Spectracom VelaSync 1232 User Manual page 162

3.3 Managing References
For more information on the TFOM value and Phase Error Limit, see
the Oscillator" on
What is the recommended setting for the Holdover Timeout period?
The factory
increased to up to 5 years. During this time period, VelaSync 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 VelaSync runs in Holdover, the larger the offset to true UTC
time will become, because the undisciplined oscillator 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 more
accurate timing, over extended durations upon the loss of GPS input. For instance, a
Rubidium oscillator will maintain significantly better time over a longer Holdover
150
page 153.
Note: Changes made to the Holdover Timeout always take effect
immediately. If VelaSync is in Holdover and the Holdover timeout is
changed to a value that is less than the current time period that
VelaSync has been in Holdover Mode, the unit will immediately declare
loss of synchronization.
default Holdover period is 2 hours (7200 seconds)
CHAPTER 3 • VelaSync User's Manual Rev. 3
"Configuring
. The value can be