Sonic.net guesses 14000 feet (will be 18000 if it got measured rather than guessed)
There is only one set of phone lines (installed in 1940's)
and one physical base station. Long long ago Rhythms (a company)
had better modems and we could get 356Kb/s for $55 a month, but company paid
for that pitiful service. Satellite is of course pitiful compared to hard line Comcast
speeds. At one time (for a few lucky people) there was a microwave link
to San Bruno Mountain that gave a few Mb/s for $65 a month but the company
lost rights to the spectrum, leaving that business, and anyway few
homes really had good line of site (a
single tree could block the signal).
It is an effective monopoly now, just one service is any good at all.