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6 Troubleshooting
60 AgGPS 332 GPS Receiver User Guide
6.1 Introduction
This chapter describes some problems that can arise and explains how
to solve them. It includes a series of flowcharts to help with
troubleshooting.
As you work through this chapter, you may need to view the receiver
status or change values in some fields. For information on how to do
this, refer to the document called NMEA-0183 Messages Guide for
AgGPS Receivers. This document is on the Trimble website
(www.trimble.com).
6.2 Problems with GPS
Problem Possible solution
Poor accuracy
The accuracy of GPS positions is poor because
the receiver is picking up poor quality signals
from the satellites.
The receiver always calculates the most
accurate position it can, given the current GPS
satellite differential operating conditions.
Change some or all of the following GPS
settings:
• Minimum elevation – Increase the setting
(the default is 8°).
• Minimum Signal Strength – Increase the
System Mask AMU setting (the default is 3).
• Maximum PDOP – Decrease the setting
(the default is 13).
• GPS Mode – Change to Manual 3D
(the default is Auto 2D/3D).
• DGPS Mode – Change to DGPS
(the default is DGPS Auto/On/Off).
GPS signals are reflecting off nearby trees
and/or metal buildings and horizontal
surfaces.
To reduce multipath noise, mount the GPS
receiver so that it has a clear view of the sky.
The receiver must be away from trees and
large metal objects.
Intermittent loss of lock on satellite
The receiver loses the satellite signal from
time to time.
Make sure that the receiver is mounted on the
highest point of the vehicle and is clear of
metal surfaces.
Check Maximum PDOP and Minimum Signal
Strength settings (see Poor accuracy, above).