[Therion] Thanks Beat for the DistoX, PocketTopo

[Andrew Atkinson]

On 25/01/11 19:21, Bruce wrote:
> Firstly I’d like to thank Beat for;
>
> -developing the DistoX and for the regular improvements to PocketTopo,
>
> -repairing our DistoX when it was faulty after our initial assembly, and
>
> -‘walking’ me through and troubleshooting on numerous times I’ve been
> confused or one of the devices was not working.

I will second that, its adaptability keeps amazing me, just done a 
survey in a cave with too much metal to use a compass, therefore had to 
use a total station, it does not do negative inclination but give out 
350 for -10. Pocket Topo took it in its stride. (therion gives an error, 
which I will mail about shortly)
>
> We just found 2.5km of 10-30m diameter passage, and would not have been
> able to face surveying with a tape measure and paper (too slow and
> inaccurate). It’s big muddy light absorbing passage. Having launched
> into the project I have a suggestion for PocketTopo development, (and
> distoX observations) that the forum might like to comment on.

Well done, sounds like fun, do we get to see a survey soon?
>
> *PocketTopo v1.35*

Must upgrade to this!
>

<snip>

> shots and ‘.’ shots).
>
> *Disto Distance*
>
> Our distoX occasionally gives one off spurious distance (and rarely
> compass) readings. On our most recent trip it went one step further – a
> ~15m survey leg gave ‘3 in a row’ readings of 0.21m and some time later
> (after many readings that looked OK) on a similar ~15m survey leg it
> gave ‘8 in a row’ 52.0m readings with the odd 48m and 82m reading thrown
> in for good measure. We chose another station and the anomaly
> disappeared. We are quite sure that for the majority of these bogus
> readings the laser was squarely on the target. This survey (but not
> these legs) included a 100m loop, which closed at 1.25%. This is among
> the worst we’ve had with the distoX, but it does not suggest any gross
> distance errors occurred within the loop.
>
> Some 100 distance readings later the lithium AAA batteries died. (The
> indicator suggested the batteries were full at the start, and the survey
> included probably 300 shots).
>
> Has any one else noticed similar issues?
>
> Are the spurious readings likely to be battery level related? Or do they
> suggest something more sinister?

In reverse order, for lithium batteries when they die they die quickly, 
all bars showing to dead in less than 10 shots. I have no idea how many 
reading the distoX takes on one set, but it must be thousands, I am on 
my second set, and covered many km's of passage, with splays, it must be 
about 1 leg per metre.

As for the spuriuos distance reading, yes occasionally, but never 3 of 
similar length together, it usually occurs in damp or drippy areas, we 
have also managed to reflect it off a wet surface of a wall or a pond, 
and get a more consistent error, but not enough to form a leg in 
PocketTopo. I have seen silly short measurements, again in damp 
conditions, usually with steaming or muddy front, not necessarily on the 
lens, can be on the rubber bit round the edge. I have not been able to 
reproduce it back at home, when I try to it just works or does not work.

Also on 2 occasions the clino has 'frozen' repeatedly given the same 
measurement, while the distance and the bearing seemed fine. both times 
I have had to calibrate the DistoX to fix the problem

 From my experience 1.25% seems a little high for a loop closure using a 
DistoX. Since using DistoX anything above 0.5 is suspicious, I regularly 
get 0.0 (the output is only 1 dp)
>
> *Disto Display*
>
> A new distoX, recently acquired and upgraded by a colleague has
> developed some permanently ‘lit’ pixels (about 20 of them) in the middle
> of where the inclination is displayed – even when the device is powered off.
>
> He is a ‘distoX & paper’ surveyor (and like me has aging eyes) so the
> difficulty in reading the display is particularly frustrating.
>
> Is there a solution to this?
>
> -New display from Leica?
>
> -New circuit board from Leica?

I have some weird lines on one of mine, so might need a solution to this 
soon as well, let's face it they were not built for caving

Andrew