"P. Backus" <pbackus@seti.org> skrev i meddelandet
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"Bjorn Damm" <bjornd@mail.invalid> wrote in message

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"David Woolley" <david@djwhome.demon.co.uk> skrev i meddelandet
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The Allen array is claimed to have the ability to detect the

equivalent of

our analogue TV carriers from local stars.  (I suspect this is with
a long observation time.)

The analogue TV transmitters will 'soon' be replaced by digital. The

chance

of ET having an analogue TV-transmitter is aproximatly zero.

Nobody assumes ET will have analog TV.  TV carriers are cited as an
example of a strong narrow signal.  That is all.

The statement contains an unspoken question. How can we expect to receive a
signal if we are not transmitting any? There has been one message sent from
Arecibo towards one star cluster. There has also been attempts to transmit
signals on satellite uplinks (I don't know but I guess they don't contain
enuf power to be detected). There also are 'random' pointings by the
interplanetary radar at Arecibo that could be detected by ET. But could the
identify them as originating from an intelligent being or do they have to
classify them as a phenomenon.

I think it's safe to assume that ET has a much better detection capability
than we. Wouldn't it be more efficient to transmit a signal. Assuming we
will reach our peak detecting capability in 100 years, transmission would be
the most efficient method of establishing a communication if the star is
withing a range of 50 ly.

And I repeat my question: How can we expect to receive a signal if we are
not transmitting any?

On the other hand, I don't think the ATA will have that sensitivity.