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
EstimatedTime Error or ETE. The larger the TFOM value, the less accurate
SecureSync believes it is aligned with its 1PPS input that is used to perform dis-
ciplining. If this estimated error is too large, it could adversely affect the per-
formance of oscillator disciplining. The available TFOM range is 1 through 15. You
may refer to the following for the TFOM to ETE conversions:
Table 3-5: TFOM to ETE conversion
Reported TFOM Value Estimated Time Error (ETE)
1 <= 1 nsec
2 1 nsec < ETE <= 10 nsec
3 10 nsec < ETE <= 100 nsec
4 100 nsec < ETE <= 1 μsec
5 1 μsec < ETE <= 10 μsec
6 10 μsec < ETE <= 100 μsec
7 100 μsec < ETE <= 1 msec
8 1 msec < ETE <= 10 msec
9 10 msec < ETE <= 100 msec
10 100 msec < ETE <= 1 sec
11 1 sec < ETE <= 10 sec
12 10 sec < ETE <= 100 sec
13 100 sec < ETE <= 1000 sec
14 1000 sec < ETE <= 10000 sec
15 ETE > 10000 sec
Example
TFOM is a value between 1 and 15. TFOM can never exceed the default MaxTFOM
value of 15.
Typically the MaxTFOMrequires no adjustment, but in some instances it may be
advisable to decrease MaxTFOM so that TFOM can potentially exceed it: For
example, by lowering the MaxTFOM to “5” it is now possible for TFOM to be
always higher than the MaxTFOM value:
254
CHAPTER 3 • SecureSync 2400 User Manual Rev. 5.2
3.5 Managing the Oscillator
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