Problem: GPS Fix Test Fails
GPS Fix Problem
18-2
80-JB566-1 Rev. G
MAY CONTAIN U.S. AND INTERNATIONAL EXPORT CONTROLLED INFORMATION
If the vehicle is in the open with a clear view of the sky, the mode should show 3-D. The Last
Update time should be current, Precision should be <2 and at least 5 Satellites should be
used in the fix. If this is not the case, follow the steps below:
1.
Verify the antenna is in a location where the view to the sky is not blocked or obstructed.
Check for any metal obstructions that may block or degrade the GPS signals, such as
wires or cables directly above the antenna. If there are any obstructions, remove the
obstructions or relocate the antenna.
The GPS screen has a couple of indicators which may point to a problem with
obstruction:
•
The Precision value should be <2. If it is consistently above 3.00, there is likely
something interfering with the GPS signals.
•
The Satellites field shows xx/yy, where xx is the number of satellites used in the
position fix, and yy is the number of satellites recently viewed. The xx value should
be 5 or greater. If it has a value less than 5, there is likely some obstruction.
2.
Confirm the antenna is not upside down or has shifted on its side.
Verify antenna is mounted securely in a horizontal/flat location with arrow pointing to the
sky.
3.
Check to see if the antenna GPS lead has become disconnected from the VTM.
Reseat both antenna leads.
4.
Test for a faulty antenna or pinched cable lead.
Test with a known good antenna. Give the unit several minutes to acquire GPS and then
check the Mode and Last Update time/date on the GPS screen. If No Fix still appears,
the original antenna and cable are probably okay.
5.
Test with known good VTM.
