Fully compliant Advanced Mezzanine Card for time code synchronization of ATCA chassis
The AMC-SyncClock32 from Brandywine Communications is an Advanced Mezzanine Card (AMC) module. Precision time is provided to the host computer with zero latency. The onboard microprocessor automatically synchronizes the clock to reference signal inputs. The reference signal inputs handled by the AMC in its standard configuration are IRIG’s A, B/IEEE1344, and NASA 36. Alternatively, the clock in the AMC can be set using commands from host computer and free run using its on-board oscillator as the time base.
- IRIG A & B/IEEE-1344, and NASA 36 inputs standard
- HaveQuick sync option
- Propagation delay compensation
- Zero latency time reads
- Match Time output (P4)
- IRIG B time code output option
- External Event time tag (P4)
- Three user programmable rates
- Ruggedization option
- Multi-pin Front Panel P4 I/O option
When synchronizing to time reference the micro-processor constantly measures the time error between the on-board clock and the reference input and adjusts the error measurement for propagation delay. When the disciplined TCXO option is selected the residual error is used in an adaptive gain loop to adjust the frequency of the 10 MHz oscillator for minimum error. Before being used as the time reference, the input code reference is checked (to code carrier resolution) for consistency with itself. If the incoming code is missing or corrupted by noise the on-board clock is updated by the 10 MHz oscillator. When the input code is again useable the correction loop is smoothly closed.
58 bits of BCD time are available to the host computer using two zero latency time reads. The time message contains units of microseconds through units of years digits. A status word is available using an additional read. The time-of-occurrence of external events may be captured (time-tagged) by using the Event Time input (P4). When the event input is sensed the current time is saved in a buffer for later interrogation by the host. The resolution of the time tag is 100 nanoseconds.
The Match Time feature may be used to automatically initiate or terminate an external process. The resolution of the Match Time comparison is one microsecond. The Match Time output is asserted when the time of the internal clock matches that of the user input start time. The Match Time output may be terminated by a user command or when the previously set stop time is encountered.
Three user programmable pulse rates are provided. Two pulse rates, Clock Low and Clock High, are available on the multi-pin P4 connector option. The third pulse rate provides heartbeat timing to the host computer and is also available on the multi-pin P4 connector option. The divider for each of the three pulse rate generators is programmable by the host computer over the range 2–65,535. The inputs to the rate generators are 3 MHz or 100 Hz for the heartbeat, 100 PPS for Clock Low and 3 MHz for Clock High.
The Ruggedization option provides electronic grade RTV staking of BGAs and acrylic conformal coating qualified to MIL-I-46058C.