[raducu]

> And synthetic aperture radar can be disguised such that its nearly indistinguishable from background noise

So the transmit power is the same as background noise and you can still get useful radar pictures out of it? Amazing. I roughly know you can recover repeating signals that are below the noise floor, but still amazing.

[ars]

See: https://en.m.wikipedia.org/wiki/Spread_spectrum along with cryptographically randomized frequency hopping, you would not be able to figure out when there is an actual signal rather than noise.

[Retric]

Picture a point source frequency hopping different collars of visible light on your wall. There are real limits to how many photons it can send before it becomes really obvious.

As satellites need to detect returns bounced off the ground hundreds of miles away they have some hard minimums for high resolution images vs aircraft or ground stations. 10x distance needs 100x the signal.