Geocaching GPS

Definition of 'GPS': A global positioning system; also sometimes referred to as a GPSr (Global Positioning System receiver). A hand-held, or vehicle (car, boat, airplane) mounted system for determining your Lat/Long (Latitude/Longitude) position on the face of the earth. A series of satellites orbiting the earth transmit signals which allow a receiver to determine an accurate position, depending on the number of satellites that can be picked up at one time and the signal strength. Dense foliage can reduce signal strength or block it all together, as can rough terrain or driving through an area many tall buildings.



What brands to look for: Garmin and Magellan are two popular brands. DeLorme is another up and coming brand that also packages Topo (Topographical) and/or street maps with the GPS, for a price comparable to other GPS units alone.


What features are important for geocaching?: A first consideration would be sensitivity. Garmin is producing units with 'High Sensitivity' chips ('H' series/models, i.e., eTrex H, eTrex Legend HC, eTrex Vista HCx, etc.) and has models with 'quadrahelix' antennas (Map 60CSx). Both dramatically increase the sensitivity of these units. Increased sensitivity means an improved ability to receive a signal under dense foliage or rugged terrain. A basic unit, like the Garmin eTrex H is a very good unit to start with, for around $125. The Garmin Map 60 CSx may be over $400.

Beyond that, other features to consider:

• Waterproof: Most GPS units are 'water proof' or water resistant (IPX2-light mist; 4-rain/splashing; 7- 1 meter @ 30 minutes) to a degree that will resist damage from an accidental dunking or exposure to rain. Geocaching takes you outdoors. You may get wet. Some units are 'marine' units and may float, or be fully immersible (a GPS will not work very far under water). The standard 'water proof' rating is acceptable for geocaching.
• WAAS: Most new units on the market feature WAAS (Wide Angle Augmentation System) capability. WAAS uses two additional satellites on East & West coast, synchronized with ground stations, and can increase accuracy by 10-15'.
• Color screen vs. monochrome screen. Monochrome will work fine. The color screens show more detail and may be more useful if you start adding maps.
• SD Card or micro SD Card Slot: Maps come on either DVD or pre-installed on SD Cards. Maps on DVD allow you to load the portion that you will use into the on-board memory and/or the memory card and cannot be transferred from one unit to another. Maps on SD cannot be edited, but the card can be moved from unit to unit, i.e., from a Garmin Nuvi (for an automobile) to a hand-held unit, or to a friends compatible unit. SD cards also allow the creation of MANY custom POI's (Points of Interest).
• Number of waypoints the unit can hold: For geocaching, a waypoint is the location, or geocache, you are searching for. The etrex H can hold 500; other units 1000, or more if you use the SD card (the 'x' part of the description of "CSx" or "HCx". Beginning geocachers will just need to load a few caches at a time. Advanced cachers may load 500-1000 in the unit itself, or use the SD card to load many thousands as Custom POI's (Points Of Interest). This can be useful for driving trips across the country.
• USB cable included, or extra, vs. no PC interface: Basic geocaching can be done by entering coordinates manually. An unit with a cable can be connected to a PC and receive coordinates directly from a web page description on geocaching.com, or by sending 1 -1000 at a time using geocaching software. Downloading coordinates can help eliminate embarrassing position errors, where a misplaced digit may place you in a river, ocean, the street or a private backyard. Some units are still sold with a Serial Data Cable, which may require the purchase of a 'USB/Serial Converter' to allow interface with a PC (your PC may, or may not have a Serial Data Port and may ONLY have USB Ports). There can be driver and Com Port setup issues to troubleshoot when using a 'USB/Serial Converter' and may not be for the computer novice.
• Maps: Garmin units, unless purchased 'bundled' with Topo or street maps, come with a 'base' map of the United States, or the world, which show major features like larger cities and towns, larger rivers, main highways. Base maps are not useful for navigating by themselves. Topo maps, showing terrain/elevation changes, are useful to outdoor enthusiasts. Street maps, in some units, will allow them to auto-navigate, much like a dedicated car unit and can be very useful when trying to determine which street will take you to a cache. DeLorme units come bundled with Topo and/or Street Atlas at a very competitive price.
• Battery: GPS devices that use 2-4 AA batteries are probably the most common and preferable to those with built in batteries. It is easy to carry a spare set of batteries as part of your geocaching gear and change them out if the unit dies in the field. And you can count on this happening. If the unit uses rechargeable batteries and it dies in the field, you are done until you can get it charged again. Many geocachers prefer to use the new generation NiMH rechargeable batteries; some have extended shelf lives and come charged.
• Other useful features may be built into the unit such as an electronic compass and barometer, tide tables, GPS games, hunting fishing tables, sun and moon tables (position in the sky, rise, set times), trip computer, calendar, calculator, stopwatch, etc.

What about software?:

Beginning geocachers can start looking for these treasures with a GPS out of the box and a set of coordinates from a cache description on geocaching.com. Advanced users may be interested in one of several programs to assist in organizing lists of caches and loading geocache waypoints to their GPS. Some of these programs are:

• ClayJar Watcher (GPX) - Windows Freeware application that helps you manage your Pocket Query GPX files
• EasyGPS -free application for managing both LOC and GPX file types
• ExpertGPS -Shareware application that can convert GPX files to iSilo and Plucker format
• GPX Spinner -Shareware application that can convert GPX files to iSilo and Plucker format
• GPSBabel -A free Windows, Linux and Mac console-based application for converting LOC and GPX to various other formats.
• Geocaching Swiss Army Knife (GSAK) -All in one application that allows you to manage GPX/LOC files, upload to your GPS, and convert to various other formats.
• GPS Connect for Mac OS X (GPX) - Garmin Specific application that works with GPX
• MapSend Lite - (GPX/LOC) is a free application from Magellan that now has built-in geocaching functionality

Advanced users may prefer to go 'paperless'; A Premium Member on geocaching.com is able to generate Pocket Queries (PQ's) of up to 500 geocaches to put on a GPS and/or Palm or PocketPC. This entails using one of the above programs to organize and load waypoints, both to the GPS unit and to a PDA (Personal Digital Assistant) which will run one of several programs to read the information. There are several advantages to going paperless, which include:

• Decreasing wear and tear on the environment by not wasting paper and creating additional waste in the form of discarded paper, ink and cartridges.
• Saving money by not printing out cache description to go geocaching. Cache descriptions contain important information like: coordinates, name (often a hint in itself), current status (active, temporarily archived or permanently archived), short and long descriptions, maps, hints and past logs. Most geocachers print out a cache description, either the entire page, or the print friendly page, to go hunting. When you go 'paperless' all of this information can be loaded to your PDA.
• Having multiple cache descriptions on-hand for one, or many, areas. If they are saved in the PDA, coordinates can always be entered into a GPS unit 'on-the-fly' or in the field.

Links for more information on 'paperless' geocaching:

• 'Geocaching U' - Geocaching Without Paper
• Miragee's Blogspot - Musings about Geocaching
• Wikipedia on Paperless Caching

Programs used for the PDA/Phone side of paperless caching include:

• CacheMate for Palm, Windows Mobile or Linux
• Cetus GPS (LOC) - Free Palm OS application that interfaces with your GPS through a serial port (or connected GPS).
• Geocache Navigator application works on a variety of GPS-enabled phones.
• GPXView (GPX) - Donateware application for managing GPX files on PocketPC 2002 or later
• iSilo - Document reader for Palm OS®, Pocket PC, Windows®, and Windows® CE Handheld devices. GPX Spinner can "spin" GPX files into this file format.
• Plucker - Alternate web viewer that works with Palm OS® based handheld devices. GPX Spinner can "spin" GPX files into this file format.

Approximate cost for a good gps:
Garmin Models (MSRP):

• eTrex H ($106.24)500 waypoints, 64 x 128 pixel display, 17-hour battery life, high-sensitivity GPS receiver
• eTrex Legend ($ 160.70) 1000 waypoints, 160 x 288 pixel display, 18-hour battery life, detailed basemap, 8 MB for optional maps
• eTrex Summit HC ($246.41)1,000 waypoints, 176 x 220 pixel display, 14-hour battery life, detailed basemap, 24 MB for optional maps, color screen, compass, altimeter, high-sensitivity GPS receiver
• eTrex Vista HCx ($321.41)1,000 waypoints, 176 x 220 pixel display, 25-hour battery life, automatic routing capabilities, color screen, microSD card slot, compass, altimeter, high-sensitivity GPS receiver
• Map 60 CSx ($374.99)High-sensitivity GPS receiver, color display, microSD card slot, 64 MB microSD card
• Colorad 300 ($533.32)High-sensitivity GPS receiver, color display, SD card slot, barometric altimeter, share data wirelessly with other Colorado users, built-in North American basemap

DeLorme Models:

• Earthmate PN-20 (419.95)The PN-20FULL VERSION of the newly-released Topo USA 7.0. Includes DeLorme Topo USA 7.0 DVD software with full, updated U.S. topographic & street maps to export as needed to your PN-20. Also includes an on-device highway-level world base map.

Magellan Models:

• Explorist 100 (109.99) Powerful, affordable GPS with track-plotter. TrueFixTM technology provides reliable accuracy to within 3 meters.
• Explorist 210 North America (149.99)22 MB of available memory, USB port and MapSend compatibility for topo or street navigation.
• Explorist 500 LE North America (199.99)High-speed USB port and unlimited SD card data storage make it easy to add detailed maps, for topo, marine or street navigation. Save track logs and more to 8 MB free memory.
• Triton 400 North America (199.99)Full-color navigation that's amazingly easy! SD-card compatibility enables you to add unlimited optional maps, tracks, waypoints, routes, geocaches and other user generated content.
• Triton 1500 North America (399.99) Touch screen control, built-in voice recorder and LED flashlight. SD-card expandability to add unlimited detailed maps and user generated content.

The MSRP (Manufacturers Suggested Retail Price) is just that and these units can often be found on sale if you shop around. You can try the manufacturers web sites and numerous on-line and box stores. For some help in deciding which unit you should buy, you might check the geocaching.com Groundspeak Forums with a search for something like, "which GPS should I buy" (keywords: "+which +gps +should +buy") in the GPS Units and Software Forum.

Where to buy GPS units (on-line and retail):

• Amazon.com "handheld GPS"
• Buy.com "handheld GPS"
• Ebay "handheld GPS"
• REI "GPS"
• Wal-Mart "handheld GPS"

Tips and tricks for using a handheld gps unit:

• When you get close to the point the GPS says the cache is located, i.e., within a couple of feet, put the GPS away and start looking for where something could be hidden. This may be a USP (Unnatural Pile of Sticks) or UPR (Unnatural Pile of Rocks), a cavity in a tree, magnetically attached to any metal surface (for smaller, or micro, caches) or camouflaged to look like something else.
• Geocachers don't like to bushwhack much more than you do. If a path takes you part-way to the cache and then your GPS starts leading you off the path into deep brush, you may be embarrassed to find the cache and discover the path wound back to within 5' of the cache.
• Units with a 'patch' antenna (Garmin eTrex/H, eTrex Legend/HC, eTrex Vista/HC/HCx, etc.) work best with the unit held horizontally, slightly in front of the body, for best satellite reception.
• Units with a 'quadrahelix' antenna (Garmin 60/CSx, etc.) will get good reception with the unit held horizontal or vertically.
• Carry a spare set of batteries!
• Heavy tree cover or rugged terrain may decrease your satellite signal, sensitivity, accuracy. Most units will display EPE or EPA (Estimated Position Error or Estimated Position Accuracy). Your GPS will get you close, but not stand you on top of, the cache.
• If the owner/hider of the cache had something like a 10' EPE or EPA when the cache was hid, the cache may be anywhere within 10' of the ACTUAL GEOPHYSICAL Lat/Long. If you have a 10' EPE or EPA when searching, you could theoretically be up to 20' away from where the cache is hid, due to this error. When you get close, put your GPS away and start searching.
• Mark your parking spot! If you're going for any length of hike, this may be how you find your way back to your car. Don't forget that most units keep track of the route you've walked with an electronic trail of 'breadcrumbs' and you can use your track to retrace your steps.