wrote:
I was interested to read this on the Seti League web site:

__________________________________________________ ________
Parasitic SETI
Dear Dr. SETI:
As a Satellite dish owner and a strong interest in SETI, I was
wondering if anything is available to allow the home satellite dish
owner to 'search' when he is not watching TV. I do a bit of programing
and would love to help make it so home dish owners could do this. Is it
possible? What would it take? Does the dish have to follow a spot or
can it sweep the sky from a fixed position? If this is possible it
could add a million listeners to the system.

Bill T.

The Doctor Responds:
Absolutely, Bill! Parasitic SETI with a home satellite TV dish is not
only feasilble, it's widely practiced. A second feedhorn and preamp
assembly are mounted next to the C-band horn/LNB at the apex of the
dish (see Figure 2 of this article). This assembly feeds the rest of a
SETI system (see our online Tech Manual). You can then sweep out the
sky, as described here. And yes, a million participants would be nice,
but our goal is a more modest 5000 stations.
__________________________________________________ ________
http://www.setileague.org/askdr/parasite.htm

I believe they are referring to the 6 ft. backyard type antennas,
judging from the linked images on the page. But could the roof mounted
DirectTV and Dish Network type antennas be used for SETI?

Sure, they'd work. The dishes are smaller (1 ft diameter or so) but the
same principles apply as for the larger dishes (8-12 ft).

The only thing is that you'd need to work at much higher frequencies.
You'd need to do SETI at the 12GHz band.
Al

The mentioned extra equipment are an extra feedhorn and a
preamplifier. The feedhorn can made cheaply but the preamp seems
expensive. If these preamps were mass produced for this purpose could
their per item cost be brought under $50?
I'm envisionig a government agency such as NSF, or a scientically
interested billionaire, paying satellite TV companies to attach this
extra equipment to their satellite dishes. Say $100 million is
earmarked for the program. Then you would want the extra cost to be
under $100 for each dish for say 1,000,000 subscribers. Judging from
the diagram in the online Tech Manual linked to on the page, the other
equipment should be doable by the equipment that comes with the
satellite TV system. Computer processing would be done separately at a
central location.
If you had a 1,000,000 of these .5 meter wide antennas it would have
the detection sensitivy of a single antenna 500 meters wide.
Bob Clark