When do radio and tv signals become indistinguishable from background noise of the universe? I understand the rate an EM signal broadcast uniformly from the Earth will decrease in its power is governed by the inverse square law. How far from Earth will radio and tv signals become indistinguishable from background noise from varied sources in the galaxy, even CMB. 

I know nothing about the type of equipment that would be used to gather and analyze such a signal.  I don't know what the geometry of the observation means.  Assuming the optimal equipment and conditions we currently have and no other line-of-sight sources.
If an extraterrestrial civilization has a SETI project similar to our own, could they detect signals from Earth?
  In general, no. Most earthly transmissions are too weak to be found by equipment similar to ours at the distance of even the nearest star. But there are some important exceptions. High-powered radars and the Arecibo broadcast of 1974 (which lasted for only three minutes) could be detected at distances of tens to hundreds of light-years with a setup similar to our best SETI experiments.  


SETI FAQ