>
> What was the condition for which 31 was derived?
Sorry Kent, I don't understand what you are asking. Condition of what?
Hello Jim,
But this is essentially what I'm doing in reverse. I'm sighting back out to the scale. Any difference in my position should show up as a difference in reading in angular values to my target.
The uncertainties in the values were expressed as 1-sigma (~68%). 3 sigma (~99.7%) gives 0.24mm northing.
I'm going to do the test again some time with a different methodology to better determine the accuracy/repeatability of what I'm doing.
> >
> > What was the condition for which 31 was derived?
>
> Sorry Kent, I don't understand what you are asking. Condition of what?
I was interested to know what 31 represents, whether a replacement in the same pattern of lugs as a former setup or something else.
> Yes I understood what he is doing
Well, a centering error of 5mm in a Leica tribrach would be unheard of. The usual values quoted are below 0.1mm. It's called "forced centering" for a reason and is an easy thing to test rather than simply relying upon anecdotal evidence..
> I'm going to do the test again some time with a different methodology to better determine the accuracy/repeatability of what I'm doing.
If targets at 0-90-180-270 were possible, that would give a means of testing the uncertainties of the directions, also. Repeat sets in same setup would give a measure of the direction uncertainties.
Try it on a Monument like this
> The 1 meter extension gets the antenna well above the fence.
Not that it matters for most practical purposes, but the stability of the monument gets kind of lost in the use of the extension pole. The tribrach can be finely-leveled, but if the extension threads aren't perfectly aligned, the plumb condition may not get projected up to the antenna. And then there's the effect of every stray breeze on that great big lever.
Just for grins, have you set up a gun and sighted up and down the extension under different orientations? I did this with my 2-meter tripods and found them to be within 1 mm plumb when properly leveled, but then they're supported both top and bottom, unlike the tribrach extension.
I always flinch when I see a pole sticking up up out of a tribrach; the mechanicals are all wrong.
Try it on a Monument like this
> I always flinch when I see a pole sticking up up out of a tribrach; the mechanicals are all wrong.
:good:
yes, .007mm, I'll go check that out........;-)
MM,
0.007 was only one of the components. None of those results show 0.007. Setups 12 and 13 were .021 mm different from the base starting coordinate. I also reported the uncertainties as coordinate standard deviations which were more than twice as large as the movement calculated.
I hope you aren't misunderstanding what I'm showing. The noise in the SD looks larger than the changes in coordinates themselves. the 99% confidence interval for any of these coordinates according to the solution output is in the tenths of a mm range. I think some people are getting a bit excited over the raw numbers. I have, however, devised a better, more controlled test which may well show the real accuracy to be expected.
No, and that was one of the failings in the method. I should have returned to the starting lug position to make sure my house or the tripod wasn't drifting.
stations were lug position A, A, A, B, C.
I have devised what I think is a quite good method to get controlled, quantified, minute movements of the telescope to see if it can be measured for the next test.
> 2.8 m =~ 10'
>
> 20" =~ 0.01'/100'
> 20" =~ 0.001'/10'
>
> Get a bigger room with targets set 28 m away.
Mate, I will gladly take donations to buy a bigger house for this purpose.
Conrad, I applaud your efforts, and I will continue to watch your posts, I can learn something new even at my advanced age
> I have devised what I think is a quite good method to get controlled, quantified, minute movements of the telescope to see if it can be measured for the next test.
Sounds very interesting. I'll look forward to reading about the results.
NB: Some of the static posted to this thread is from folks who have never conceived that the measured world had any smaller dimension than 0.04 ft. 🙂
