Actually, Shannon's Law is more of a guideline now ;-}
Sort of weasel-worded, but you can beat Shannon by using multiple paths. I
forget who exactly did it, but it was very cool - you transmit different
channels in slightly different directions, and use reflections and
multi-path discrimination at the receiver to separate the channels. Not
truly busting Shannon, because Shannon's Law is about a single channel.
But for all intents and purposes, you are transmitting more data than the
Shannon limit between two points. It does require a nearby building,
mountain, or something like that though. Applying that to GEO birds is
left as an exercise for the student...
-David Summers
On Fri, Feb 9, 2018 at 5:11 PM, Norman Yarvin <yarvin@xxxxxxxxxxxx> wrote:
On Fri, Feb 09, 2018 at 02:15:41PM -0700, Paul Mueller wrote:
I'm no EE (it's all magic to me), but I was thinking about things like
frequency hopping, used for lots of transmitters and receivers in close
proximity (e.g. RC aircraft). Maybe that's not an option for going 22,000
miles with one end that's very difficult to service--I could be totally up
in the night. But I also figure those EEs are pretty clever and have all
kinds of tricks up their sleeves.
Not the kind of tricks that violate Shannon's Law, we don't.
Frequency hopping and such can't increase the data rate that can be
transmitted over a given bandwidth. And the bandwidth slots that are
allocated to satellites are fixed by national laws and international
agreements.
The reason why frequency hopping works with RC aircraft (when it does
work) is that there is enough bandwidth available for everybody, and
all that needs to be avoided is accidental use of the same channel by
two different aircraft.