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5 GPS170PCI features
The satellite controlled clock GPS170PCI is a plug-in board designed for computers with 3.3V or 5V PCI bus
running with clock frequencies of 33MHz or 66MHz. The rear slot cover intergrates the antenna connector, the
modulated timecode, two status LEDs, and a 9 pin Sub-D male connector.
The antenna/converter unit is connected to the receiver by a 50
Ω
coaxial cable with length up to 300m (when
using RG58 cable). Power is supplied to the unit DC insulated across the antenna cable. Optionally, an over
voltage protection and an antenna distributor are available. The antenna distributor can be used to operate up
to 4 Meinberg GPS receivers using a single antenna/converter unit.
The navigation message coming in from the satellites is decoded by satellite clock's microprocessor in order
to track the GPS system time with an accuracy of better than 250nsec. Compensation of the RF signals prop-
agation delay is done by automatic determination of the receivers position on the globe. A correction value
computed from the satellites navigation messages increases the accuracy of the boards temperature compen-
sated master oscillator (TCXO) to +- 5(10
9
) and automatically compensates the TCXOs aging. The last recent
value is restored from the nonvolatile memory at power-up. Optionally, the clock is also available with a higher
precision time base.
Monitoring software shipped with the board can be use to check the cloick's status and congure some op-
erational parameters
5.1 Time zone and daylight saving
GPS system time diers from the universal time scale (UTC) by the number of leap seconds which have been
inserted into the UTC time scale after GPS has been initiated in 1980. The current number of leap seconds is
part of the navigation message supplied by the satellites, so the satellite clocks internal real time is based on
UTC. Conversion to local time including handling of daylight saving year by year can be done by the receivers
microprocessor. For Germany, the local time zone is UTC + 3600 sec for standard time and UTC + 7200 sec if
daylight saving is in eect.
The clock's microprocessor determines the times for start and end of daylight saving time by a simple algo-
rithm e. g. for Germany:
Start of DST is on the rst Sunday after March, 25th, at 2 o'clock standard time.
End of DST is on the rst Sunday after October, 25th, at 3 o'clock daylight time.
The monitoring software shipped with the board can be used to congure the time zone and daylight savings
parameters easily. Switching to daylight saving time is inhibited if for both start and end of daylight saving the
parameters are exactly the same.
The timecode (IRIG, AFNOR, IEEE) generated by GPS170PCI is available with these settings or with UTC
as reference. This can be set by the monitor program.
5.2 Asynchronous serial ports
Two asynchronous serial interfaces (RS232) called COM0 and COM1 are available to the user. Only COM0 is
available at the rear panel slot cover, COM1 must use another submin-D connector which can optionally be con-
nected to the 5 pin jumper block on the board. The monitoring program can be used to congure the outputs. In
the default mode of operation, the serial outputs are disabled until the receiver has synchronized after power-up.
However, they can be congured to be enabled immediately after power-up.
GPS170PCI
Date: 12th July 2012
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