Re: [off-topic] side bands and polarization

[wolf <wolf@xxxxxxxxxxxxxxxxxxxxxxx>]

Dear David
Did you receive my answer ?
Can you done the 3D equation needed ? or know one who can ?
THXS
BEST
Daniel

On Sun, 30 Jan 2000, David Cary Wrote:
>
>Dear wolf,
>
>My understanding is that 2 beams that happen to share the same path but are
>polarized at right angles to each other are pretty much independent of each
>other. This is very similar to the way synchronous sine wave and cosine
>wave reception are pretty much independent of each other, which led to the
>QAM signal constellations used by all modern modems. My understanding is
>that all possible waveforms can be generated with QAM. In other words, a
>person building a transmitter could either send the desired waveform
>directly out one antenna, or make 2 completely separate antennas, one which
>transmits AM modulated sine wave of some arbitrary frequency, and another
>which transmits AM modulated cosine wave of the same frequency, to transmit
>exactly the same waveform.
>
>My understanding is that all possible polarizations of a signal can be
>generated by transmitting the "horizontal part" with a horizontal antenna,
>and transmitting the "vertical part" with a vertical antenna. (With the
>proper feed circuit, these can emulate the circular polarization generated
>with a helical antenna and popular in satellite communication). Say your
>transmitter modulated *only* by switching polarizations a fixed frequency
>and amplitude carrier wave. In theory, a reciever aligned with one of the
>polarizations would see a on-off AM modulation (with all its characteristic
>sidebands). A reciever turned an eightth of a turn from alignment might see
>positive-negative bipolar modulation (with all its characteristic
>sidebands).
>
>So I suppose that one could, in theory, squeeze up to twice as many bits
>per second into a given frequency band by taking advantage of polarization.
>But my understanding is that horizontally polarized waves bounce
>differently off the earth and off the ionosphere than vertically polarized
>waves, so you would have to compensate for the amplitude and timing
>differences between them.
>
>If you know of anyone taking advantage of both polarizations in a
>communications system, I'd be interested in hearing about it. I don't know
>of anyone actually doing this.
>
>>From: MISC-d-request@pisa.rockefeller.edu
>...
>>Date: Wed, 1 Jan 1997 00:00:00 -0000 (PST)
>>From: wolf <wolf@mail.interserver.com.ar>
>>Subject: Re: [HM] Mathematical proofs. Some esoteric aspects.
>...
>>what happens with side bands on a
>>fixed carrier whos electromagnetic wave polarization is modulated
>>with a digital signal ?
>...
>>Daniel Wolf
>>PS: Know you if some body are using this spatial modulation ?
>...
>
>--
>David Cary "mailto:d.cary@ieee.org"; "icbmto:N36 08.830' W97 03.443'"
>  http://www.rdrop.com/~cary/
>Future Tech, Unknowns, machine vision ><> <*> O-
>
>
>