Back in 2007 I bought a bluetooth GPS receiver to use with my PDA. I had thought of getting a GPS receiver for a while but not really been able to justify it. What would I use it for? In-car navigation looked fun, but sadly I don't own a car. Then I happened to come across the sport of Geocaching, and thought that a GPSr might be a worthy toy after all. I've never looked back!
Geocaching is a sport/game where you hunt for caches hidden by other players, using GPS coordinates posted on the internet. When you find a cache you write an entry in its log book, and report your find on the web. You can also swap some of the "treasures" hidden inside. There are many variations on the theme, including puzzle caches where you have to solve clues to work out the co-ordinates, virtual or webcam caches, and trackable "travel bugs" and coins to follow around or send on missions. I find that the best part of Geocaching is that it gives you an incentive to get out and about and visit places you've not been to before. Most of the caches are hidden in places that are interesting for some reason or other, whether out in the countryside or deep in the urban jungle.
Useful caching websites
- www.geocaching.com - The most popular cache listing site.
- OpenCaching.org.uk - A UK alternative cache listing site. There are also OpenCaching sites in the Czech Republic, Germany, Norway, Poland, Sweden and the USA.
- Follow the Arrow - Lots of links to useful bits and pieces.
- Get-a-Map - Free Ordnance Survey electronic mapping service.
- Ordnance Survey Coordinate Transformation Tool - Allows conversion between GPS coordinates and the British National Grid. Also gives background information on how geodetic coordinate systems work.
- CalSky - An astronomical website which includes an orbital calculator for the GPS satellite constellation. This lets you work out how many will be in the sky above you at any given time (useful for knowing when to get accurate co-ordinates for placing a cache).
- National Geophysical Data Centre - US Government site hosting an online calculator to work out magnetic declination at any time and place. Declination is the difference between magnetic north (from your compass) and true north (from a GPS).
- Geocaching 101 (suggested by Jeremy from WB Goodwin Community Centre)
What I use for Caching
- Globalsat BT-338 GPS receiver. This is a bluetooth unit, with no display of its own. Being screenless makes it cheaper and improves battery performance, but means that you have to have some other device with you to use it. It has the SiRFstarIII chipset, which is supposed to be very sensitive. I've nothing to make a comparison against, but have never had reception problems unless underground or deep within a building.
- Palm Tungsten T3 PDA. I use this as the display and the brains for my GPS. It's got a good colour screen which is bigger than most all-in-one receivers, and will run lots of useful software (see below). A PDA isn't as rugged as a normal GPSr, but is more versatile (and I had one anyway!)
- Petzl Tikka head torch. Useful on so many occasions. [~£25]
- My bike. How else would I get to the caches I can't walk to?
- Cetus GPS. This the Swiss Army Knife of GPS and lets you display all the data provided by your receiver, record and manage tracks and waypoints, and navigate using range and heading. Best of all, it's free! It runs on the Palm and is the most useful bit of caching software I've got. It's what I use to actually home me in on a cache. [Free]
- Fugawi UK Maps 2. This provides electronic Ordnance Survey 1:50000 scale maps, covering the UK in four packages. The software works, but is very clunky. I wouldn't use it apart from the quality of the mapping. It's primarily PC-based, giving 2D and 3D views, but you can get a 2D moving map from it onto the Palm. One of the best features for me is the ability to click on the map, get a list of nearby Geocaches displayed in my web browser, then show all those caches on the map and copy everything to the PDA. I've had problems getting it working with the Tungsten T3, and have only managed to get maps on there by Hotsyncing them to a (very old) Palm m105, then using Infra-red to beam them over to the newer unit. [Commercial, £50 / region]
- Pathaway GPS 4. Another mapping program, but more Palm-based. It's got many more features than Fugawi, but also more bugs. I use it for maps of areas not covered by my Fugawi package. The tricky bit is getting the maps calibrated properly... [Shareware $60]
- GPS Babel. Tool to convert the .LOC cache location files from Geocaching.com into waypoint files suitable for Cetus, Fugawi, Pathaway or pretty much any other software. [Free]
- SiRFDemo. Configuration/diagnostic software for SiRF chipsets. I use this since it gives far more options than the software supplied by Globalsat with my BT-338. [Free]