Hi farmall and all all,
It's kinda like a spinal tap, extremely painful but produces results. It's simply "tapping" the output of the frequency discriminator (detector) ahead of the demphasis circuit and audio amplifier in an FM receiver. The raw output contains whatever was modulated on the carrier in the first place such as the full digital information that may be processed by a computer or whatever device you feed it to.
You need proper electronics knowlege and good mechanical skills to properly install one, it's not for the faint of heart so Careful With That Axe Eugene to borrow a title from Pink Floyd.
Christa, live the life? (I think you meant to say viva la vida.) I understand what you mean but still it's an oxymoron. (;->)