What Is 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.

Other organizations such as NASA and IEEE have released synchronization standards based on or extending the IRIG specifications. These timecodes allow the synchronization and recording of accurate time as well.

Many types of equipment and facilities throughout the world use IRIG timecode to synchronize their time-scale to one time source. This allows 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 format.

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. To see if these control functions are compatible with your requirements, you’ll need to refer to your specific product documentation.

Flexible Implementations of IRIG Timecode

As the world leader in Resilient Positioning, Navigation and Timing solutions, Orolia offers 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. Orolia solutions are well-suited to the modification of IRIG timecodes to provide the exact signals and timecode structure required.

All of our products that offer IRIG timecode synchronization can be configured as IRIG timecode readers either as a slave clock (synchronizing a local clock to IRIG, then generating other time and frequency signals with the same time base as the IRIG master) or as a IRIG timecode generator (synchronization to another time base such as GPS, then generating the exact IRIG timecode required by other equipment).

Typical use cases include:

  • IRIG timecode reader 
    A facility has a master clock (cesium, maser clock, etc.) that requires using that clock’s time base throughout the facility, including synchronizing computers and servers via NTP. An Orolia SecureSync® synchronization system can be configured to synchronize its internal NTP server to an IRIG signal input.
  • IRIG timecode generator
    You may have a piece of time-sensitive equipment that can synchronize to an IRIG signal but does not have an available IRIG source. An Orolia SecureSync 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 the IRIG time need not be accurate, 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 the IRIG timecode reader and generator. Similar functionality is available in plug-in computer slot cards (PCI express).

Product Type Supported Timecode Formats 
SecureSync® 1U Rack Mount Master Clock Input:  IRIG A, B, G, NASA36, IEEE C37.118
Output:IRIG A, B, E, G, NASA36, IEEE C37.118
TSync Timing Boards: PCI Express Bus-Level Timing Input: IRIG A, B, G, NASA36, IEEE C37.118
Output: IRIG A, B, E, G, NASA36, IEEE C37.118
VersaSync™ Line-Replaceable Unit Input: IRIG B DCLS
Model SAS-E Epsilon Switch and Amplifier System 1U/2U Rack Mount Distribution Amp Input: IRIG DCLS

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