These things only need to be set up once: In VmDAS, under Options: Edit Data Options
Assuming you have:
Set up com ports for ADCP, gps, and otherheading
optionally VTG messages, but nothing else
a GGA message (if one is available), the attitude (heading and tilts) message, and any quality messages that are relavant. (For instance, a Seapath should have PSXN,20 for attitude, and PSXN,22 for quality.
- until a VmDAS bug is fixed, if you have a POSMV, you should output
BOTH PRDID and PASHR messages. Then someone can use PRDID if they want, but the quality information is still there for later. (PRDID has no quality indicator)
Keep the number of extra messages to a minimum. VmDAS can choke if it has too many serial messages. (The LOG files get really big and can stop data acquisition)
Recommend using a text file for data acquisition rather than the gui options at the top of the tab. The two main advantages of using a text file for data acquisition are:
Make sure the appropriate files exist so they can be chosen later (see below). When setting up these files, make sure to edit the transducer depth and transducer alignment angle for your installation.
(the cruise name will change for each cruise, but go ahead and set the rest) (let VmDAS pick the “number”)
Max size 2-5Mb (you choose, but don’t go over 5Mb or they’re too large to load easily)
You choose whether there is a dual output directory (but don’t write to a networked disk – it tends to cause problems)
You choose primary and secondary path
“tilt source” choose one if you have it
DISABLE heading correction (VmDAS will use the correct value from the text file)
Evidently if you enable heading correction here, VmDAS sends EA0 to the instrument and then uses the value specified in the gui.
There will be only one EA command in use, but it can be in one of two places.
DISABLE tilt correction (this is our recommendation, but we make no comment on this, having not studied the results. This is your choice)
None of these things should change between cruises.
These might change on a specific cruise, but probably not:
heading source or someone might want the otherheading (POSMV etc) to be the primary heading.
Unless there is a compelling need for highly accurate real-time velocities (i.e. withing 2-3cm/s), UH ADCP recommends gyro as the primary heading (that is much more reliable and will give currents good to 10cm/s). Data can be post-processed to incorporate the better heading source if it was reliable during the cruise, and it’s much easier to do that in post-processing than to fix bad data if the POSMV or Seapath or Ashtech had problems. But it’s your (or the chief sci) choice.
Processing software for turning VmDAS data into edited and calibrated velocities suitable for use in scientific calculations and public release to the National Ocean Data Center ADCP archive is available at http://currents.soest.hawaii.edu/docs/adcp_doc/index.html
University of Hawaii firstname.lastname@example.org