Description This counter system is designed to achieve high reliability and synchronized count-down or count-up operation when operated in Master-Slave configuration. For operation in Master-Slave mode two counter units shall be operated with interconnection. Each unit has One Pulse Per Second (PPS), Binary Coded Decimal (BCD) and IRIG-B(dc) corresponding to the count as its output. In Master -Slave mode outputs of both the units will be synchronized to each other with an accuracy of 100ns (typical).

Each Counter unit has Time Code Generator (TCG), Time Code Reader (TCR) and Health Monitoring (HM) subsystems which are Digital Signal Processor (DSP) based. TCG and TCR have independent power supplies and HM can operates with the availability one of the supplies. This improves the overall availability of the system.

TCG subsystem generates PPS, IRIG-B(dc) and BCD outputs synchronized with any source. TCG operates with high stability Oven Controlled Crystal Oscillator (OCXO) to get good timing accuracy. If better timing accuracy is needed it can be operated in synchronization with a PPS from a GPS receiver, whose accuracy is +/-100nS with the atomic standard GPS time. GPS receiver can be integral part of the unit and provision is made to connect the antenna for this purpose. TCR subsystem also generates PPS and BCD signals based on the IRIG-B (dc) input. HM subsystem selects the outputs from one of the subsystems and gives out as unit output. HM subsystem also provides necessary user interfaces for operation and control of the unit. If any of the subsystem fails in one of the units in Master-Slave mode of operation, it will not affect the output of either of the units. This ensures very high availability of outputs from the system.

Counter system operates in countdown mode till the count reaches zero and operates in up-count mode after that. IRIG-B(dc) and BCD outputs correspond to the current count value. Initial count can be set in the range 2 seconds to 99 hours 59minutes and 59 seconds. During countdown mode hold command is accepted to stop the operation from either of the units. Each unit has facility to accept hold command from external potential free contacts or from the hold key on the front panel. System will start down counting once the hold command is released and run command is given.

Each unit can operate in standalone generator or Reader mode apart from the Master-Slave mode. In generator mode it can output PPS, IRIG-B(dc) and BCD signals . In Reader mode it displays the IRIG-B(dc) data and along with PPS and BCD outputs.

Counter unit can be mounted on standard 19" rack and has 2U height. For input and output connections MIL-C-26482 round shell connectors are provided.