In article ,
Rob Dekker wrote:

I'm sure there are some radar systems which indeed transmit in this 40GW EIRP range.

40GW EIRP for Parkes would have to be in 0.1Hz, or so, bandwidth. Most
radars will have 100kHz of bandwidth, and might therefore need 1,000
times the power.

Arecibo will easily be able to do that, but only points at a fixed point in the sky
twice a year or so. Not much repetition for any ET that is listening.

Even if it were fixed, it would point to the same place once every
sideral day.

However, it is not fixed; it is steerable to about 20 degrees below
the azimuth in all directions - this is done by moving the feed point.

We need a radar expert to give us some better idea of trade-offs of
what kind of signal we could expect to hear from what kind of application.

I'm not an expert, but the most powerful radar with simple signals
are, probably, the weather radars which are, I think, given as one of the
examples in the FAQ.

High power military radars will use pseudo-random coding, probably
phase modulated, with chipping rates upwards of 100kHz, so will be
completely rejected by S@H as having a flat spectrum in the 10kHz
analyzed, and will have fairly low power spectral densities. They
will be indistinguishable from natural sources.

Arecibo is pseudo-randomly phase modulated about half the time, but
at lower chipping rates, but is also pure CW for about half the
time, when transmitting.

We know from previous SETI's (project Phoenix etc) that there are no obvious,
super-loud microwave signals out there. And beacons are also hard to find.

I think you are assuming that anyone thought that detection was likely.

Maybe it is time to focus on applications that ET really could use, and then
figure out how the signals of these applications would sound like here, and where

I believe that, by doing targetted observations, using long averaging
times, it is practicable to detect leaked analogue TV carriers (unfortunately
analogue TV is going out of fashion after less than a century, here).


If in the end it turns out that we would need to build a $100B device to detect
(with some certainty) a civilisation of our own level within a 1000LY range from earth,
but it would only take $10B to build a device which can detect (with some certainty)

Neither of those budgets is realistic. You are talking of budgets in the
low millions.

PS Please trim the quoting. I have ignored most of this thread because
the articles exceed a quite liberal size limit designed to catch binary
posting and incompetent posters.