OFF TOPIC-GPS advice sought please

Greetings All, It looks like using a GPS for locating features on my 10 wooded acres would be a real bonus. Especially since my wife cannot tell where she
is on the parcel. There are many available for around $100.00. I don't really want one for driving directions, or that has a bunch of maps in it. I just want to know, with reasonable accuracy, where I'm standing in relation to a map of the parcel. It looks like a 3 meter circle is standard accuracy for the $100.00 units. I think this will be OK. So, opinions and advice please because there are so many options and so many well educated folks reading this NG. Thanks, Eric R Snow
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3 meters for a low end unit CAN be seen on a good day, with clear skies. One thing you need to remember is that GPS units do not work well (or even at all) under shade trees. If you're trying to locate things on a wooded lot, you're not going to be pleased. They MUST have a clear view of the sky to work, and they MUST pick up at least 3 satellites to work (the more satellites they can see, the better the accuracy).
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Eric R Snow wrote:

The el-cheapo ($100) one that I have experience worked fine as long as there was blue sky in all directions. Standing under a tree blinded it to the satellites. They work at 2.5GHz (IIRC), which is strongly attenuated by wood, either still in a tree or dried and made into a house.
A more expensive unit could probably handle the attenuation, but then it'd be more expensive...
It may be more effective in the end to discretely mark the trails, and note them on your map.
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Tim Wescott
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It's more like 1.5 GHz.
Joe Gwinn
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Eric R Snow wrote:

Eric, I have used both the Garmin ETREX and the GPS60 (non-mapping version) for a use similar to what you describe. Either worked perfectly for that use, the etrex is sold for around 90 bucks in lots of places. The GPS 60 has a few more features for around 150.00. Both let you mark points you want to save and allows you to navigate to them, and can create a record of the path you walk. The etrex is simpler, so that may actually be an advantage. I like the USB port on the GPS60, as I often upload and download stuff, but the etrex will do that also vis RS232 (you need a special connector, garmin wants 30 bucks for it, so I made my own. Using a mill. Machine shop content). I use my GPS 60 all the time and love it. Most excellent unit for that type of use. The GPS 60 seemed to have the best battery life for the "big name" units of similar cost, at least when I got mine (early last year), but that may have changed by now. I have not used any other brands, so I cannot give an opinion on any of them.
There is freeware/shareware on the web that allows you to upload/download locating and waypoint data from your computer, that is better than the stuff that Garmin bundles with the GPS60. It will download topos and ariel photos from the web (mostly USGS data) and then put your waypoint data on it. Way cool.Works with other brands of GPS also, I think. The name is escaping me at this moment, but I can find it at home, if anyone is interested.
Hope that helps, AL
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On 20 Mar 2006 08:24:15 -0800, snipped-for-privacy@gmail.com wrote:

Greetings Al, The Garmin web site said that most GPS units will not work indoors, but will work in the woods. Posts previous to yours said that woods will block the signal. Of course, the density of the trees will determine the blocking potential. Your post is great though because you are using the GPS with success just the way I want to. Thanks, Eric
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buy a delorme map for seven bux.
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I like hunting for meteorites. When you find one, there is usually a pear shaped debris field where you can find more fragments of the main body. You then set up search grids with those orange soccer cones.
If I have to leave, I know that I can come back next weekend, and find this needle in a haystack. Within ten feet. Try that with a seven bux map.
Would that be like putting an X on the bottom of the boat when you find a good fishin' hole?
Steve
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Eric R Snow wrote: from the web (mostly USGS data) and

Hi Eric, The website is correct, it won't work indoors, the signal is heavily attenuated by most construction. I generally use mine in the woods. How the new england woods compare to where you are, is hard to guess. I am not any sort of expert, but as I said, i generally use mine in the woods, when hunting, hiking, etc. I've never had occasion to try it in a rain forrest, but it has worked around here for me thus far. I still carry a map and compass if I am in unfamiliar areas. I usually only want to be able to navigate back to my truck, camp, stand or whatever, should I get completly turned around, so the mapping is not a big deal to me. My unit gets me plenty close for that. I have not had problems getting reception in the woods. Where I am, there are usually 5 or more satelites in view, so perhaps that gives the unit enough "choices" that at least 3 are useable most of the time. I understand that can all be very area and terrain dependent, so YMMV, as we say.
Someone else gave an excellent bit of advice, find someone you can borrow one from, and try it out. That is exactly what I did. I tried a friends etrex and loved it. I got the gps60 because my wife liked it a bit better than the etrex (longer battery life rating & better antenna), and bought it for me. Great woman, she is. I'm keeping her.
-AL
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Hi Eric
Find a friend who already owns a GPS receiver. Walk around in your woods with him and his receiver so he can tell you if his receiver works in your environment.
Jerry
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On Mon, 20 Mar 2006 16:32:43 GMT, "Jerry Martes"

Greetings Jerry, That was my first thought. But the only guy I know who has one told me he broke it. Thanks , Eric
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Eric sez:
" . . .I just want to know, with reasonable accuracy, where I'm standing

I've had GPS since it wasn't cool - Garmin GPS 45. I still have it. If I understand your question correctly you wish to locate specific points in your parcel of land and then reference those points to a map. In order to do this you must have a highly detailed map to begin with. I can't say with any certainty how detailed that map should be. I don't know of any sources that have maps of sufficient detail for one to pinpoint locations within a 10 acre parcel. The DeLorme maps of residential areas are an exception, but I assume your parcel is not residential.
The GPS will give you the latitude and longitude coordinates of any point you pick to "waypoint". This means you hit the waypoint key and the GPS records the current location as a point for future consideration. Then to find that waypoint on a map the map would have to show sufficient detail to discern a specific plot of 10 acres. That would be a very detailed map, indeed. AFAIK, such a detailed topo map doesn't exist. Maybe there'd be an aerial map of the specific area, maybe not - I'm not sure about that.
So, getting back to "waypointing". You could walk the parcel and "waypoint" as many spots as you'd like. This in essense, stores a map of the parcel in your GPS. You could then open the "page" that contains the map you just drew and walk over it and see a moving cursor defining your present position on the map. Some GPS's can be read on a PC and allow printing of the maps (pages). This would allow you map the area with as much detail (numbers of way points) as you desire and download the map to a PC and printer.
Bob Swinney
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On Mon, 20 Mar 2006 11:17:34 -0600, "Robert Swinney"

Greetings Bob, My plan is to use the legal description which gives the latitude and longitude descriptions. And the county also has recent aerial photos it uses for keeping track of changes. My brother, the geologist and cartographer, is going to use this info to draw a map which will basically be a rectangle with the outline of the triangular parcel in question within. A grid will be drawn on this. The line spacing of the grid will be either 10 or 20 feet. Then I can place marks on this map and show my wife where things will be in relation to existing roads and structures. Thanks, Eric
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Go for it, Eric! GPS's are very practical devies. Lots of fun also. I got into GPS many years ago from a limited background in celestial navigation. It was a natural step - I bought a GPS instead of a new sextent. I'm still interested in celestial, though. One of my shop dreams is to build a sextent.
Bob Swinney
Bob Swinney
wrote:

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wrote:

A friend of mine in the UK is building his own sextant and has put together a web page covering his efforts.
http://www.geocities.com/richardandtracy/SextantPage1.htm
You may want to check it out.
Regards, Marv
Home Shop Freeware - Tools for People Who Build Things http://www.myvirtualnetwork.com/mklotz
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Marvin sez: "> A friend of mine in the UK is building his own sextant and has put together a

Thanks Marvin for the great ref. to building a sextent. It was quite informative.
Bob Swinney

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Robert Swinney wrote:

I'm still trying to figure out the C.Plath sextant my wife bought me a couple years ago.
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On Mon, 20 Mar 2006 15:28:04 -0600, with neither quill nor qualm, Rex

There's a good straight-line there somewhere, I'm sure. <g>
Has anyone looked into Google Earth? You can see your property down to one meter resolution through the satellite's eyes. It's downright muckin afazing.
www.earth.google.com Download the app and view away!
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Larry Jaques wrote:

I don't have the PC power to run "Earth", but I've looked up our house on the sat pix in Google Map's. There is a stone wall running down the middle of our back yard. It's 2' wide max and I can see it on the Google pix!!.
So, if that's the resolution available to the public, for free(!), I'll bet the military satellites can see when my shoe lace is untied!
Bob
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Eric R Snow wrote:

RE: Maps, check for USGS maps online, possibly available for download from a university site. The USGS maps and photos for the CT area are available on one of the UCONN servers, check universities in your area for similar.
RE: Reception, if you do have trouble getting reception in the woods, an external GPS antenna mounted to the end of a telescopic painting / window washing pole may elevate the antenna enough to get a decent signal.
Pete C.
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