IRIG
IRIG (Inter-Range Instrumentation Group) timecodes are a set of time code standards developed to transmit precise timing information for synchronization across various systems. The E9 system uses IRIG-B which runs at 100 bits/s. A good IRIG source, usually synchronized to GPS, can acheive an accuracy of < 1µs.
Input
Digital In
Uses unmodulated DCLS (Direct Current Level Shift). Any of the flexible User I/Os may be used as an IRIG digital input. Only 1 input may be set to IRIG at a time. The following time codes are supported.
| Carrier Frequency | Supported Time Codes |
|---|---|
| DCLS | B004 (100pps) |
Analog In
Uses amplitude modulated signal with various carrier frequencies. Only the Analog I/O may be used as an IRIG analog input. The following time codes are supported.
| Carrier Frequency | Supported Time Codes |
|---|---|
| 1 kHz | B124 (100pps) |
If any User I/O's are set to IRIG In, the Analog In will be disabled
Output
Digital Out
Uses unmodulated DCLS (Direct Current Level Shift). Any of the flexible User I/Os may be used as an IRIG digital output. Any number of outputs may be set to IRIG at the same time. The following time codes are supported.
| Carrier Frequency | Supported Time Codes |
|---|---|
| DCLS | B004 (100pps) |
Standard Documentation
The latest IRIG standard published in August 2016 can be found here.
http://www.irig106.org/docs/rcc/200-16_IRIG_Serial_Time_Code_Formats.pdf