OFF TOPIC-GPS advice sought please

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).

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.

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

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

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

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

Greetings Jerry, That was my first thought. But the only guy I know who has one told me he broke it. Thanks , Eric

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

buy a delorme map for seven bux.

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

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

A friend of mine in the UK is building his own sextant and has put together a web page covering his efforts.

You may want to check it out.

Regards, Marv

Home Shop Freeware - Tools for People Who Build Things

I'm still trying to figure out the C.Plath sextant my wife bought me a couple years ago.

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.

Hi Eric

I've got it -- Buy your brother a GPS with a USB connection so he can use it with his lap top. They cost about $100.00. A geologist should have something like that anyway. It'll identify your location on an overlay map so you can track yourselft as you move.

Jerry

My son and I use an eTrex, and we host the AustinMusicBox cache - check out

for 78731 or geocaching is a lot of fun

Thanks Pete. I'll check out both. ERS

I bought a Garmin 12XL, about $150, and I love it. It is such a good GPS that it is standard equipment in USAF survival gear packs.

It will get you within 10' on a good day. The accuracy varies. Depending on what you want to locate, this may or may not be acceptable.

If you have landmarks you can enter, like corner markers, a big rock, a huge oak, and the like, it can give you a pretty good idea. I have seen the smaller $100 ones by Garmin, and they have a smaller screen that doesn't give you as good an idea. The top of the line ones have maps and all, but you don't need all those bells and whistles.

I vote for the Garmin 12XL, and you can probably get one on ebay for cheap. Download cables, car power supplies, nimh rechargeable AA batteries .......... all relatively inexpensive compared to some models and brands.

I use mine on trips as an accurate speedometer, and distance traveled to figure mileage.

Once you use one and get the hang of it (a short time), you will be surprised how often you use it. You can even use it to get back to a spot on the water where you caught fish, like over a cliff, or some bushes, and be pretty accurate. If you find some mineral deposit out in the desert or in the woods, you mark it, and you can get back within spitting distance of it the next trip.

HTH

Steve

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