>But it is clear that we need more power/range than what current
802.11x can offer.
Apart from range (limited) the real killer with something like 802.11 is
latency. You probably won't notice it with just one or two people flying
but if you had a contest with a couple of dozen then the transmitters
would share the bandwidth by waiting their turn. (An individual
transmitter could wait quite a long time before getting use of the
medium, in the order of many tens of milliseconds.)(Actually, I've found
that in practice a handful of transmitters get to dominate the medium
and the rest rarely, if ever, get out.)
The present PCM system works extremely well for what it is -- its cheap,
its quite reliable and its economical on spectrum.
The problem is that there are lots of other users contending for band
space who could easily move to modern radio technologies but are
reluctant to give up "their" slice of spectrum. So the public uses like
R/C and wireless networking tend to be crammed into little corners of
the spectrum that nobody else wants (the 2.4GHz band used by most
wireless network equipment is open because its a set of frequencies that
are absorbed by water molecules -- not that good for communication but
excellent for microwave ovens). Now that governments have discovered
that there's a cash cow to be milked auctioning off the spectrum -- one
of the reasons for the move to digital TV is to free up half the old UHF
TV band and the VHF TV bands for sale -- so the chances of us getting a
slice for free is, I'd guess, relatively slim.
I'd love to move to spread spectrum. Just not at microwave frequencies.
If we could get our hands on just one redundant UHF TV channel that
would keep us happy for a very long time.
Martin Usher
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