[Ham-Mac] Rayming TN-200

[Chris Smolinski]

>>Anyone know what the accuracy of this beast is? I need to find some 
>>property markers that are way back in the woods, in brush and 
>>thorns. Could this or a hand held GPS unit get me to within say 5 
>>or 10 feet so that I might be able to find the marker?
>
>
>My Garmin GPS V never says the accuracy is better than 16 feet, even 
>with WAAS enabled and 6 birds accessed. 5 feet is a real push, and 
>if you're in the woods, surrounded by trees, your results will 
>suffer as reception diminishes. But, walking in a circle, with the 
>compass display, you can zero in on it pretty well.

Some googling for WAAS claims the accuracy approaches an RMS value of 
1 meter, that's about 2 meters or 6 feet 95% of the time, as you 
average for a long time (time = an three hours or so). Here's the 
site: http://users.erols.com/dlwilson/gpswaas.htm

I would guess that with a USB unit, I could average for as long as 
I'd like by taking readings and averaging them myself (if my iBook 
batteries hold out that long!), do the handheld units allow you to 
set long averaging periods?


>If you've ever tried Geocaching, you know that it's pretty tough to 
>pinpoint a lat/lon position. Think about it -- your arms 
>outstretched span is about 6 feet. At least you know the markers are 
>on the ground and not hidden in a hollow tree.

Sounds like an interesting hobby. Someone mentioned that he used to 
do work for the USGS finding markers, and used GPS to get close (back 
in the days before WAAS) and then just poke around in the brush to 
find the marker, which got me to thinking I could use it for my needs.

>Wear long pants and gloves.

Oh definitely, especially as I only need to approach with 2 or 3 
meters of poison ivy to get a rash, it seems. This would be a better 
exercise to undertake in the winter, when that stuff is all dead.

To add to the challenge, there's a small stream back near the 
property line as well. Supposedly there is a concrete marker back 
there which will pin down at least one corner. I still need to figure 
out if I can convert a location on the map to some sort of absolute 
lat/lon position. I'm assuming the marker is still there, they have a 
habit of getting [re]moved by kids. :-(

To keep somewhat related to the list - it's all so I can install a 
very long longwire antenna ;-)

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Chris Smolinski
Black Cat Systems
http://www.blackcatsystems.com