IRIG Timecode Synchronization

IRIG timecodes are a set of standard specifications originally developed by the Inter-Range Instrumentation Group to transmit very precise time via a pulse rate.

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Other organizations (NASA, IEEE) have released synchronization standards based on the IRIG specifications. These timecodes allow the synchronization and recording of accurate time. Many types of equipment and facilities throughout the world uses IRIG timecode to synchronize their time-scale to one time source to allow the correlation of data to microsecond levels of accuracy.

IRIG timecode formats are designated A, B, D, E, G, and H to differentiate between pulse rates. Additionally, various combinations of sub-words and signal forms make up the timecode word. All formats do not contain every standard coded expression, and various signal forms are possible. Therefore signal identification numbers are assigned to each combination. The timecode designated as IRIG-A137 has the format A pulse rate (1KPPS), amplitude modulated sine wave, 10 kHz carrier/0.1 ms resolution, and coded time expressions in Binary Coded Decimal and Straight Binary Seconds (BCD(TOY), BCD(YEAR) and SBS). Some IRIG signals include various control functions. Refer to specific product documentation to compare its compatibility to user requirements.

Flexible Implementations of IRIG Timecode

As a leading provider of precise time & frequency systems, we offer highly accurate, reliable and flexible solutions to synchronize communications and other systems using a wide range of IRIG timecode formats, signal forms, and time expressions. Spectracom products are well-suited to the modification of IRIG timecodes to provide the exact signals and timecode structure required.

Any of our products offering IRIG timecode synchronization can be configured as an IRIG timecode reader in the case of a slave clock (synchronization of a local clock to IRIG, then generating other time and frequency signals using the same timebase as the IRIG master) or as a IRIG timecode generator (synchronization to another timebase such as GPS, then generating the exact IRIG timecode as required by other equipment).

Typical use cases include:

  • IRIG timecode reader: A facility has a master clock (cesium, maser clock, etc.). It requires the use of that clock's timebase throughout the facility including the synchronization of computers and servers via NTP. A Spectracom SecureSync synchronization system can be configured to synchronize its internal NTP server to an IRIG signal input.
  • IRIG timecode generator: A piece of time-sensitive equipment can synchronize to an IRIG signal, but no IRIG source is available. A Spectracom SecureSync synchronization system can be configured with a GPS receiver to receive accurate time from GPS satellite signals, and generate the IRIG signal as required by the equipment. If it is not required that the IRIG time be accurate, the SecureSync can still be used to generate the IRIG timecode output without GPS by setting its internal clock.

In these examples, a modular 1U instrument (SecureSync) is described as the IRIG timecode reader and generator. Similar functionality is available in plug-in computer slot cards (PCI, PCI express) or other standard instrument boards (compact PCI, PMC, PCI-104, VPX etc.). A simple distribution amp is also available to distribute existing signals.

Product Type Supported Timecode Formats 

SecureSync Synchronization System

1U Rack Mount Master Clock Input: IRIG A, B, G, NASA36, IEEE-1344
Output: IRIG A, B, E, G, NASA36, IEEE-1344
TSync Timing Boards: PCI Express, Compact PCI, PCI-104, PMC, and VPX Bus-Level Timing Input: IRIG A, B, G, NASA36, IEEE-1344
Output: IRIG A, B, E, G, NASA36, IEEE-1344


Line-Replaceable Unit Input: IRIG B DCLS
TPRO, TSAT PCI Timing Boards Bus-Level Timing

Input: IRIG A, B, NASA36
Output: IRIG B

Model 7535-001 IRIG Quad (1:4) Distribution Amplifier 1U Rack Mount Distribution Amp 

Input: IRIG B
Output: IRIG B 

Model SAS-E Epsilon Switch and Amplifier System 1U/2U Rack Mount Distribution Amp