Safran SecureSync 2400 User Manual page 264

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3.4 Holdover Mode

What is the recommended setting for the Holdover Timeout period?

The factory default Holdover period is 2 hours (7200 seconds). The value can

be increased to up to 5 years. During this time period, SecureSync will be useable

by its NTP clients (or other consumers) after GNSS reception has been lost.

The length of time is really based on the type of oscillator installed in a unit, and

what the typical accuracy requirements are for the NTP clients. The longer it can

run in Holdover mode before it expires, the longer it can continue being a central

time source for all of its clients. But the longer SecureSync runs in Holdover, the

larger the offset to true UTC time will become, because the undisciplined oscil-

lator will drift over time:

The better the type of oscillator installed, the more stable it is while in Holdover

and therefore, the less its time will drift away from true UTC time. This results in

For more information on the TFOM value and Phase Error Limit, see

figuring the Oscillator" on

Changes made to the Holdover Timeout always take effect

immediately. If SecureSync is in Holdover and the Holdover timeout

is changed to a value that is less than the current time period that

SecureSync has been in Holdover Mode, the unit will immediately

declare loss of synchronization.

SecureSync 2400 User Manual Rev. 5.2

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