Replying to my own thread because I wanted to emphasize the following paragraph, which came to mind after reading the submission about camera sensor fingerprinting (or photo response non-uniformity).

Horizon also plans to compile a library of unique radar-pulse “fingerprints” of the world’s vessels, for the tiny differences in componentry that exist even between examples of the same make and model of equipment mean that signals can often be linked to a specific device. It will thus be able to determine not merely that a vessel of some sort is in a certain place, but which vessel it is, and where else it has been.

Don't know if any user of Ramble has his own vessel, but I guess this form of surveillance based on unique (unspoofable?) differences in componentry will be extended to other fields.