Dac wrote:
Because they sure seem scratchy? Is this just added for effect? Why
don't they go digital? I am guessing because the voice coms are some
sort of seperate system that would be most robust FM on set
frequency? It does seem kind of stupid though, especially after
listening to some digital russian transmissions, the cosmonaught
sounded clearer than the ground control.

Lousy microphones and high levels of cabin noise are the likely
suspects. Shuttle communications have been all digital since the start.

See, for example,

IEEE Transactions on Communications - Special issue on Space Shuttle
Communications and Tracking, Vol. COM-26, No. 11, November l978

--
Dave Michelson