Symmetricom, Inc.
bc620/627AT Time and Frequency Processor
A-1
APPENDIX A
IRIG TIME CODE FORMAT
A.0 GENERAL
The widespread use of coded timing signals to assist in the correlation of intercept and test data
began in the early 1950’s. These signals can be decoded in real time to indicate the current Time
of Day (TOD) or recorded along with intercept/test data on magnetic tape recorders for post
processing and time correlation.
Hundreds of time code formats were developed - one for each agency involved. During the early
1960's the InterRange Instrumentation Group (IRIG) promoted a series of “standard” time code
formats now loosely referred to as “IRIG Time Codes.” The bc620/627AT decodes the most
widely used format, IRIG B, as well as IRIG A. Figure A-1 illustrates a frame of IRIG time
code.
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