The math does work on the entire sample memory, there is an existing "filter" menu for channels, with a "Type", "low limit" and "high limit" however its not obvious to me how to get to it, I suspect its like the EDUMODE menu, where if you get to it, it works, but just lacks a path to get there normally,
My current attack has been trying to find exactly what file they save the last viewed menu to when you power cycle the device,
It seems like its /usr/bin/siglent/usr/config/temp_setting.xml but manually editing this then causing an unexpected shutdown does not seem to over-ride it. equally its not entirely clear to me how the "menu_ID" is mapped, the numbering does not follow what they use for the menu tree text, If we can figure out a way to control what menu the scope starts up in, we can see if the function is available and just hidden, or if its like some of the decoder option SCPI commands where its there but does nothing (some decoder SCPI queries are hard coded to return with no data, the commands work, just find it odd)