Nice link to the patent. I just wish I could understand what they were saying. That's some of the least understandable text I've seen in ages. I can only assume it was translated somewhat verbatim from Japanese by someone who's not quite fluent in English. That's the only explanation for a sentence such as, "Therefore, when a firstly captured and received radio wave does not correspond to a target radio wave, the remaining frequency range is frequency-swept following its capturing to thereby capture the target radio wave." I have no clue what that means other than a whole lot of capturing is going on.
I did understand enough of it to verify that it works the way I thought I'd read elsewhere. Spectrum Sweeper combines a frequency counter with a limit search. It uses frequency counter techniques to find 1MHz segments with combined energy that exceeds some preset threshold, then does a limit search sweep of those segments. In theory this should allow you to pick up on many more active frequencies than a conventional frequency counter alone could do.
As to how a frequency counter does what it does, which I think was what the OP was asking, I haven't a clue.
I do wonder why the same technique isn't applied multiple times. When a 1MHz segment that exceeds the threshold energy level is found, subdivide that segment into 100kHz segments and apply the frequency counter again, rapidly narrowing the search down to 100kHz segments. At some point I assume there would be diminishing returns. Perhaps that point is 1MHz and that's why it stops there.