Suggested upgrades to documentation, range file format and addition of acoustic head depth

[WayneCrawford]

OBSrange seems to be written for one setup: a hydrophone anchored to the ship's hull (and assumed to be 0m deep?) and a specific GPS input line. It's a great tool and would be even more useful if it could be generalized to more cases. For example, we didn't have that GPS information on our last cruise, so we had to enter the range values by hand. And we didn't have a hull-mounted hydrophone, so we hung the head about 10 m below the surface (and up to 20m in bad reception conditions. We were able to work around most of these issues, but some simple feature additions and documentations would probably make the suite more generally useful. Here are my notes.

Allow hydrophone depth to be specified

Both with a default value (in the setup file) and a way to modify for each ping (or group of pings)

Allow pip installation

Currently we put a copy of the code in each directory we create for each cruise. If obsrange could have a simple global installation (for example, using conda or pip) we could keep only the deployment-specific information with each deployment

Allow comments in the range file

Since we can't range while moving (the hydrophone isn't fixed to the hull), we go to cardinal points and overhead, and range from each of these. It is helpful to note this in the range file. By trial and error we found out that the following works:

* Center point
 2292 msec. Lat: 12 47.007 S   Lon: 45 24.591  E  Alt:  0.00 Time(UTC): 2024:090:10:26:00
 2291 msec. Lat: 12 46.980 S   Lon: 45 24.578  E  Alt:  0.00 Time(UTC): 2024:090:10:26:50
 2294 msec. Lat: 12 46.951 S   Lon: 45 24.567  E  Alt:  0.00 Time(UTC): 2024:090:10:27:30
 2300 msec. Lat: 12 46.913 S   Lon: 45 24.551  E  Alt:  0.00 Time(UTC): 2024:090:10:28:00
* North point
 2486 msec. Lat: 12 46.547 S   Lon: 45 24.617  E  Alt:  0.00 Time(UTC): 2024:090:10:37:00
 2499 msec. Lat: 12 46.534 S   Lon: 45 24.610  E  Alt:  0.00 Time(UTC): 2024:090:10:37:30
 2509 msec. Lat: 12 46.526 S   Lon: 45 24.606  E  Alt:  0.00 Time(UTC): 2024:090:10:38:00
 2522 msec. Lat: 12 46.518 S   Lon: 45 24.603  E  Alt:  0.00 Time(UTC): 2024:090:10:38:30

but it would be convenient if there were a defined appropriate comment line/format

Add documentation on how to acquire the range file

What GPS system and acoustic ranger needs to be used, how are they connected to each other and the computer?

Add a possibility for a generic range file

For example:

TWTT.msec   Latitude.dm   Longitude.dm   Alt.m   Depth.m   Time.UTC
# Center point
 2292       12 47.007 N   45 24.591 E     0.00     5.0    2024:090:10:26:00
 2291       12 46.980 S   45 24.578 E     0.00       *    2024:090:10:26:50
 2294       12 46.951 S   45 24.567 E     0.00       *    2024:090:10:27:30
 2300       12 46.913 S   45 24.551 E     0.00       *    2024:090:10:28:00
# North point
 2486       12 46.547 S   45 24.617 E     0.00       *    2024:090:10:37:00
....

Where '*' for depth means "same as default or previous"

And maybe an option for digital degrees:

TWTT.msec   Latitude.deg   Longitude.deg   Alt.m   Depth.m   Time.UTC
# Center point
 2292       -12.78345      45.40985        0.00       5.0    2024:090:10:26:00
 2291       -12.78300      45.40963        0.00         *    2024:090:10:26:50
 2294       -12.78252      45.40945        0.00         *    2024:090:10:27:30
 2300       -12.78188      45.40918        0.00         *    2024:090:10:28:00
# North point
 2486       -12.77578      45.41028        0.00         *    2024:090:10:37:00
....

[jmsaurel]

Hello,

To take into account the depth of the acoustic head is really easy and very little modification of the code is necessary. I tested two solutions.

• Add a new parameter in the main python script (similar to the GPS to head offset correction). This acoustic head depth would apply to all the pings. This additional parameter could somewhat break compatibility with older experiment and older main python script.
• Use the Alt: value from the existing range file to specify the acoustic head depth at each ping. The drawback here is that it seems this value comes from the GPS when the files are generated by SIO utilities. This would require to modify the survey files when Alt: is given by the GPS directly.