FM multiple frequency broadcasting

I'm not _sure_, but if you're in the U.S., this sounds like something which the Federal Communications Commission (FCC) would NOT like, and would be knocking on your door shortly after you power up.

I suspect you wouldn't be popular with similar agencies in the U.K. and the rest of the E.U., or in Japan or any other industrialized / developed nation.

And 15 _kilowatts_ out of a card you plug into your PC???

Bob Pownall

Nice one. Grudge match?

Please note that you can only transmit on one 200kHz wide channel at a time. Dominating the entire FM broadcast band is not a good idea. If you want "multiple frequency broadcasting", you'll need multiple transmitters.

For only a few hundred meters, you can do it without a license.

If you want to go the licensed route:

15 kilowatts on a PCI card is rather improbable. For FM broadcast, there's really no reason why you would want the xmitter on a PCI card since there's nothing that really involves a computer in the transmitter.

--
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

Of course, that doesn't mean someone hasn't done it:

Made for listening to MP3's on an FM receiver.

--
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

NOTE: DO NOT TRY THIS AT HOME! FCC WILL NOT LIKE!

Just a thought ... what is the feasibility of transmitting on the IF frequency (commonly 10.7 MHz)?

You would have to take great care to have a well-filtered signal (passing the signal through plain old ceramic filters) and have *very* low output power, just enough to capture the intended receiver.

This because of the other users of that frequency band, and because of the of the propagation of 10.7 MHz frequencies.

Of course, this means the range would be in the range of meters rather hundreds of meters, and the receivers may have to be 'prepped' by adding some form of antenna to the IF system (which in turn has to be designed in a proper way to prevent leakage of IF frequencies from the receivers mixer).

I'm asking this, not so much because of the OP's question but because I've been toying with the concept at times, as means of a 'Emergency Broadcast System' for fire and/or evacuation alarms.

I could also see law enforcement applications for such a transmitter, like being used in parallel with the PA found on most cars, or as a diversion when doing a raid on some place.

Any more thoughts?

/T.

--
Teodor Väänänen                | Don't meddle in the affairs of wizards,
   | for you are good and crunchy with
http://www.algonet.se/~teodor/ | ketchup.
Remove stupidity to reply.     |

NOTE: DO NOT TRY THIS AT HOME! FCC WILL NOT LIKE!

Just a thought ... what is the feasibility of transmitting on the IF frequency (commonly 10.7 MHz)?

You would have to take great care to have a well-filtered signal (passing the signal through plain old ceramic filters) and have *very* low output power, just enough to capture the intended receiver.

This because of the other users of that frequency band, and because of the of the propagation of 10.7 MHz frequencies.

Of course, this means the range would be in the range of meters rather hundreds of meters, and the receivers may have to be 'prepped' by adding some form of antenna to the IF system (which in turn has to be designed in a proper way to prevent leakage of IF frequencies from the receivers mixer).

I'm asking this, not so much because of the OP's question but because I've been toying with the concept at times, as means of a 'Emergency Broadcast System' for fire and/or evacuation alarms.

I could also see law enforcement applications for such a transmitter, used in parallel with the

--
Teodor Väänänen                | Don't meddle in the affairs of wizards,
   | for you are good and crunchy with
http://www.algonet.se/~teodor/ | ketchup.
Remove stupidity to reply.     |

NOTE: DO NOT TRY THIS AT HOME! FCC WILL NOT LIKE!

Just a thought ... what is the feasibility of transmitting on the IF frequency (commonly 10.7 MHz)?

You would have to take great care to have a well-filtered signal (passing the signal through plain old ceramic filters) and have *very* low output power, just enough to capture the intended receiver.

This because of the other users of that frequency band, and because of the of the propagation of 10.7 MHz frequencies.

Of course, this means the range would be in the range of meters rather hundreds of meters, and the receivers may have to be 'prepped' by adding some form of antenna to the IF system (which in turn has to be designed in a proper way to prevent leakage of IF frequencies from the receivers mixer).

I'm asking this, not so much because of the OP's question but because I've been toying with the concept at times, as means of a 'Emergency Broadcast System' for fire and/or evacuation alarms.

I could also see law enforcement applications for such a transmitter, used in parallel with the

--
Teodor Väänänen                | Don't meddle in the affairs of wizards,
   | for you are good and crunchy with
http://www.algonet.se/~teodor/ | ketchup.
Remove stupidity to reply.     |

NOTE: DO NOT TRY THIS AT HOME! FCC WILL NOT LIKE!

Just a thought ... what is the feasibility of transmitting on the IF frequency (commonly 10.7 MHz)?

You would have to take great care to have a well-filtered signal (passing the signal through plain old ceramic filters) and have *very* low output power, just enough to capture the intended receiver.

This because of the other users of that frequency band, and because of the of the propagation of 10.7 MHz frequencies.

Of course, this means the range would be in the range of meters rather hundreds of meters, and the receivers may have to be 'prepped' by adding some form of antenna to the IF system (which in turn has to be designed in a proper way to prevent leakage of IF frequencies from the receivers mixer).

I'm asking this, not so much because of the OP's question but because I've been toying with the concept at times, as means of a 'Emergency Broadcast System' for fire and/or evacuation alarms.

I could also see law enforcement applications for such a transmitter, used in parallel with the PA of the police car, or as a diversionary tactic during raids.

/T.

--
Teodor Väänänen                | Don't meddle in the affairs of wizards,
   | for you are good and crunchy with
http://www.algonet.se/~teodor/ | ketchup.
Remove stupidity to reply.     |

There is a way to do this: pick an on channel frequency in the center of the band and AM modulate the FM signal with a short duty cycle pulse at 200 kHz, (the channel spacing). A multitude of side bands, all with your audio mixed in. And, as the power gets quite low as the pulsed signal has a low duty cycle, you'd have to raise the peak power to the point where YOU WILL GET NOTICED.

This will guarantee that you'll get your butt kicked by the FAA (or whatever your local aviation authority is) , as the band above the FM band is used for the VOR radio-direction finding system used for air navigation. Jamming broadcasters is one thing, risking lives is another. If they have problems, they don't just send a car around a few weeks from now, they send up an airplane and find what's going on. (Well, I hope they still do. You never know, with the way they run things now).

In the US, a couple of hundred meters is a bit over the limit (250 uV/M at 1 meter or something like that). I worked that out as 30-50 nanowatts radiated. Good for about 50 yards or so with a good radio. And only one 200 kHz wide signal at a time.

Mark Zenier snipped-for-privacy@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)