Garmin GPSMAP 175 Owner's Manual

Garmin GPSMAP 175 Owner's Manual Manual pdf 9 page image

15GETTING STARTEDAcquiring Satellite SignalsAcquiring Satellite SignalsBecause the GPSMAP 175 relies on satellite signals to provide you withnavigation guidance, the receiver needs to have an unobstructed, clear viewof the sky for best performance. What exactly does this mean? In a nutshell,the GPS receiver’s view of the sky will generally determine how fast you geta position fix, or if you get a fix at all. GPS signals are relatively weak, anddo not travel through large obstructions made of metal, rock, or wood, forexample.Once the GPS has calculated a position fix, you’ll usually have anywherefrom four to twelve satellites in view. Your GPSMAP 175 will nowcontinuously select the best satellites in view to update your position. Ifsome of the satellites in view get blocked or “shaded,” the receiver cansimply use an alternate satellite to maintain the position fix. Although a GPSreceiver needs four satellites to provide a 3D fix (latitude, longitude andaltitude), the GPSMAP 175 can maintain a 2D fix (latitude and longitudeonly) with just three satellites.Before You InitializeTake your GPSMAP175 outside and find a large, open area (try a nearbypark) that has a clear view of the sky from horizon to horizon. Hold thereceiver at a comfortable height, at arm’s length from your body with thebuilt-in antenna (the top part above the display) parallel to the ground.