What and How to Use GPS Receivers

GPS receivers are manufactured for both consumer and commercial applications.  Engineers, surveyors, and aviation manufactures use special application equipment.  There are also special product lines for marine use.  They include sonar and other features specifically for boating.  This guide primarily focuses on consumer and recreational use gear.

You’ll need to know the basics before knowing exactly what equipment to buy.  First we will introduce the basic features available to help determine what features will be important for your application.  Then provide a list of major brand manufacturers.  We group GPS receivers into three different categories.  Each category will include the benefits, applications, and brand name models available.  Read on to help determine what equipment best fits your application and price range.

FEATURES

Like most modern electrons, GPS receivers are packed with features and options, more than many us will ever use.  Understanding the features available will allow a more informed purchase, as well as provide the opportunity to use the equipment to its fullest potential.  Fortunately the modern receivers share many of the same features, and are consistent in accuracy, regardless of price.  The following is a list of the typical, optional, and required features.  Review this checklist before you buy.

Typical features of any modern GPS receiver

Accuracy:  Reports of accuracy vary greatly.  With Selective Availability (the US Government’s scramble mode) shut off, the average accuracy anywhere in the world should be within approximately 5 to 15 meters.  Accuracy seems to be consistent in most receivers, (assuming the antenna has a clear view of the sky), regardless of the style or cost.

 

Alarms:  An alarm notifies the user of an approaching waypoint.  Text Alarms flash a message on the screen.  Audible alarms sound a tone.

Antenna:  The options available are built in, detachable or external.  The antenna option is important because it is a determining factor on how the equipment will be used.  Receivers with built in antennas are more durable for hiking, but are somewhat restricted in their use.  Detachable antennas are ideal for receivers used in and out of vehicles.  External is for vehicle applications where equipment is mounted with no clear view of the sky.

Battery Duration:  Battery life is important for extended hikes with no other source of power.  Receivers are rated for battery life duration for both continuous use and power saver modes.

Clock & Timer:  Receivers provide precise atomic time in either a 12 or 24 hour display.  Various timing features include date, time traveled and estimated time of arrival.

Compass Data:  Receivers provide a compass bearing if traveling over 10 MPH, as well as a compass bearing to next waypoint.  They adjust the compass reading to account for magnetic declination.  They also provide a pointer to help maintain a correct bearing.  Some of the most recent units include a electronic compass which will provide direction while the receiver is stationary.

Computer Interface:  Input capable allows the unit to receive (upload) information from a computer.  Output capable allows the unit to send data (download) to a computer.  Most of the latest receivers allow data to be uploaded and downloaded.

Coordinates Displayed:  Most receivers provide the option to display mapping coordinates in multiple formats.  The primary two of interest are latitude/longitude and UTM, Universal Transverse Mercator.

Cursor Dialog Box:  Receivers with a rocker pad can scroll a cursor arrow on the map page.  Data displayed in the dialog box includes the coordinates of the cursor’s location, as well as the distance from the current location.

Directional or DGPS Ready:  These receivers are capable of accepting radio signals which increases accuracy.  This requires an additional radio beacon, and can provide accuracy to a few centimeters.  Primarily used in marine applications.

Route Tracking:  A series of waypoints are organized in the form of a Route.  Routes typically contain up to 30 waypoints, designed to guide to a destination.  They can also be reversed to track back from the destination to the starting point.  Unless otherwise stated, all of the receivers in this guide offer at least 20 routes.

Satellite Status Page:  Information includes the number of satellites being locked into with a signal strength bar for each.  They may also provide a battery strength indicator.

Track Log:  Plots a bread-crumb trail, a series of dots showing the area traveled.

Travel Data:  Includes distance and time to next waypoint, current speed, average speed, and trip odometer.

 

Water Resistance:  Receivers are rated for their resistance to water.  Water-resistant usually means the equipment can be splashed or briefly dunked.  Waterproof means the equipment can be submerged for a specific amount of time before damage occurs.  Regardless of rating, use a zip lock bag anyway.

 

Waypoints:  Specifically recorded locations stored within the receiver’s memory.  Saved waypoints allow the return to exact locations.  We recommend the ability to store a minimum of 200.  Unless otherwise stated, all of the receivers in this guide offer the ability to store at least 500

 

Optional Features

Electronic Base Map:  More advanced receivers include a basemap stored within their memory.  Basemaps include general information on cities, roadways and waterways.  The maps are not highly detailed, but impressive considering they typically include such large geographical areas like North America or Europe.

 

Warning:  Using a receiver without mapping emphasizes the requirement to read map coordinates.  These mapless receivers provide map coordinates in typically latitude/longitude or UTM, Universal Transverse Mercator.  These coordinates are useless to the user without the ability to understand how they correspond to a map.

 

Memory:  Most receivers have a capacity to store additional point of interest and mapping information.  Basic units without mapping have the ability to store waypoints and routes.  Mapping units can accept additional mapping detail including topographical maps.  Some models also have the capability of receiving memory cards for greater detail of cites, waterways, and other specific areas.

 

Required Feature

12 Parallel Channels:  Make sure the unit includes 12 Parallel Channels.  New units are equipped with this feature, however the first GPS receivers available were single channel.  Some of these older units have similar model numbers with marketing stating they can scan 12 satellites.  The older single channel equipment processes information much slower from each satellite through a single channel, one at a time.  This is not the same as a 12 Parallel unit that can process information from 12 satellites through 12 channels all at the same time.  Recently manufactured receivers including all of the units in this guide all feature 12 parallel channels.