NorthStar 951X Operator's Manual page 73

Viewing GPS
satellite status
951/952 Operator's Manual Rev. B
To display more information about signals received from the
GPS satellites, press the 6$7 ,1)2 menu key on the GPS POSI-
TION screen. The GPS SATS screen is displayed showing the
received Signal-to-Noise Ratio (SNR) for each satellite (the
higher the ratio, the better the quality of the satellite signals),
and a satellite map indicating where the satellites are currently
located in the sky. Satellites are identified by their PRN num-
ber, a two-digit number assigned by the U.S. government.
The center of the satellite map represents the center of the sky,
and the outer (or last) ring is the horizon. The view is looking
down from above, with East to your right and West to your
left.
The following GPS data is also displayed:
•
ACCURACY: The estimated accuracy--in feet--of the GPS
system to be expected at the current time. Your position
readings should be more accurate than this estimate 95
percent of the time.
•
HDOP: This is a technical measure of the quality of your
fix. HDOP (Horizontal Dilution of Precision) is calculated
from the satellites' current positions. You'll usually see an
HDOP value displayed immediately after the unit is
turned on, and before it's ready to navigate. HDOP can
range from an ideal value of slightly less than one, up to
poor values of 10 or more. Any value less than two indi-
cates excellent performance.
Chapter 5 - Determining Position Coordinates
Page 63