FM Interference & Potential Coinkidink
December 26, 2009 10:05 PM   Subscribe

Heard some strange radio interference Christmas day, wondered if a hypothesis is correct in relating it to the local 'terror' attempt at DTW???

So the family had gotten home from a Christmas gathering, and someone checked the radio randomly to see what was on the low end of the FM spectrum (88-89, 88.7 and 89.1 to be exact), and we heard light static followed by some horrific beeping that could have came straight from a loud Atari game. Not quite bass, not quite tenor, just loud, obnoxious, and alternating (low then high, repeat). It did not last long.

Thus the question: what could this have been. We live within 30 minutes of Metro, so it was thought that since this noise had not been heard since 2001, it might have had something to do with the terror attempt. Otherwise, no clue, and would like to know for later reference.

Ideas?
posted by JoeXIII007 to Technology (17 answers total)
 
Beeping could be caused by a digital transmission that you're unable to pick up with your radio, but I find it pretty unlikely that they would be transmitting some kind of signal on public radio frequencies.

Can you elaborate on "had not been heard since 2001"?
posted by DMan at 10:07 PM on December 26, 2009


Can you elaborate on "had not been heard since 2001"?

Unfortunately no, since that's all my dad had recalled, a simple 'heard it last time then, likely around 9/11.'
posted by JoeXIII007 at 10:08 PM on December 26, 2009


I've heard that stuff for 25 years and have never figured out what it was.
posted by Ironmouth at 10:17 PM on December 26, 2009


Try tuning it to a blank station down there, put your cell phone on the receiver and/or speaker and have someone call it. It'll cause some kind of interference, but maybe not what you heard.
posted by cmoj at 10:21 PM on December 26, 2009


88.7 is 89X, no?
posted by ofthestrait at 10:29 PM on December 26, 2009


Nothing in the reports about the bombing attempt suggest any radio involvement.
posted by Chocolate Pickle at 10:34 PM on December 26, 2009


And you're sure it wasn't just like, GSM interference?
posted by floam at 10:36 PM on December 26, 2009


I would bet cash money that it was the sound of interference from a GSM cell phone, as floam and cmoj have speculated. I found some videos that have examples you can listen to.
posted by ErikaB at 10:56 PM on December 26, 2009


I found some videos that have examples you can listen to.

Ahh! I listened to it and it was like reliving to my own horrific experiences! I hate that sound.
If that was it, I can appreciate how frightening it must have been. That sounds weirds me out.
posted by lhude sing cuccu at 11:16 PM on December 26, 2009


It may be related to the fact that local broadcast TV uses some of the same below-90 frequencies.
posted by megatherium at 5:11 AM on December 27, 2009


-88.7 is 89X, no?

Correct. Not interference from them though and the noise was heard from 89.1.

-I would bet cash money that it was the sound of interference from a GSM cell phone, as floam and cmoj have speculated. I found some videos that have examples you can listen to.

Unfortunately: louder and ~second long tones (an alternation after each second, whereas GSM is a series of blips). BTW: I realize I should have said Treble instead of Tenor up in the OP, if that may help.

-Nothing in the reports about the bombing attempt suggest any radio involvement.

Right, I was thinking security of some sort might have been the source of the noise...

This might be a bit more accurate to what we heard, difference being ~deeper tones, a more steady pattern, and higher frequency from which it was heard.
posted by JoeXIII007 at 7:36 AM on December 27, 2009


The sound JoeXIII posted above sounds a lot like the interference caused by airport radar. I used to hear a very similar sound through the band's amplifiers at a bar near Selfridge Air Force Base many years ago.

My first thought (until you posted the sound clip) was perhaps you somehow managed to pull in CHU Canada, a time station that broacasts on shortwave.
posted by Oriole Adams at 10:31 AM on December 27, 2009


If the sounds of cell phone interference you've found so far have been that similar, then this can safely be written off as cell phone interference. Each phone will interfere with speakers a little bit differently, and each set of speakers will sound a bit different.

If you wanted to get really scientific about it, gather up every cell phone and electronic device (including pacemakers, cordless phones, what have you) which was present at the time, and set it beside the speakers from which you heard the noise.

At any rate, we can conclusively rule out "security." If you were actually ON the airplane at the time you heard the noise, then maybe. But from 30 miles away? I'm not aware of any kind of interference that would mess with your radio from that far away. I'm not even sure it would be possible, short of a signal so strong that it would boil people alive near the source.

Honest, it's not security. It's not related to 9/11. It's from something in your pocket, or your dad's pocket, not from the airport, I promise you.
posted by ErikaB at 11:50 AM on December 27, 2009 [1 favorite]


This page has examples of all sorts of radio noises.
posted by gjc at 2:21 AM on December 28, 2009


From the video clip that JoeX posted, that sounds similar to the serial output from my GPS receiver. I had picked that up in the 6 Meter (50 MHz) band. It took me months to figure out what it was.
posted by Climber at 8:35 AM on December 28, 2009


I dunno if anyone is reading this, but my dad and I have heard it again, and obviously, nothing going on national security wise tonight. He took a recording of it to someone who might know something about it, and this someone said its likely someone in the neighborhood messing around. Hopefully I'll get a copy of the recording tomorrow, and link it up here...
posted by JoeXIII007 at 5:59 PM on January 7, 2010


Apologies for the delay, but here's a recording of what I attempted to describe.
posted by JoeXIII007 at 3:15 PM on January 18, 2010


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