archive: Re: SETI modulation of ETI transmission

Re: SETI modulation of ETI transmission

David Woolley ( david@djwhome.demon.co.uk )
Sat, 29 Aug 1998 12:16:54 +0100 (BST)

Jim Glover,

> Now, specifically-- who says you have to have a carrier wave? We
> are in our RF infancy, as a society (in the cosmic, billions of

I think this is what Chip Cohen is trying to say when he uses his
phrase "polychromatic SETI". It's actually true, though, that even
the current generation of commercial systems don't have a well defined
carrier (e.g. CDMA digital mobile phones).

I think Chip is speculating about a particular class of modulation scheme,
rather than all those that don't have discrete frequencies present.

I also think that, in the short term, project Argus has rather little
chance of detecting signals which are not deliberately targetted at SETI
searchers and I believe such signals would have a large single frequency
("monochromatic") component. So, from the project Argus point of view,
attempting to achieve the possible would still lead to a strategy similar
to the current one.

What it would mean is that there could be a lot more technological
ETIs out there than might have been deduced from the negative results of
SETI on the basis of past knowledge.