John Deere OMPC20964 User Manual

Page 81

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Original GreenStar Display—StarFire iTC



GPS Accuracy Indicator: StarFire iTC includes GPS
Accuracy Indicator (GPS AI). GPS AI gives indication of
GPS position accuracy achieved by receiver, and is
displayed as a percentage (0-100%). GPS AI is displayed
on RUN Page of Parallel Tracking (Figure 1), AutoTrac,
and Field Doc and INFO – GPS – Page 1 (Figure 2).

When receiver is initially powered, GPS AI will display 0%.
As receiver acquires satellites and calculates a position,
GPS AI will increase as accuracy improves. Acceptable
guidance performance for Parallel Tracking and AutoTrac
is achieved when GPS AI displays 80% or greater. This
may take up to 20 minutes. GPS accuracy is affected by
many factors. If 80% accuracy or greater is not achieved
within 25 minutes, consider following possibilities:

• Unobstructed view of sky – trees, buildings, or other

structures may block receiver from receiving signals
from all available satellites

• L1/L2 signal to noise ratio (SNR) – radio interference

from 2-way radios or other sources may cause low SNR

• Satellite position in sky – poor GPS satellite geometry

can reduce accuracy

• Number of satellites above elevation mask – this is total

number of GPS satellites available to your receiver that
are above 7

° elevation mask

• Number of satellites in solution – this is total number of

satellites that are being used by receiver to calculate a

GPS Signal Quality: This cell shows quality of signals
being received from constellation of GPS satellites.

Differential Signal Quality: This cell shows quality of
differential correction signal being received by receiver.