First of, I was hoping maybe AWprime had a newer,faster way of sending signals.
As far as signaling goes, what SETI will pretty much have to find is a deliberate attempt at communicating with unknowns. I read an article recently-don't have a link, but will try to find one--that there is literally a 50-100 year period in civilization (ours, anyway) where we blast the universe with radio waves.
The day of the 50,000 Watt "clear channel" AM radio is pretty much dead, now--and most of those signals stayed within the wave guide that is the ionisphere and Earth's surface.. FM is lower power (no sense blasting out power when line-of-sight is your range limit) and thus limited in detectability.
Even our exploratory probes signals are low-power, and we rely on precise aiming and a big dish to recover them. So, unless we are in exactly the right place and time in a civilization's history, the likelyhood of detection of general broadcast is very, very small.
All SETI can hope for is that some civilization is booming out gigawatts of signals on 11 M wavelength, intent on attracting attention...
Actually TV and FM radio broadcasts frequently exceed 50k watts. But, that isn't really important.
If other civilizations are going to detect us by our radio leakage rather than a deliberate transmission, RADAR emissions would be likely. They are high enough frequency to readily escape and are much higher power than typical TV or radio transmission. They would look very artificial. And, they have very little modulation, (just a bit of phase modulation typically) which keeps the spectrum nice and narrow, perfect for long range detection.
Even as we move towards less 'communications' leakage, high power radar will continue to shine like a beacon from the Earth for many years to come.
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