Anybody have any ideas on

1) Where ya can get a 40' Tower ± and Costs...rigid enough for GPS position, and still accessible at the top ??

or
2) Plans for build your own version of above ??
I was thinking a 6-8" casing set into ground, 10' ± protruding and a "slot" cut into it. Then drill stem, 2 7/8", 40' pinned at the top of the casing for a hinge point, removable pin near bottom for locking pin, and a hand crank for tilting and raising.

I'll post a "picture" if I get it drawn up.....but wind stability has me concerned...

Any thoughts ??

Jimbo

EDIT: Would you potentially get any unwanted signal interference from the pole as described ??

Modified By James Webb on 12/10/2001 at 1:16 PM

Jimbo

What I would really like to have is the top 40 feet or so of an oil derrick for an observation tower. But I'd guess that due to thermal dynamics the "fixed point" wouldn't be very well fixed. An adjustable tribrach mount would take care of the horizontal shift, but I can't see an appropriate means of monitoring the vertical displacement. Of course the thermal problem would be more pronounced over a lengthy session, or due to typical sun/shade problems. I understand the logistical problem you're having in picking your position. It just came to mind that I may have to revise my own future home remodeling plans. I'd planned to replace the standard asphalt shingle roof with metal, but after looking at the possibility of more pronounced multipath problems with "POST" have decided to just re-do the old asphalt shingles. I won't mention this reasoning to the wife as she's content with the reasoning the economics in cost difference.

I'm just wondering how much displacement you mak have with a tall tower, both horizontal and vertical, due to coefficient of expansion and just plain old mechanical shifting.

J.D.

p.s. You're plan sounds almost identical to a break over tower I built in 1976 during the c.b. radio popularity. I had it balanced such that one person could raise and lower it with one hand (as long as the antenna weight remained similar). I was constantly raising and lowering this thing to trim and tweak my homemade bamboo and aluminum wire 3 bay directional. There was some obvious instability in the position at the top due to wind alone.

email me a fax number and I'll fax you a sketch of what I built back then.

Modified By J.D. Billings on 12/10/2001 at 1:55 PM

JD perhaps you could just build a new house with a tower built into it,...sort of an EXTREME version of taking the wife on a GPS picnic...

Tom Bryant........on the ground in ST Louis MO

Tom,

I gave up on the whole derrick in the yard thing. First I'd want a roof on it, then walls, then an elevator, central heat/air, plumbing, beer fridge, etc. Then I'd have to go outside to the roof to mount the gps antenna anyway.

I'm satisfied with good old POST at this stage of the game. If I can just figure out where it is now (hahahaha).

We gotta get Jimbo up and running now. He be the one with the tree problem.

J.D.

Hey, why don't you build yourself a permanent/fixed station. That would work right into the next major L1/CORS test for the joint Texas-Louisana Not Quite OPIE but Damn Close Research and Development Consortium. Might be interesting to see how St Louis MO would fit with Northeast Texas and Southwest Louisana via a whole bunch of CORS stations.

Ain't Ashtech Software great?

Once upon a time a guy named Jasper Bilby saw a need and came up with this idea.

http://www.photolib.noaa.gov/historic/c&gs/theb2520.htm

Since NGS (aka USC&GS) scrapped their triangulation program, I'm sure there are Bilby towers rusting away that could be had for a song.

but I think I have the tree problem solved!!!!!!!

No, not a chainsaw !!

Jimbo

PS: It might take an act of Congress to be able to buy them from the Gov. !! Usually stuff has to be auctioned off as surplus, etc., from my limited experience.
Modified By James Webb on 12/12/2001 at 8:22 PM

What if you got the local college or university to make a request to the NGS for a loan of the Bilby tower for some educational purpose or other? Then it might not have to change ownership.

Sort of like fire trucks that get handed to volunteer fire departments on the condition that they be on call to fight grass fires and such. For those deals the fire department just has to fill out papers and fix the truck up well enough to get it back to their fire station.