XMC SyncClock32
The XMC-SyncClock32 from Brandywine Communications is an advanced switched Mezzanine Card (XMC) module. Precision time is provided to the host computer with zero latency. The on-board microprocessor automatically synchronizes the clock to reference signal inputs. The reference signal inputs handled by the XMC in its standard configuration are IRIG’s A and B, NASA 36 and 1 PPS. Alternatively, the clock in the XMC can be set using commands from host computer and free run using its on-board oscillator as the time base.
Features
- IRIG A & B, NASA 36 and 1 PPS inputs standard
- HaveQuick sync option
- Propagation delay compensation
- Zero latency time reads
- Match Time output
- IRIG B time code output
- External Event time tags
- On-board GPS receiver option
- User programmable heartbeat rate
When synchronizing to time codes or 1 PPS the micro-processor constantly measures the time error between the on-board clock and the reference input code and adjusts the error measurement for propagation delay. When the disciplined TCXO option is selected the residual error is used in an adap-tive 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 cor-rection 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. A status word is avail-able using an additional read.
The time-of-occurrence of external events may be captured (time-tagged) by using the Event Time input. 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 out-put 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.
One user programmable heartbeat rate is provided. The heartbeat pulse rate provides heartbeat timing to the host computer and is also available on the multi-pin connector.
The GPS synchronization option offers worldwide time transfer capability to the XMC-SyncClock32. Very precise synchronization, automatic leap year and leap second correction, plus accurate position information are additional benefits provided by the GPS option.
Specifications
General Input Specifications
| Input Signals | IRIG A & B, NASA 36 |
| Input Amplitude | .25 to 10 Vpp |
| Input Impedance | >10k Ω |
| Ratio | 2:1 to 4:1 |
| Frequency Error | 100 PPM maximum |
| Code Sync Accuracy | One microsecond |
| 1PPS Input | RS-422 or TTL, positive edge |
| 1PPS Sync Accuracy | 300 nanoseconds |
| External Event Resolution | 100 nanoseconds–units year |
| Minimum Event Spacing | None |
General Output Specifications
| IRIG B DC Shift | TTL |
| Match Pulse Resolution | TTL level at Start–Stop time Microseconds–eight millisecond |
| Heartbeat Rate | Interrupt, flag, TTL, negative going |
| Clock Divisor | 2–65,535 |
| Clock Input | 1 MPPS |
| Default output | 1 kPPS |
| BDC Time | Microseconds–unit year on demand, zero latency 58 bits in two 32 bit words |
| Status Word | 8 bits |
| Status Indicator LED's | Flashes Coded Patterns |
| Interrupts | External Event, RAM FIFO, Heartbeat, Match Time |
| Flags | Dual Port RAM data ready, FIFO data ready, In sync, Heartbeat, Match Time, External Event |
| Connectors | SMB, high density IEEE–1284 |
| Mean Time Between Failures | 141,000 hours per Mil-217-F, Notice 2, 25° C, ground benign |
Physical
| Dimensions | 74mm X 1437.5mm single CMC |
| Type | PCIe endpoint |
| Power Consumption | +5 Vdc: ±5%,150 mA maximum +12 Vdc: ±5%, 60 mA maximum -12 Vdc: ±5%, 25 mA maximum |
Environmental
| Temperature | |
| Operating | 0°C to +70°C |
| Non-Operating | -40°C to +85°C |
| Humidity | To 95% without condensation |
Options
| GPS Sync Input (External) | C/A code |
| GPS Sync Accuracy | 100 nanoseconds |
| Position Accuracy | 25 meters SEP |
| Tracking Satellites | Twelve parallel channels |
| Antenna | L1, 25' cable |
| Antenna Options | Hi-gain: L1, mast mount, 100' cable |
| Input Code Isolation | Transformer coupling |
| Input Codes | IRIG G, XR3, 2137, IRIG E, 109-60 |
| Output Codes (DSLS) | IRIG A, NASA 36, IRIG G |
| External Event Inputs | 8x TTL, Positive or Negative Edge |
| Have Quick Input | Per ICD–GPS–060 |
| Have Quick Output | Per ICD–GPS–060 |
| Binary Time Words | Replaces BCD |
| Oscillator Upgrades | Disciplined TCXO, 1 PPM |
| 1 PPS 10 Vdc Input | Sync input, +10 Vdc, 50 Ohms |
