98Clubs
98Clubs
Joined: Jun 3, 2010
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April 2nd, 2014 at 7:58:35 PM permalink
Quote: Mooseton

When travelling through the airport tunnel, why does am radio come in either crystal clear (more clear than normal) or completely white noise?



The tunnel as previously mentioned has an antenna (pipe) in it. Otherwise the signal vanishes. There are matters of propagation that do factor, but generally, don't count on AM RX in a tunnel. FM with a very short wavelengtth can enter a tunnel as generally the height and width are greater than the FM wavelength (about 3-4 meters). In long tunnels the FM can fade. Along this line of reasoning, the AM wavelength (170-550 meters) does not "resonate in the tunnel, it needs an antenna to carry the signal inside. HTH
Some people need to reimagine their thinking.
Mooseton
Mooseton
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April 2nd, 2014 at 8:06:39 PM permalink
But why the change from day to day? Same tunnel, same lane, same time usually, same weather usually. I'm honestly not trolling intentionally; just being curious.
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98Clubs
98Clubs
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April 2nd, 2014 at 8:36:11 PM permalink
Must be a propagation issue. And its possible if the tunnel is long, say 1200 feet (300 meters) that in some spot(s) a weak resonance does occur. The electrical wiring for the lights in the tunnel can act as an antenna. A bad ground might cause occasional reception at various places. Lotta intangibles here and generally not-well-understood things happen. I like to think of it as 20 variables that occasionally add up to reception.
Some people need to reimagine their thinking.
MathExtremist
MathExtremist
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April 2nd, 2014 at 10:58:01 PM permalink
Quote: Mooseton

But why the change from day to day? Same tunnel, same lane, same time usually, same weather usually. I'm honestly not trolling intentionally; just being curious.


When you're in a weak reception area, little things can make a difference between usable signal and no signal. Are there cars/trucks next to you or are you mostly unsurrounded, are the overhead lights in the tunnel on or off, what's going on above your head as you travel through the tunnel (and you can't usually know this), etc. The last time I was in Vegas, my cell phone got sporadic reception from my room (facing away from the strip, up about 20 floors) and where I stood in the room actually changed the number of bars. Also, I just upgraded my home WiFi and the orientation of the router determines whether I get signal out on my patio. Radio waves can be finicky.
"In my own case, when it seemed to me after a long illness that death was close at hand, I found no little solace in playing constantly at dice." -- Girolamo Cardano, 1563
Tomspur
Tomspur
Joined: Jul 12, 2013
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April 2nd, 2014 at 11:02:03 PM permalink
If my memory serves,. doesn't the airport connector tunnel also have tiles inside? Would that not help with the reflection of the radio waves?

I don't have any experience here just what I would imagine would happen?
“There is something about the outside of a horse that is good for the inside of a man.” - Winston Churchill

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