Using a GPS on a Hike Using a GPS on a Hike

A How-To Guide Using a GPS on a Hike

GPS units have become quite affordable over the past few years. They can be a useful tool for hiking, but they can also be a little overwhelming. What are they useful for? Can they be useful along the Heysen Trail?

By Jeremy Carter

Let’s Distinguish GPS Units What is the GPS System? There are hundreds of GPS units GPS stands for Global Position on the market, and not all will be System. It is a system of orbiting useful to hikers. We need to make satellites that a GPS unit, or more a distinction between the handheld accurately, a GPS receiver, will use portable receivers for hikers, and to find its position anywhere on the myriad of GPS units for other the surface of the planet. GPS is a uses such as car navigation. A GPS US military application developed unit filled with road maps and in the 1970s. A network of 24 driving directions isn’t going to be core satellites with six additional very useful when you are out hiking satellites orbit the planet, each in the bush. GPS units suitable for completing two orbits of the planet hiking tend to be small, fit in the a day. A GPS receiver needs to hand, contain a map screen, and be have an unobstructed line of sight waterproof and durable. with four satellites in order to find its position. Each satellite has an atomic clock installed - a very 186 Trailwalker Spring 2011 Trailwalker Spring 2011 7 Using a GPS on a Hike Using a GPS on a Hike accurate clock. The GPS receiver 3. Load a GPS file onto the GPS compares the time a signal left receiver and use it to navigate How does Trilateration the satellite to when it arrived at along a trail, or to a known place. work? the receiver in the hand, the time Imagine you are somewhere in difference is used to calculate The first is easy, the second a little Australia and you are TOTALLY lost the distance. Receiving signals more complex, the third even more - for whatever reason, you have from four or more satellites, the so. Let’s look at each one in detail, absolutely no clue where you are. GPS receiver can determine its and how you could use them on You find a friendly local and ask, x, y and z coordinate (longitude, the Heysen Trail. “Where am I?” He says, “You are latitude, elevation.) This is called 1290 km from Adelaide.” 3D Trilateration - don’t worry, 1. Use the Trip Computer to This is a nice, Anywhere display how far you have walked, along this you never need to remember that hard fact, circle term or understand how it works and for how long but it is not in order to use GPS. The panel This is similar to how a dashboard particularly useful by Adelaide on the right of this page explains in a car will display the speedo and trilateration in more detail. itself. You odometer. You can see how long could be you have been moving for, and anywhere on a circle Other Satellite Systems how long you have been resting. If around Adelaide that has a radius You’d be right wonder about you know how long the hike is you of 1290 km, you could be in long term access to a US military can work out how much is left and Newcastle, Towoomba, Alice application. During times of war estimate how long it will take. Springs or on the Nullabor. or conflict the US could disable You ask You will need to reset the Trip somebody or suppress the GPS system for Cairns non-US military use. Indeed, prior Computer at the start of each else where or here to 2000 the signal was encoded hike. On most receivers you you are, and she so only the US military could can customise which fields are or here says, Adelaide accurately use it. US military GPS displayed, and sometimes how large or how many fields appear. “You are receivers are far more accurate, 1451 km and less prone to interference than from Cairns.” Now the civilian GPS receivers available you’re getting somewhere. If you to the public. combine this information with the Current Distance Adelaide information, you have speed covered Other countries have sought over day two circles that intersect. You now to secure their own satellite know that you must be at one of Total Average these two intersection points. navigation network, the Russians walking walking speed time have built the GLObal NAvigation (when moving) If a third Satellite System (GLONASS), which person Cairns was opened to the public in 2007. tells Broome Average The European Union is developing you that Alice Springs Total walking speed resting taken over you are the Galileo positioning system, whole day You can time 1368 km only be here due to commence in 2014, and the Adelaide Chinese the Compass navigation from Broome, you can system, which will consist of 2. Use the coordinates to eliminate one of the 75 satellites. find your location on a possibilities, because the third topographic map circle will only intersect with one Three Basic Ways for a Hiker of these points. You now know ex- to use a GPS Receiver By default GPS receivers report actly where you are - Alice Springs. their location in longitude and There are three basic ways to use The example uses only three latitude. Whilst some topographic a GPS receiver when hiking, you locations - not four - because it is maps include some references to could use one, two or all three: only working in two dimensions. longitude and latitude, generally it GPS uses a fourth location to 1. Use the Trip Computer to would be very difficult to find your determine the elevation, and to display how far you have walked, precise location on the map using improve accuracy. and for how long. these figures. Much easier is to Source: 2. Use the coordinates to find use grid references. Grids overlay http://electronics.howstuffworks.com/ your location on a paper topographic maps, including the gadgets/travel/gps.htm topographic map. maps in the Heysen Trail 6 Trailwalker Spring 2011 Trailwalker Spring 2011 197 Using a GPS on a Hike Using a GPS on a Hike guidebooks. On paper we often refer to grid references in six digits, ie

We’ll meet you at The two 7-digit numbers in the Location field The Dutchman Hut represent a measurement GR 809 228 on that map. The Grid Reference here is 810 220 (ie xx810xx and xx220xx)

GR means The first The second along the trail, or to find campsites. Track, route and waypoint are the only Grid Reference 3 digits are for 3 digits are for the horizontal the vertical or Depending on the brand or model of possible things a GPX file can contain. or east-west north-south You will often see these terms used axis axis GPS receiver, it could be an easy or complex task to load the file onto the on GPS receivers. Each Heysen Trail This system is called UTM for short. GPS receiver from your computer. guidebook chapter is a different track UTM covers the planet with a grid, - so six chapters in each of the two each grid line at a 1000m (1km) To download the file, visit guidebooks equals 12 tracks. spacing. www.heysentrail.asn.au, select ‘Heysen Trail’ from the top menu, The GPX file on the Heysen Trail However GPS receivers will display then ‘Maps’ from the side menu - or website also contains waypoints of each of these UTM fields as a visit www.heysentrail.asn.au/heysen_ campsites, shelters and huts along or seven digit field (as in the photo trail/maps.php. near the Heysen Trail. above right), not the two sets of three digits as seen on the GR The files are in GPX format, a 3.1 Navigating Using a Track note above. The seven digits are universal file format which can be Once loaded onto the GPS receiver, a measurement in metres, and used on most GPS receivers. Once you will see the 12 tracks under the is too accurate for our needs. you have connected the GPS receiver Track Manager menu. For Garmin 2cm on our topographic maps to the computer, you can save the receivers, if you select the relevant represents 1000m, or 1km - this GPX file onto the GPS receiver via track and select ‘Show on Map’ you is true of all 1:50 000 topographic Windows Explorer (for PCs). In the will see the track on the map screen. maps, including the Heysen Trail case of Garmin receivers, you would When you are out hiking, you can guidebook maps. A single metre save it onto the drive of the GPS use the TrackBack feature on Garmin will appear as only 0.02mm, receiver, not the drive of the SD card receivers to navigate - access this 10 metres will appear as 0.2mm. (the SD card is only for background feature via the Where To menu 100 metres will appear as 2mm. So topographic maps.) Place the file in or Track Manager menu. The GPS of the seven digits, the last two digits the GPX folder. receiver will already know where you are of little use, we can discard them. are, you might be at the start of the We really only need the middle three Older GPS receivers, like some of the chapter track, somewhere along it, or digits of each set of six digits. The Garmin eTrex series, will not accept at the end. Each Heysen Trail chapter first two of these three digits are the this format. They require files to be track heads in a south to north numbers seen on topographic maps. loaded in their native file format, in direction. Activating the TrackBack The third digit you will need to the case of the Garmin eTrex this is feature, some GPS receivers will ask measure off on the map yourself. usually Garmin Mapsource program if you which direction you wish to - GDB files, or Garmin Trip and head, ie from start to end, or end to You will need to set the GPS receiver Waypoint Manager program. You will start, others will work it out for you. to display UTM coordinates. Usually need to use a program to convert If you are heading northwards along found in the settings menu, you’ll the GPX file to the GDB format. the trail, it will be start to end. If you see formats like hddd°mm’ss.s” and GPSBabel (www.gpsbabel.org) is a start somewhere along the chapter New Zealand TM - choose UTM UPS free/donation piece of software for track - not at the chapter end, this is - this is what we use on Australian converting files from GPX files to not a problem, select the TrackBack topographic maps. GDB files (it can convert to and from direction and navigation will begin almost any GPS file type.) You can from where you are. If you move 3. Load a GPS file onto the GPS then open the converted file in the over to the compass screen, the receiver and use it to navigate Garmin Mapsource program/Trip arrow will now point you in the right and Waypoint Manager program and along a trail, or to a known place direction to walk, and may show send it to the GPS receiver. you a few extra fields like distance This is the most complex of the three to destination (which is the end of basic ways to use a GPS receiver. The GPX file on the Heysen website that chapter track - it might be many There are files on the Heysen Trail contains the entire Heysen Trail as a days walk away), and may as you website you can download onto your Track. Track is a GPS receiver term, walk attempt to provide an estimated GPS receiver and use to navigate and differs from route and waypoint. arrival time. 206 Trailwalker Spring 2011 Trailwalker Spring 2011 7 Using a GPS on a Hike Using a GPS on a Hike

Distance to 3.2 Navigating to a Waypoint a waypoint. A route is a series of destination waypoints you create on a computer, Once the GPX file is loaded onto the placing them at significant junctions GPS receiver, you can also see all the Estimated time along a map. You then navigate to destination waypoints, one for each campsite, along the route, from one waypoint shelter and hut along or near the to another. You don’t need to do Arrow points Heysen Trail. With Garmin receivers, in direction this on the Heysen Trail as you can to walk these will all appear on the map navigate along the track provided in screen by default - unlike the chapter the Heysen Trail GPX file. tracks in which you need to select ‘Show on Map’. In the Waypoint Manager the waypoints will appear GPS Receiver in a list, sorted by how close they Advanced Use are to your current location. Distance to destination Further to the three basic ways to Using the Where To or Go To use a GPS receiver, there are more function, select to navigate to a advanced uses. You could find and Destination specific waypoint. The arrow on download GPX files containing the compass screen will point you tracks or campsite waypoints of in the correct direction, and inform other walking trails. Firstly, try you how far away that waypoint is. visiting the official website of the The map screen will also show you trail as the files may be available there. Sometimes published as a straight line between your current KML or KMZ files - these are Current point and your waypoint. Location the native file types of Google Earth - you can use GPSBabel (www.gpsbabel.org) to convert these KML/KMZ files to GPX files. This can be very useful as it can save Distance to destination If you can’t find an official file, try you from getting lost when you can’t trail doing an internet search for other see any Heysen Trail markers (the Destination people who have walked the trail white posts with red markers, this and published files. Be wary of isn’t another GPS term.) I’ve used Straight following their track too closely, this feature before on many trails, line path to Current you could end up wandering off destination Location including the Heysen Trail, and I’ve the trail where they did. met plenty of independent hikers using it. Generally you follow the In turn you could share your Heysen Trail markers, also reading GPX files with others. Many the map from the guidebook. If you people publish their GPX files on www.everytrail.com come to a Y-junction on the trail, It may not be as useful as it first and can find no marker, or stumble seems, as the distance to the Software programs are available off the trail, or just haven’t seen a waypoint will be in a straight line, which automatically assign the marker in a while, this is where the rarely are trails straight paths. longitude and latitude to each TrackBack feature and the compass However this can be very useful for photo. Comparing the photos you screen will be so useful. Head finding the camp site when you are have taken on your hike with the just four or five metres down the close by, but can’t see the camp site. GPX file, the program can add wrong trail from a Y-junction and the position data to the metadata You could create a waypoint at the of the photo file. This means the compass arrow will move from start of the walk. If you have already when you upload the photo to pointing straight ahead to pointing to been to the end of the walk, say say, Picasa Web Albums, you can the other trail, the arrow being left or when you left a car there, you could view on a Google Map where the right rather than upwards. Continue have created one there too. This can photo was taken. Using such a merrily in the wrong direction, help you to return to the same place program though relies upon you the compass will eventually point later, and know how far the end of synchronising your camera date downwards, instructing you to the walk is (as the crow flies.) and time with your GPS receiver. turn around go back. Continue a You could also self-publish files on long way off the trail it will start to 3.3 Navigating using a Route your own website via the Google recalculate the shortest distance Maps Javascript API interface. This to get back onto the trail, it might Route is the third item that can involves code programming, visit not necessarily be backtracking appear in a GPX file. Creating and http://code.google.com/apis/maps/ but be a straight line which might using a route is much more complex documentation/javascript/ not passable. than navigating along a track or to 6 Trailwalker Spring 2011 Trailwalker Spring 2011 217 Using a GPS on a Hike Using a GPS on a Hike Walking with white screen. Some GPS receivers have a map screen but come with no a GPS Receiver maps, or come with very basic maps. The GPS receiver should always be left An example of a track from poor placement of a GPS A very basic map can be of little use to receiver. The two tracks overlaying each other are along on while you are walking, including the same path through a wide gorge, from the same GPS hikers. Often called a Base World Map, breaks. When the GPS receiver is on it receiver, but on different days. The bolder track is when it includes broad detail of country the GPS receiver has been poorly placed, in this case a saves your path to a track, sometimes Garmin eTrex receiver in a side pocket of a backpack. The boundaries and major highways - but referred to as a breadcrumb. In the track points fluctuate, successive points taken just a few none of this will be very accurate as a seconds apart are some distance apart. The light track in Track Manager it is often referred to the background is from the same receiver, but when it has minimum number of points make up been placed lying flat in the top pocket of the backpack. as the Current track. If you get lost, It shows a consistent smooth path, the points appearing each object. you can use this track to navigate at regular distances and times apart - providing a much back along your path to a previous more accurate track and overall hike distance. Most GPS receivers allow this map to known place (refer to the instructions be upgraded. There are a number of shoulder strap. Newer GPS receivers on the previous page - 3.1 Navigating options, ranging from free open source are often designed to hang vertically, Using a Track.) software, to expensive highly detailed and with significantly improved topographic maps. reception are less prone to make errors The signal from satellites can still like in the above diagram. be received through your backpack Both Garmin and Magellan sell GPS material, so you can place it in a receivers with preloaded 1:250 000 pocket close to the edge of the pack. What to Look for When topographic maps - if purchasing one The signal can travel through fabric, Purchasing a GPS Receiver of these receivers ensure you buy canvas, plastic, glass, clouds - but from an Australian retailer and double Determining which of the three basic not metal, brick, rock, wood or heavy check that you are receiving Australian uses of a GPS receiver you will use can foliage. However, poor placement of topographic maps. Highly detailed help determine which features to look the GPS receiver in or on your pack topographic maps of the US or Europe for in a GPS receiver. GPS receivers can affect its ability to receive satellite may not be of much use to you in can cost as little as $100 for an entry signals. This is particularly true of older Australia. This can often be a very level unit, receivers with more features GPS receivers. In some older GPS cost effective way of getting on-screen up to a $1000. receivers the GPS chip faces upwards topographic maps. when you are looking at the screen - so Most newer GPS receivers are easy if you stow the receiver vertically in a You can also purchase topographic to use with large colour screens. pocket or around your neck, it can only maps from a third party and load them Some have touchscreens, memory see up to 50% of the sky and available onto your GPS receiver. These start cards, compasses (that function even satellites, which could be a problem from several hundred dollars. They when stationary), altimeters (using in gorges or heavily treed areas. You come supplied on a DVD and you will barometric pressure to improve should stow such a GPS receiver near need to use a program to upload the elevation accuracy and monitor the top of your pack, preferably laying maps onto your GPS receiver. Some weather changes) and cameras. flat in a top pocket or attached to a retailers offer preloaded SD cards as an Know what you are purchasing, check alternative, this is a no-fuss solution, A GPS Receiver or a the manufacturer’s website for the you simply insert the SD card into your Paper Topographic Map? model details, you might find the GPS receiver and it is ready to use. model you thought was quite new is a OzTopo sell Australian topographic For many years people discussed discontinued model. maps for Garmin receivers - visit whether a GPS receiver, loaded www.oztopo.com.au. These maps are with topographic maps, could On-Screen Maps based on 1:250 000 topographic maps. negate the need to carry paper topographic maps. An electronic Most GPS receivers come with a map A free option for Garmin receiver could break, fail or run screen, but some do not. Navigating receivers is ShonkyMaps - visit flat, but paper maps could be lost along a track or to a waypoint will be www.shonkylogic.net/shonkymaps/ or water damaged. Neither is the much more difficult without an on- Allegedly based upon GeoScience clear winner. If you carry a GPS screen map, and easier with a larger Australia’s 1:250 000 topographic receiver you’ll still need your paper rather than smaller screen, and easier maps, there are reports that the level topographic map. For one, most on- on a colour screen than a black and of detail is not the same as that offered screen topographic maps available by Garmin or OzTopo. for Australia are based upon 1:250 000 scale topographic maps - Another free option is to use the the Heysen Trail guidebook uses the Open Source Map of each Australian more detailed 1:50 000 topographic state - anyone can update these maps (around 5 times more detail.) An example of two different GPS receivers, one maps online. These maps are not Secondly, even the larger GPS recording its position more often than the other. topographic, but show highways, receiver screens still can’t parallel The bolder track shows the less often recorded track, recording just 20% of the points. This has resulted in a roads, dirt roads and some tracks. Visit unfolding a large topographic map to shorter distance being measured - 3.3km compared to www.osmaustralia.org/garmin.php, get a sense of where you are walking the more detailed receiver’s 3.7km - amounting to 3km over a 25km hike. The problem is more pronounced you may need to use something like over several days. when the track meanders over short distances, and could be barely discernible on long road walks. Img2gps (www.wpkg.org/Img2gps) 226 Trailwalker Spring 2011 Trailwalker Spring 2011 7 Using a GPS on a Hike Using a GPS on a Hike

to upload the map onto your GPS receiver. Why Different Results?

Whether topographic maps are Why do people report different hike • Different GPS receivers update their preloaded or not can significantly affect lengths when they have undertaken the position more often than others - same day hike? No two GPS receivers between one and perhaps 15 times the price - if you intend to purchase will report exactly the same figure, the a minute. The more often, the more topographic maps factor this in. same GPS receiver will often not record accurate the overall walk length. the same figure if the trail is followed Battery Life • The more satellites visible to the again. I have tested out someone else’s GPS receiver the more accurate Some feature rich receivers can use a GPS receiver alongside my own - the tracking - the signal from the almost identical models. I placed them lot of battery power. 20 to 30 hours of satellites is weak, dense foliage, tree hanging vertically side-by-side in my battery life is good. Battery life could trunks or narrow gorges will block pack, yet they slightly yielded different signals. be more important if you undertake results. Why? multi-day hikes where you won’t have • Although the GPS receiver attempts • GPS receivers are complex devices the opportunity to recharge or replace to compensate, the signal from a performing many calculations on satellite slows the further it travels batteries. Lithium batteries tend to last signals from many satellites (up to through the atmosphere - particularly the longest amount of time, followed 12 at a time.) affecting signals from satellites close by alkaline, and rechargeable batteries • Poor stowing of the GPS receiver in to the horizon. the shortest. Lithium batteries are or on your pack will affect its ability • The signal from a satellite can be much more expensive, but can last to receive satellite signals. reflected off objects such as large up to a week - however some GPS • Newer GPS receivers generally rock surfaces and buildings. receivers will not permit lithium provide far more accurate results • Each GPS receiver is using its batteries as they may interfere with the than older receivers. own internal clock to measure the screen display. • Old GPS receiver software may length of time since a signal has contain bugs which cause over or left a satellite. When four or more Track & Waypoint Memory under reporting of walk lengths. For satellites are locked in, it can start instance, Garmin Oregon receivers checking the accuracy of its clock, Some older GPS receivers can only (the x50t models) with early software but regardless its clock is not store a small number of tracks and under report the walk length on- anywhere near as accurate as the waypoints. The Heysen Trail GPX file screen by around 20%. atomic clocks on board the satellites. contains 31 tracks (12 chapter tracks and 19 spur and alternate trail tracks) A Popular, but Old, Model Product Reviews and 135 waypoints. Some devices can store as little as 20 tracks. Garmin’s basic eTrex, the original Excellent non-biased, thorough yellow one, although once trusted product reviews can be found Smart Phones amongst walkers, is old technology in BackPackingLight articles now - first produced in 1998. Unless (http://www.backpackinglight.com). A smart phone (an iPhone or Android your computer is a decade old you will Single articles can be purchased phone) may offer a viable GPS receiver need to buy a serial to USB connector for $4.99, or by annual article alternative. There are apps available for your computer. Saving waypoint subscription. Conduct an Advanced that function as trip computers, names is limited to 8 character names. Search for articles with your GPS brand showing your track on the map No maps are displayed and its accuracy and model. and allowing you to add waypoints. level is not as good as others, despite Weatherproofness and battery life the “Now with high signal capability” Run the Latest Software could be issues. A fully charged stickers on the box. It doesn’t record as GPS receivers operate on software, many points in its breadcrumb track as smartphone may last as little as three much like your PC needs Windows other GPS receivers, and there isn’t a hours whilst running a hiking GPS to run. You should periodically app. Also, the basemap is likely to setting to adjust this. check you have the latest software be Google Maps - principally a road version, manufacturers may release In mid-2011 Garmin upgraded their navigation map - and only visible software updates to fix bugs - eTrex range of receivers, releasing where there is mobile phone coverage, visit the support section of your a new, updated version of the however there are some topographic manufacturer’s website. maps coming onto the market which yellow eTrex. complement Google Maps. Where to Purchase Further reading for smart Purchasing online could save you Want to Comment phone users can be found by money, but be wary of preloaded maps on this Article? purchasing (from $4.99) a copy that might be for the US or Europe. If you want to comment on this of this BackPackingLight article: It could be reasonable for a shop to article, clarify a point or ask http://www.backpackinglight.com/ assist you in setting some of the basic further questions, please visit cgi-bin/backpackinglight/smartphone_ receiver settings for Australia so it is http://bit.ly/hiking-gps navigation ready for you to use. 6 Trailwalker Spring 2011 Trailwalker Spring 2011 237