Note that all
posts discussing PI
be deleted here, to keep the innocent safe! (that's why you cannot find any). Its not a "FM" transmitter in any sense, more a [expletive-deleted - this is a family-and-education-friendly forum, you poor excuse for a moderator - _you_ need to be deleted] illegal broadband transmitter, worst idea -ever-!
Your overly-broad description of using a Pi to generate FM signals is not only ill-informed, it's just plain wrong. There are quite legal ways of doing this, the internationally-recognized method being to have an amateur radio license and broadcasting in appropriate amateur bands, which doesn't even require knowledge of Morse code any more. What you are apparently conflating is FM broadcasting technology vs. the reserved FM broadcast spectra of 87.5 to 108.0 MHz in Europe, Australia, and Africa (ITU region 1), 88.1 to 107.9 MHz in the Americas (ITU region 2), 76.0 to 90 MHz in Japan, and 65.8 to 74.0 MHz in the OIRT band in Eastern Europe (except that Russia now primarily uses the 87.5 to 108 MHz ITU region 1 band). You're also ignoring the difference between just slapping a wire onto a GPIO pin and using additional passive or active elements to filter out-of-band harmonics generated by pulse-width-modulated (PWM) signals that would be created on a bare GPIO pin.
Then, there's the whole subject of Software-Defined Radio technology:
Amateur radio projects:
and other perfectly-legal uses of RF technology using a Pi:
http://cpc.farnell.com/wirelessthings/b ... dp/SC13019
Instead of the typical heavy-handed, police-state, government-knows-best approach exhibited here (and you keep wondering why the former colonies ran away as fast as they could, taking most of the great, world-improving ideas with them), you should adopt the educational tone that this forum is supposed to portray. You should point out the differences in laws between various locales (e.g., the 200-foot FCC Part 15 rule in the U.S. that allows micro-power transmitters in the 88.1 to 107.9 MHz band), the additional filtering components needed to eliminate out-of-band harmonics generated by a GPIO pin, the amateur bands where FM transmissions are perfectly legal with links to the requirements for earning an amateur license, etc.
Amateur license applications have fallen steadily over the years due to the very fact that there is no commercial interest in promoting the hobby. Any organization purporting to have an educational mission should consider what it can do to foster this very important segment of information science and electrical engineering. Most professional radio/video broadcast technicians start out studying for and earning amateur licenses, which requires knowledge of the very issues noted above, and we can't have enough people of every age educated in this area. Amateur radio is extremely critical in rural and remote areas outside the comfy climes of Merry Olde England, particularly in times of emergencies (and I certainly remember the deadly storms and floods in the UK and the rest of Europe not that long ago). 24+ tornados ripped across 150 miles of the U.S. South last night, that killed people and destroyed structures and vehicles, less than 100 miles from where I am.
Let's reserve the knee-jerking for when the doctor knocks your leg with the little rubber hammer. When someone uses a term such as "Pi-rate radio", hooking up a bare wire to a GPIO terminal just to see what happens, etc., steer the conversation to the legally and technically proper methods. If they insist on continuing discussions clearly meant to promote illegal activity, then remove their posts, or edit them with plain language as to why the Foundation can't support publici(z/s)ing the specific use they're discussing.
Again, watch your language here - it's at least as bad as the discussions you're complaining about.
The best things in life aren't things ... but, a Pi comes pretty darned close!
"Education is not the filling of a pail, but the lighting of a fire." -- W.B. Yeats
In theory, theory & practice are the same - in practice, they aren't!!!