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distox [2018/12/10 01:59] brucemuttondistox [2018/12/19 01:04] – move disto [Troubleshooting Erroneous Measurements] brucemutton
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   *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 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: 5 years ago
  • by brucemutton