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A boon for outdoor recreation
New features you can find
Geocaching: the search for hidden treasure
Professional uses for conservation work | An economic engine
Geocaching lingo | GPS terms | Where the caches are
It hasn't always been so easy, knowing exactly where you are on earth. Learning how to get there from here perplexed explorers, armadas and merchants for centuries.
In October 1707, a returning British war fleet led by Admiral Cloudesley Shovell foundered in dense fog on the rocky Isles of Scilly off the coast of southwestern England. Four ships sank and nearly 2,000 sailors died. The calamity in home waters pushed Parliament to pass the Longitude Act of 1714, establishing a prize of £20,000 for a practical and reliable method of calculating longitude at sea.
Latitude – the distance of a position north or south of the Equator – was easy to determine by celestial navigation using the elevation of the northern pole star, Polaris, or of the sun at noon. But two lines of position are needed to determine location. To find longitude, or one's east-west position, ocean navigators needed to know two things: the exact time in their home port, and the exact local time on the ship. Pendulum clocks, then the most accurate clocks available, did not work properly on the rolling seas, leaving sailors to rely on dead reckoning, which was inaccurate out of sight of land or in bad weather.
In 1736, John Harrison, a largely self-taught clockmaker, finally succeeded in building the key to calculating longitude. His invention, the chronometer, was a spring-driven timepiece accurate enough and rugged enough to work reliably at sea.
Today, finding your place on the planet is as simple as turning on a handheld electronic instrument known popularly as a GPS unit. In moments your position is displayed to within a few meters of absolute accuracy. Mark a hot fishing spot on open water, navigate to a camping spot deep in a wilderness, find a portage on an overgrown shoreline, note the location of a rare plant, or direct rescuers to your location? No problem with GPS, which correlates to a set of built-in maps programmed into the unit.
The geographic positioning system (GPS) links to a system of satellites orbiting at fixed locations around Earth. The satellites send signals down to the surface. The unit in your hand picks up and triangulates the signals from several of the satellites to compute your location. Some units are capable of measuring altitude as well.
Outdoor enthusiasts have been quick to pick up the new technology for recreational use. Law enforcement, search and rescue teams, foresters, biologists, surveyors, engineers, pilots, utility workers and many other professions use GPS daily. The relatively inexpensive technology also has spawned a popular new outdoor recreation called geocaching.
A boon for outdoor recreation
Hunters, anglers, hikers and other people who spend a lot of time enjoying the outdoors appreciate the additional measure of accuracy a GPS unit lends to their adventures.
"We sell to a variety of customers," says Rich VanDoorn, a manager at a local Gander Mountain store. "We see the hunters and anglers you'd expect, but we are also selling units to farmers who link GPS to computers in their tractors to measure the boundaries and sizes of their fields and accurately calculate pesticide and fertilizer application rates.
"Some GPS units can be programmed to read lake maps, including depth contours, stored in the unit's memory. These are popular with anglers. Other units can carry detailed topographic maps, sun and moon cycles, and a built-in barometer, which are popular features with both hunters and anglers."
Because they are used outdoors, most GPS units have some degree of weatherproofing. Some models float, a desirable feature if you are fishing, paddling, boating or sailing. VanDoorn says the most popular unit his business sells runs about $200 and is packaged with map software.
GPS is a great tool – but like any technology, it may not operate properly due to environmental conditions and shouldn't be used exclusively, say experts.
"GPS doesn't replace traditional map and compass skills," Tom Ponik at REI [another outdoor equipment retailer] told me. "It's a great addition to backcountry navigation but it can fail or get dropped and broken, and if you can't find your way with a map and compass, your trip will be spoiled at the least or you may end up in a serious situation at the other end of the trouble scale."
Of the retailers I talked with, only REI offers classes on how to use GPS. The course is called, appropriately, GPS 101, and is offered periodically based on demand; advance registration is required. Students have a classroom session then get some hands-on experience in the store's parking lot.
Most of Ponik's early customers were backcountry travelers, and they are still important users, but geocachers are catching up. Lately he's been selling small wrist- and handlebar-mountable GPS units to runners and cyclists, who use the units to accurately record mileage and route information on their rides and runs.
New features you can find
Spawned by the military's need to accurately navigate across oceans and continents, the GPS satellite system originally had what's called "selective availability" (SA). Considered necessary for national security, SA intentionally produced an error of up to 150 meters in non-military GPS receiving units on earth. Military-issue units could work around the error.
Due to the growing civilian demand for the best accuracy possible, selective availability was turned off in May 2000, instantly upgrading the accuracy of GPS receivers available to civilians to within a few meters under good conditions. Newer units can also take advantage of WAAS, or Wide Area Augmentation System, that adds a bit more accuracy.
Older units had limited internal memories and offered only black and white screens. These units had sufficient memory to display crude maps but not much useful detail. Now it is possible to buy units featuring removable memory cards similar to the matchbook-sized removable memories used in digital cameras.
With the expanded memory capacity, units can hold a large number of highly detailed maps. Most places selling GPS units also carry map databases on compact discs with the quality and detail of the 7.5 minute, 1:24,000 topographical maps published by the U.S. Geological Survey. Users can download data to a CD using a home computer and then load the desired maps onto the GPS unit's removable memory.
Mapping software allows detailed route planning that displays elevation gains and losses, distances and waypoints. Waypoints, which are essentially dots on a map, can be recorded in the field; these points of interest can be transferred to a map when the user returns home. There are a number of software brands and features for GPS units with prices starting at around $100.
Units sold these days are capable of displaying your position and your destination in several ways. In addition to maps, numerical latitude and longitude readings are also displayed. Positions are pinpointed electronically using other numerical systems. Many users choose the UTM or Universal Transverse Mercator system that shows 1,000-meter-square grids, making it relatively easy to calculate distance from one waypoint to another, or to plot your position onto a paper map in the field using the information displayed on the unit.
Direction-of-travel may be shown graphically as in an electronic "road" on the screen, which the user follows. Or, users can choose a more traditional compass bearing. Backcountry users still need to interpret a map because the direction between two points is shown as the shortest possible distance – in other words, a straight line. Straight-line travel often is not possible due to rivers, lakes, canyons or steep terrain that require the hiker to assess the topography and plan a route.
"All GPS units can show the user where they are, what direction to head to get somewhere, and can record waypoints for future use," says Steve Collins, manager of Fontana Outdoor Sports in Madison. "Additional features come at a cost."
Collins characterized GPS units as "navigational units" and "mapping units."
"Upgraded features like color screens make certain mapping details easier to read, which are great, but they usually come at the cost of faster battery drain," he says. For folks taking units into the backcountry for days at a time, a simple no-frills "navigational" unit will have a longer battery life. "Using the unit as a positioning tool along with a standard paper topo map makes the best use of both items, since it's difficult to get a real sense of what's around you from a small portion of a map on a 2x3-inch screen," Collins says. Topo maps provide the true lay of the land and point out rivers, roads, wetlands, cliffs and other landmarks that are a bit farther away.
Other features adventurers may want to consider are built-in altimeter and compass functions. Collins advises against relying solely on satellite signals to produce accurate altitude and compass readings.
"Altimeters that are barometer-based tend to be more accurate," says Collins. "Satellite-signal compasses only show direction when you are moving, unlike a magnetic compass that shows direction whether you are stationary or moving."
Geocaching: the search for hidden treasure
Geocaching, a new recreational sport, uses GPS technology in a kind of high-tech scavenger hunt. The 2005-2010 Statewide Comprehensive Outdoor Recreation Plan (SCORP) reports that 83,000 people participate in geocaching in Wisconsin.
Geocachers place small treasures in waterproof containers in a variety of locations – at a scenic vista, along a favorite hiking trail or picnic place, deep in a forest, on a rock cliff face, at the bottom of a shallow lake bed, or in urban settings such as parks, greenways and boulevards. Sometimes the "cache" is a larger landmark. The latitude and longitude of a cache is posted on the Internet so others can download the coordinates and set out to find the cache for themselves. It sounds simple, and some caches are relatively easy to find and reach, but others can involve strenuous cross-country hiking over a variety of terrain. Some cache directions combine latitude-longitude coordinates with compass bearings, distance clues and riddles.
"One of the great things about geocaching is that the whole family can partake in the activity," says Jeff Prey, recreational planner for the Wisconsin state parks system. "Many caches are easy enough for young children to find, while others can challenge even the most skilled outdoors person." The new trend is "virtual geocaches" that typically require finding certain information about the location's natural or cultural history, then checking your answer with the cache creator by e-mail or online at one of the many geocache websites.
The Department of Natural Resources recently developed guidelines for its property managers to use in overseeing geocaches placed on state lands. State parks and forests are popular sites for establishing geocaches and a visit to the DNR website provides links to maps showing the locations of more than 1,000 documented geocaches in Wisconsin.
In general, most land managed by the Department of Natural Resources is open to placing geocaches with permission from the property manager. A site registration form can be downloaded from the website and a key tells you where to send the form based on the kind of property, such as a park, a forest or wildlife area. Geocaches are not permitted at environmentally or culturally sensitive sites such as natural areas, archeological or historical sites.
Geocachers are asked to remember that many families participate in this new sport and certain items are not allowed to be placed in a cache such as food, pocket knives or weapons of any kind, illegal items such as drugs, or other materials normally restricted from minors.
Professional uses for conservation work
"We're all about where things are," says Bill Smith, a conservation biologist with a special interest in dragonflies. "We use waypoints to describe where we are and what's there at a specific point in time. By comparing repeat visits to the waypoint over time we can note any changes."
Before GPS technology was available, field biologists used aerial photos and quad maps to document the location of observations. It was and is difficult to precisely document in latitude and longitude where a sample point is from photos or maps. "An affordable handheld GPS unit does it within a few feet," says Smith. "In the case of field observation, GPS provides a degree of accuracy of observation unavailable to researchers only a few years ago."
Smith notes that "repeatability is a basic premise of good science." To that end, over the next four years the DNR's Division of Forestry will establish 4,000 permanent survey plots to measure changes in forest cover over time. Each plot will be visited once every four years by a forester who will meticulously record data on tree sizes and species, ground cover species and abundance, amount and type of woody debris, soil types, depth of coarse organic material such as leaves and needles, and a number of other environmental benchmarks.
"These recordings will give us a very accurate picture of what kinds of changes are taking place over time in our forests," said Teague Prichard, DNR public lands specialist. "The power of this project is in the ability to revisit the exact same place time after time to repeat and compare measurements. Each plot will have latitude and longitude coordinates and the foresters will use handheld GPS units to guide them to the survey plots. Before this technology was available, foresters would use survey stakes and flagging, all of which can disappear or be difficult or impossible to find four years later."
GPS is indispensable in aviation today. "Visual flight rules are still important for orientation and navigation in conservation aviation work, but GPS adds a degree of accuracy and repeatability we never had before," says John Jorgensen, acting chief pilot in the DNR aviation program.
"We use it every time we go up; not only as a navigational aid but as a precision tool that has many, many, specific applications for conservation programs," Jorgensen says. "It provides easy and accurate locations for everything from aerial population surveys for deer and wolves to nest counts for eagles, ospreys and trumpeter swans. It's also used to define areas that will be sprayed for gypsy moths and to determine the size of a forest fire."
GPS-equipped aircraft also have a public safety and law enforcement mission. Using GPS, pilots are able to pinpoint possible violations and pass information along to wardens on the ground for investigation. And GPS-generated latitude and longitude coordinates are used to direct initial attack ground crews to wildfires spotted from the air. Aerial photography benefits from GPS as new cameras are available that include GPS coordinates on the photo, similar to the familiar time and date stamps.
GPS adds an additional measure of safety in the cockpit, says Jorgensen. The location of towers and other structures that are a concern to low-flying survey aircraft can be programmed into an onboard GPS unit, alerting the pilot to the danger.
GPS coordinates are used to note environmental changes on the landscape, such as the locations of abandoned wells, new wells, spill sites, underground buried tanks and field inspections.
An economic engine
The GPS industry is growing. Estimated at roughly $12 billion in 2002 by The Economist magazine, it's difficult to walk into any outdoors shop, automobile showroom or electronics store and not run into a GPS display. The transportation industry has incorporated the technology into onboard navigation systems in trains, planes, trucks and automobiles.
The folded road map likely will never be replaced, but many paper-based mapping companies are expanding into digital mapping. A familiar purveyor of printed maps, the DeLorme Company of Yarmouth, Maine, is one of several businesses producing detailed digital mapping software for use with GPS units.
"Wisconsin is in the top five states for the number of DeLorme Gazetteers sold," said the company's Charlie Conley. "Similar to our home state of Maine, Wisconsin is a destination state for many people and that is typically where we have our strongest sales, year after year."
The familiar red, white and green DeLorme Atlas and Gazetteers are found in all kinds of shops across the country and under the seat of most automobiles at trailheads, boat ramps, parks and forests.
"Gazetteers do a great job of getting you to easily identifiable places," says Conley. "They have a great deal of information and longitude and latitude tick marks in the margin of every page. At the scale of the maps we print to fit on the page of the Gazetteer, which is typically in the 1:150,000 or 1:250,000 range, they are only able to get the user into the ballpark in terms of pinpointing a location. [To get within] a few meters of accuracy handheld GPS units are capable of measuring, users need the digital version of our maps."
As an example, Conley notes that at large-map scales, a fine ink line on paper can represent several football fields on the ground. Conley recommends that people use the Internet to search out the features they would find most useful in a digital mapping application.
Another strategy? Ask as many GPS users as you know what they like or dislike about their mapping software, join a geocaching organization, or check out some online chat rooms. None of the retailers we visited loaned out software for field trials, and sales staff might be familiar only with product lines they sell. The software can cost hundreds of dollars, and in most cases, once you open and install it, you're stuck with it, so it's worthwhile to make the effort to learn as much as possible before you buy.
It was nearly 20 years after clockmaker John Harrison produced his durable timepieces that he finally received the prize for finding the solution to the longitude problem. It took much of that time for his system to prove itself simpler and more reliable than the complex astronomical observation systems his competitors advocated. Today, GPS technology is found in cell phones, portable computers, snowplows, delivery vehicles and even shoes. What would Harrison think now?
Robert J. Manwell is a DNR public affairs manager and an avid backcountry explorer.