On Sat, 23 Dec 1995 08:20:28 -0800, Steven Weller wrote:
Thus in a frequency-hopping radio you can push the retuning (read RF phase-locked loop) technology to its limit and build transmitters and receivers around them. These typically hop in the order of 100 times a second. The adversary has to find the uncorrelated signal very quickly indeed *and* have PLL technology at least as good as yours to recover anything from it. Finding the signal generally means listening to all frequencies at once, requiring huge amounts of hardware parallelism and/or realtime computing power. Once you throw ten or so radios onto the same band, it's no longer any use looking for the strongest signal, making that approach useless.
This is nowhere near the limit of the technology. 15 years ago, I was working on PLLs that would stabilize within a couple degrees of final phase within 3.5 microseconds. That permits you to do useful work at 100,000 hops per second.