archive: Re: SETI: Polarization Modulation

Re: SETI: Polarization Modulation

Dr. H. Paul Shuch ( (no email) )
Fri, 04 Sep 1998 14:48:11 -0400

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
>cross-talk, but the levels would be low.. It might even be practical on
>FM voice.

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 reuse."
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).

H. Paul Shuch, Ph.D. Executive Director, The SETI League, Inc.
433 Liberty Street, PO Box 555, Little Ferry NJ 07643 USA
voice (201) 641-1770; fax (201) 641-1771; URL
email work:; home:

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