Some strange data from DistoX2 and DistoX-BLE

[KsCaver22]

Wow, this is sure a quiet forum! I hope there are still people reading the posts.

Over the last year several people I know have acquired DistoX-BLE devices. These use a mainboard sourced from China. They are otherwise very similar to the DistoX2 boards that Beat Heeb designed.

All three devices have had problems staying calibrated. Even if calibrated the same day as a cave trip, they often will start giving wonky readings after a few hours. We are trying to figure out why this is. "Wonky" means that the forward and backward shots no longer agree within the usual tolerance of +/- 1 degree.

As a test, I set up a three station loop at the entrance to a cave. I shot around it with both a DistoX2 and a DistoX-BLE. The results don't help the situation very much!

The DistoX-BLE was off by as much as 3 degrees between forward and backward shots. However! When I ran loop closure, the data from the DistoX-BLE was three times closer! The DistoX-BLE closed the loop to 0.09% while the DistoX2 closed to 0.30%. WTF???

Here is the data we collected, in Survex format. This should be easy to translate into either Walls or Compass. Run the calculations yourself. The "S" shot are from the DistoX-BLE while the "B" shots are from the DistoX2.

*units tape feet
*data normal from to tape compass clino backcompass backclino

S1 S2 14.44 278.8 +4.9 96.1 -3.5
S2 S3 11.99 186.8 -5.5 5.3 6.9
S3 S1 18.50 56.0 1.3 238.4 -0.1

B1 B2 14.44 276.7 3.7 97.1 -4.4
B2 B3 11.98 185.8 -6.3 5.8 5.8
B3 B1 18.54 57.7 0.2 236.8 -1.0

This brings up an obvious question: Which device do you trust? The one with wonky readings but better loop closure? Or the one with sane readings and a less accurate loop closure? And WHY do you make that choice?

Bill Gee