (tA) from the received time stamps; obtaining a time value (tR) of the local time-of-day clock for the new time adjustment (tA); calculating an upper acceptance level (tH) and a lower acceptance level (tL) for the new time adjustment (tA) based on the following equations: tH=tB+dtB tL=tBâˆ’dtB where tB=tP+(tRâˆ’tP)*(1+dfR) and dtB=dtP+(tRâˆ’tP)*d2fR; and determining whether the new time adjustment (tA) falls between tH and tL.