GPS tips

I am looking for GPS tips/lessons learned for my GPS classes. I have been teaching GPS classes in the Pacific Northwest for 10 years. I'd appreciate some feedback on what you have learned about using a GPS. I am not looking for product endorsements or discussion of what unit is best; just sound feedback based on experience.

For example. I recommend having just the minimal number of waypoints needed to do the job. I suggest saving important waypoints (from previous trips)on the share ware program from www.easygps.com.

For background on my classes and some great links please visit www.outdoorquest.biz.

Thanks a bunch.

Blake

GPS is an aid to navigation and not the be all and end all of it.

batteries run out, so always check them before using.

GPS navigates in straight lines, watch out for cliffs.

GPS isn't much good unless it references to something. I see waypoints as the reference. If I'm on a road trip, my GPS has every waypoint along the way.

A waypoint that may seem unnecessary in planning a trip may be needed as events unfold. You don't know what you don't know.

If you enter nothing else, mark where you put the car.

What Unimog Bert said is vital.

I use GPS with a map for position fixes.
That means I am only running it for a few minutes at a time. Even at that I carry spare batteries.

A lesson learned from experience?

Make sure that the latest Firmware is installed on the GPS.

Make sure that the GPS Datum and paper map Datum are in agreement.

Make sure the batteries are fresh or are fully recharged before going on a wilderness expedition and always carry some spare batteries.

Make sure that the GPS Magnetic and Grid deviation is correctly set within the GPS to the actual Grid Magnetic variation for your geographical position i.e. such as locations near to the magnetic poles can vary over very short differences in geographical location.

Never trust your life to a GPS to get you out of a fix. GPS is very accurate 99.9% of the time but the 0.01% of the time the GPS may be some furlongs or even hundreds of miles out. Use a map and compass so that you never end up getting into a fix in the first place.

Never trust a GPS to point you in the right direction - they aren't very good at this.

Learn how to use a map and compass properly, how visualize the terrain from the map contours, know how far the distance is between each of your own walking paces, how to count etc - its the only way you can appreciate how to use a GPS properly and safeguard yourself against all the things that can go wrong with the GPS reciever and the NAVSTAR satellite constellation.

If you become really proficient at map and compass work you can then just use the GPS for fun and trivial activities such as marking out way points then uploading them into Google earth. You can even then decide to leave the GPS at home if you wanted to.

You can even have some fun with some of those cheap Chinese GPS jammers when teaching your class.

And lastly; Using a GPS is navigational cheating, if you have to constantly use one in the wilderness then you should think again whether you should be there in the first place without the appropriate skills i.e. not knowing how to use a map and compass.

I don´t have a GPS device (yet). But if I had one I would stop say every 30 minutes or 1 hour and write down the position readout on the piece of paper along with actual time. If the GPS dies on you later on, you can estimate from this data your current position and plot it on the map. (It doesn´t mean I wouldn´t navigate myself using a map. But with written down coordinates from GPS estimating your position might be more precise).

It comes in handy especially for those people that use mainly GPS and map + compass is just their backup (as long as they know how to plot coordinates from GPS on a paper map and have the tools for the job).

Just an idea.

Learn how to talk over a radio or a phone about your location - reception may be bad and fading.

How do you tell a stranger where you think you are. My store is in Idaho. So I am interested in using the grid that will get me the most accurate and fastest response. Local agencies all use NAD 83/84.

I keep a scanner on at all times. I listen to all of the calls for rescues, accidents, marijuana fields and collared wolves. In most cases the people on the ground cannot communicate to the 911 operator or the helicopter on the way. In Idaho DO NOT USE UTM OR DEG/MIN/SEC. Do not pronounce the decimal point! Only pronounce the numbers - talk slow - they are writing.

The LIFE FLIGHT, NATIONAL GUARD, SEARCH AND RESCUE, DEA and the 911 dispatch all want you to read the location as -

"The accident is at 4396679 by 11618880"

I keep a window open in http://mapper.acme.com/

ACME comes up as -

N 43.96679 W 116.18880 MY FRONT DOOR

N 44.08265 W 115.82877 A WOLF DOWN

The closer you get to certain US Government facilities, it seems the less accurate they sometimes become. When I am working in the field, I have three different GPS devices on-board. All three are from differing manufacturers, and all three show me to be in a different place when near some USAF bases. The same day, I ran into a group of Air Controllers, and their GPS was dead on, while my three thought I was in three different places at the same time. I also had some surveyors with me, and their GPS was giving them fits also.

Desperado:
do you thing maybe the have a force field around the base so bad people can't use a GPS guided bomb

...Pulls out tin foil hat...

Heck I don't know, but I am very lucky I had someone with me who knew where we were going. Would have sucked to end up in an artillery impact zone by accident.

All of the deviations were either 300 meters or 1000 meters. Doesn't sound like much until you take the wrong road and wind up DOWNRANGE.

Removes tin hat....

Get good at map orienteering (map reading skills). Practice compass navigation. Those are invaluable skills.

Use GPS together with paper charts. It gives a much better understanding of how you move in relation to your environment. (And when the batteries die, you'll have a pretty good idea of where you are).

Make sure the datum of map and GPS are the same.

Use the waypoint functionality as you move along. Don't mark everything, but mark those spots which are handy to reach in a pinch (water, shelter) or constitutes important corners for your route (such as a bend to avoid nasty terrain).


If your map has UTM grid, choose MGRS coordinate for the GPS. It is the same grid as UTM, but you ignore the smaller numbers and the really big numbers are referenced to by alphabetic code which typically is written on the map. This code refers to the 100*100 kilometer square you'll find yourself in. So with a 100 meters accuracy, your only concern is to keep track of 3 digits (2 kilometer digits plus the 100 meter digit) in east and north direction, a total of 6 digits. A LOT more easy than all the digits of the full UTM system... 100 meters is plenty for outdoors navigation, and you won't be able to fix your position on the map any better than that in the field anyway.

The FAA routinely publishes areas where the signal is purposely degraded.

FL = Flight Level. Always add two zeros to altitudes, so FL400 = 40,000' MSL (mean sea level)

KEDW EDWARDS AFB

L0954/09 - NAV GPS IS UNRELIABLE (152100Z-2300Z, 162300Z-2359Z, 170001Z-0100Z, AND 171400Z-1600Z) AND MAY BE UNAVAILABLE W/IN A 344NM RADIUS OF N3556'52" W17734'35" NEAR BEATTY (BTY) VOR 218.3 RADIAL AT 65NM AT FL400 DECREASING IN AREA WITH DECREASE IN ALTITUDE TO 308NM RADIUS AT FL250, 228NM RADIUS AT 10000FT MSL AND 188NM RADIUS AT 4000FT AGL. THIS TEST IMPACT AREA ALSO EXTENDS INTO THE MEXICAN FIR. 15 SEP 21:00 2009 UNTIL 17 SEP 16:00 2009. CREATED: 14 SEP 16:16 2009

Good guess. But incorrect.

I lost the car BEFORE getting the GPS :-)

Returned to the road and wasn't real sure which way to turn. Did a little extra walking that day.

LOL! One of my brothers in northern Ontario used to paint his jeeps sunshine yellow (Tremclad), he said it was so he could find them when he was coming back out from fishing.

Another thing about all electronics is you should test them before leaving home. Especially if they were stored with the batteries in them. Corrosion is insidious.

I'd modify the statement to add INSPECT THE BATTERIES AND CONTACTS as well as testing. Any leakage must be dealt with quickly and further use should be done understanding that corrosion of contacts may cause problems.

Batteries don't leak as much as they used to but... all it takes is that one time when you really, really need the item to work...

Blake,

Tips for GPS users:

1. spare batteries.
2. Even so, carry a compass.
3. Understand how a GPS works so that you can use it. On mine, the compass only works while you are moving.

1. First learn navigation with map and compass.
2. Waypoints are free, use them.
3. Use the GPS sparingly, but carry spare batteries.

Use rechargeable batteries of the low self discharge (LSD) nimh (nikkel metal-hybride) type. Sanyo eneloop is the most recognized type and brand, but there are others.

Not only will they never leak - they also have much better performance than alkaline batteries (that WILL leak, sooner or later, no matter what the brand is). The low self discharge part means that they will loose charge when stored, but the rate is so slow that it's not an inconvenience - the battery will still be at 80% after 2 years. Here's a little to read on the matter: http://www.stefanv.com/electronics/sanyo_eneloop.html

Of course, the ultimate long storage battery is lithium primaries (1.6v), but they are so expensive you don't really want to use them. Makes excellent emergency backup, though.

Eneloops seconded. I was using lithium but with the runtime being just as long with these newer rechargeables I've been able to stop buying the lithium. I use my gps often so I just top them off when done and once a year put them through the analyze cycle in my charger (c9000) to test them.

Understand the implications of the almanac and the ephemeris.

Almanac: if you've not used the device for a few months, the device almanac may be out of date and it will benefit from being left on for 30 minutes so it can download a new one.

Ephemeris: this expires after a few hours; the time to download a new one is the reason a cold start takes 45 seconds or so. Moving the unit will this is happening can interrupt the download, so it's best to switch the unit on before you start travelling.