The sensors aren't too slow, they're showing you exactly what the signal is the instant it sees it. The fact that the graph is spinning and shows a history of the previous frames sensor readings is confusing people I think. The only bar that means anything to you is the leading one as that is showing you the exact signal it's receiving in that frame in the general area the sensors are looking. The spinning just makes people think of radar no doubt and expect more information than just the strength of the signal in the direction the sensors are pointing. Basically there could just be a huge number inside that circle instead giving you a value from 0 to something the shows how high a signal you're detecting at that moment and it would be functionally the same as the current implementation (minus the history aspect)
I guess at some point that signal could be variable from a ship source (pulsing for example) so that if you manage to look pretty much just at the target ship you would see the leading sensor bar rise and fall at a certain frequency and the history of that bar would highlight this pulsing effect nicely. Then by knowing a thing or two about pulse rates for various ship engine types and looking at the amplitude and noise levels you could estimate range as well (this is all very much the same as submarine hydrophones btw).
I guess at some point that signal could be variable from a ship source (pulsing for example) so that if you manage to look pretty much just at the target ship you would see the leading sensor bar rise and fall at a certain frequency and the history of that bar would highlight this pulsing effect nicely. Then by knowing a thing or two about pulse rates for various ship engine types and looking at the amplitude and noise levels you could estimate range as well (this is all very much the same as submarine hydrophones btw).