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imc C-SERIES - Manual, Version 4 R 3 - 2018-10-19

80 Device description

5.2.5 IRIG-B module

This external IRIG-B module can convert a time signal in IRIG format to the GPS format NMEA 0183 and

thus be used for synchronization of different devices.

The extension module exclusively supports amplitude modulated IRIG signals according to the standards

IRIG-B1xx! This is why it can be used both to upgrade older imc device generations which provided no

IRIG-B support at all, and to enhance current imc device generations with additional capabilities

regarding modulated signals: While many up-to-date imc device series (CRFX, CRC, C-SERIES-N) offer

IRIG-B synchronization via their standard BNC synchronization plug as a standard feature (including DCF-

77 / IRIG-B auto-detection), this path only supports direct unmodulated TTL-signals (IRIG-B0xx).

The definition of the various IRIG time codes is specified in the IRIG standard 200-98. This adapter

module supports sub-standards IRIG-B120 through B127. These are characterized by 100 pulses per

second, AM (amplitude-modulated) sinusoidal signal, 1 kHz carrier frequency, BCD Time-of-Year.

The module’s rear panel holds the DSUB-9 plug, which is connected to the measurement system’s GPS

plug via the included RS232 extension cable. The pinout of the DSUB-9 plug directly conforms to the

“GPS” connectors pin configuration, which is uniform to imc measurement systems.

When using the IRIG-B adapter in conjunction with this GPS port, absolute time information is captured

via this RS232 interface, and additionally, synchronization of the device’s system clock is performed by

means of an additional clock signal (“1 pps”) provided on a dedicated pin of the DSUB-9 terminal. While

this occupies the port, simultaneous capture of GPS geo positioning information is not supported at the

same time.

Note

The operating software (imc STUDIO / imc DEVICES) will denote the used synchronization type as "GPS",

simply because the respective port is used to interface the IRIG-B module.

The module’s front panel has one BNC plug and two LEDs. The LOCK LED shines when the input signal is

synchronized with the IRIG-B module. If the input signal is not valid or not synchronized with the IRIG-B

module, the FAIL LED shines.

IMC C SERIES User Manual

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