Convert PI codes recieved from US RBDS transmissions into their appropriate callsign. This is a relatively simple routine to take the Program Identification codes that are transmitted in US RBDS and convert them into the callsign that they represent.
It only does simple error checking, so you should be able to fool it into giving you false callsigns very easily. The source that I borrowed from, http://www.w9wi.com/articles/rds.htm, checked for a few corner case stations in addition to applying the general formula. You can check out the source of the afformentioned webpage to see how it works.