I work in a factory that, the am radio band is interfered with. Is it unlawful to rebroadcast am on a low power fm transmitter, such as an mp3 type ?

 

It is very likely illegal because you don't have the permission of the copyright owners; this for sure applies to music and I'd imagine the radio station would probably deem their material copyrighted too.

That said, I doubt if anyone would come down on you if you were just doing it to get around an interference problem and you don't break any relevant FCC rules (I'm assuming you're in the US; change appropriately for your country).

 

For what it is worth, I've done exactly that for coworkers. IMO this is not a copyright issue, since this is not copying the material. It is a rebroadcast live, with call sign and advertising intact. I suspect the station would approve given this fact.

The FCC regs are clear on home made unlicensed transmitters. No more than 10mw broadcast power, and the antenna can not be more than 10 feet long.

 

I agree with someonesdad. Broadcasts are copyrighted and redistribution is most likely protected. A commercial setting would not come under an exclusion for home use, regardless of how much you like your co-workers.

However, the onus to enforce copyright is on the copyright owner, and it seems unlikely that entity would come after you in a legal sense. If your workplace were Disneyland, and it decided to rebroadcast an AM station, then the copyright owners might pay attention.

Most copyright cases begin with a letter asking the offender to desist. If the offender refuses, then the matter can become serious. It is a fuzzy area (see NPRM link below).

Some links:
http://www.ehow.com/about_6706871_broadcast-copyright-law.html
http://www.museum.tv/eotvsection.php?entrycode=copyrightlaw

NPRM
http://www.copyright.gov/fedreg/2008/73fr31399.pdf

John