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

> So, in theory, there should be no two cars anywhere that respond to the same
> code.

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

In article <6a0dcc88-715f-4d67-8a14-45819e1744a5n@googlegroups.com>,
rdelaney2001@gmail.com says...
>
> So, each manuf'r has its own allocation of ID numbers. And, presumably, its own
> RF format. Are there FCC regs on that?
>
>
>

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.