The goal of SETI is not to decode the signals, it's just to see whether they are there.
There simply aren't any natural narrowband radio sources in the relevant channels. In the bands that we use for communications, Earth is at least 1000 times brighter than any natural source in the galaxy. You can't hear the sun with a transistor radio, even though it subtends an area far larger with respect to your radio than any antenna you're likely to listen to.
Amature Telescope Maker, but I quit before it was complete.
The goal of SETI is not to decode the signals, it's just to see whether they are there.
In order for it to be a genuine LGM signal it has to be more than just a carrier, it has to have some non natural occuring signal. Carl Sagan's favorite LGM beacon was a series of prime numbers of pulses which could be AM'd, FM'd or PSK'd or even on off modulated onto a carrier.
There simply aren't any natural narrowband radio sources in the relevant channels. In the bands that we use for communications, Earth is at least 1000 times brighter than any natural source in the galaxy. You can't hear the sun with a transistor radio, even though it subtends an area far larger with respect to your radio than any antenna you're likely to listen to.
So you believe that at 107.9 MHZ, from 50 light years away, the earth, or sources on the earth, emits more signal than the sun? No Way.