GPS Guide Things to look for in a GPS

What is a GPS?

The GPS system was designed by and is controlled by the United States Department of Defense and can be used by anyone, free of charge. True accuracy of each GPS receiver varies depending on a number of factors including time of day, weather, satellite geometry, WAAS signals (explained more down the page) and more. Most GPSrs are accurate to within three meters. Many geocachers allow the GPS to get them close and then use their intuition to guide them the rest of the way.

A GPS unit's price can range from a little over $100 to more that $500 depending upon the features of the model.

Selecting a GPS for Geocaching

The Essentials

First a word about WAAS. You will see this mentioned in the descriptions of many available GPS units. Here is a brief explanation that will hopefully help you understand this technology: Most all GPSr units available in North America now are WAAS enabled, and that should be considered a necessity. The Wide Area Augmentation System (WAAS) uses a series of ground reference stations to calculate GPS correction messages. As of 2004 only a few WAAS satellites were available, but further advancements have been made. Eventually WAAS will provide sufficient reliability and accuracy to be used for critical applications such as GPS-based instrument approaches in aviation (landing an airplane in conditions of little or no visibility). The current WAAS system only works for North America (where the reference stations are located), however, variation systems are being developed in Europe (EGNOS, the Euro Geostationary Navigation Overlay Service), and Japan (MSAS, the Multi-Functional Satellite Augmentation System), which are virtually identical to WAAS.

There are a few other necessary features to look for in a GPS unit, or GPSr:
The unit must definitely be small and a hand-held size for easy portability. Most GPS units sold these days, meet this specification. Another nice feature is a mapping screen. This gives you an overhead map that helps you get your bearings. Most modern units will have some sort of mapping screen. Do not confuse this with a mapping unit which includes detailed real-world maps including roads, rivers, and more. Autorouting is a more common feature in modern units and really a must to make the GPSr more easily useable and can be extremely helpful in geocaching as you go from one cache find to the next. Autorouting will give you turn-by-turn directions from your present position to the selected destination. Another must is having a GPSr that is waterproof. Many caches are hidden near water. Sometimes you may want to use your GPSr in the rain. Units need to be watertight, submersible (some caches are even hidden under water!) and able to stand the unpredictable weather that accompanies outdoor adventures. All GPS units we offer for sale include these minimum requirements. Of course, there are more functions and frills in some models at a higher price tag.

Advanced Features There are a lot of features available on GPS models today that aren't necessary for every geocacher. Some features do make life easier and can increase a GPS receiver's usefulness to do more than geocaching. Personal preference and considering the possible ways you may use your GPSr is helpful in deciding how much money you want to invest in one. You may want a data cable to reduce the time spent entering coordinates and eliminate personal errors that may occur when inputting them manually. Some new and even experienced geocachers have been frustrated when they inadvertently enter the wrong coordinates. Most mid to higher end GPS units allow you to add real-world maps to your units. These maps can be detailed roads and streets maps, topo maps with detailed topographical features or both. The amount of detail and maps a unit can hold is determined by the amount of data that will fit in the unit's memory. Some units have removable memory so that you can use large data sets or swap smaller ones out for others. Another optional, but great feature to consider is an electronic compass. Because a GPSr that doesn't have a built-in compass relies on the movement of the unit to determine which way it is headed, it is hard to get an accurate reading when you are sitting still. When you stop and turn in any direction, the unit can not tell you which way to proceed until you start moving again. An electronic compass will tell you which way you are pointed regardless of speed. Some units also come equipped with a fish calculator. The GPSr can use information from the satellites and moon cycles to predict the best fishing times for any given location. An altimeter is a great function found on the better GPS units. This shows you how high up you are, necessary for vertically hidden caches, but otherwise a fun extra when you are out exploring in the mountains. You'll be grateful that you have an external antenna if you ever find yourself searching for a cache under heavy tree cover or difficult terrains, but this is not necessary to receive satellite readings under normal conditions. Another feature to notice in higher end GPS receivers is a color display screen. This is certainly not necessary and most GPSes come with a backlight whether in color or monochrome for easy readability day or night - but color adds an extra dimension to the ease of use and some geocachers would never dream of buying a unit without a color display.

We hope that this will answer most of your questions concerning the basic and other GPS features available. Please go to our webstore to check out the different GPS units we offer and a listing of their specific features. If you would like more information or individual help in selecting the GPS that may be right for you, please contact our customer service. We are always happy to help you.