DRAFT 3 – JANUARY 10, 2005 NOT FOR RELEASE
ORBITGPS USER GUIDE
SERIAL GPS RECEIVERS
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Latitude – Displays the current location on the face of the Earth north or south of the
Equator. Latitude is an angular measurement ranging from 0° at the Equator to 90° at
the poles (90º N or 90º S). In the GlobalPoint GPS application, North is shown as a
positive value and South is show as a negative value.
Longitude – Displays the current location on the face of the Earth east or west of a
north-south line called the Prime Meridian. Longitude is an angular measurement
ranging from 0° at the Prime Meridian to +180° east ward and −180° westward. In the
GlobalPoint GPS application, East is shown as a positive value and West is show as
a negative value.
UTC – “Coordinated Universal Time or UTC,” is the equivalent of Greenwich Mean
Time, the astronomical basis for civil time.
Quality – Displays whether current fix is a “Normal” uncorrected fix or a WAAS
“Corrected” fix.
HDOP – “Horizontal Dilution Of Precision” is a measure of how the satellite geometry
influences the latitude and longitude data accuracy. A good satellite geometry and
hence a good accuracy is obtained if the satellites being tracked are located as far
away from each other as possible, while the geometry is poor if the satellites are
located close to each other. If the HDOP value is higher than about 10 the latitude and
longitude data likely to be inaccurate.
Speed – Displays the current velocity in miles per hour.
Heading – Displays the current direction of travel in degrees with North being 0°.
Sats Used – The number of satellites used in the current fix. Note, WAAS and
EGNOS satellites are not included in the number, even if they are being used.
Protocol – The current mode of operation. This can be SiRF or NMEA.
