Support for ActiveTarget in *.sl3 files

[DJ5MG]

Hey Ákos,

first up I would to ask, if you consider SL3Reader as a project still active (from your side) or if you basicly closed it as done?

I use SL3Reader for *.sl3 files from StructureScan 3D (as intended), but since I got an Active Target 1, I checked the box 'record sonar log' when recording AT as video and was surprised to find *.sl3 log files.
Running those files through SL3Reader (with no additional transducer connected) gives no output (obviously) but throws exceptions:

Unhandled exception. System.NotImplementedException: Unsupported frame version. Contact developer at GitHub!
at SL3Reader.Frame.<get_HeaderSize>g__UnsupportedFrame|156_0() in D:\SL3Reader\Frame.cs:line 135
at SL3Reader.SL3Reader.ExportImagery(String path, SurveyType surveyType, Boolean exportGeoreference) in D:\SL3Reader\SL3Reader.cs:line 286
at SL3Reader.Program.Main(String[] args) in D:\SL3Reader\Program.cs:line 90

Are you interested in adding support for ActiveTarget?

best regards, Martin

[halmaia]

Dear Martin, @DJ5MG

Please, send me a sample file to check. However I have the bad feeling, that ActiveTarget won't save the live view, just the basic sonar parameters, like depth.

Best regards,
Ákos Halmai

[DJ5MG]

Dear Ákos, @halmaia

I narrowed it down with imhex: Lowrance introduced a new 'frame version' (as you call it), where the payload (or packet length) is 16 bytes larger (apparently in software 26.x).

Please see pull request #12.

It seams that with only ActiveTarget hooked up, the sonar log file contains an attempted conversion to the down scan and side scan channels (more precise down + composite) - wich contains valid data, but no useful imagery.

I still try to understand your approach in reading the *.sl3 files, so I don't know where the change with V14 also has impacts. But so far the changes i put in the pull request work on my machine.

Attached is the smallest log file I have for this issue.

Sonar_AT_Forward_2026-05-23_22.54.51.zip

best regards