GPSPCI 2/72008 Rev 1.2.1
2
Masterclock, Inc.
The GPSPCI’s GPS navigation module has its own backup battery that maintains startup data
when the PC is powered down. If, when starting up, the location, time and number of satellites
that the GPSPCI can receive has not changed significantly since last power down, then the
GPSPCI time will be available much faster.
ANTENNA LOCATION
Depending on the type of building where the GPSPCI is located and obstructions that may block
reception of signals from the GPS satellites, the antenna may have to be located where it has an
unobstructed view of the sky. In some cases, this can be accomplished by placing the antenna
next to a window. However, usually it will require mounting it outside of the building or on a
roof. In the worst case, the basic requirement for assured system operation is that the antenna
module has a clear and unobstructed view of the sky for initial satellite acquisition and lock
(generation of time information by the GPSPCI). It is possible that the system will operate
indoors and under other obstructions. However this can only be determined empirically; it is not
guaranteed.
If a longer cable is required, cables of various lengths (up to 500 feet) with pre-amplified
antennas are available from Masterclock.
Bringing the GPSPCI up for the first time with an
indoor antenna may prevent or significantly increase the time to first fix.
INITIAL OPERATIONS AND I/O CONNECTIONS
1.
Locate the antenna in a suitable area so that the top of the antenna module has a clear view of
the sky. Do not move it until after the GPSPCI has initiated operation (explained below).
2.
Connect the antenna coax to the SMA connector on the PC card bracket.
3.
The unit first calculates coordinates and distances for acquisition of GPS satellites. The LED
will remain off until satellites are acquired and precise location and timing references are
established.
NORMAL OPERATION
After acquisition of satellites the GPSPCI will begin generating time information and the card
LED will flash once per second.
FREEWHEELING
During continuous operation it is likely that the GPSPCI will experience occasional outages and
loss of satellite reference time. This can be caused by atmospheric and many other outside
conditions which are essentially unavoidable with a simplex system. Such signal losses can last
from a few minutes to hours. When the condition disappears and the unit re-acquires satellite
timing reference, it will automatically resync to the satellite time reference.
