Legality of a billboard with an FM broadcast

[themarcshow]

Hello all,

What are the rules regarding a business setting up an FM transmitter on top of a billboard that plays a loop of commercials?

A local car dealership has a billboard that says "tune to 105.1FM". Then on that frequency is a continuous loop of their employees making commercial announcements about the dealership.

The FCC Database has no license for this site. Also LPFM rules clearly state "These stations are authorized for noncommercial educational broadcasting only (no commercial operation)". The reach of is FM signal is 1/3 to 1/2 mile while in the car. Is that low-power enough to fall under Part 15 rules?

Is this an illegal operation? Would the responsibility fall on the billboard owners or the business engaging in the advertising? This is new and no other businesses have done this previously.

Just curious.
Thanks

[Deep Thought]

Part 15 allows very low power unlicensed operation on the FM band, and it is possible that due to antenna height, low interference levels and your car radio being able to detect signals down into the single digit microvolt range that it would be audible for a half mile and still be legal. Most likely it is running a bit over the limit but not enough to draw FCC attention. You'd be surprised how little signal a decent radio needs for reception.

There was one on the Kennedy Expressway just north of downtown Chicago which broadcast on 1550 KHz for awhile, and the "talking house" transmitters have been used by real estate agents for years.

If the transmitter is illegal, the regulatory finger would point to the billboard owner.

[NECRAT]

Most likely it is running a bit over the limit but not enough to draw FCC attention.

I can name 30 stations in Boston alone operating a lot over the FCC limit which don't have the attention of the FCC...