Can DirectTV-type satellite dishes be used for SETI?

"Robert Clark" wrote in message
oups.com...
Another possible problem is that I'm not even sure the receivers that
come with the satellite dishes can even detect frequencies other than
the 12 Ghz the satellites broadcast at.

True, 12 gig only.

In regard to the wavelengths that the .5 m antennas could usefully
collect, I've seen references that a dipole antenna should be a quarter
of the wavelength. Is this different for parabolic antennas?

Yes, it is different.

I'm thinking perhaps you could simply attach flat metal dipoles to the
surface of the .5 meter antennas so they could collect megahertz
frequencies. Then at a quarter wavelength you could collect down to 2
meter wavelengths or 150 Mhz.

nope, dish too small.
Dish needs to be 10 wave lengths or bigger.
@150 that is too big
Flat dipoles on surface are basiclly shorted out

While we're at it, the thought of using dipoles, like TV antennas,
raises another possibility. You need receivers for these frequencies.
Where could we get large numbers of receivers already existing at these
frequencies? Inside TV's!

Noise figure is no good.

Assuming we could solve the problem of
tranmitting the data to a central site (ultra wideband, broadband over
power-lines, amateur packet radio, etc.),

None of those have enough bandwidth/range to work.

we could have all new TV's
come installed with a circuit that transmits received signals to the
central site. The number of new TV's sold yearly worldwidde is 90
million. This would result in markedly larger numbers of possible
receivers even above the satellite TV approach.

TVs create considerable RF noise and will cover the signals you want to
recieve.

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

Not true at all.
complete fiction,
how do you handle the pointing errors of 1,000,000 dishes?
You have to phase lock all the received signals to combine them, a
nd 0.5 meter dish works poorly at 12 GHz, and below.

In regard to the computations that might be required there is also
this:

Who's been using your PC?
"From the user's point of view, surfing the web is simple - you type
a URL (uniform resource locator) into a web browser and, most of the
time, the correct web page appears on the screen. Behind the scenes
however a sophisticated process regulated by layers of complex
protocols is responsible for finding, checking and delivering the page
that has been requested. In the latest issue of Nature, Barabasi et al.
describe a way of 'hijacking' this communication infrastructure and
creating a distributed network made up of unwitting web servers."
http://www.nature.com/nature/fow/010830.html


Parasitic computing.
Albert-Laszlo Barabasi*, Vincent W. Freeh=B2, Hawoong Jeong*
& Jay B. Brockman=B2
* Department of Physics; and =B2 Department of Computer Science and
Engineering,
University of Notre Dame, Notre Dame, Indiana 46556, USA
"Reliable communication on the Internet is guaranteed by a
standard set of protocols, used by all computers1. Here we show
that these protocols can be exploited to compute with the communication
infrastructure, transforming the Internet into a distributed
computer in which servers unwittingly perform
computation on behalf of a remote node."
NATURE | VOL 412 | 30 AUGUST 2001 | p. 894-897
http://www.nd.edu/~parasite/nature.pdf


Bob Clark