Orolia SecureSync 2400 User Manual

holdover, and eventually out of sync. When disciplining is performed such that
TFOM is no longer greater than max TFOM, the system will transition back
into sync.
Holdover Timeout(s): The default is 7200 s (= 2 hours).
For more information on holdover timeouts, see "Typical Holdover lengths in
seconds" on page227. For additional information on holdover, see "What is
"Holdover Timeout"?" on page225.
Phase Error Limit: [Default=0 (disables this feature)]. Setting a Limit (valid
for +/-) for the Phase Error between an external 1PPS reference and the Sys-
tem 1PPS will cause the disciplining tracking to restart automatically (after a
few minutes delay) if that limit is exceeded. This will help to quickly re-align
the System 1PPS with a reference.
When using a Host Reference as a primary or backup reference, for improved
performance it is recommended to set the phase error limit for NTP to a sug-
gested value of 100000 ns (= 100 µ second). Adjust this value as needed,
based on your accuracy requirements.
Restart Tracking: Check this box, and click Submit if you want to manually
restart disciplining tracking.
This option causes the disciplining algorithm to stop tracking the input ref-
erence and start over (as if it was just acquired). This can be useful if there is a
large phase offset between reference 1PPS and system 1PPS, as it may occur
when going back into sync to the external reference after a long holdover. A
Restart Tracking will re-align the system 1PPS with the reference 1PPS very
quickly, but may cause the 1PPS output to jump.
Recalibrate: In rare cases, existing calibration data may no longer be suitable
to calibrate the oscillator. This function will delete the existing calibration data,
and begin a new calibration process (not applicable for low phase-noise Rubid-
ium oscillators).
4.
Click Submit.
3.5.2.1 Time Figure of Merit (TFOM)
The TFOM reflects the estimated error range values between the reference 1PPS (such
as GPS 1PPS) and the System 1PPS which is being aligned to the 1PPS. The estimated
error is referred to as the 1PPS Phase error. TFOM values are ranges of these phase errors.
The larger the phase error estimate, the larger the TFOM value will be. For example,
TFOM 3 is reported when the estimated phase error is any value between 10 ns to less
than 100 ns of the offset between the selected 1PPS reference and the system’s 1PPS.
TFOM is SecureSync’s estimation of how accurately it is synchronized with its time and
1PPS reference inputs, based on several factors, known as the EstimatedTime Error or
ETE. The larger the TFOM value, the less accurate SecureSync believes it is aligned with
3.5 Managing the Oscillator
CHAPTER 3 • SecureSync 2400 User Manual Rev. 2
231

Orolia SecureSync 2400 Specifications

General

Brand	Orolia
Model	SecureSync 2400
Category	Recording Equipment
Language	English