IRIG timecode: Difference between revisions

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{{Short description|Standard formats for transferring time information}}

'''Inter-range instrumentation group timecodes''', commonly known as '''IRIG timecode''', are standard formats for transferring timing information. Atomic frequency standards and GPS receivers designed for precision timing are often equipped with an IRIG output. The standards were created by the Tele Communications Working Group of the U.S. military's [[Inter-Range Instrumentation Group]] (IRIG), the standards body of the [[Range Commanders Council]]. Work on these standards started in October 1956, and the original standards were accepted in 1960.

'''Inter-range instrumentation group timecodes''', commonly known as '''IRIG timecode''', are standard formats for transferring timing information. Atomic frequency standards and [[GPS receiversreceiver]]s designed for precision timing are often equipped with an IRIG output. The standards were created by the Tele Communications Working Group of the U.S. military's [[Inter-Range Instrumentation Group]] (IRIG), the standards body of the [[Range Commanders Council]]. Work on these standards started in October 1956, and the original standards were accepted in 1960.

The original formats were described in IRIG Document 104-60, later revised and reissued in August 1970 as IRIG Document 104-70, upgraded later that year as the IRIG Document to the status of a Standard, IRIG Standard 200-70. The latest version of the Standard is IRIG Standard 200-16 from August 2016.

The original formats were described in IRIG Document 104-60, later revised and reissued in August 1970 as IRIG Document 104-70, upgraded later that year as the IRIG Document to the status of a Standard, IRIG Standard 200-70. The latest version of the Standard is IRIG Standard 200-16 from August 2016.

== Timecodes ==

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In IRIG G, bits 50–53 encode hundredths of seconds, and the years are encoded in bits 60–68.

Not all formats include all fields. Obviously those formats with 60-bit frames omit the straight binary seconds fields, and digits representing divisions less than one frame time (everything below hours, in the case of IRIG D) are always transmitted as 0.

No parity or check bits are included. Error detection can be achieved by comparing consecutive frames to see if they encode consecutive timestamps.

Unassigned 9-bit fields between consecutive marker bits are available for user-defined "control functions". For example, the [[IEEE 1344]] standard defines functions for bits 60–75.

== IRIG timecode ==