> This is very poor choice. Faraday depolarization will de-polarize all but
the
>closest possible LP microwave interstellar signals.
Here I respectfully disagree, Chip. My experience with 23 cm EME indicates
that Faraday rotation de-polarizes linear, but not circularly polarized,
signals. Binary circular polarization, as envisioned by Sagan, involved
transmitting the "ones" RHCP, and the "zeroes" LHCP. To a linear feed (as
used in the book) it looked like a steady carrier. To RHCP *or* LHCP it
looked like ICW, and to dual CP, it looked like binary with built-in
redundancy. I don't see how Faraday rotation could affect that.
-----------------------------------------------------------------
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 http://www.setileague.org/
email work: n6tx@setileague.org; home: drseti@usa.net
"We Know We're Not Alone!"