GPS receivers are wonderful, but ...

Sometimes people place far too much faith it modern electronic widgets that supposedly do everything. Now, I spent most of the last 10 years before I retired working on various aspects of the GPS, but I always warn people not to do as this fellow did -
http://www.engadget.com/2007/07/21/driver-follows-gps-onto-pedestrian-walkway-into-cherry-tree/

Bill, that event may have happened, but it wasn't with that truck.

Here is the an article about "the truck in the tree".

http://truckinthetree.com/4.html

So were you joking or serious Bill? I still can't figure it out.

Thanks, Bill.

I just wasted a perfectly pleasant hour clicking on various links stemming from your post.

Doesn't taken much to distract me from work, I guess.

MTB416 -

Serious about what? You should know by now that I am rarely ever serious about anything. But I am serious that people do incredibly dumb things with their GPSRs, like blindly following them (staring at the screen while hiking into obstacles or into ponds and streams - which I have seen too many times in my land navigation workshops), or getting tired of hiking, then using the cellphone to call for a ride home. And I am serious that in my workshops, I tell people right up front that the GPS receiver can tell you where you are and which direction to a previously marked location, but it cannot tell you how to get there, and its batteries can die. So don't rely on the electronic widget as your sole navigation device. It won't keep you from falling off a cliff (I do know of a case where someone rode their mountain bike off a steep embankment trying to follow the straight line path shown on the GPSR he had tide to the handlebars). Use your head. etc etc etc. Doesn't always do a lot of good, though.

Ed -
If you follow the various links and do a little probing, the incident as described in the article did happen, but the photo was from something completely different, a publicity stunt. The incident itself happened in Switzerland, but the truck in the photo is an old Chevy pickup, and the tree isn't even a cherry tree. In the real incident, when the guy finally realized he was on a pedestrian walkway, he tried backing up, managing to hit a couple lamp posts and the tree (not clear from the original source what kind of tree it was), which had low-hanging branches (it was a park of some sort). The park workers had to do a bit of pruning of the tree's branches to get him out of there. The detail links I went to weren't clear whether the truck was towed out ultimately or whether it got driven out, but it was on the ground, not up in the air.

Some day I'm going to have to enter the modern age and get a GPS. So far I have only ever used a compass. But it would be a question of whether to get a cell phone or the GPS first, as I have neither.

Chumango said "So far I have only ever used a compass."

You don't use a map? Gee, I would suggest you get a map before a GPSR. Then all you would have to worry about is the map getting wet and disintegrating ;)

Somehow, Chumango, I can't imagine that an electronic widget would ever be more than an amusing toy for you, as it is mostly for me. But then, since I worked on system design for the system for a number of years, I feel obligated to keep testing my handiwork. See, as I stand there on the summit, I can look at the GPSR's screen and find out that I am actually on the summit. Otherwise, how would I know?

Bill - you can tell you're on top because as you look around, everything is below you!

I've yet to allow the digital age to intrude on my backcountry time or space. I rely on fairly good skills with a map and compass and the absolute understanding that my personal built in sense of direction got drunk one night and never recovered.

Were I to head towards one pole or the other or be inclined to paddle across the ocean I'd probably accept the use of a GPS. It's been years since I used a sextant, but I'd keep one handy as a backup to the GPS.

You keep referring to it as "GPSR". What does the R stand for? Am I missing something?

My map and compass skills are pretty poor, so I use a GPS. I generally stay on the trail or close to it, so I don't feel I'm in any harm. I generally use the information to judge my speed and elevation changes. Anyone know of any good books on the subject of compass/map use?

braden asks "You keep referring to it as "GPSR". What does the R stand for? Am I missing something?"

"GPS" = Global Positioning System, which is short for the full name "Navstar Global Positioning System". To say that you have "a GPS" or "use my GPS" is saying you yourself personally own a global positioning system, including satellites and a ground control segment with its attendant computers and transmitters that control the satellites and specify the messages they send.

"GPSR" = a receiver capable of receiving and decoding the signals transmitted by the satellites that form the Space Segment of the Navstar Global Positioning System, or "GPS receiver" for short. The "R" means the receiver that you can hold in your hand or is built into the dash of your car.

There are other global navigation satellite-based systems, generically known as GNSS, One is GLONASS, the system put up by the former Soviet Union, currently operating in a crippled state by Russia. Another, under construction by the EU, is Galileo. China is working on one and has a couple test satellites in orbit, with India having one test satellite in orbit. Japan is developing a system as well, though still in the early planning stages.

"GPSR" is the accepted acronym for the receivers used by the User Segment of the GPS. Calling it a "GPS" is sloppy slang.

MTB -
There are a number of good books on map and compass. The classic is Bjorn Kjellstrom's, still in print. Kjellstrom and his brother started Silva, a Swedish company that makes compasses from the very simple to very advanced survey-grade instruments. They also developed the sport of orienteering from Scandinavian military navigation games. Silva compasses are distributed in this country under the Brunton name, an old-line survey instrument company based in Montana (now into lots of outdoor gear). Compasses sold in North America with the Silva logo are distributed by Johnson Worldwide Associates, the company that distributed the Silva of Sweden compasses until Silva bought Brunton (in the 1990s). JWA Silva compasses have been made by Suunto (Finland) since that time. Suunto imports Suunto compasses under its own name as well.

Some other excellent books on map and compass are published by the Seattle Mountaineers and NOLS (National Outdoor Leadership School). But the best thing is to get a knowledgable mentor or take a basic course from your local orienteering or backpacking club, then just get out there and do it.

Bill, obviously I DID a little probing since it was I that posted the true origin of the truck in the tree.

"R" for reciever makes sense. I just never heard of them being referred to as GPSR. Thanks for the clarification.

Yeah, Ed, you found the tree, but you didn't make it to Switzerland ;)

"Be Expert with Map and Compass" Björn Kjellström - everything you'll need to know and nothing extra. Read, practice and you might never miss your GPS - plus - you'll be able to find your way if the batteries die or the GPS gets dropped on a rock!

I had heard that the Air Force is looking at turning the selective availability back on again bacause of the terror threats. Accuracy will go from the current 4-6 meter to 45-50 meters. Better start honing your land nav. skills.

FMD, turning SA back on is unlikely because of the widespread usage of the system in life-critical applications, and in view of the agreement just reached for interoperability between Navstar Global Positioning System and Galileo. The life-critical applications include the increasingly wide-spread use of e911 based on GPS location (the vast majority of cell phones sold in the past 2 years have embedded GPS-capable chips that supply your location to the 911 system whether or not you activate the mapping services), along with the almost universal use of the system for airline navigation and landing systems (ILS is decreasing in its use outside the private aviation arena) and for marine services (container ships are virtually all GPS-navigation based).

Besides, there are ways to implement local deniability that are far more effective than SA. And yes, that is a part of what I worked on professionally for many years, but I can't tell you any more than what has appeared in the press. You can get current information from the trade magazines (no, not "Aviation Leak"). However, your accuracy numbers are incorrect. The error budget numbers for 50% (1 sigma) and 95% (2 sigma) are different, plus you have omitted DOP.