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Re: R: P3D Report



But doesn't this assume that the aliens' planet has no doppler
shift around its own sun?

Doug
NA1DB


At 03:54 PM 12/23/00 , you wrote:
> >I'm looking for write some code to "filter out" signal with "no / almost
> >low" doppler, and to recognise carrier doppler affected, marking these that
> >fit into the possible range of the spacecraft.
> >I suppose that this kind of task is used regulary by some other people
> >(NORAD et related Organization) HIHI
>
>This is exactly the algorithm the SETI folks use. They look for
>doppler shifts represent the motion of the earth around the sun, and
>the motion of the solar system relative to the rest of the galaxy.
>This excludes a lot of terrestrial and earth satellite interference,
>since they don't have the right doppler shifts.
>
>You do this by pre-chirping the signal by the expected doppler shift,
>then doing a FFT on the result using a longer integration time. If the
>chirp is correct, then the signal energy will land in a single, narrow
>frequency bin.
>
>Phil
>
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