Irig-b time quality flags, Output – Symmetricom XL-GPS User Manual
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997-01530-01, Rev. C-25, Jan 2008
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beginning of each frame and a position identifier marks the end of every ten elements. IRIG-B has ten
position identifiers per frame.
The elements prior to position identifier P5 comprise the time of year segment. The first ten elements
encode the seconds, the second ten elements encode the minutes and so on through days. Each
element is a digit in a binary number with a place value sequence 1 2 4 8.
IRIG-B Time Quality Flags
Five flags are encoded in the control function segment of the IRIG-B code. The first flag encoded at
element P5+40ms is the LOCK indicator. It is a binary 1 when the XL-GPS is not locked to a reference.
The second flag encoded at element P5+60ms is a binary 1 when the worst case time error exceeds
threshold 1 (refer to "Function 5 -- Time Quality Enable/Setup"). Element P5+70ms is a binary 1 when
the worst case time error exceeds threshold 2. Element P5+80ms encodes a binary 1 when the error
exceeds threshold 3 and P5+90ms when the error exceeds threshold 4.
Output
The XL-GPS provides the following IRIG time code outputs (refer to IRIG Standard 200-95):
IRIG-B: B120
1 kHz sine wave amplitude modulated with BCD, CF, SBS
B000
DC level shift, width coded with BCD, CF, SBS