Question about ADV processing using Dolfyn

[cmaier95]

Hello everyone,

I would first like to thank you for developing this Dolfyn toolbox.

I have a question regarding the data processing for ADV sensors. We have datasets from both fixed stem and cable probe Nortek Vector ADVs and we would like to process these datasets using Dolfyn.

Does the Dolfyn rotation2 function, used for ADV datasets (.VEC files in our case), work for both the fixed stem and cable probe sensors since the XYZ frame of reference orientation seems to be different for both of these sensors. Mainly the z axis seems to be inverted relative to the sensors orientation:

Does Dolfyn automatically determine which sensor the read file belongs to and does it take this into account when performing the rotations?

Is the processing for both of these sensors the same, or should we perform some extra steps for the cable probe sensor?

Thank you for your help and for providing this toolbox, we really appreciate it!

[jmcvey3]

Hi @cmaier95, my apologies for missing this!

The short answer your question is yes, DOLfYN does automatically handle both.

The longer answer is that Nortek specifies a specific variable that flags whether the user needs to incorporate the flipped z-axis or not, which we save as "orientation_down" in DOLfYN. If this flag is set to true, we know it is a fixed stem ADV pointed downwards, and then we rotate 180 degrees about the x axis. For cabled ADVs, this flag is always set to False, and we let the saved instrument-to-earth rotation matrix handle the rest.

[cmaier95]

Hi, it's good to know, thanks for your answer!

[jmcvey3]

Yw, and if you have further questions, feel free to open an issue as well! For whatever reason, new "Discussions" don't trigger a notification in Github.