July 16th 07, 12:24 AM
posted to sci.electronics.basics,rec.radio.shortwave,rec.radio.amateur.antenna,alt.cellular.cingular,alt.internet.wireless
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First recorded activity by RadioBanter: Mar 2007
Posts: 58
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How I would like to change the cell phone industry [was AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency]
On Sun, 15 Jul 2007 14:45:06 -0700, Radium
wrote:
On Jul 15, 2:14 pm, Jeff Liebermann wrote:
Radium hath wroth:
how would u like to change the cell phone industry?
Analog cells phones should stop using FM and should start using AM
with SHF frequencies - at least 3 GHz and at most 30 GHz.
http://en.wikipedia.org/wiki/Super_high_frequency
There will probably need to be 8-10 times more cell sites
built than are currently in use on 800/900 and 1800/1900MHz.
Why?
Equally important, SHF frequencies can efficiently transmit signals
using extremely small transmitters. Longer wavelengths require larger
transmitters.
They do? I didn't know that. My 49MHz automobile alarm dongle isn't
much larger than my 2400MHz USB wi-fi dongle. Are you sure the
transmitter has to be bigger or were you thinking of the antenna?
Maybe the antenna.
I choose AM because it requires less bandwidth than FM. In addition,
AM tends to retain reception of rather weak signals, while FM
"considers" such signals to be absent.
I'll make it really simple for you. FM is "hi-fi", while AM is noisy
"no-fi".
FM has too much hiss. FM signals are lost very easily. AM tends to
retain reception of a signals even when this signal is extremely weak.
In FM, once you go below a certain wattage, you completely lose the
signal, and the annoying hiss begins. With AM it is much easier to
receive the low-power signal.
AM maybe more vulnerable to electronic disturbances but so what? The
magnetic RF interferences that are heard on the AM radio are
entertaining compared to the deafening hiss on the FM radio.
For decent quality, you
gotta have FM.
Nope. For decent quality sound you need audio that is uncompressed PCM
[similar to CDs and WAVE files] with a sample rate of at least 44.1
KHz and a bit-resolution of at least 16-bit. Or the analog equivalent.
---
Wrong.
--
JF
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