Timecode Reader/Generator with VME Interface
- IRIG-A, IRIG-B, NASA36, XR3, and 2137 timecode reader
- Multifunctional timecode reader/generator
- Time-Tag input
- Optional GPS synchronization
- Two configurable pulse rate outputs
- 1 MHz TTL output
- Freewheel capability
- Continuous parallel time output
Product Overview
The Spectracom Model TPRO-VME performs timing and synchronization functions referenced to an input timecode signal. The board synchronizes its on-board clock to the incoming timecode. The clock is also provided as an IRIG-B output. Other features include a time-tag TTL input, a 1MHz TTL output, and two user-configurable TTL pulse rate outputs.
The board continues to increment time (“freewheel”) in the absence of an input timecode. Thus, the host computer can set the on-board clock over the VMebus, and the board can be used as an IRIG-B generator.
The input timecode format (IRIG-B, IRIG-A, NASA36, XR3, or 2137) is automatically detected. Synchronization to the input timecode is also automatic and a propagation delay offset may be specified to compensate for cable delays.
Front panel indicators include presence of input timecode and successful synchronization. An option seven segment LED display shows day and time in DDD:HH:MM:SS format.
The timecode input is an amplitude modulated sine wave. The peak amplitude can be between 0.5Vp-p and 8.0Vp-p. The timecode input is differential; the board does not reference this signal to ground. A single-ended input (referenced to ground) is also acceptable.
VME Interface
The board supports A32, A24, and A16 addressing modes using the standard address modifiers. Other address modifiers can be supported by custom modifications.
All board functions can be generated when time is available or when a time-tag event has occurred. The interrupt level (IRQ1-IRQ7) is selected by jumpers, or the user can disable interrupts and poll the status register instead. Customized periodic interrupts are also available.
The VME bus specification permits rows A and C of the P2 backplane connector to be user-defined. The on-board clock time is output as 54 TTL signals on these pins, providing continuous time with zero latency. However, this usage may conflict with other user-specific boards in the system. To prevent such a conflict, order the board with the –03 option to eliminate these outputs.