GPSGPS

Choosing the right receiverChoosing the right receiver

What Is GPS???What Is GPS???

GPS stands forGPS stands for

Global Positioning SystemGlobal Positioning System Satellite-based navigation systemSatellite-based navigation system 24 satellites orbit 2x per day24 satellites orbit 2x per day 12,000 miles above : 7,000 miles/hr.12,000 miles above : 7,000 miles/hr. Originally designed for militaryOriginally designed for military

How does GPS work?How does GPS work?

The Receiver triangulates signals The Receiver triangulates signals received from the satellitesreceived from the satellites

3 Satellites = 2D position3 Satellites = 2D position (Longitude and Latitude)(Longitude and Latitude) >4 Satellites = 3D position>4 Satellites = 3D position (Long. And Lat. + Altitude)(Long. And Lat. + Altitude) Tracking BeginsTracking Begins

Where does it work?Where does it work?

Low power radio signalsLow power radio signals Travel by line of sightTravel by line of sight

Clouds / Glass / Plastic = YESClouds / Glass / Plastic = YES

Solid Objects (Dense Forest)= NO!!!Solid Objects (Dense Forest)= NO!!!

Models of InterestModels of Interest

Garmin GPS III PlusGarmin GPS III Plus

AndAnd

Garmin eTrexGarmin eTrex

Garmin GPS III PlusGarmin GPS III Plus

Garmin eTrexGarmin eTrex

ComparisonComparisonsource: http://www.garmin.comsource: http://www.garmin.com

GPS III PlusGPS III Plus eTrexeTrex

MemoryMemory 1.44 MB1.44 MB N/AN/A

Battery LifeBattery Life 36 HR36 HR 22 HR22 HR

AntennaAntenna DetachableDetachable InternalInternal

WeightWeight 9 oz.9 oz. 5.3 oz. 5.3 oz.

WaterproofWaterproof YesYes YesYes

PricePrice $300.00$300.00 $119.00$119.00

Urban CapabilitiesUrban Capabilities

The GPS III Plus works better in The GPS III Plus works better in

urban areas.urban areas.

Interstate Exit information Interstate Exit information

Food / Lodging / Service StationsFood / Lodging / Service Stations

The Best Choice?The Best Choice?

Garmin GPS III PlusGarmin GPS III Plus

More capabilities:More capabilities: Battery LifeBattery Life Works with the ComputerWorks with the Computer Urban compatibleUrban compatible

References:References:

http://www.garmin.comhttp://www.garmin.com

http://www.rei.comhttp://www.rei.com