Related.. I wonder why the transponders in these sats (not ours, the regular transponders) need to have such a high stability?
After all, regular TV transponders are 8MHz "bent pipe" frequency translators.
For analog CATV on modern, I know that all the carriers of all the analog TV signals were phase-locked, the reason being that the intermodulation product of the carriers of these AM signals would then be a DC signal, and hence not visible, so CATV operators were able to push more channels on the bandwidth.
I'm not sure the same argument applies for sat-TV: on CATV, the signals all have the same strength and there is quite some amplification / processing in the network. On sat-TV, signals are spread by direction and polarization so I'd expect intermodulation to be less of an issue.
Yet, sat operators use these ultra-stable frequency references. What am I missing?