automobile remotes

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A question concerning the car remotes; door lock, headlights, etc.

Each car/handset must be a matched pair, regarding the ID  
and security codes.  Obviously only one car in the parking  
lot ought to respond.

Are the ID codes determined by each manufacturer, as  
they choose?  Or is there an intern'l body which allocates  
them, such that each is guaranteed unique, just as  
every telephone has a unique number?

Additionally, anybody know anything about their modulation  
methods, or FCC regs?  i.e. simple on/off key?

--
Rich

Re: automobile remotes
Rich D wrote:

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Well, they have a chip that is programmed at the factory, probably with a  
sequentially-incremented number.  The car is then trained to accept several  
key's serial numbers.  The all-in-one keys/fobs have two chips, one operated  
by pushbutton with a coin cell for door unlock, and one RF-powered by the  
engine computer through a coil near the ignition lock, for immobilizer.
So, in theory, there should be no two cars anywhere that respond to the same  
code.

Jon

Re: automobile remotes
OnFebruary 18, Jon Elson wrote:
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So, each manuf'r has its own allocation of ID numbers.  And, presumably, its own
RF format.  Are there FCC regs on that?

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Well, no.  There's no intern'l body allocating the codes, so in theory, there
 could be duplication.

Whereas, in the phone network, you dial a number, it's guaranteed to ring exactly  
one target device.

--
Rich

Re: automobile remotes
snipped-for-privacy@gmail.com says...
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For many of the low powered devices the FCC just states what frequency  
and power level they can use.  Just about anything else is up to the  
designer.  Very little FCC regulation.

They are unlicensed devices and often stated that they must accept any  
interference and not cause any to a licensed service.


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