A Practical Guide to GPS -UTM

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A PRACTICAL GUIDE TO GPS - UTM

by Don Bartlett

QUO VADIS?

Last revision - January 10, 2007

With respect to the use of two portions of the Canadian topographical map, BOUCHETTE, 31 J/4,

used in this Guide, I hereby acknowledge, with thanks, the copyright of the Canadian Government:

Her Majesty the Queen in Right of Canada reproduced with permission from National Resources

Canada.

Because of my agreement with the NRC, I am not able to give anyone permission to reproduce the

Guide.

Table of Contents

Introduction.Warning.Limitations.Accuracy.How the GPS works.Beware.Dilution of Precision - DOP.Elevation (Errors).Differential GPS (DGPS).Latitude/Longitude vs. Universal Transverse Mercator Grid.Maps.Traveling.Way-points - WPs.UTM - an attempt to explain.Using UTM coordinates.User Grid for non-standard Maps, e.g. Qubec.Setting up your unit.Buying a GPS unit.Hooking up to an external power supply.Mapping - Transferring a Track to a Map.Speed.


http://www.dbartlett.com/index.htm#table 1/


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Variable readings.How not to use your GPS.For more information and links.

INTRODUCTION

(N.B. This Guide started as a text posting to rec.backcountry Feb.10,1995) Most of the articles and literature onthe Global Positioning System until then had only described the use of a GPS unit in a nautical setting. As

valuable as they are on water, they are equally as valuable in the bush, desert, mountains, tundra, or, just inCentral Park.

This is written therefore for hikers, fishermen, hunters and all persons who wish to traverse the wilderness in thefull knowledge of where they are, where they have been and where they wish to go, primarily in conjunction witha gridded topographical map and a compass.

In this discussion, I will at times use "GPS" to mean the actual hand held unit itself as opposed to the wholesystem of satellites and their control. I will also use "fix" to mean the actual position indicated by the unit in UTMcoordinates or Lat/Lon.

The most basic requirements for land use of a hand held GPS are:

1. The ability to give a position reading when not unduly impeded by overhead tree cover, thus virtually requiringa 12 parallel channel receiver unit such as the Eagle Explorer, Garmin 12XL or Magellan 315 or comparableunits by these manufacturers.

2. The capability to store at least 100 way-point (WP) positions in the unit's memory and preferably, many more.

3. The ability to list these WP positions giving their distance and direction from the current position.

4. If to be used with gridded topographical maps, the unit must be able to handle the most common UTM datum.(explained later.)

5. Automatic track recording should be available and as well, a Track Back feature.

6. If there is any thought of hooking the unit up to a computer for uploading, downloading, map making or havinga computer map available during travel, then there must be a cable connection for the computer.

7. In regard to the above, the unit must be able to accept and send data in the standard format, I believe thatused by Garmin is the most common.

Now that most units have maps in software and/or may have maps uploaded to them, see my cautions belowbefore choosing a unit Any added features are a bonus but not necessarily needed and must be judged on theirown usefulness.

All of the units have many other features, most of a nautical nature which may or may not be useful on land,depending on the circumstances.

The basic requirement for the ease of use of a GPS on land and the correlation of the readings directly to a maprequire that the GPS be capable of handling the UTM grid system (Universal Transverse Mercator grid). Whilethere are other grid systems in use, the UTM system is by far the most common. Within the UTM system, thereare many map datums specific to the area of interest. (More about this later.)

When we have roads, power lines, heights of land, mountains, rivers and lakes, these are often sufficient alongwith the map and compass for us to establish with a reasonable degree of accuracy, where we are on the map. In




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those featureless areas however, where all looks the same for miles and miles of slowly rolling bush-land,grassland, dessert, tundra, sea etc., the GPS takes over and will give a definitive location which may be foundand plotted on a map.

The usefulness of a GPS is now well recognized and interest is increasing all the time. As a result, there are thosewho do not know how to use a compass and map but, who after buying a GPS feel that they now have theultimate tool for ease of travel in backcounry. If a person does not have a basic understanding of how to use acompass nor the desire and/or ability to learn, a hand held GPS is not for them. Indeed, in a hostile environment,they may well come to grief. There is a learning curve in using a GPS intelligently and until time and effort hasbeen spent, a user may well be a hazard to himself and others.

A GPS is just another aid to traveling, high tech, yes, BUT must be used in conjunction with at least a compassand hopefully a detailed gridded topographical map. While using a GPS greatly assists in traveling in featurelessareas, it does not mean that there is no need to still maintain an independent record of way-points, routes anddirections in case of a system failure.

Back to Table of Contents

WARNING

No one should venture out in any area where being lost would present a danger with only a

GPS. It is essential to carry spare batteries, a compass and a map and to have the

knowledge of how to use them.This message is so important that those who read this

should pass it on to others, now that GPS receivers are becoming more and more popular.

See the excellent tutorial available at:

Kjetil's Compass Lesson

I always travel with a compass in the bush as the compass compliments the GPS and saves its batteries. I don't

always have a map with me. I do however always carry a small coil bound notebook and pencil for making verybasic notes in case something untoward happens to the GPS unit or the whole system (and I admit not using themenough!). The GPS should not be left on and used in place of a compass when on internal battery power in thewilderness unless there is an ample supply of batteries! In fact, unless the GPS is moving at several miles an hour,a GPS WILL NOT TELL YOU DIRECTION. When it is moving, it will give direction in relation to thedirection that you are travelling. Let me reiterate, A stationary GPS will not take the place of a compass. Thinkabout it, it knows its position in relationship to the satellites but it has no idea how it is oriented. Some peopleknow exactly where they are in a large department store but have no idea of north. Others in the same situationinstinctively update their internal sense of direction and know roughly where to find north.

Like any other sophisticated instrument, a GPS unit is only as good as the person using it. A lack of knowledge

of the limitations of the GPS system is responsible for many of the reports of so-called unit/system failure.


LIMITATIONS

A GPS antenna will not receive good signals from within a building. Likewise, leaves and branches of trees willinterfere and degrade the signals with the result that the readings, if any, are slow to obtain, if at all. The




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sophisticated units (meaning multi-channel receiver units) are better at obtaining readings under these conditionsthan the older cheaper units.

The GPS system has been is use for a number of years and used by sailors and pilots, with great success. BUT,in an airplane or on a boat, the sky is in view, from horizon to horizon. Any GPS, even the least sophisticated,lowest price model single channel multiplexing unit will give good results under these perfect conditions. Inaddition in most planes and boats, an external power source is available.

Now that all units now have at least 12 parallel channels, the speed of obtaining a usable reading is only a fraction

of the time that the older multiplexing units needed and the frustrations experienced by earlier users will beminimized. Be aware however in buying a used unit that is is not an older unit. They are at times listed for sale.

From four seasons hunting and fishing in the Canadian bush with my old single channel unit (a Garmin 75), Ifound that the readings were always sufficient for my needs, if I took the time to pick a clearing with as much skyand horizon showing as possible and took readings about every 1/2 hour. Now with my 12 parallel channel unit(Garmin 12XL), I have no difficulty obtaining a fix.


ACCURACY

The GPS satellites are owned and controlled by the US Department of Defense and this agency has theprerogative to degrade the accuracy for purposes of national defense. This is done by what is called "SelectiveAvailability" or what is commonly known "SA." SA is now turned "off" and the accuracy of GPS readings arenow much better. Preliminary reports suggest 95% time, 10 metre accuracy and 50% of the time 5 metreaccuracy. See Sam Worley's site linked below.

As a Canadian, I am very grateful for the GPS satellite system paid for by US taxpayers. And SA never hinderedme in any way

The gain in accuracy without SA is still not sufficient for me to do my own surveying, to mark a hidden treasureor to find a bow-hunting tree-stand in the middle of a cedar swamp at 4am in the morning.

On June 16, 2000, I did a easy test on the Babbage site and within 5 minutes, when I knew satellites would be ina good position, obtained a fix, ONLY 5 metres east of the position and with the northing exactly correct.

DGPS is a system whereby the GPS unit receives corrections by way of radio signals from a GPS unit at aknown location. While most hand held GPS units are said to be "DGPS Ready," that is for hook-up, this is mostcommonly used by boats. Units now are able to use WAAS to obtain even greater accuracy.

If you intended to bury a treasure and come back in five years to dig it up, then a simple GPS would not be the

answer by just taking a reading. Instead, take a reading on a feature that you will recognize easily from at least 25to 50 yards. Then take a compass bearing and measure with a tape measure to the treasure and record thecoordinates (of the recognizable feature), the bearing (compass direction) and the distance. Another way toaccomplish this would be to choose two ground features readily recognizable and to take compass bearings fromeach to the treasure.

There is some evidence that different makes and models of various GPS units are slightly more accurate thanothers.




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HOW THE GPS WORKS

This explanation is not technically exact but will give the basic idea of how it functions.

The GPS unit does not send out radio signals, it only receives them. There are some 28 navigation satellites inorbit about 12,000 miles above the surface of the earth, and more might be added. Each makes an earth orbitevery 12 hours.

Each satellite knows from reference to land based control stations where it is at any given instant. Likewise, itknows the exact time in UTC (Universal Time Coordinated, formerly Greenwich Mean Time). Each satellite alsohas the "almanac" which gives the same information about the other satellites as well their own orbits.

When you turn on your GPS and point the antenna to the sky, it starts picking up signals from the satellites,starting with the strongest signal. It will obtain the almanac information for all of the satellites.If an oldermultiplexer, it will cycle one by one through the next three satellites best in view, before starting to make itscalculation to give a position. If it is a newer multi channel parallel unit, when four channels have good data, it willthen calculate its distance from each of the satellites to itself.

Let me digress here to explain just why a 12 parallel channel unit is so much better than a single or doublechannel multiplexing unit. Here is an analogy to compare a multiplexing unit with a newer parallel channel unit.Imagine two hunters entering a forest to shoot birds (the satellites. The bag limit is four, the number needed for a3-D fix). The first hunter is normal, two eyes, arms, legs and uses a pump shotgun holding four shells. When aflock of birds take flight, he swings on the first one and it drops. He reloads and starts to aim for a second, but itflies behind a tree just before he shoots, so he picks another and gets it. He must still kill two more but they aregetting further away. He will be lucky if he gets the third and fourth. BUT what about the other super hunter, whois endowed with four pair of eyes, ears, arms, legs etc. has a brain capable of processing all of the incominginformation at once and has four single shotguns, one for each pair of arms, eyes etc. When his flock of birds getup, each gun, separtately and independently controlled, picks a target and in one loud "bang", four birds drop.Same with the GPS units. A multiplexer is slow and might not get a fix in tough conditions, whereas the multiparallel channel unit has a much better chance of getting the data in a fraction of the time. In my opinion and withno evidence other than my use of Garmin 75, Garmin 38, Magellan 2000, Garmin 12XL and Magellan 315, Iwould estimate that the latter two units will get a fix between 10 and 100 times faster than the three units, allmultiplexers. While a minimum of four receiving channels is necessary for parallel processing, the extra ones areused to keep track of whatever satellites are in view and to be ready to replace one of the four being used.

Back to how the unit works. Let's say it receives data from three satellites and thus knows the distance fromeach one to itself. If you picture a satellite for a moment stationary, with a line, the length of which is the same asthe distance from GPS to the satellite, if you extend this line to the earth, you could trace a circle which touchesthe earth's surface making a circle or an arc, depending whether or not it is overhead or towards a horizon. Youand the GPS are somewhere on that arc or circle. Now with the line from a 2nd satellite, you have another circleor arc on the earth. You are at either of the two points where the two arcs or circles intersect, but which one?The third satellite settles the matter and you will have a position. At this point, you will be given a positionreading, Garmin calls this 2D mode, that is, no elevation update. If a fourth satellite is in view, it brings moreprecision to the calculation and an elevation will be given, that is 3D mode.

For a good positional fix, the required four satellites should be located around yet well above the horizon.Unfortunately, the opposite is true for an elevation reading. In the latter case, the satellites should be more




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overhead. Generally speaking, the GPS system does not give accurate enough readings of elevation to be useful,the error being normally 150% to 200% of the horizontal error - for example, if the position error is 50 metres,the elevation error could be 75 to 100 metres.

With respect to the delay of giving a reading when turned on, the oftener a GPS is used, the faster it will give areading when next turned on. The first time that a new single channel unit is used it could take up to 15 minutesfor a reading! This is termed a "cold" start and has nothing to do with the temperature. Once it has the initialreading and orients itself, it will take much less time. Normally, after 20-30 minutes, less than a minute is neededfor a reading (a "hot" reading). But some of the older units even with a "hot" start are slow. On the other hand,my Garmin 12XL never ceases to amaze we how quickly it will get a position, "hot" or "cold", near or far fromwhere it went to sleep.


BEWARE

When the 12 parallel channel units (Eagle Explorer and Garmin 12XL) first appeared on the market, there was alot of misinformation floating around, particularly concerning the older and now outdated single or dual channel

units.

Tracking 8 or 12 sats is NOT the same as having 8 or 12 parallel receiver channels in a unit! And to make itworse, some sales people either through ignorance or worse, will state that a unit tracking 12 satellites is a 12channel unit. Not so!

My old Garmin 75 "tracked" up to 8 sats but it only read data from one sat at a time and had to cycle throughthem to get data from four for a fix. It is was much slower than a Garmin 12XL which has 12 parallel channels.

Do not buy anything less than a 12 parallel channel unit.


DILUTION OF PRECISION - DOP or ETIMATED POSITION ERROR - EPE

Some GPS units will give you an idea of the quality of the reading. Usually it is called DOP for dilution ofprecision, as in the Garmin 75. Also given is a average error in metres or feet. Some other makes call this thePosition DOP or PDOP.

The Garmin 12XL only gives an EPE (estimated position error) in metres or feet, depending on the setup. Whenthe satellites are well positioned, this EPE figure will drop close to 4.0 meteres.

The lower the number, either DOP or EPE, the more accurate will be the coordinates given for the position.

With SA now OFF, much more accurate fixes for waypoints may be obtained from a GPS. Most newer unitsmay be left for a period of time to average out the readings. In my experience using my Garmin 12XL, I find thatif after turning it on, I immediately and rapidly, push the arrow keys in a clockwise or counter clockwisedirection, then when the satellite status page comes on the screen and a 3D fix is obtained, the DOP figure isdisplayed on the satellite page in the lower right. Thus, if I want to average a wayoint position reading beforesaving, I can choose the most advantageous time to do so. I try to average only for the brief of time when theDOP and/or EPE are/is very low. (See last paragraph below under SA and How to Defeat It.)

Because the satellites are moving across the sky, when a reading is attempted under tree cover, they will move in




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and out of sight quite rapidly. This is where a unit with parallel receivers excels because it takes much less time(about 1/10 or less) to have enough data to work out the fix. As mentioned earlier, it is the moisture in the leaveswhich absorbs the signal (or more correctly, the dissolved constituents of the moisture.)

You will at this point ask, but what about rain, snow, fog and clouds.

Evidence is that weather does not unduly affect the accuracy of the units.

There are at times brief periods when not enough satellites are in sight and positioned well enough to give

acceptable readings, especially in hilly wooded country. Usually within 20 minutes or so however, a usefulreading is possible. Fortunately, this is not common. When this is seen, it will probably be experienced againabout an hour later the next day. This is fortunately rare when using a a 12 parallel channel unit. I only mention itso that if it happens, it will be recognized for what is is, and nothing to be alarmed about

For those readings taken on water, with a clear horizon and good geometry of the satellites, the readings will bemuch better but you may find the elevation puts you below water level. This is not a system error but involves thedistance from the GPS to the center of the earth. Remember, elevation given by a GPS is not to be relied uponfor accuracy.


ELEVATION -ERRORS IN

Generally, the elevation errors will be great enough to make the readings useless.A GPS is not to be depended on for accurate elevation readings. For those of you who are fortunate enough toown a hand-held altimeter, don't expect the GPS to take its place.


DIFFERENTIAL GPS - DGPS

Where DGPS radio stations broadcasting the corrections to be applied because of SA are locally available, andthese corrections are fed to the GPS unit, accuracy is much improved, perhaps giving an error of 20 metresinstead of closer to 100.I don't view differential corrections of any practical use for my hiking, even if they were available. The WAASsystem accomplishes the same thing.


LATITUDE/ LONGITUDE VS. UNIVERSAL TRANSVERSE MERCATOR

(UTM)

When I initially started using the GPS, I worked with latitude and longitude and struggled making the conversionsback and forth between the map and the GPS. In realizing that there had to be a better way than this, I found therelationship between the topographical map grid (UTM) and the GPS.




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If UTM gridded maps are available, don't waste time fooling around with Lat. & Long, at least on land.

On the other hand, if you already have an older GPS (e.g. Eagle/Lowrance) that does not handle UTM, all is notlost but you will need to use latitude /longitude. This is fine for bush work without a map. But for ease ofconversion from map to GPS and back, you can't beat a grid system, UTM being by far the most common.

Although most of the world has been mapped using UTM in one datum or another, gridded maps are not alwaysavailable being kept to the military in some countries.


MAPS

Most maps have latitude and longitude and can be used by making the calculations between degrees, minutesand seconds. However, the topographical maps of scales, from 1:100,000 down to 1:50,000 and below usuallyalso have the entire map gridded with the UTM system. Whenever possible, only purchase these maps. TheCanadian topos in the 1:50,000 series, have a grid 2 cm. square, which is 1 kilometre on the ground. This meansthat each mm. on the map is 50 metres (or about 55 yards). If your map is not 1:50,000, check the scale to

establish the grid size. While 1:24,000 US topos are gridded at 1,000 metres ( 1 kilometre), I have seen a USForest Service 1:100,000 map with a 10 kilometre grid. Likewise, the Canadian 1:250,000 maps have a 10kilometre grid. My aviation advisor tells me that these are great for flying.

Also, many hiking and outdoor shops carry local maps.

There has been some talk of the USGS dropping the UTM grid from their maps and only leaving a + where theintersections occur. If you only have such maps, that is with a + mark at the intersections of the grid lines, thentake a very sharp pencil or fine pen and add the lines. (And complain to your maps source.)

Other Map Sources: Phone 1-800 USA MAPS for topos


TRAVELING

Previously, when traveling any great distance, when I would stop for gas or a coffee, I took a GPS reading, notsaving it. This is because when first turned on, the GPS remembers where it was the last time that it was used.When it finds that the satellites are not where they should be, it must then update its data and work out the newcalculations (a cold start). This might take a couple of minutes. There is no need to save this point. By doing thison the trip, when you arrive at your destination, the GPS will rapidly give a reading (a hot reading). My old

Garmin 75 would give a fix from a cold start after moving hundreds of miles within 2 to 3 minutes. Now, with thenewer units, the delay for a reading with a cold start is no great problem (with a garmin 12XL at least.)

If you have hooked up the unit to the car electrical system, then you may have continuous read-outs right to yourdestination. (see below)


WAY POINTS -WPS




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Way-points are locations worth recording and storing in a GPS. They may be check points on a route, significantground features, e.g. camp, the truck, a fork in a trail, where Charlie shot his deer, or whatever. They may be putin manually, having taken the coordinates from a map. This can be done before ever leaving home. Or moreusually, they are entered directly by taking a reading with the unit at the location itself, giving it a name and thensaving. They may also be put into the unit by reference to a WP already stored, giving the reference WP, thedistance and compass bearing to the new WP. Most GPS units permit the name and/or an icon to show on thenavigaton map screen along with the track and/or route.

Pictured in this second image is my old Garmin 75, my first GPS and although a single channel multiplexer, wasan excellent unit for 1995.

Arriving at a new camp, the GPS should be turned on, and the location stored as CAMP. You may choose atent icon to show on the GPS map screen. As the days unfold and more territory is explored, more way-pointsare named and stored. But be selective of those that are saved. Too many can be very confusing. Better, a smallnumber of good ones than too many poor ones. In this regard, before you store any, think out a nomenclature.With units now able to record track travelled, you may only wish to save WPs of road/trail intersections, bridgesetc.

USING WPs in TRAVERSING THE BUSH

With a GPS, a person may explore a new territory as he wishes, without having to worry about becoming lost.The GPS, after locating itself, will give the distance (in kilometres or miles) and direction (magnetic coursepreferably, true course or grid course) for the nearest 10 or so way-points. Say that you want to go to camp.The GPS says 3.4 kilometres at a direction of 120 degrees. Turn off the GPS, head out about 120 degrees withcompass in hand and walk the easy route. You do not need to travel 120 degrees exactly. Walk around each hilland swamp. After traveling for a while in the general direction, turn on the unit take another GPS reading andcheck distance and direction now to CAMP. You will find you are now only 2.2 kilometres but must head 145degrees. You now can turn it off and alter your course further south. You repeat this until the distance drops towithin 50 or so metres. Yours camp should be in sight.

Remember, these units are mostly all oriented for nautical use and as such, when left ON, will do a GOTO andgive continuous updated readings of direction to go and remaining distance to the destination. They will in effect"navigate" all the way. BUT, this technique presupposes that you have ample battery power (external hook-up)AND a clear view of the sky. This technique is standard procedure on the water and must have worked well forDessert Storm.

But this "navigation" with a live hand held GPS in the wilderness where topography and tree cover can giveintermittently poor reception in my opinion is a NO NO. I believe that much of the frustration of earlier users wasbecause they were asking too much of the system, had only marginal units and were using them under much lessthan ideal conditions.




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While this advice of not "navigating" on land was pertinent with the units of several years ago, since 1997 and thelower battery drain of current units, it is not as important and indeed is acceptable, remembering the need toalways carry spare batteries. But in doing so, much that is to be seen will be missed if too much focus is on theGPS and not more on the terrain and scenery. When I am travelling in the bush, my GPS is at the back of myhead, securely closed up in a very small belted pack, in a platic bag and turned on to record track.

See:How not to use your GPS.


UTM - AN ATTEMPT TO EXPLAIN

Here is the exercise that I went through to discover how to use Universal Transverse Mercator grid system.

If you already have a GPS with way-points stored in Lat-Long, have no fear of losing them in the followingexercise. The GPS will convert them back and forth effortlessly.

For the Garmin 12XL , from the MAIN MENU choose SETUP MENU and from the this screen, chooseNAVIGATION.

From the screen now showing, choose for the POSITION FRMT: UTM/UPS.The other choices are variousversion of Latitude/Longitude degree, minute, second formats. The UPS, by the way, is a type of grid systemused in polar regions.

Now, move the cursor down to MAP DATUM and if you know the datum of the map at hand, choose it fromthe hundred or so presented. They are in aphapebical order and can be scrolled through very fast. If you don'tknow the correct datum, then use WGS 84, or NAD 83. In Canada, most maps are either NAD 83 or NAD 27Canada.

Now, from same screen, cursor down to CDI. I leave this as is, at 0.25 and go on down to next field, UNITS.

Here I choose METRIC for the UTM system is so based. For those none too familiar with metric, a metre(meter?) is a super yard of about 39 inches e.g.100 metres=110 yards and a kilometre about 2/3's of a mile.

Lastly from this screen, go down to HEADING: and there are several choices. If you choose AUTO, as I have,your unit in giving bearings, will give them directly as compass bearing, magnetic declination being automaticallycalculated for your location and applied to the true bearing. In my own case, here in Ottawa, the declination isWest 15 degrees . The other choices are User, True or Grid. The latter, Grid refers to the UTM grid lines of themap which are not exactlly true north/south, east/west but close enough, they can be accepted as true for allpractical purposes.

Now with the gridded map of your location, go OUTSIDE, turn on your GPS. (I am certain that these directions,

with some modification will work with all hand-held units). Keep away from trees and buildings as much aspossible.

Wait until you get a 3D reading, and the "speed" shown in the Navigation screen drops to zero or close andappears something like this:

18T 0439535

5024750

Record this reading, turn off GPS and go inside to the gridded map, put a pencil mark on your location (hopefully




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you know where you are!) If you look along the edges of the map, you will see that the grid lines are numbered.Look at the lower left hand corner of the map. You should see a 6 digit number, printed horizontally with the 2ndand 3rd digits printed slightly larger than the others. The larger numbers are the ones relating to the vertical gridlines and will increase from left to right. Look again at the lower left hand corner and left of map, printedvertically will be another number with 7 digits, the 3rd and 4th printed larger. These are the numbers increasingfrom bottom to top numbering the east/west grid lines. Now with the grid numbers on the map and what yourecorded from the GPS, look for the relationship. Look at the grid numbers along the bottom of the map and seehow they match up with the first number, e.g. 0439535 above.

Close to where my house is on the map, the grid line 39 appears along the map bottom. Likewise, looking at thegrid numbers going up the left (and right) side of the map, I see 24 which is also close. My house is east andnorth of where north-south grid line 39 and east-west grid line 24 cross. The difference east and north of the 39and 24 crossing is given by the last 3 digits in each number, e.g. 535 meters east and 750 meters north.

As I said earlier, the UTM grid on the map is the key to coordinating the map with the GPS. By using it, you caneasily go back and forth with an accuracy of 50 meters or about 55 yards on a 1:50M map. You will do evenbetter on larger scale map. The UTM grid has been in use for many years. To understand the grid, imagineinstead of longitude, that the north-south lines are based on meridian lines 6 degrees apart. These strips are 6degrees wide, centered on these meridians, starting at 180 degrees west and numbered towards the east.

Thus, all of North America (with the exception of the western Alaskan islands) is covered by those zonesnumbered from #5 to #22. Here in Ottawa, I am in zone 18. Where we hunt moose is zone 16, to the west.Yellowstone Park is in zone 12. In referring to the grid, it is important to know what zone you are in and in givinga UTM reading, the GPS will give the zone first. The letter, "T" in this case, is the UTM reference to how farnorth or south of the equator you are. In normal use you can disregard the zone number and letter. Take a lookat

A map of UTM Zone Numbers for the world.Please note that the above explanation is for a position north Lat. and west Lon.


USING UTM COORDINATES

In using UTM grid coordinates, the "easting" from the zone meridian is always given first, and then the "northing".Also take note that for UTM, measurement is from the west, going EAST, the "easting" which is opposite tolongitude. In reading coordinates, youREAD RIGHT UP. In other words, the easting is always given before thenorthing. The coordinates of a point could be given several ways. Here is an example:

18T 0439535 5024750

This is the full location description of my home in Ottawa. The 18T refers specifically to the area of the earthwhere I am located, and normally is not used. The other 14 digit number must be broken up:

0439535 is the EASTING from the zone 18 meridian, down to the closest metre. If you place a decimal thus:0439.535. (The leading 0 is redundant as EASTING only needs 6 digits).

To the right of the decimal is 0.535 of a kilometre or 535 metres and to the left are whole kilometres, 439.




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It will be recognized that there will be a repetition in numbers going from one location of the country to another.To alleviate this confusion, in using 6 or 8 digit coordinates, the map must be identified. If not, then the wholenumber must be given, e.g.18T 0439535 5024750

A grid coordinate usually has an even number of digits, the first half being the easting and the balance, thenorthing. But, when the number of digits after the zone (18T here) is odd, e.g. 18T 439535 5025750, the extradigit belongs to the northing.

As a matter of interest, the northing, 5025750 in the above example, is the distance in metres north from the

equator. The metric system defines the metre as 1/10,000,000 of the distance from the equator to the north pole.As a verification of this, I live close to 45 degrees north, half way from the equator to the north pole and mynorthing is 5,025 kilometres.

If you refer to a UTM grid on a map, of either 1:50,000 or 1:100,000 scale, the grid squares will usually be 1kilometre (1000 metres) to a side. It is simple to estimate between grid lines to 1/10 or 100 metres. For closerprecision, on a 1:50,000 map, each 1 mm. is 50 metres on the ground. On the newest 1:25,000 US topos, 1mm. would represent 25 metres on the ground. Note, the most common Silva compasses have a mm. scale onone side and this may be used to measure east from a grid line and north from the E-W grid lines.

All of this sounds much more complicated than it really is. It is harder to explain in words than to take a map and

demonstrate.

So lets try it. This is a cut from the lower left corner of BOUCHETTE, QUBEC, a 1:50,000 Canadian topo,31J/4 Edition 2. N.B. See above Crown Copyright Notice.

Remember, I said that with UTM, youREAD RIGHT UP that is you do the Easting and then the Northing.

The blue numbers along the bottom margin are the grid numbers for the Easting. The first whole number is424000m.E The 24 is emphasized because this is the number which goes up by 1 for each N/S grid line going tothe right, e.g. East. The line of 424000m.E is 424 Kilometres East of the base line for Zone 18. Thus going fromthe line numbered 24 to that to the right, 25, is one kilometre or 1,000 metres.

The same applies for the blue numbers going up the left margin, the first line being 5095000m.N which is 5,095Kilometres North of the equator.




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Looking at the dot that I inked in with the 3 arrows surrounding it, the full UTM coordinates for it would be:

18T 0424200 5097850

Where did I get the 200 for easting and 850 for northing? Just by eyeballing the map. (Note: If anybody gets tothis little lake, give me a report on the fishing.


There are areas of the world where a non standard UTM grid is used. An example in North America is theprovince of Qubec, which has a series of MTM (Modified Transverse Mercator) maps, 1:20,000, formerly inblack and white, but now in colour which are more detailed than the standard Canadian 1:50k topographicalmaps. Furthermore the new maps have all of the information printed on them needed to set up a GPS to this non-standard grid.

For the older black and white maps, the information given below should be sufficient to set your GPS. Ifhowever you have a newer map with the required information on the map, use those settings in the manner that Idescribe below.

These Qubec maps, instead of using a 6 degree slice of longitude, uses a 3 degree slice. Here is how to set aGarmin 12XL to use this map grid.

You must have such a map available first of all. My Qubec map is NAD83 so the GPS must be set to thisdatum. Now pick the whole degree longitude to your west that is divisible by 3. In my case, this is 75 deg. west.To this figure, add, 1.5 degrees. Go into the Setup Menu and choose Navigation. On this page, NAV SETUP,

for Position Frmt: choose User Grid, which is adjacent to UTM/UPS. When the USER GRID screen comes up,set the Longitude of Origin to the figure you calculated earlier, in my case, W076 degrees 30minutes.Now movecursor down to Scale. In this case, use 0.9999 whereas standard UTM used 0.9996.

Now, you must put in a false Easting figure. Use the figure 304800 (same as one million feet).

As for False Northing, just leave it as 0.0 as the False Northing on the Qubec maps is the same as standardUTM.

You are now ready to test the settings. Choose a location that may be positively identified on the map. Forexample, where two roads meet. Using your knowledge of how to read a UTM grid, write down the easting andnothing.

Turn on the GPS at this spot and leave it to average out the readings for a few minutes. When you have areading, write it down and go back to the map. If all has gone well, you will find that your test point GPScoordinates now agree with the the MTN map.

Although the false northings used my UTM and MTM are both 0.0, due to the scale difference, a northingposition given in MTM will appear 1,081 metres north of that given by UTM

That's all there is to it.




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SETTING UP YOUR UNIT

In setting up a unit, there are a number of choices to be made. What will suit one will not suit another.Furthermore different makes of units use different terms for some of the functions and available screens are notalways the same.

Generally speaking, all units will permit certain choices to be made in the SETUP menu. If the unit is being usedfor other than position finding, e.g. setup, uploading or down loading data, entering waypoints and/or routes, thenunder the System Setup, the mode chosen should be Simulator.

In explaining how to use UTM, I gave directions in setting a unit to use UTM and some other basic settings.

With the Garmin 12XL, there are several other settings to be made.From the SETUP MENU, for this exerciseand any other where you are not outside to receive satellite data, choose, SYSTEM first and at the top of thescreen, under MODE:, choose Simulator. This prevents the unit from attempting to obtain a fix and savesbatteries. Now, on same screen, go to OFFSET: and input the number of hours that your time zone deviatesfrom UTC (Greenwich Mean Time.) For Ottawa, EST in North America, my setting is "-05.00" hours. InSummer is is -4 hours. I also choose HOURS: as 12, preferring this to the 24 hour system. On this same page, I

choose how long the light will stay on in seconds and whether or not I want Tone signals. Being partially deaf, Idon't use the audible signal function. This recalls a story I heard of a man who wanted to know how to turn offthe beeps, they frightened his horse.

The above is the basic type of setup needed before using a unit and relating the readings to a map.For a more complete explanation for Garmin, see Dale DePriest's site and for Eagle/Lowrance, see theGPSNUTS, URL's for both are at the end.

Much of the setup was done when I explained UTM. There are however a few more odds and ends to mention.I am using NAD27 Canada for most of my maps although some of the newer one are NAD 83. If you choose adatum different than used by the map, your coordinates will not agree. If you find the GPS does not agree with

the map coordinates, check this. Usually the error will be in the easting.

If you examine your topo map carefully, you should find the map datum given . On my 1:50M older Canadiantopos, at the bottom in fine print, just to the right of the map name and the scale, it states "North AmericanDatum 1927". The newest map dated 1995 gives North American 1983 (which is essentially same as WGS 84).I therefore have my unit set to the NAD27 Canadian datum but would change for to NAD 1983 or WGS 84 forthe newer map. Similarly, on a US Forest Service 1:100M maps, on the lower right hand corner, it states"Universal Transverse Mercator Projection 1927 North American datum". This is sufficient reason to reset theGPS to the NAD27 datum. Therefore, check a map over carefully to find out what datum is used and set theGPS to it. The Garmin comes set with WGS 84 which may be left as is but if you compare a reading with a mapusing NAD 27, you will find a discrepancy of 100 metres or so in the easting and a smaller one in the northing.

As a matter of interest, if you are using a GPS without reference directly to a map, the Datum to which the GPSis set will not matter as all readings will be relative. Only if you try and compare one of these readings with a mapwill the error appear.

OPT MAP SCREEN AND SETUP

From the Map Screen, cursor over to OPT at the top, right and push ENTER. Now choose the first, MAPSETUP and from this new screen, I like North UP. I keep the RINGS on YES; normally ROUTE is OFF;NEAREST, YES; NAMES usually NO; Tand finally TRACK LOG is a YES.

Going back now to the OPT (0ptions) screen by pushing QUIT, I now choose TRACK SETUP. Because I am




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often down loading a previously travelled Track to a computer mapping program (QuoVadis) I leave RECORDset to FILL. This means, once all of the 1024 track points in memory are used, I do not overwrite them. If Iwere not mapping but just wandering, I would set the RECORD to WRAP or even OFF. Too much wanderingwith the track being recorded makes a cluttered map screen. As for METHOD, I use AUTO rather than aTIME but I have not really explored the difference.

This same Track Setup screen is where you can check how much of the memory is used and where the log canbe cleared. N.B. Always CLEAR the Track Log before starting to record a new trail for later uploading andmapping.(see Mapping - Transferring Tracks..below)

To use Route and/or Track, you must leave the unit on with antenna clear. In the earlier units, this used too muchbattery power but this caveat no longer applies with the new units. For easy mapping, first clear the Track fromthe map screen then set to record the Track at your point of departure. With my Garmin 12XL ON and noexternal antenna, I carry the unit in a very small bag at the back of my neck (a minature fanny pack) and my trackis kept until I return home and download it to the computer.

As far as the Route is concerned, I do not normally set a Route for bush travel and so leave it OFF. If however,I had earlier made a Route from a Track, created a new one using Waypoints, I would then turn on the ROUTEplotting on the Map screen.

Note- by all means when you first buy a GPS, after taking a reading leave it and go for a walk with the trackrecording turned on. The graphics are great and you may be able to zoom in and out on the plotting screen. AWARNING- don't try this for the first time in a strange bush unless you have lots of batteries with you. Thiswarning is not so important with the newer units. I have no problem saving a track of well over 250 points over3-4 hours and having battery power to spare with my Garmin 12XL. If you bought the unit with a cigarette lighterplug, try this in your vehicle.(see below)

INTERFACE

When your GPS is correctly cabled to a serial port on your computer, desktop or laptop, and you have the

proper software installed on the computer, tracks, routes, waypoints may be downloaded, added to maps andsaved.

Touratech QV on the WWWTouratech QV has a sample of their software which may be downloaded and will function I believe for 25 days.Also, they now have Canadian topographical maps in 1:50K and 1:250K in digital raster format for theprovinces of Qubec , Ontario, British Columbia and the Maritimes under licence form Natural ResourcesCanada, of the Canadian Government. A description of the maps may be had at their website.

Ozie Explorer is another flexible program hor handling maps and the interface between the GPS and computer.

Fugawi, also now have Canadian topos 1:50,000 and 1:250,000 on CD disk but I have no experience usingthem.

MAP DATUM

I am using NAD27 Canada for most of my maps although some of the newer one are NAD 83. If you choose adatum different than used by the map, your coordinates will not agree. If you find the GPS does not agree withthe map coordinates, check this.

If you examine your topo map carefully, you should find the map datum given . On my 1:50M older Canadiantopos, at the bottom in fine print, just to the right of the map name and the scale, it states "North American




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Datum 1927". The newest map dated 1995 gives North American 1983 (which is essentially same as WGS 84).I therefore have my unit set to the NAD27 Canadian datum but would change for to NAD 1983 or WGS 84 forthe newer map. Similarly, on a US Forest Service 1:100M maps, on the lower right hand corner, it states"Universal Transverse Mercator Projection 1927 North American datum". This is sufficient reason to reset theGPS to the NAD27 datum. Therefore, check a map over carefully to find out what datum is used and set theGPS to it. The Garmin comes set with WGS 84 which may be left as is but if you compare a reading with a mapusing NAD 27, you will find a discrepancy of 100 metres or so in the easting and a smaller one in the northing.

The above is cut is from the bottom of the same map pictured above, topo map, 31J/4, titled . N.B. SeeAbove Crown Copyright Notice. Underneath the left end of the conversion scale for elevations, you will find insmall print, "CONTOUR INTERVAL 50 FEET" and below that in even smaller print

Elevations in Feet Above Mean Sea Level

North American Datum 1927

Transverse Mercator Projection

Therefore in using this map with your GPS, you would set the DATUM as NAD 27 (Canada.)


BUYING A GPS

See the basic requirements under INTRODUCTION.But, take note:

"Tracking" satellites, as quoted in some promotional material is a confusing term. It means very little as units havealways "tracked" at least 5 or more satellites. Such units, using old technology, still only have one (Magellan saystwo) receiver which must process the data sequentially, i.e. multiplex.

By September, 2003, Garmin, Magellan and others have added features to their basic 12 parallel channel unitswhich have maps already in the unit and/or will permit the uploading of maps in one way or another. Theirdisplays will show a map and your position, track etc. WARNING! Before committing to the purchase of such aunit, BE SURE that the maps installed and/or available give you the detail that you require. Most are sufficient forhighway travel, cities, large bodies of water etc. BUT may be deficient in the detail found in most topographicalmaps used in backwoods use. I know that Touratech QV (see link below) have most of the CanadianGovernment topographical maps available on a number of CDs, likewise for many other areas of the world.




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Because my Garmin 12XL does not handle maps like the newer units, I personally have no experience uploadingto it. To get up-to-date information on mapping features and maps, check the links below, especially those of JoeMehaffey & Jack Yeazel, Dale DePriest and Ron Wilson & Andrew Kalinowski.In buying a unit, if you are unsure of how well your needs will be served, try and obtain a commitment from theseller that you may exchange the unit for another make or model if need be.

TWELVE PARALLEL CHANNEL UNITS

With the newer units which have twelve parallel channel processing (Eagle Explorer and newer Garmins such as12, 12XL, II, III are good examples), it means that the 5 (or more) best SATs are being tracked and data fromthe 4 best processed at the same time which in practice means faster fixes, particularly under difficult conditionse.g. wet trees. Previously, the trade-off was that they used more battery power than the older multiplexers, wereusually larger and cost more. But that has all changed and these new units are much easier on batteries than oldersingle channel units!A unit must be able to use UTM grid data or a local grid if available. In north America, topo maps are almostalways have a grid whereas in some parts of the world, only the military have access to such maps. The Garminshandle over 100 different UTM map datums. If you have access to UTM gridded maps and wish to use them,then by all means look for a unit that will serve your needs and handles those UTM maps datums needed. Mostunits may be set for the common datums used worldwide. There are however some areas where the

topographical maps are based on a datum which is not found on some units.

The descriptions in some catalogs refer to M.G.R.S. standing for Military Grid Reference System. This is anewer grid reference system, similar to UTM if not the same.

BATTERIES

Batteries are no longer the problem that they were a few years ago. Most Garmins use 4 AA cells and the newerMagellans only need 2. Furthermore, they use much less power than older units.While I originally used rechargeable alkalines, I now use straight alkalines. If you are going to use the unit inextreme cold, try and get lithium batteries. Radio Shack and some battery specialy shops carry them however,

they are very expensive.

ALWAYS CARRY EXTRA BATTERIESWARNING-Leave fresh batteries in your unit at all times andcheck on a regular basis to be sure they are OK. Not to do so could prematurely run down the internal lithiumbattery which maintains your data.

As an extra thought to the above, it would be prudent to record in a log-book the coordinates of important way-points and the compass courses between them just in case your batteries fail or your unit becomes inoperable. Inthe event of GPS failure, system or unit, your will be able to extricate yourself.


HOOKING UP TO AN EXTERNAL POWER SUPPLY

Since this article was first written in February 1995, I have mounted my G75 in my Explorer, drawing on the carbattery. I bought a BNC cable from Radio Shack so that I may place the antenna externally on a rear sidewindow or set it on the dash board on the passenger side. In initially getting a fix, the external antenna mount isquicker but once locked on the SATs, the dash board location works fine. It gives me direction of travel inmagnetic (or would do so in Grid or True), speed as well as the UTM coordinates as they change. The plotscreen will give the track I have covered as well.




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With my Garmin 12XL, I use elastic bands to hold it to a small sand bag and leave it usually beside the frontseats on the low console. Even this low, it has never failed to hold a lock once obtained.

This is a great set-up for mapping the bush roads we use in the north in the fall. Simply, clear the map screenTRACK settings, then leave the unit to record as you travel. The unit will faithfully record your track over theground which later may be uploaded directly to the map in your computer through the interface cable.

This 9 year old clip shows an old Garmin 75 unit on an ATV and was said by the European motorcyclists then tobe the only unit robust enough to take the pounding on the fron of a XC mororcycle. b

If your unit does not have an external antenna and you wish to use it on the dash board of the car, turn the unit onoutside the car and wait until it gets a reading before bringing it inside and placing it on the dash or in a mount.

The windshield on some cars has a metallic coating through which the GPS can't receive the weak signals fromthe satellites. In such a situation, you can change cars or, cheaper, use an external antenna outside the vehicle.

If you are going to use the unit in a vehicle or boat, then be sure to get whatever you need to hook into theelectrical system and save your batteries.


MAPPING - Transfering a Track to a Map

I have only started interfacing my GPS to my computer since buying the Garmin 12XL and obtaing TourateckQV with the Qubec maps on CD. The process is much easier than I had anticipated. I have no external antennaon my Garmin and find that one is not needed. In the vehicle, maybe using the power cable if I am travelling anydistance, or on internal batteries, I leave the unit on the low console between the front seats (after always turningon the unit outside the car and getting a position). If I am afoot, I use a very small fanny pack bag with the strapadjusted short and the GPS in the bag and at the back of my neck. It rides there very nicely and I can swivel itaround to the front to open and set a WP very easily. Otherwise, the GPS is out-of-site and forgotten although Ido occasionally check the battery reserve power and the memory unused. I see no need to have the GPS in myhand when I am traversing new country or trails. Generally speaking, in the hilly forested country that I traverse, I

am continually adjusting my path around trees, swamps, rock out croppings etc., following the easiest path. If Iam targetting a particular spot and mapping a tril, then before setting out, I have entered the coordinates of thespot as a WP in the GPS. I therefore know from my starting position and and at any subsequent check, exactlywhat my compass course should be and the distance to travel. I do not do a GOTO as such, just get the infofrom the entry on the nearest waypoint list. This means that my compass is checked for direction if necessary andnot the GPSThere is a very important point here to be noted. A stationary GPS will NOT tell you North or any otherdirection!The GPS will only give direction when it (and you) are moving.At the end of the trail or point for which I was aiming, and if I will not be using the TrackBack function, I turn theGPS off.When ready to upload the data to the mapping program e.g. Touratech QV, Fugawi, OziExplorer or whatever, I




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hook up the GPS and computer, turn on the GPS and set it for Simulation, then set for Interface and invoke thecomputer program for receiving data. Each program will have its own character but the end result is the travelledtrack is recorded to the pertinent map. N.B. Be sure the GPS and map agree on the datum. If you don't knowfrom the map which datum to use, choose WGS 84, which I believe is the format in which Garmin saves all data,translating it as required.

This is a very brief explanation to encourage those (like myself) who have held back from interfacing. GoodLuck!


SPEED

Given that the system can guide flying cruise bombs at whatever speed they travel, most units will have no troubletracking a hiker or boater. I have tried my Garmins in my vehicles at 60 MPH and the speed reading was moreaccurate, I am sure, than the speedometer of the car. Also, it was giving changes in position, heading, andkeeping a plot. This is great fun but drains the AA cells very quickly, unless plugged in to the car electrical

system.Now with no SA, the speed given will be useful for sailing and trolling.I have now found that in using my Garmin 12XL while trolling slowly, that the speed will be accurate down to 1.6Km/hour which is about 1 MPH. Below that, no speed will show. Likewise, the compass heading will not changeuntil I speed up to about 5 KPH. At that point, it will correct the heading and not change if I again slow down.The above has relevance to hikers too. You must move fast enough that the heading is correct, if you wish theGPS to keep you headed in the correct direction. Also, the map plot will only update as you move above 1MPH or 1.6 KPH.For hikers who because of terrain can not travel above the lower limit, the best plan is to have chosen a waypoint, and occasionally stop, take a reading which will update the direction to that way point. If you have notrouble getting a hot fix, then you may turn off the unit, there by saving batteries. If there is overhead cover, then itould be best to travel with the unit ON. Thus when you stop to check the required way point direction anddistance, your readings should be instantaneous.Note:With the Garmin 12XL and the city database, one may pick the cities of interest prior to a trip and the GPSwill show these cities as you approach or go by them.


VARIABLE READINGS

A GPS left on and stationary will give a continuous but variable reading. A series of readings over many hourswhen averaged will come very close to the correct figures.I am fortunate in Ottawa to have access to a bench mark, the location of which is exactly known. While testingmy unit, I took ten readings over 3-4 minutes. By using the Pythagorean theorem, I worked out the hypotenuse(or error) for each of the 10 readings and the average was about 5 metres (5.5 yards) off! This was NOT ascientific test and my good results were as much chance as anything. What it means is that during the period that Itook the readings, SA just happened to have a minimum error. Next time I try it, I could be off 60 metres, or100 or perhaps much more!If you are fortunate enough to find a BM, the exact location of which is known, you can conduct the same test.




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Usually a BM's location is given in latitude/longitude. Enter the BM as a WP with the unit set for lat/lon, changethe unit to UTM, then take your 10 or more readings. The differences in easting and northing from the correctreading. For each pair of differences, square them, add them together, take the sq. root of the product and this isthe distance in metres that that pair of readings varies from the stated position. Even better,let the GPS averagethe readings over as long a time as possible. Plot a right angle triangle of the easting and northing differences andthe hypotenuse will be the error.Note: The Ottawa BM is called "Babbage" and found at N 45-19-43.5 and W 75-52-1.2, on Corktown Roadat entrance to Nepean Municipal Campground. (Note: I give the lat/lon as these coordinates in UTM would vary

depending on the Datum (e.g. NAD 27, NAD 83 etc.)It is important to stress however that one should not depend on obtaining accuracy of better than 20 yards ormetres. This warning has meaning if you are in a boat, aproaching a narrow harbour mouth on a pitch black night,with no light!

With some care and a bit of time, I am relatively confident that I can take a reading that is within 6 or 7 metres.


HOW NOT TO USE YOUR GPS

In the fall of 1995, I read an account of a man with a new GPS who took a reading (WP) of his car, then wenton a long hike. To return to the car, he did a GOTO on it, leaving the unit on to give direction and distance.When he got within 100 yards or so of he car (which was hidden in bushes), his GPS was pointing every whichway. It took him some hours to find it.Why?First of all, he should have parked near some feature which could be identified from 50 or so yards away. Hiscar could not be seen from 20 or 30 feet away! Secondly, he had no compass and relied on the GPS completely

for direction. When he got close to the car, he was expecting accuracy better than the system can yield becauseof SA. He also used up his batteries and his buddies were less than impressed with him and GPS.Now, with SAoff, he would possibly find the car.Note, before SA was removed because of the inaccuracy introduced by SA, if a WP is saved and a return to itis made, in theory, the error could be of the magnitude of 200 metres! That is a 100 metre error when it wassaved added to the 100 metre error when trying to find it. So what is the answer? Quite simple, now with SAOFF,if you have a spot that you must find e.g. the car and there are no easily seen geographical features, make aa line, perpendicular to the road for 50 or so yards on each side of it, intersecting at the car. (I am not suggestingblazing the trees or using a spray bomb but the use of surveyors' tape or toilet paper, which will also degrade intime.) When the GPS says you are within 100 metres of the car, TURN IT OFF and use your compass to goback and forth until you hit the road or the marked line.

There is also the technique used by those skilled with a compass to navigate. They aim either to left or right of theobjective and when it is reached, turn and follow the coast, road, trail or stream on which it is located.

Back to UTM- AN ATTEMPT TO EXPLAIN

This has been written in an effort to assist in making the right purchase decision and to shorten the learning curvein using a GPS. I have been accused of being biased towards Garmin and UTM. I make no apology for theseperceived biases. The Garmin 75 was my first unit. I bought another model from a competitor, sold it, bought aGarminn 12XL As for UTM, where gridded maps are available, to use lat/lon is masochistic in the extreme.

The information I have given is thought to be accurate butI assume no liability for errors, omissions or for




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someone getting into difficulties in using a GPS and this guide.I have no connection with Garmin or any retailers although I can recommend

Prairie Geomatics I found their Canadian price at least as good as the best U.S. price in 1998.

*I am far from an expert & I can't answer questions of a technical nature.*

This is the product of my own experience and those of many others with whom I have communicated over thepast 6 years.

I would also like to mention a remarkable young Norwegian, Kjetil Kjernsmo, in Oslo, a physics graduatestudent, well on his way to becoming an astronomer, who in 1995 picked up my original gpsutm.txt version ofthis article and mounted it on his Home Page. This gave it widespread exposure.

Kjetil's Home Page

Kjetil also has an excellent tutorial on compass use which is also available from his homepage.


FOR MORE INFORMATION AND LINKS

For those looking for more information, check out:

sci.geo.satellite-nav

There is a wealth of information in the postings to this group. Often FAQ's (frequently asked questions) appearhere and this is the place to ask techical questions.

Here are some links and I urge readers to check them thoroughly.:

Sam Wormley's Web site with a great deal of information and many links.National Resources Canada-Geodetic Survey Division, online applications. Very interesting!NASA's World Wind site lets you zoom from satellite altitude into any place on Earth.Joe Mehaffey's and Jack Yeazel's GPS Info website that is not to be missed!Peter Bennett's very complete collection of help files and FAQ'sFugawi Mapping SoftwareDes Newman's OziExplorer Page where a modified shareware version may be downloadedThe Tourateck page in Germany where a working copy of the Tourateck QV mapping software may bedownloadedMapMan is a free generating tool designed primarily for owners of Garmin units with mapping capability.

Dale DePriest's very complete Garmin site.Ron Wilson & Andrew Kalinowski site with info on Lowrance/Eagle, Magellan, Rand MacNally andsoon, Delorme (earthmate) reviews.Roelof Odden's Bookmarks - The Fascinating World of Maps & Mapping, U. of UtrechtA very complete Search & Rescue page from British Columbia with much other material and links. Wellworth a look!The Coop CORS site providing access to GPS data from other than Nat. Geodetic Survey.Wikipedia GPS Pages.




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Don Bartlett

at 18T 0439457 5024584 (NAD 83)

or 45* 22.329' N 75* 46.391' W

in Ottawa, Ont. Canada

or at 18T 418270 5117050 (NAD 83) Blue Sea Lake, Quebec.

Mail to:[email protected]

"...where da Fugawi?"..?

January 31,1998, first mounted with the graphics.

The WEB COUNTER says that since January 31, 1998, you are visitor

Last Revision:Jan. 10, 2007Top of Guide


A Practical Guide to GPS -UTM

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