6
\$\begingroup\$

I'm sorry if this comes to wrong forum, but here goes.

I got this new action camera which tracks the following kind of data (edited):

$OLTIM,20170224,045641// Time obviously, no probs here
$OLCMP,23.7 // Compass
$OLPRE,963,421.2,1389.9 // Pressure
$OLTMP,20.5,1,0 // Temperature in F's, no probs here
$OLACC,-1007.1,-3.6,4.7 // Acceleration
--
$OLTIM,20170224,045712
$OLCMP,24.2
$OLPRE,963,422.0,1392.6
$OLTMP,20.5,1,0
$OLACC,-1007.1,-3.6,8.5
--
$OLTIM,20170224,045743
$OLCMP,23.2
$OLPRE,963,419.5,1384.4
$OLTMP,20.5,1,0
$OLACC,-1003.1,-3.6,4.7
--
$OLTIM,20170224,045814
$OLCMP,24.3
$OLPRE,963,422.2,1393.3
$OLTMP,20.5,1,0
$OLACC,-1007.1,-3.6,4.7
--
$OLTIM,20170224,045846
$OLCMP,24.5
$OLPRE,963,419.3,1383.8
$OLTMP,20.5,1,0
$OLACC,-1007.1,-3.6,4.7
--
$OLTIM,20170224,045917
$OLCMP,256.5
$OLPRE,963,423.4,1397.3
$OLTMP,20.5,1,0
$OLACC,274.5,-901.2,-116.8
--
$OLTIM,20170224,045938
$OLCMP,273.4
$OLPRE,964,415.8,1372.2
$OLTMP,20.5,1,0
$OLACC,405.5,-878.4,168.1

I've maneged to solve this:

  • first digits (963) of $OLPRE must be the average air pressure in hPa

For this, I've got a hunch:

  • $OLACC could refer to x,y & z accels

Conditions when data was captured:

  • Outside, ~ -7c
  • ~95m (312ft) over sea level
  • Clear sky

So the question is:

Any ideas what $OLCMP and the second digits of $OLPREwould stand for? And the rest too actually.

\$\endgroup\$
  • \$\begingroup\$ You might want to check if this is a better fit for reversengineering.se \$\endgroup\$ – PlasmaHH Feb 24 '17 at 9:51
  • \$\begingroup\$ The third vale of $OLPRE can't be elevation. That wouldn't the coherent with your 250m above sea level (not even if converted to feet). \$\endgroup\$ – Enric Blanco Feb 24 '17 at 12:39
  • \$\begingroup\$ You must be right again. I had to double check the elevation, since that 250 felt quite high. Real altitude is somewhere between 90-100m (Jyväskylä, Finland). \$\endgroup\$ – Shamppi Feb 24 '17 at 13:09
1
\$\begingroup\$

The Olympus TG-tracker has a built in compass, so it seems reasonable that $OLCMP is a compass reading. Try rotating the camera to see if the reading changes.

If you have App that works with this camera try comparing the readings from the App with the log data and try to tie them together.

I'm not convinced that $OLACC is acceleration data, the readings don't seem to make any sense when interpreted that way, and the user manual doesn't say that it logs acceleration data. But check against the App.

The one thing that seems missing from the log is the GPS data.

\$\endgroup\$
  • \$\begingroup\$ I actually tried to compare data between app and raw logs, but could not find a suitable answer. GPS-data is located in different file, so thats why it's not included. \$\endgroup\$ – Shamppi Feb 24 '17 at 12:29
  • 1
    \$\begingroup\$ Why don't you think think $OLACC is acceleration? I think it's acceleration in thousandths of a G. If you take the vector magnitudes of the $OLACC numbers you get 1007, 1003, 1007, 1007, 941, and 967 - numbers which all make sense for a device sitting stationary on the ground under gravitational acceleration, with maybe a little bit of calibration mismatch between X, Y, and Z channels when rotated. \$\endgroup\$ – Peter Jan 17 '18 at 21:26

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.