Garmin GPS III A Owner's Manual

Also see for GPS III: Declaration of conformity Quick guide Owner's manual Owner's manual

What is GPS?GETTING STARTED The Global Positioning System (GPS) is a system of 24 satellites which circle theearth twice a day in a very precise orbit and transmit information to earth. The GPSIII must continuously “see” at least three of these satellites to calculate your positionand track your movement. At times, additional satellites may be needed to determinea position.By using an almanac (a timetable of satellite numbers and their orbits) stored inthe receiver’s memory, the GPS III can determine the distance and position of anyGPS satellite and use this information to compute your position.Your GPS receiver can only see satellites above the horizon, so it needs to knowwhat satellites to look for at any given time. To use this almanac data, your GPSneeds to either be told its general location (“initialized”) or given the opportunity tofind itself. Once you initialize the unit to a position, it will typically compute a fixwithin a few minutes. We’ll show you how to initialize your new GPS III on page 5.Initialization is only necessary under the following conditions:• The first time you use your receiver (new from the factory).• After the receiver has been moved over 500 miles (with the power off) fromthe last time you used it.• If the receiver’s memory has been cleared and all internally stored data hasbeen lost.Because the GPS III relies on satellite signals to provide you with navigationguidance, the receiver needs to have an unobstructed, clear view of the sky for bestperformance. In a nutshell, the GPS receiver’s view of the sky will generally deter-mine how fast you get a position fix—or if you get a fix at all. GPS signals are rela-tively weak and do not travel through rocks, buildings, people, metal, or heavy treecover, so remember to keep a clear view of the sky at all times for best performance.Hold the receiver at acomfortable height with theantenna pointing up.When new (or if a positioncannot be determined after 10minutes), the GPS III willprompt you to initialize thereceiver. The unit needs astarting position to determinewhich satellites are in view.4