Quote:
Originally Posted by RMak
I don't know if this is a hidden feature or if my X5 was just bugging out.
My wife's cellphone was charging and it was connected to jack behind the center console... right were the rear passenger vents and heated seats are. Right before my wife's phone got the ringing sound of her text message, I over heard this "dadaduuuummm" (3 x's) sound like thing over the bmw speakers/sound system. The sound would only happen once before she recieved her text message. She recieved 2 text messages and oddly it happened twice. Of course this only happened when her phone was charging through the jack?
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Actually, cell phones send their data in bursts (called frames) that happen to have a frequency in the audible range (around 27Hz). the frequency itself is 900MHz/1800MHz for GSM, but the bursts are sent every 37ms for a duration of 4.615ms each (8 time slotes on each channel)..
anyway, that's why we hear this interference when a mobile is activated next to a Radio, because the magnetic waves are bursty in a way that makes the speakers "capture" those waves and translate them into audible sounds (isn't it the job of a speaker?)... about SMS, you hear the interference before it actually arrives, because the mobile will start negotiating the connection with the base station and do the call setup procedure before the message actually arrives.
Respectable audio makers have their speakers/systems shielded againt electromagnetic interference (I know BOSE do that) so yes, i was surprised to notice that BMW have no shielding whatsoever in a way that makes listening to the radio while on the phone almost impossible!!!