XMC SyncClock32

Advanced Switch Mezzanine Card Timing Module

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.


  • 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.


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
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
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
Operating 0°C to +70°C
Non-Operating -40°C to +85°C
Humidity To 95% without condensation
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

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Data Sheets