Did they implement something like a new signal analysis method that enabled it? Well, we do keep building bigger and bigger antennas and antenna arrays. So whi

Did they implement something like a new signal analysis method that enabled it? Well, we do keep building bigger and bigger antennas and antenna arrays. So while Voyager can't change, we do. And we can build more and more sensitive (i.e. noise rejecting) equipment. X is 8–12 GHz and S is 2–4 I don't know much about the Voyager design but the beam width is related to the frequency and so the S-band transmitter will have a larger beam width and thus can point less accurately that the X-band when trying to talk to Earth. Conversely, X-band is higher frequency than S-band and it's likely they would be able to use more bandwidth. So, interesting trade offs.