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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<ol start=0 type=1>

<li>[[Direct current|DC]] level shift (DCLS) ([[Pulse-width modulation|pulse width coded]] without carrier)</li>

<li>Sine wave carrier ([[Amplitude modulation|amplitude modulated]])</li>

<li>[[Manchester code|Manchester]] modulated</li>

</ol>

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Thus the complete signal identification number consists of one letter and three digits. For example, the signal designated as B122 is deciphered as follows: Format B, Sine wave (amplitude modulated), 1&nbsp;kHz carrier, and Coded expressions BCDTOY.

The most commonly used of the standards is IRIG B, then IRIG A, then probably IRIG G. Timecode formats directly derived from IRIG H are used by [[National Institute of Standards and Technology|NIST]] [[radio station]]s [[WWV (radio station)|WWV]], [[WWVH]] and [[WWVB]].

For example, one of the most common formats, IRIG B122:

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* Bits 10–13 encode minutes, and bits 15–17 encode tens of minutes (0–59)

* Bits 20–23 encode hours, and bits 25–26 encode tens of hours (0–23)

* Bits 30-33 encode [[Ordinal date|day of year]], 35-38 encode tens of days, and bits 40–41 encode hundreds of days (1–366)

* Bits 45–48 encode tenths of seconds (0–9)

* Bits 50–53 encode years, and bits 55–58 encode tens of years (0–99)