IRIG-B

The IRIG-B Adapter Card mounts to the solder side of a PCIe motherboard using a cable to receive power from the mainboard. When mounted to a PCIe motherboard, the combination of the mainboard and the IRIG-B Adapter Card takes up two slots. Power is not drawn from the second slot.

A trigger input is provided which is buffered and sent down the cable to the attached CPE. The trigger is also buffered and sent back out an SMA allowing the card to be attached to other boards including Annapolis Micro Systems, Inc. ADCs configured with a 3.3V LVPECL Trigger Input. The trigger is commonly used for the 1pps clock associated with IRIG-B data streams.

The analog input is AC-coupled and has an anti-aliasing filter to provide for optimal purity when sampling the IRIGB Serial Time Code Data stream. IRIG-B Serial Time Code Data stream has a time frame of one second, with an index count of 10 milliseconds and contains time-of-year and year information in a BCD format, and seconds-of-day in SBS.

Supported carrier signal formats include B120. The 74-bit time code contains 30 bits of BCD time-of-year information in days, hours, minutes and seconds, 17 bits of SB seconds-of-day, 9 bits for year information and 18 bits for control functions. The BCD code (seconds sub-word) begins at index count 1 (LSB first) with binary coded bits occurring between position identifier bits P0 and P6: 7 for seconds, 7 for minutes, 6 for hours, 10 for days and 9 for year information between position identifiers P5 and P6 to complete the BCD word. An index marker occurs between the decimal digits in each sub-word to provide separation for visual resolution. The SBS word begins at index count 80 and is between position identifiers P8 and P0 with a position identifier bit, P9 between the 9th and 10th SBS coded bits. The SBS time code recycles each 24-hour period. The eighteen control bits occur between position identifiers P6 and P8 with a position identifier every 10 bits. The frame rate is 1.0 seconds with resolutions of 10 ms (dc level shift) and 1 ms (modulated 1 kHz carrier).

• 16 Bit ADC for sampling IRIG-B Serial Time Code Data
  • AC Coupled Input
  • Anti-Aliasing Low Pass Filter
  • 6Vpp input range
  • 3dB Bandwidth: 200Hz – 2kHz
• Internal 8kHz Sample Clock Oscillator
• 5V TTL Trigger Input
• Buffered 3.3V LVPECL Trigger Output
• 50 Ohm SMA Inputs and Outputs
• Compatible with WS5 PCIe Mainboards configured with 3.3V AUX I/O Voltage
• Can be cabled to CPE0 or CPE1 Generic I/O Connector
• All boards use industrial temperature rated parts (-40 to +85 degrees C)