Re; Newbie Q on cell phone interference

["Jim Cash" <j.cash@xxxxxxxxxxxx>]

Bob asks

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My new '00 528iA sport-premium came with a dire warning (GLUED! to the

inside of the windshield, took me a half hour to get off with Goo Gone!)

about using non-BMW-approved cell phones inside the car. Claims that a

cell phone with an antenna inside the passenger compartment may cause

damage to the poor baby car's sensitive electronics.

True? Or just a ploy to get me to spring for the expensive BMW StarTAC

phone?

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While it may help some BMW phone sales, there is validity to this issue even
if you think BMW may be overly cautious.

There are between 20 and 35 different computerised modules located
throughout the car (depending on the car and optional features) all
controlling different operations. They all communicate with each other via
digital messages across several digital buses (sort of like your internal PC
components all spread out around the house and linked by a single wire).

One of the avenues for signals to get into the system is via the
"telecontrol" system (remote key with antenna in the rear window).

Also the digital bus wiring is located throughout the cabin, trunk, engine
comp, etc.  So there is lots of wire that can act as an "antenna".  A
portable phone,  transmitting inside a metal box (the cabin) , causes the RF
to bounce around and be somewhat absorbed by any metal it hits (including
the antennas in the rear window and wiring in the car).



So there is a possibility that these transmissions could cause interruptions
the digital operation of all those computers. It might be as simple as a
garbled command for movement of a mirror or seat, or some other minor
glitch. But, in theory, lighting and even engine/transmission operation
could be affected.  It is also possible, though unlikely, that one of the
computer chips could be damaged by the RF transmission.

So BMW, to avoid dealing with these possible issues ,gives you that warning.



But - since BMW mount their own phone antennas outside the car (on he
outside of the back window) they are following their own advice. They would
not bother if there were no reason.



Regarding your comments about the DSP stereo - it helps if you set the
treble and bass toward max, and also set the equaliser high in these
frequencies, while keeping the mid frequencies flat.

Lots of discussion on the details of this issue on other forums.



Cheers

Jim Cash

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