What does IRIG stand for?

Inter Range Instrumentation Group

What is IRIG Standard?

Modern day electronic systems such as communication systems, data handling systems, and missile and spacecraft tracking systems require time-of-day and year information for correlation of data with time. Serial formatted time codes are used to efficiently interface the timing system output with the user system.  Standardization of time codes is necessary to ensure system compatibility among the various ranges, ground tracking networks, spacecraft and missile projects, data reduction facilities, and international cooperative projects.   These digital codes are typically amplitude modulated on an audio sine wave carrier or transmitted as fast rise-time TTL signals.

The use of the IRIG standard is to provide a standard protocol for serial time codes that are generated for correlation of data with time.

What is the latest IRIG specification?

IRIG Standard 200-04 (added year information to format).   Previous revisions are IRIG Standard 200-98 (added Manchester modulation) and  IRIG Standard 200-95.   IRIG Document 104-60 was the original standard accepted in 1960.

What is IRIG-B?

IRIG-B refers to a serial time code format.   This a timing signal that has a rate of 100 pulse per second signal,  There are other rate that are designated in accordance with the IRIG Standard 200-04  (see below).  IRIG-B sends Day of Year, Hour, Minute and Second data on a 1KHz carrier, with an update rate of one second.  IRIG-B DCLS  (DC level shift) is IRIG-B without the 1KHz Carrier.

What are the IRIG Formats?

Note IRIG-C was replaced by IRIG-H

IRIG Formats,  IRIG code designations

The name of an IRIG code format consists of a single letter plus 3 subsequent digits. Each letter or digit reflects an attribute of the corresponding IRIG code. The following table contains standard code formats defined in IRIG standard 200-98:

IRIG A	IRIG B	IRIG D	IRIG E	IRIG G	IRIG H
A000	B000	D001	E001	G001	H001
A003	B003	D002	E002	G002	H002
A130	B120	D111	E111	G141	H111
A132	B122	D112	E112	G142	H112
A133	B123	D121	E121		H121
		D122	E122		H122

*Note  IRIG-C was part of the original specification, but was replaced by IRIG-H

The code format names are composed as described below:

First letter: Rate Designation	A B D E G H	1,000 PPS      ( 1 ms count ) 100 PPS         ( 10 ms count ) 1 PPM             ( 1 minute count ) 10 PPS           ( 0.1 second count ) 10,000 PPS    (  0.1 ms count ) 1 PPS             ( 1 second count )
1st Digit: Form Designation	0 1	DC Level Shift (DCLS), width coded, no carrier Sine wave carrier, amplitude modulated
2nd Digit: Carrier Resolution	0 1 2 3 4	No carrier(DCLS) 100 Hz / 10 millisecond resolution 1 kHz / 1 millisecond resolution 10 kHz / 100 microsecond resolution 100 kHz / 10 microsecond resolution
3rd Digit: Coded Expressions	0 1 2 3 4* 5* 6* 7*	BCD, CF, SBS BCD, CF BCD BCD, SBS BCD, BCD_Year, CF, SBS BCD, BCD_Year, CF BCD, BCD_Year BCD, BCD_Year, SBS

*IRIG standard 200-04 added year informaion.
Abbreviations used in the table above:

• BCD - Binary Coded Decimal, coding of time (HH,MM,SS,DDD)
• BCD - Binary Coded Decimal, coding of Year (HH,MM,SS,DDD)
• SBS - Straight Binary Second of day (0....86400)
• CF - Control Functions depending on the user application
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