archive: Re: SETI: Polarization Modulation

Re: SETI: Polarization Modulation
Sat, 5 Sep 1998 00:23:31 EDT

>At 09:38 AM 9/4/98 EDT, wrote:
>>I think it would be feasible to transmit two different channels on
>the >same freq, if they were on opposite polarities. On the receive end,
there would
>be some cross-talk, but the levels would be low.. It might even be
>on FM voice.
Paul Shuch, Ph.D. Wrote:
>Or FM video! That's exactly what the C-band DOMSATs (Vert and Horiz)
>and Intelsats (RHCP and LHCP) do. The technique is called "frequency
>About 30 dB of isolation is achieved. It squeezes 24 transponder
>channels, each 40 MHz wide, into 500 MHz of spectrum (3.7 to 4.2 GHz).

Rich comments once again:
I noticed how tightly packed the H & V channels were, when I first looked
C-band TVRO. Move the probe servo a little and press 'Fine-tune' and
your'e on the next channel..
The app I was thinking about for FM voice, would be to double up on the
2 meter FM repeaters in areas where they want more repeater channels.
Or, It might be just the thing for 2 meter packet.. (or is packet dead)?

73, Rich <>

Richard Tyndall NJ1A Woburn, MA. USA or
ARGUS Observatory FN42jl

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