its 1PPS input that is used to perform disciplining. If this estimated error is too large, it could
adversely affect the performance 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:
Assuming the MaxTFOM is set to 5 and the TFOM happens to go to a 6, i.e. TFOM is now
exceeding MaxTFOM. This condition will cause a 1PPS out of specification alarm to be
asserted and the oscillator disciplining will change in order to speed-up the alignment of
the system 1PPS to the selected reference (causing it to take less time getting closer into
alignment with the reference):
This will cause the TFOM to start to decrease faster. Once TFOM no longer exceeds
MaxTFOM because the System 1PPS is now much closer to the reference 1PPS, the dis-
232
CHAPTER 3 • SecureSync 2400 User Manual Rev. 2
3.5 Managing the Oscillator
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