Spectracom TPRO-cPCI, User Manual, Page: 7 / 46

Spectracom Corporation TPRO-cPCI/TSAT-cPCI
Synchronizable Timecode Generator User Manual 1-1
1 Overview
This manual provides comprehensive information on the system architecture, specifications,
and operation of the Spectracom TPRO-cPCI and TSAT-cPCI Synchronizable Time Code
Generators with PCI Bus Interface.
The TPRO-cPCI and TSAT-cPCI provide high-accuracy timing functions on a plug-in board for
the CompactPCI
®
computer bus. The board has an on-board clock, which is kept in sync to
either an external time code input (TPRO-cPCI) or to time provided by GPS satellites (TSAT-
cPCI). Several timing functions are derived from the on-board clock, including a programmable
periodic pulse rate output ("Heartbeat"), a programmable start/stop output ("Match"), a
selectable frequency output ("Oscillator Out", 1 kHz, 1, 5, or 10 MHz), and a time-stamping input
("Time Tag").
The TSAT-cPCI includes an externally-mounted GPS antenna and a 100-foot cable to connect
the antenna to the board. The GPS satellites provide continuous time and position information,
available anywhere in the world. It automatically syncs its on-board clock to the time
transmitted by the GPS satellites and disciplines the onboard 10 MHz oscillator to maintain a 1
microsecond accuracy. The board outputs a time code signal, in IRIG-B format, which conveys
the day, hour, minute, and second, and also has a 1 kHz carrier referenced to the on-board
oscillator.
The TPRO-cPCI is similar to the TSAT-cPCI, with the exception that it obtains time from an
input time code. The time code can be in IRIG-A, IRIG-B or NASA36 format; the board
automatically detects which format is being used. The time code conveys the day, hour, minute,
and second. The on-board 10 MHz oscillator is disciplined to maintain an accuracy of 10
microseconds for IRIG-A and 15 microseconds for IRIG-B and NASA36.
Either board may be used as a stand-alone time code generator. The computer programs the
day, hour, minute, and second. The board then continues to count from that time, using the on-
board oscillator as the time base reference. This is called
freewheeling .
The host computer communicates to either board through a set of memory-mapped registers.
When the computer boots up, the board identifies itself to the CompactPCI® bus by specifying
the unique Subsystem Vendor ID and Subsystem Device ID. The host computer can then read
the instantaneous time, and command the board to set time, and/or to provide an interrupt at a
periodic rate, at a specified time, and/or when a time-tag event occurs.
Front panel indicator lights indicate when the board is in the process of synchronizing
("acquiring") the GPS or time code input signal, and when the board has established valid
synchronization. The host computer can also interrogate the status register to determine these
and other conditions.
1.1 General Information about GPS
NOTE: GPS applies only to the TSAT-cPCI board; the TPRO-cPCI is not equipped for GPS.
The United States government operates a set of approximately 32 satellites, collectively known
as the "GPS Constellation" or "GPS Satellites." Each satellite has an internal atomic clock and