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Superfly
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Discussion Starter · #1 ·
Parnelli_001 wrote:

I am going to be purchasing a GPS soon, what are some suggestions on what i should get?
Geez, this question comes up a lot.
Read my article:
http://www.bc4x4.com/features/1998/gpsfcflu/gpsfcflu.cfm

Since then, the biggest change that has occurred is the elimination of SA (Selective Availability). Public GPS signals are no longer purposely degraded so accuracy is now extremely high. It was deactivated on May 1, 2000.

Stationary data plot BEFORE SA was turned off:


Stationary data plot AFTER SA was turned off:


I strongly recommend Garmin GPS units simply because they enjoy the widest aftermarket support. Virtually all GPS-related software can speak to Garmin receivers. For 4x4-use, particularly in BC, I recommend getting a GPS that can use an external antenna. When buying a GPS, you should buy these two items to go with it:
- 12V power adapter since they are power hungry.
- PC data cable. The utility of a GPS quadruples when you start managing the data on a PC and using mapping software such as OziExplorer to review your travels or plot waypoints or new routes.

...lars



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I know a lot has changed since '98. Any special models that we (non-gps users) should be looking into? I know you get what you pay for, but if we're only using it for 4-wheeling, what new models are recommended that won't blow our wallet but have the neccessary components? Are there any bullet-proof older used models that have proven themselves and might be on the market for cheap (second-hand)? thx.
 

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Superfly
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Discussion Starter · #3 ·
I know a lot has changed since '98. Any special models that we (non-gps users) should be looking into? I know you get what you pay for, but if we're only using it for 4-wheeling, what new models are recommended that won't blow our wallet but have the neccessary components? Are there any bullet-proof older used models that have proven themselves and might be on the market for cheap (second-hand)? thx.
The key point is to make sure you only buy a 12-channel parallel GPS receiver. Anything else (8-channel multiplex, 4-channel parallel, etc) won't give you the same performance. The 12-channel parallel receiver gives you the best performance for locking onto the satellite signals in dense tree cover. Virtually every new GPS on the market today uses the 12-channel receiver.

Aside from that, make sure the GPS can use 12V power, exchange data with your PC, and support an external antenna. There are so many new models on the market that I can't keep up to date on them but their websites will have all the specs.

Some of the higher end models like the top of the line Garmin eTrex, Garmin 3+, Garmin V, and various Magellan and Lowrance/Eagle models support uploadable maps but for fourwheelers, these maps are not of much use. Little detail for offroad trails and quite pricey. There are third-party tools that let you build your own maps for the Garmins and Lowrance/Eagles but they require a lot of effort to use them.

If I had the opportunity to buy a used Garmin II+ or a brand new low end Garmin eTrex, I'd probably get the II+ because it (as well as the III, III+ and V) can display its data in landscape or portrait mode. When in landscape mode, you can lay the GPS on your dash which makes it very convenient for 4x4 use. Add some velcro and it'll stay on your dash.


GPS Usage
The simplest and most common way to use a GPS is to read your current location and then look up the location on your map (for backwoods navigation, you must always have a map and compass, even if you have a GPS!!).
The second most common use, IMO, is to leave it on (that's where the 12V cable comes in) and set it to record a track log. This log, when displayed, will show up as a bread crumb trail showing the path your vehicle took during your fourwheeling trip. If your GPS doesn't support built-in or uploadable maps, the track log is still useful. How? Because it provides an additional way to identify the trail you're on by comparing the twists and turns you made with routes that you see on the map.
When I get home, I upload the track log into OziExplorer and overlay that onto a scanned map of the area I was in. This makes it easy to see where I was and what trails I was on, as well as how close I was to other trails.

eg:


The GPS can also be used to mark waypoints. You just press MARK and it will record the current location. Later on, this waypoint can be recalled and displayed on the GPS's map display so you can get an idea of how close (or far) it is and where it is in relation to your current location. You can use waypoints to mark favourite fishing spots, mine entrances, important intersections, camping spots, etc. You can also upload them to a mapping program on your PC to overlay them onto a map to see where those locations are in relation to other topographical points of interest.
For navigating new areas, I use OziExplorer to view maps of the area I will be exploring. I create waypoints (just by making a simple mouse click) for the areas I want to see or to mark the important turns and intersections along my proposed route. I also print out a copy of the map which also shows those waypoint marks. Finally, I download the waypoints into my GPS and head out for the trail. While I'm driving, I can glance at my GPS' map display to easily determine where I am in relation to those waypoints. And from that, I can easily figure out where I am on the more detailed, paper map that I had printed out. This is much faster than stopping and taking a reading and then manually looking it up on a map. Using this technique, I confirm my location (and the fact that I'm on the planned route) far more often which means the odds of taking of wrong turn are drastically reduced and if I did make a wrong turn, I find out very quickly.

Whew. That's enough for now.

...lars



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If you have some money to blow..........


Go for the Compaq iPaq, used in conjunction with a NavMan!
This is a wireless, satellite receiver that can be used for GPS, web browsing, e-mail, etc. It will give you a live link via satellite and display your position on a map of the area (that needs to be up-loaded from various free sources). It will clock your speed, elevation, collect waypoints, track your route, etc.....

I demo'd this in the Arctic for MapInfo, works sweeeet!

iPaq, $850
NavMan, $1000 (?)
software, free
getting back to the campsite first - priceless!
 

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Hey lars, sorry for asking such a general question... but i just wanted your personal opinion of which you gave in great detail! thank ya kindly. My search&rescue group use the garmin 2 plus i do believe which i find to be simple and somewhat accurate. records your speed, waypoints and is pc compatable. Any ideas on the cheapest place to buy these? i might have a chance to by discount from the S&R supplier. also OziExplorer, how much is that software?
 

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Where to get a GPS...

I picked up my Garmin 12 on ebay for about 130 Cdn...

The Garmin 12 is pretty much all you need. The only thing in hindsight that would have been nice would be an antenna option. I believe the Garmin 12XL has that ability.

BTW,

I tried out the VBS script for calibrateing Toporama Maps that Lars posted earlier for and it rocks. I was gonna throw something together similar but no need now. I had a directory of maps that I hand calibrated over the course of many late nights. For comparions(laughs) I redid all 400+ maps using the utility and it took about 2 seconds....ARggggghhhhh!!!!
 

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Ok i have used and love the garmin 12xl. used it to grab the coords for some spots on pheonix. I will buy one of these unless someone can recommend otherwise, next question is where do i buy from, walmart, radioshack, internet or supplier?
 

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Parnelli_001 said:
also OziExplorer, how much is that software?
you can download it free here
http://www.oziexplorer.com/ it $75 if you want it registered.

at work we buy Garmin 12XL's they're pretty good for your money, we get them from IRL in PG for just over $300.

I'm pretty spoiled when it comes to this department. I make maps for a living and have access to all kinds of cool shiet at work. I just build my own wheeling maps.
 

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If you want to use GPS in your truck then a remote antenna is nice.

Bigger displays use a lot of battery power especially in the cold. Rechargeable battery packs are nice.

Exposed LCD screens are vulnerable to damage.

I dropped an Eagle GPS in the bush in September and didn't find it until the following May. I charged it up and it worked as good as new.

I've been using GPS for quite a few years as a forestry contractor and they are a fantastic tool.

You still should carry and know how to use a good compass because sometimes the GPS just doesn't work or runs out of batteries.
 

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Superfly
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Discussion Starter · #17 ·
JOG said:
I dropped an Eagle GPS in the bush in September and didn't find it until the following May. I charged it up and it worked as good as new.
I gotta ask: how did you find it again??


I've been using GPS for quite a few years as a forestry contractor and they are a fantastic tool.
Has the removal of SA affected your use of GPS at all?


...lars



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When I was GPSing cutblock boundries a few years ago and SA was still on we were able to download correction files. You had to know when you were GPSing to get the right files and all that but it worked out pretty well.

Corey
 

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Superfly
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Discussion Starter · #19 ·
How did that work? Were these after-the-fact correction files? I guess they'd have to be since the US Mil wouldn't be making that info available ahead of time (they probably wouldn't know what it'd be, anyway). I'm guessing you guys recorded the variation from a known position and then downloaded the offset or correction info from that time. What I'm curious about is how close, geographically speaking, the correction data point had to be to the cut blocks in question. In other words, would correction data 100 miles away be good enough to use? The larger question (although moot these days) is whether or not SA was constant over the entire GPS constellation? That is, would the correction data you use in BC be usable in Brazil?


...lars



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lars said:
How did that work?
I'm guessing you guys recorded the variation from a known position and then downloaded the offset or correction info from that time. What I'm curious about is how close, geographically speaking, the correction data point had to be to the cut blocks in question.
...lars
If I remember correctly we had to know what times of the day we were GPSing and where we were. I'm not sure how close we had to be with where we were but I'm thinking if you were new the mapsheet you were in that was enough. Its been a few years though so don't take it for gospel. So no correction data for here would not work say in Brazil.

As far as the correction data went it made our infomation dead nuts. Because each point had a different amount of error it wasn't like doing a nad shift 100 east 200 south or anything globaly. Each point had to had a different correction applied to it, so our odd shaped cutblocks would turn out proper after correction.

Corey
 
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