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Pirate station locks people out of their cars

How about this. It's happening around the country.
FBI is trying to figure out what crooks are using to disable a cars alarm and unlock it with the push of a button on a little box. Possibly it hacks the cars computer.
 
My 50kw 104.9 disables remote entry in the parking lot. Have had to bump the TX off more than once to let someone in their car. Passes all spurious tests on the analyzer...but...I don't imagine the receivers in the cars are very high quality.
 
Any loose piece of metal rubbing against another piece of metal in such a high RF field will generate harmonic energy. Your transmitter is probably clean as a whistle.
 
level42 ... the difference in power between your station and that key fob is roughly 130 dB (50 kW vs. 10 mW). Your transmitter can interfere in normal operation, the FCC spec for 3rd Harmonic is approximately 85 dB down from a class B station.
 
As "seen" by a demodulator, the electronics currents in modern vehicles become, essentilly, a bunch of wildly running "BFO" oscillators, which are perfectly capable of "creating" all kinds of harmonics that aren't "really" there, except by "unfortunate" heterodyne mixing and detection malpractices.
 
So, after reading all the comments, it looks like it was more the frequency, not the fact that it was a pirate, right?
 
Unless we could see a spectrum analysis of the pirate's signal, it would still be hard to say.
At least one licensed station has seen a similar effect.
It may be likely that the low elevation of the pirate antenna put more signal into the local area,
causing this problem. Any licensed station would likely not have so much direct radiation at near-ground level,
nor would they as likely be in a residential area.

Strong signals create many spurious responses "within" electronics as a result of too few or NO "real" tuned circuits.
It's almost as easy to blame the manufacturers of the cheap key fobs, who do not test the operation of the devices in
"near field" levels of broadcast transmitters.

Modern AM "radios" with no physically tuned circuit and varactor tuning diodes are very susceptible to detecting things that aren't really there. I'm not all 'sprised that key fob receivers in vehicles are prone to false detection.
 
Odds are as with most pirates, they had no low pass filter, thus allowing spurs all across the RF spectrum in close range, especially if it was some kind of homebrew or cheap Chinese transmitter.
 
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