Do you think this actually works?

Discussion in 'Other Off Topic Forum' started by richard_wallace, Aug 4, 2004.

  1. richard_wallace

    richard_wallace Formula 3
    Rossa Subscribed

    Feb 6, 2004
    Cincinnati, Ohio
    Full Name:
    Richard Wallace
    Just got this e-mail and will be verifying that this does not work.

    My thought is that most alarms are either FM, AM or IR frequency... So trying to transmit a non Audible frequency over a cell phone - will not work. To verify this - I am in Michigan today - (I live in Cincy) - I am going to have my wife try this by transmitting my FX45 "unlock" while standing like a goof ball with my cell phone next to my car... I feel like a myth buster...

    Here is the e-mail...
    Subject: Locked Out of Car - try this

    This only applies to cars that can be unlocked by that remote button on your
    key ring. Should you lock your keys in the car and the spare keys are home, and you don't have "OnStar," here's your answer to the problem!

    If some one has access to the spare remote at your home, call them on your cell phone (or borrow one from someone if the cell phone is locked in the car too!)

    Hold your (or anyone's) cell phone about a foot from your car door and have
    the other person at your home press the unlock button, holding it near the

    Your car will unlock. and it works. Saves someone from having to
    drive your keys to you. Distance is no object. You could be hundreds of miles away, and if you can reach someone who has the other "remote" for your car, you can unlock the doors (or the trunk, or have the "horn" signal go off, or whatever!)
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  3. Doody

    Doody F1 Veteran

    Nov 16, 2001
    MA USA
    Full Name:
    Mr. Doody
    it is radio frequency, so it's not outside the realm of possibility. i'd think it would depend on the frequency since i assume the telcos these days toss anything outside of normal human hearing - less bandwidth usage that way.

    i assume you'll need to put your cell on speakerphone mode so it "broadcasts".

    keep us posted!

  4. gentry

    gentry Guest

    I dont think that would work considering that the degredation of the signal from normal to the 24hz used in phones would distort anything that precise.

    Also, they are RF, not audible.

    Who knows, maybe Ill try it sometime.
  5. richard_wallace

    richard_wallace Formula 3
    Rossa Subscribed

    Feb 6, 2004
    Cincinnati, Ohio
    Full Name:
    Richard Wallace
    That is what I was thinking as well... Another myth busted by the f-chat board...

    Here is the post as mention by Bryan..

    Here's why:

    Your remote car key operates by sending a weak, encrypted radio signal to a receiver inside the automobile, which in turn activates the door locks.

    Since the system works on radio waves, not sound, the only conceivable way a signal from your spare remote could be picked up by one cell phone and relayed to your car's onboard receiver by another would be if both phones were capable of sending and receiving at exactly the same frequency as the remote itself — which they can't be, given that all remote entry devices operate at frequencies between 300 and 500 MHz, while all mobile phones, by law, operate at 800 MHz and higher.

    It's apples vs. oranges, in other words. Your cell phone can no more transmit the type of signal needed to unlock a car door than your remote key is capable of dialing up your Aunt Mary ... though no one can predict what miracles the future may bring.
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