Interference On A Speaker


by BOAS
Tags: interference, speaker
BOAS
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#1
Dec19-13, 07:41 AM
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Hello,

I have a question or two that I suppose will include the nature of light and how that links to electromagnetism.

Sitting at my desk doing some work, listening to music over my speakers, I get a text. But I know i'm about to receive the text before my phone vibrates, because my speakers emit a series of buzzing/beeping noises.

So, what's going on here?

I have a few half baked ideas in my head, but it's been a while since I did electromagnetism in school and I don't start studying it at uni until january, so my memory is rather fuzzy on the subject + we never did look at how light is related to electricity and magnetism, though the name 'electromagnetic wave' certainly suggests that it is.

I remember the picture of an EM wave from my text book that looked like a wave oscillating 'up' and 'down', with another (can't remember if it was phase shifted) moving in the 'left' and 'right' directions. I know the moving a wire through a magnetic field can induce a current, so is there a tiny magnetic field involved with the broadcast of my text message that can induce a current in my speakers?

Or perhaps I have it backwards and my phone is emitting some kind of 'receipt'.

Thanks for any light you can shed on the matter :)

BOAS
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tfr000
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Dec19-13, 08:59 AM
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Quote Quote by BOAS View Post
Or perhaps I have it backwards and my phone is emitting some kind of 'receipt'.
That is the most likely explanation. Try moving your phone closer or farther away from the speakers and see what happens.
BOAS
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Dec19-13, 09:42 AM
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Quote Quote by tfr000 View Post
That is the most likely explanation. Try moving your phone closer or farther away from the speakers and see what happens.
I'll have to wait for someone to text me, but it doesn't look like i'll be moving from my desk much today.

Do you know what the bit of hardware is that is responsible for emitting signals from a phone?

davenn
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Dec19-13, 03:49 PM
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Interference On A Speaker


Quote Quote by BOAS View Post
I'll have to wait for someone to text me, but it doesn't look like i'll be moving from my desk much today.

Do you know what the bit of hardware is that is responsible for emitting signals from a phone?
Yes the transmitter that is used to get your phone signal back to the cellular tower

Your phone and the cellular tower are in almost constant ( at least, very regular) communication
There is polling going on so that the cellular system knows where your phone is located in the network so that it knows which base station tower to send any comms to your phone
This is really critical when you are on the move, say in your car, heading across town. You may move through several base tower coverage areas

Edit: I have also heard that buzzing/burbling set of tones even as an incoming call is coming in

cheers
Dave


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