Dave wrote:


broadcast is more likely. there are many more broadcast stations on the air
24x7, over the same range of spectrum that we use, and running much higher
power than we use. the most likely signals to reach out from earth are
likely fm broadcast and tv signals since those are normally well above the
critical frequency that reflects from the ionosphere and can be fairly high
power. lower hf, mf, and lf are less likely to get out as they reflect from
the ionosphere even at very high angles.


Radar is the best we do, but not much information is transmitted beyond
the fact that we are here, the beam is usually narrow, and the direction
varies quickly. EME is a distant 2nd, carries real information in
simple codes, the direction varies slowly, the beamwidth is usually low
(on high GHz bands it can be less than the width of the moon), and the
number of transmitters is very low.

Either one of the previous could be picked up from a fair distance, but
not likely because of the narrow angles and varying direction. And
commercial broadcasting doesn't have the ERP in any particular direction
to carry far. We live next to a very large noise source that would tend
to swamp out what we generate.

tom
K0TAR