Geocaching

Geocaching is a world-wide sport where people use Global Positioning System (GPS) receivers to find hidden treasures (caches). Before May 2000, GPS satellites were configured with "selective availability," which limited the accuracy of personal GPS units. In May 2000 the Clinton Administration officially removed this limitation, giving civilian GPS units much greater accuracy. Soon after this a GPS enthusiast hid a cache and posted the coordinates on an Internet newsgroup. A few months later, Jeremy Irish created Geocaching.com, the major Web site supporting this new sport. In the six years since the first cache was hidden, geocaching has grown dramatically. Currently, there are 250,000 active caches in over 200 countries.

The basic object of the game is to find these caches and log your finds on Geocaching.com (or another geocaching Web site). "Take something, leave something" is the geocaching motto, and most caches contain trinkets to trade and a logbook to record your find. Caches are located everywhere, from remote forest locations to busy mall parking lots. I live in a typical suburban neighborhood and there are over 200 located within a 5 mile radius of my house. You can find a list of all caches near you on Geocaching.com.

Pocket PC, GPS Receiver, and the cache "Farewell Beavers" located in Roseville, CA

GPS receivers and accessories

The Pocket PC is an ideal tool for geocaching. Not only can you store information about the caches you seek and find, you can add a GPS receiver and navigation software to the device to create a powerful, portable GPS system. The receivers come in a number of formats, but the most useful for geocaching are the CF/SD card or the Bluetooth-enabled receivers. Smartphone and Pocket PC magazine's online Encyclopedia of Software and Accessories (http://www.pocketpcmag.com/_enc/encyclopedia.asp) lists over 40 GPS receivers, as well as a variety of GPS navigation programs you can use with your Pocket PC. Here are some things you need to consider before purchasing a receiver.

CF or SD GPS receivers (Fig. 1): These receivers slip into the Pocket PC's card slot and become part of the device. There's no need to carry around a cable or a second piece of hardware. The main disadvantage is that most of these receivers pull power from the Pocket PC. If you're going to use it for an extended period of time, you might want to carry a spare battery with you. Also, if you use the Pocket PC/GPS combo for in-vehicle navigation, make sure the entire device is mounted high on the dashboard with a clear view of the sky through the windshield. This will improve reception.

Fig. 1:GPS receivers are available from TeleType and Pharos as well as other vendors.

Bluetooth GPS receivers (Fig. 2): These receivers connect wirelessly to Bluetooth-enabled Pocket PCs. Their main advantages are that they have their own batteries and don't drain the Pocket PC's, and that they can be placed in a different location from the Windows Mobile device. This comes in handy when driving; the GPS can rest on the dashboard while the Pocket PC can be in someone's hand or in a "cup holder" type of mount. The disadvantage is that you now have to carry two devices when you're walking around looking for a cache. You also have to remember to keep two devices charged.

Fig. 2: Bluetooth GPS receivers connect wirelessly with Bluetooth-enabled Pocket PCs.

I use a Teletype16-Channel Bluetooth GPS receiver (http://www.teletype.com). When I'm out on the hunt for a cache I secure the receiver to my backpack strap—for quick trips I toss it on top of my head under my hat.