SecureSync’s internal oscillator is normally disciplined to an input reference (such as GNSS,
IRIG input, 1PPS input, etc.) in order to provide the highest degree of oscillator accuracy
and to account for oscillator drift. While disciplining (with a 1PPS input reference input
present and valid), the oscillator’s output frequency is monitored and based on the meas-
ured frequency, the oscillator is steered to maintain a very accurate 10 MHz output. If no
valid 1PPS input references are present (or input references are present but not con-
sidered valid), the oscillator will be in Freerun mode instead.
The Oscillators Settings page provides the user with some control of the disciplining pro-
cess. This page is also used to configure the length of time SecureSync is allowed to
remain in the Holdover mode when all references are lost.
3.5.1 Oscillator Types
SecureSync units are available with different types of internal oscillators:
TCXO (Temperature-Compensated Crystal Oscillator)
one of two different types of OCXO (Oven-Controlled Crystal Oscillator) oscillators,
or
one of two different types of Rb (Rubidium) oscillators.
The two different types of OCXO oscillators are a precision OCXO oscillator and a high-pre-
cision (low phase noise) OCXO oscillator. The two different types of Rubidium oscillators
are a precision Rubidium oscillator and a low-phase noise Rubidium oscillator. All of these
internal oscillators are self-calibrating and can be disciplined to a 1PPS input reference for
maximum accuracy.
To determine which oscillator is installed in your SecureSync unit, navigate to
MANAGEMENT > OTHER: Disciplining. The first entry in the Status panel on the left
indicates the type of oscillator:
Because of its high degree of stability, the Rubidium oscillator provides the greatest ability
to extend the hold-over period when input references are not present. Extending the
hold-over period allows the unit to provide very accurate and useable time stamps and a 10
MHz output for a longer period of time once time synchronization has been lost.
3.5 Managing the Oscillator
CHAPTER 3 • SecureSync 2400 User Manual Rev. 2
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