Issues managing dual ping in MBedit with mb261 format

[almandBAS]

I have been trying to edit kmall/mb261 data that were collected using the dual mode and it seems that the dual pings are represented with the same timestamp meaning that the two pings are on top of each other making editing almost impossible with mbedit.
I would have expected the two pings to be separated with two slightly different timestamps maybe to avoid the two pings to be on top of each other.

See screenshot below:

A sample dataset can be found here: https://drive.google.com/file/d/137RkJ5vog5FuYi456JCICttJVzO4yH15/view?usp=sharing

• MB-System version 5.7.6 (tested also with v5.8.2beta06 )
• GMT version: 5.4.4

Many thanks,
Alice

[dwcaress]

This answer mostly duplicates a post to the discussion list.

Because the sonar reports the results of a single ping cycle in a single set of datagrams whether the mode is single swath or dual swath, the MB-System i/o module treats these data as a single ping whether there is one or two acrosstrack profiles. In dual swath the beam numbers increment across the entire ping - for instance if there are 1024 beams, then 0-511 forms the first (aft) profile and 512-1023 forms the second (forward) profile.

This is different than the case of dual head systems (e.g. EM2040D), which reported separate sets of datagrams from each receive head per ping cycle, and so produced two pings with the same timestamp (and led to some complicated logic to handle ping multiplicity).

I have now fixed mbedit and mbeditviz to display the two acrosstrack profiles from dual swath separately while keeping track of them as a single ping. This is in the most recent beta release 5.8.3beta08.

The image embedded below shows mbedit with some dual swath EM304MkII data loaded. There are ten pings shown with ten timestamps and twenty separate profiles. There is also a label now indicating if single or dual swath bathymetry is being displayed.