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distox [2018/12/10 01:59]
brucemutton
distox [2018/12/20 19:14]
brucemutton electromagnetic
Line 30: Line 30:
   *Three (successful) shots to the same place means it's a survey leg, and the pda assumes you will now move to that place.   *Three (successful) shots to the same place means it's a survey leg, and the pda assumes you will now move to that place.
  
 +==== Troubleshooting Erroneous Measurements ====
 +These are more warnings to be cautious and observant, rather that troubleshooting as such.
 +===Battery Changes===
 +ALWAYS carry out the accuracy ​ test described ​ here [[http://​paperless.bheeb.ch/​download/​DistoXAccuracyPrecautions.pdf]] after changing batteries (or charging a DistoX2) and before the start of each days surveying. ​ If you do have a small discrepancy in compass or clino and you are too lazy to recalibrate,​ you can always use the calibrate statement to compensate
 +<​code>​
 +calibrate compass 0.5 # half of largest difference in accuracy test
 +calibrate clino 0.2
 +</​code>​
 +Think carefully about the sign of the correction!
 +
 +I have made a spreadsheet to help with this  [TO DO post the spreadsheet]
 +
 +===Distance===
 +We've noticed that spurious distance measurements are more common than we would like, maybe 2% of shots?? ​ All of the ones we have noticed are more than the actual distance measured, usually by more than a factor of 2 or 3 (a typical case would be a distance of about 10m measured as either ~50m or ~80m for a sequence of 5 shots, with the latter two pointing at a completely different target - and in a passage where we could see no more than 15m), but there was one case in a wide open passage where ~15m was measured as 25m (and we are sure we were not missing the target). \\
 +
 +This can manifest a little bit like the sticking of compass or clino (see below) except that the erroneous measurements are usually not identical - so leading you to believe it is a normal measurement discrepancy.
 +One explanation is that the laser is bouncing off nearby walls. ​ This is certainly sometimes the case, although I can only remember one instance where this was happening on a repeatable basis. ​ Moving the target slightly can solve this issue. \\
 +I suspect this problem is more frequent when the batteries are getting low, down to their last 1000 or so shots (although Beat has assured me that this is unlikely). ​ Note that the distoX battery indicator only deviates from 100% when there are perhaps 10 or 20 shots left (when you are using lithium batteries as recommended) so unfortunately it is not a useful indication of battery health.
 +
 +===Compass and Clino===
 +Both the compass and clino sensors seem to stick sometimes. ​ If you see that the last several compass or clino readings are identical regardless of the orientation of the distoX, then you can be sure they have '​stuck'​. ​ A very gentle tap with your finger usually fixes this (remember it is a delicate device).\\
 +Ferrous objects and (handheld) (electro-)magnetic fields will affect the compass of course. ​ Take care not to use the distoX within say 300mm of your light, SRT gear, bolts etc.
  • distox.txt
  • Last modified: 9 months ago
  • by brucemutton