Spectracom TSync-PCIe, Руководство пользователя

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The TSync-PCIe board with optional internal GNSS receiver is a complete synchronized time
code processor package that supports multiple prioritized timing inputs. When an input is lost,
the unit automatically switches to the next input in order of priority.
The disciplined onboard oscillator is phase-locked to an external timing input, providing 5ns
resolution time. This 10-MHz oscillator, central to the TSync-PCIe timing functions, uses the last
known reference to increment (“freewheel”) in the absence of a timing input.
The TSync-PCIe generates an IRIG AM and DCLS output pair, as well as 10-MHz sine wave and
1PPS outputs.
The board’s four programmable inputs may be used as event capture inputs, dedicated to your
time-tagging applications. Four user-programmable alarm and frequency outputs are also
provided. Programmable output functions include a periodic pulse or “heartbeat,” square
wave, and programmable start/stop time “alarm” output.
Key to the TSync-PCIe's functionality is the ability to generate interrupts. Using one of the many
available Spectracom driver packages, you may configure your card using interrupt-driven
algorithms to support your unique applications.
2.1 General Information about GPS and GNSS
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
transmits a signal specifying the time and satellite position. On the ground, the GPS receiver
determines its position (longitude, latitude and elevation) and the time by decoding the signals
simultaneously from at least four of the GPS satellites. Each satellite transmits a signal in the L1
band at a frequency of 1575.42 MHz. When power is first applied, the GPS receiver begins
searching for the satellites. This process can take a few minutes, as the receiver iteratively loc
ates satellites, refines its position, and determines for which satellites to search.
The GPS receiver retains the last known position when the power is switched off. This results in
faster satellite acquisition the next time it is switched on. If the antenna has been moved more
than a few miles, however, acquisition time will be slightly longer because it must first re-com
pute the position.
The US military has adopted the selective availability anti-spoofing module (SAASM) for all
new GPS deployments. SAASM GPS receivers make use of encrypted signals transmitted via L1
and L2 frequencies. Only authorized users can use SAASM GPS receivers.
This unit is capable of using other Global Navigation Satellite Systems (GNSS) alongside, or
instead of, GPS: The Russian GLONASS system is fully operational with 24 satellites each trans
mitting at a frequency in the L1 band between 1598 and 1606 MHz. This GPS/GLONASS fre
quency diversity offers improved performance in some environments when using dual-mode
GPS+GLONASS receivers. Other benefits are system redundancy and the availability of addi
tional satellites when using GPS and GLONASS together.
2.2 Spectracom GNSS Receiver
This TSync-PCIe system is available with an optional integrated GNSS receiver.
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Instruction Manual XYZ Rev. R
2.1 General Information about GPS and GNSS