Michael wrote:
Couldn't you just use a local AM radio station?


Nah. Doesn't really give you the flavor of a real approach. The
transmitter is high quality, high power, and properly tuned so the
needle is rock steady on all but the worst receivers. Listening to the
transmission is not nearly as annoying as listening to those dits and
dahs. Makes it just too easy.

The funny thing about using AM stations is the US Government fielded the
old CONELRAD system to prevent the "enemy" from doing this during an
attack. That threat is minimal these days, NDBs are going away, but the
CONELRAD system keeps being revised. I hear several tests every week.

That's how your tax dollars are working for you.