h a l f b a k e r yTempus fudge-it.
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Forgive my ignorance. Ham radio uses low frequency spectrum,
right? And sometime those signals can bounce of the clouds and
go
half way around the world. But it is relatively low bandwidth.
And
not secure, so that everyone can hear the one person speaking.
But cell phones sometimes
drop out when you go a couple of miles
outside the city... but they are secure -- you can talk one-to-one
and
be relatively certain you have a secure line.
And digital TV uses high frequency spectrum because it is easier to
get a lot of information... and advertisements... in there.
Compression and intelligence are basically synonymous.
Why isn't it possible to create a cell phone network using ham
radio
signals?
Ok it's low bandwidth. We are intelligent, we will come up with
ways of compressing the information so that it is more real-time
and
more real-space.
And if there was a platform for making that happen then it would
be
more likely to happen.... we would get more intelligent.
The competitive strugle for more bandwidth space seems to me to
be tragically reminiscent of the competitive struggle towards
flight
that led to Alexander Graham Bell inventing ailerons and Wilbur
Wright dejectedly dieing of tuberculosis or whatever.
[link]
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//Ham radio uses low frequency spectrum, right?// |
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Ham radio uses lots of frequency bands, from 1.8 MHz to over 275GHz. Some
of the most popular bands are the 2 meter band (144 MHz) and the 70 cm band
(440 MHz) for local, and the 20 meter band (14 MHz) for distance. |
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//And sometime those signals can bounce of the clouds and go half way around
the world.// |
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Sure, using an antenna as tall as a house, or enough power to cook a steak. |
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//Why isn't it possible to create a cell phone network using ham radio
signals?// |
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Lots of reasons. For one thing, cell service is inherently short range. You need
to be able to hit a cell tower in order to carry on a conversation. Any farther
than that is wasted energy, and starts to cause interference with other signals
on the same frequency that are trying to reach nearby towers. One of the
ways that they multiplex so many conversations on relatively narrow frequency
bands is by reusing frequencies many times across large areas. So you don't
really /want/ your signal to go too far. The area your signal reaches increases
with the square of the maximum distance (i.e. the radius), meaning that the
amount of usage that can be obtained out of a given frequency decreases
exponentially with the range of the signal. |
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Another problem is that an efficient antenna for a given frequency should be as
close as possible to half the wavelength of the frequency. For 900MHz cellular,
this is about 6.5 inches, and for 1900MHz, it's about three inches. For 10MHz,
it's about 50 feet. For the sort of frequencies you're talking about, a cell
phone sized antenna would be all but useless. You might get /some/ signal out
of it if you dump a whole bunch of power into it, but you'd probably still obtain
better range by using a higher frequency signal anyway. |
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//We are intelligent, we will come up with ways of compressing the
information so that it is more real-time and more real-space.// |
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There are some hard and fast limits to what can be done. The Nyquist limit
puts an upper boundary on how much information can be digitally transmitted
by a given signal. Also, it's mathematically impossible to losslessly compress
data past a certain point, and there's an upper limit to how much loss can be
tolerated before the signal degrades to uselessness; we're already pushing
that limit with existing technology. There may be room for a bit of
improvement, but we're talking small percentages here, not the orders of
magnitude that this idea would require (even if it were not for the technical
infeasibility of transmitting such signals from a cellphone). |
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[ytk], please forgive me, but you had me on your side until paragraph six. Just hit enter twice every so often. |
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There are a couple more rather abstruse
factors, but essentially that anno neatly
covers all the relevant arguments. |
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Jesus H. Christ. What a lot of beating about the bush. Aliens have had this licked for aeon's. Just drill a hole in the back of the nut, stick an aerial in and your in business with telepathy. |
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