That code seems to be a slightly modified two year old copy of our bluerobotics-ping library file ping360.py.
I watched a few of these and it looks like you’re suffering some issues with signal noise, but it’s hard to tell how severe those issues are because I’m not sure what colour scheme you’re using. Is it possible for you to try using our Ping Viewer application so we can more easily interpret your data, or can you at least provide the mapping between ping intensity value and colour used in your plot?
The parsing code doesn’t add noise, so that has to be either signal noise (e.g. other sonars operating in the same frequency around your ROV) or electrical noise. Given how it displays, and that it’s present in both water and air, it’s most likely electrical noise.
I’m not sure what you’re referring to here - what is the “ultra” setting?
Electrical noise on the communication wires would corrupt packets, so your noise issues are likely instead related to a noisy power supply/ground that’s going to the ping360. A general suggestion is to keep the ping360 power wires as isolated as possible from the tether power wires and any thruster cables. That can be achieved with physical distance separation (run the wires on opposite sides of an enclosure) as well as electrical insulation (e.g. wrap the ping360 power wires in foil to keep external noise out, and/or wrap your thruster wires and tether power wires in foil to keep noise in).
If your noise issues are coming from an unclean supply rather than noise picked up on the wires then you’ll need to smooth out the supply, possibly by using some decoupling capacitors between your 12V and ground wires to reduce unwanted high frequencies. If possible I’d suggest you probe your power wires at the ping360 end with an oscilloscope, to determine how much noise and which frequencies are present. That can then serve as a reference so you can see how much the noise is reduced by different approaches (e.g. moving the power wires, shielding, and adding decoupling capacitors).