Default Radio Signal

The Default Radio Signal is a radio signal broadcast in The Commonwealth in Fallout 4.

Radio signal source
The radio signal can be found by activating the satellite dishes at Relay Tower 0MC-810. From there, proceed to the Northeast until you find an old, bombed-out house with a basement hatch next to it. Inside the basement there is a broken Terminal, a desk, and a Ham radio that the signal is broadcasting from, and a safe.

Transcript
As the Sole Survivor nears the signal source, the player will begin hearing this message on a loop if the signal is tuned-in on their Pip-Boy: