Here is the full list of all 23 Alt-Frequencies achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
You stayed in the time loop.
Spoil Ennis' new song.
Reveal the new voice of resistance.
Confuse Ennis with the nature of your offer.
You sent Jenni's list.
Learn about the Landing Plane.
You sent the RMB-1 scoop to Talk radio.
You sent the RMB-1 scoop to News One.
Shame Ennis with his past.
Disturb Fred with the voice of his manager Margot.
Have Sadie be broadcasted on another frequency.
Complete chapter five.
You left the time loop.
Complete chapter four part two.
Complete chapter four part one.
You sent Kaya's list.
Complete chapter three.
You sent the RMB-1 scoop to Fresh FM.
Complete chapter two.
Complete chapter one.
Ask A. None a relevant (???) question.
Suggest a cure for Michelle's flu.
Complete the tutorial.