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Krampf #474 Cell Phone Noise
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KRA-@aol.com
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Jan 17, 2007 05:03 PST
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Robert Krampf's Experiment of the Week
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This Week's Experiment - #474 Cell Phone Noise
Greetings from Jenson Beach, Florida. I am doing electricity and energy
presentations at the area schools, and after the wonderful holiday break, it
feels good to be back in front of an audience. Nancy and I are also enjoying
walks on the beach, antiquing in some of the local shops, and listening to the
trains, which come through the campground every couple of hours, all night long.
Luckily, we like trains.
This week's experiment is one that I have been playing with for quite a
while. It began while Omar, my friend and video director, and I were editing one
of our science videos. Omar suddenly stopped and reached for the phone.
Just as he picked it up, the phone rang. How did he know? To find out, you
will need:
a cell phone that uses the GSM standard.
music that you can listen to through either earphones or external speakers.
someone to call your cell phone
You may have to try more than one cell phone to get this experiment to work.
Different companies use different systems, and the GSM standard is the one
we are looking for. I know that Cingular phones work, and that Sprint phones
do not. I have not had the opportunity to check other companies.
Turn on the music and listen for a minute or two. While you are listening,
bring your cell phone near the wire that connects the music player to the
speakers or earphones. Holding the phone there, turn the turn the cell phone off
and then back on again. You should hear a series of buzzing sounds through
the speakers. If you don't then your phone is probably not using the GSM
system, so try a cell phone from a different provider.
Once you find a phone that produces the buzzing sound, hold it near the wires
and have someone call the phone. Just before the phone rings, you should
again hear a series of buzzing sounds. What are you hearing?
You are hearing some of the communications between your cell phone and the
cell phone tower. The phone has to synchronize its signal with the tower,
depending on how away the tower is. During that process, your phone's radio
signal is strong enough to be picked up by a nearby music player.
When you turn the phone on, it has to "talk" with the cell system, so the
system will know where to send your calls as you move from one area to another.
Then when a call comes in, your phone will respond again, making a connection
with the cell tower. That will give you another burst of sounds, just
before the phone rings.
This also explains why you are often told to turn cell phones off in
airplanes, doctor's offices, and other places where interference with electronic
equipment could cause problems. There are still questions about how likely that
is to happen, but the current philosophy is better safe than sorry.
This does not mean that some cell phones are giving off more radio signal
than others. It just means that the signal from the GSM format phones is in a
form that can be picked up by your music player. It also does not mean that
non-GSM phones will not interfere with electronic equipment. I just could not
find a common, household appliance that they would register with.
If you want to know more about cell phones, GSM and other cell formats, a
quick Google search for "How cell phones work" will reveal tons of sites that
will give you more information.
Have a wonder filled week!
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From Robert Krampf's Science Education Company
PO Box 60982
Jacksonville, FL 32236-0982
904-388-6381
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