120 20110-003 PRELIMINARY
Gemini/PD Technical Manual
7
3.4.5 GPS Diagnostics Procedure
OVERVIEW
The detection of the POSition message shows a GPS CONNECTED LED. After about three
minutes, detection of the one Pulse Per Second (PPS) should flash the POSITION ACQUIRED
indicator, this means that the GPS has a position solution.
If the GPS has a good view of the sky and still has not generated any position solution within
three minutes (it may take up to 10 minutes or more if the sky view is partially blocked.) the
following trouble-shooting procedures should be undertaken to isolate the fault:
1) Disconnect the GPS antenna cable connector from the Gemini radio and check for + 5 VDC
on the center pin of the GPS antenna connector on the radio using a DVM. If the voltage is
present, do not reconnect the cable and proceed to step 2.
2) With the DVM, measure resistance between the shell and the center conductor of the GPS ca-
ble, resistance should be between 100 and 300 Ohms, if it measures open or short circuit the
GPS antenna is either a passive antenna which is the WRONG type, or a defective active an-
tenna, replace with a known good active antenna.
3) Connect the new antenna to Gemini and wait about three minutes for the POSITION
ACQUIRED indicator to start flashing on Gemini, if not, the Gemini radio or its GPS receiver
is defective.
