Symmetricom XLi IEEE 1588 User Manual page 108

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• Input Polarity: Positive, Negative
Propagation Delay: (Range 0 to 99999 μS in 1 μS steps) (Factory setting: 1 μS) Compensates
•
for delay caused by cable length on the J1 input.
• IRIG Mode: (Sync Gen)
• Error Bypass: (Off, 1-10 Frames) (Factory setting: 3 frames) Is used when the IRIG input is
intermittent or has a low signal to noise ratio (SNR). This allows the time code input to 'flywheel'
for the specified number of invalid time code frames before F110 generates an alarm. Off means
the F73 IRIG input alarm will alarm on the first invalid time code frame. 1-10 means the F73 IRIG
input alarm will alarm after it detects 1-10 invalid consecutive time code frames.
When TIET is selected for J1 Input Configuration, F110 presents the following series of choices:
• Input Impedance: (100 kΩ or 50Ω) Short runs (<200 ft.) get 100 kΩ. Long runs (>200) get 50Ω.
• Input Polarity: Positive only
Upon changing the settings, the last display prompt asks:
• Save Changes?: (Yes, No) Yes applies the changes. No cancels the changes.
For J1 specifications, see
Notes:
• Time Code: The XLi expects time code input that provides UTC in 24-hour format. If the time
code does not provide UTC in 24-hour format (e.g., it uses standard, local, or GPS time, or is in
12-hour format), the XLi's internal clock will be set to the wrong time when it uses the time code
reference, and its time outputs will be similarly affected.
• Time Code: IRIG and NASA 36 time code don't contain "year" information. Enter the current year
using F3 before using IRIG as a primary or secondary reference source. Failure to do so can
cause the incorrect time information to be distributed. See
• At the end of the year, the year increments by one (e.g., 2004 -> 2005) at the end of the year,
provided the XLi is operating during the transition. If it is not operating during the transition, the
time code reasserts the preceding year when used as a reference source.
• TIET: Put the F110 time code input on STANDBY first before configuring F110 for TIET.
• TIET: Stray capacitance loading on the J1 input adversely impacts TIET measurements.
Command Line
F110 can configure the J1 input port to IRIG-A, IRIG-B, NASA 36, TIET Time or TIET Event. Use F110
to enter or request the J1 Input Configuration.
To request the J1 Input Configuration, enter:
F110<CR>
The function responds with the ASCII character string:
100
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"J1 Input – Time Interval - Event Time" on page
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"F3 – Time & Date" on page
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12.
XLi IEEE 1588 Clock
997-01510-03, Rev. C, 12/12/2006
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40.