Handheld GPS devices represent a special category of all available GPS (Global Positioning System) receiver units used in various situations and for different applications. The major applicability or usefulness of handheld, portable GPS devices can be divided into two distinctive categories, i.e. for outdoor leisure and sport activities like hiking, trekking, climbing, camping and running and, secondly, for industrial applications like land surveying and position measurements at construction sites. Utilizing the GPS navigation satellite system, correct location of the GPS receiver can be determined by retrieving exact longitude, latitude and altitude coordinates. Today, most GPS receiver units, whether handheld or not, communicate through radio signals with at least four GPS satellites, whereby three satellites determine the exact location of the receiver and the fourth satellite is used for correcting the receiver’s clock. After the Selective Availability regulation, which provided certain accuracy reservation for military use, was ended in 2000, the precision of civilian GPS improved from about 100m to about 20m.

Handheld GPS devices provide tremendous flexibility and convenience for the user. Not only can the user continuously monitor his, or her, exact and current geographical location and path of travel, but handheld GPS devices can be fitted for relaying with central offices or base stations that can track or follow the user for security and safety reasons. For example, GPS devices that can communicate with and supply coordinates to a central station are very popular by mountain climbers and hikers. As the GPS system has developed and improved over the past years, many new applications have emerged for the users of handheld GPS devices. Not only can users determine their current location, but also obtain a multitude of additional and supportive information through geographical maps, inserted in the GPS receiver units, such as precise navigation, locations of restaurants and hotels, weather reports, tourist attractions, etc. Currently, there are a number of companies producing and offering many different handheld GPS devices. Some of the best known include, Garmin, Magellan and DeLorme. The devices have a broad range of features, attributes and, of course, price tags. Before selecting a particular handheld device, it is important to know what you will be using it for. For example, a GPS device used for hiking may be less applicable for mountain climbing or, even less, running. Obviously, devices for industrial applications have particular requirements and qualities. If you are looking for a handheld GPS device that can be used in different circumstances, a multipurpose unit could be the answer. Furthermore, you need to have an idea of what features you are interested in or require in addition to the standard GPS and mapping functionality, e.g.:

  • Touch screen window
  • Color screen or black and white
  • Built-in camera (like in mobile phones)
  • SD (memory) card expandability
  • Voice recorder
  • Built-in electronic compass
  • Barometer
  • MP3 Music Player
  • External antenna connector
  • Etc. etc.

Obviously, as the feature list increases, so does the price. Another important thing to keep in mind is considering what geographical maps may be included or applicable to your needs, e.g. outdoor and recreational maps, street maps or marine maps. Most handheld GPS devices come with some pre-loaded or built-in geographical maps, for example a base map of the USA and Canada containing major highways, city centers, bodies of water and more. You need to find out whether you need additional detailed maps that can be added to the handheld device, for example detailed cartographic maps, topographic maps, and more.

Still another important issue to keep in mind is the GPS software that is normally included with the purchase of a new handheld GPS for uploading GPS data to a computer. By that you can conveniently view all your maps, waypoints, trails and routes from your computer screen. Many other interesting advanced features and possibilities can be implemented with an appropriate handheld GPS receiver including, playing “hide-and-seek” and “treasure-hunting” through geocaching or importing your tracks, waypoints and routes into Google Earth for tracking and monitoring. In short, Handheld GPS devices offer a plethora of wonderful possibilities and options.

For maximizing its benefits, you should carefully consider your needs and requirements before you actually purchase a new handheld GPS. Common retail prices for handheld GPS devices range from $100 up to $800USD depending on built-in or available features and attributes.

Olafur Ingthorsson is a Consultant and an Internet Marketer. His passions include IT and Communications technologies, including handheld GPS devices, the outdoors and triathlon sports.

Handheld GPS Devices

Analyse Your Needs Before Purchasing a Handheld GPS Device

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GPS is getting to be more a part of our everyday life all the time. If you buy a new car, there is a good chance that an option is available to get a GPS navigation system with it. It is only a matter of time before GPS navigation becomes a standard feature in every new car that rolls off the assembly line. Cell phone GPS is also growing by leaps and bounds. Right now. if you make an emergency phone call to the police or fire department from a hard – wired telephone the police know exactly where you are calling from. But not so with a mobile or cell phone. That, however, will soon change. Virtually, all new cell phones will soon have a GPS inside somewhere. Even photography is getting into the act. Some new cameras have a built in GPS so when you take a photo it tells you the latitude and longitude of where you were and stamps that information on the photo.

We tend to take GPS for granted in the same way we do the Internet. We assume it is almost free for everyone and available everywhere but that really isn’t true. GPS was first developed in the 1970s and is owned, operated and controlled by the United States military. If the US military wants to cut off or control your access to the GPS system they can. In fact prior to May of 2000 all civilian GPS units had limited access to the GPS system called Selective Availability. Prior to that date your GPS would work just fine, but would not be as accurate as military GPS units. Normal GPS accuracy is greater than 20 meters but with Selective Availability it is only 100 meters. Today however, all GPS receivers – military or civilian – have the same accuracy. So at the moment, GPS is free for everyone around the world. But in the future, if a terrorist group or country were to get access to GPS guided weapons, the US military could cut off their access to GPS by encrypting the signal.

The GPS system is made up of 24 military satellites circling the earth at an altitude of 11,000 miles such that at any given time and location a GPS receiver gets a signal from at least 6 of those satellites at a time. They are set up in 6 orbital paths with 4 satellites spaced evenly in each of the 6 orbits. Signals from these satellites are available anywhere on the earth, 24 hours a day and are not affected by the weather. Older GPS receivers just had one channel so they had to cycle through the 6 or more satellites one at a time but newer units have 10 parallel channels or more so you get faster more accurate information.

The biggest headache for GPS systems is the time it takes for the signal to get from the satellite to your receiver. The 6 satellites you get signals from will all be at different distances from you and are rotating the earth at high speed. So the signals your GPS receiver gets will not automatically be time synchronized. Because of this problem, the military has limited civilian GPS units so they don’t work if they are moving faster than 900 knots or above 60,000 feet in altitude. But most non-aviation GPS units will give error messages if you are moving faster than 90 miles per hour. Clearly, if you are standing still, a GPS will be a lot more accurate.

Michael Russell

Your Independent guide to GPS

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