Re: Open car door via cell phone

>[re opening a car door via a cell phone]
>
>Isn't the real reason why it won't work is because the mouthpiece on
>the phone only responds to sound waves, not radio waves? Even if cell
>phones and car openers both operated on the same frequency, how would
>the xmitter's rf signal ever be picked up by the phone?

The real reason is that the car door receiver responds not only to a
frequency, but to a digital code sent via that frequency. You have no
way of sending that code with your cell phone. (This is also why I
can't use my car remote to open someone else's car.)

-Joel Hoffman

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"Dr. Joel M. Hoffman" wrote:
>
> >[re opening a car door via a cell phone]
> >
> >Isn't the real reason why it won't work is because the mouthpiece on
> >the phone only responds to sound waves, not radio waves? Even if cell
> >phones and car openers both operated on the same frequency, how would
> >the xmitter's rf signal ever be picked up by the phone?
>
> The real reason is that the car door receiver responds not only to a
> frequency, but to a digital code sent via that frequency. You have no
> way of sending that code with your cell phone. (This is also why I
> can't use my car remote to open someone else's car.)

Back, when I was a kid, we (me and the other science nerds) built a
variable-frequency transmitter that opened everyone's electric garage
door in the neighborhood.

*We* were the reason that technology improved! <g>

Notan