Maybe if I just shout really loud…

“…So finding extraterrestrial intelligence ought to be easy.

“Simply point a sensitive radio detector at the sky, and look for narrow-band signals. Unfortunately, it’s not that easy.

“Radio frequencies are full of artificial signals generated by humans, many of which look very similar to the kinds of signals SETI experiments are trying to detect, and so radio frequency interference, or RFI, is a major problem for our experiments.

“Also, we don’t know ahead of time which frequencies ET might be using to transmit. So we have to tune to many “stations” at once.”

Read more at SETI