Ag Leader EZ-Guide Plus Getting Started Guide - Manual (Page 46)

44 Using GPS EZ-Guide Plus Lightbar Guidance System Getting Started Guide
Configuring the receiver
This section covers receiver configuration for:
• GPS limits
• Corrections
• Filters
Note — At mid latitudes, the GPS cross-track errors that occur when you drive East–
West are typically double the cross-track errors that occur when you drive North–
South. This is a characteristic of all GPS receivers and guidance systems, and occurs
because the GPS satellite orbits do not go over the poles. For GPS system status
details, go to http://www.navcen.uscg.gov/ado/GpsActiveNanu.asp.
GPS limits
You can configure the minimum acceptable number of satellites and the Horizontal
Dilution of Precision (HDOP) that must be present before GPS guidance will start.
HDOP is a measure of accuracy based on the geometry of the satellites in the sky. An
HDOP value of 2.0 or less is considered good.
Note — The GPS Limits settings can only be altered when you use a TSIP-capable
GPS receiver. If the Input field is set to Autopilot, they are unavailable.
To allow guidance to start in an area that has many trees,
hills, or other obstacles, reduce Min Satellites to 5, or
increase Max HDOP to 3.0. This allows guidance to start
with lower accuracy positions. To configure these
settings, select GPS / GPS Limits.
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CAUTION — Changing any of the GPS Limits default settings can cause GPS position errors
greater than one foot. If you are using the EZ-Steer system, these errors can cause the
EZ-Steer system to steer the vehicle offline.
Note — If you are using the EZ-Steer system, the EZ-Steer system will disengage
when these limits are exceeded.
If the lightbar has an integrated GPS receiver, or if you
use the lightbar with a high accuracy smart antenna, you
can also specify a minimum elevation and a minimum
SNR for GPS satellites. (Satellites that do not meet the
criteria will not be used). However, if you lower these
values, this may result in more GPS position drift.