Speed_Racer

I saw the European show Auto Motor and Sport. They were talking about thieves using walkie talkies to jam remote door locks just as a person is leaving their car. The owner would leave their car and lock their doors remotely, but the thief is just close by with a walkie talkie that jams the remote and doesn't let the car lock. I always listen for the beep when I lock my car remotely, but I had never heard of this method of getting into your car. Apparently they are on the same radio frequency.

Shawn S

I never heard that, but I guess it’s possible if the frequency is the same.
I doubt it would be the 30-dollar variety you buy at Wal-Mart, probably something specifically built to be on the same frequency.

It’s kind of like the old “code grabbers” thieves used to use when automatic garage doors first came out.
Not an issue now with “code rolling”.
There must be something like that in use for the remotes considering nearly every manufacturer has them now.
There would be LOTS of cross interference if there weren’t.

Shawn S

cartan

It certainly could be possible with the right equipment. But I always make sure I hear the beep after the second press as confirmation that my doors are locked.

Speed_Racer

That was the weird thing. They just bought a set off the shelf and were able to jam lock codes for multiple cars (BMW, Volkswagon, MB, and Audi were the few that I remember). It's not a big deal to me because I also always listen for the beep, but if you weren't careful it's another way someone could get into your car without you knowing.

Shawn S

Interesting indeed.
I too always listen for the “beep” so it doesn’t matter to me.

The only thing I can think of is the handset might BLAST the nearby area with radio frequencies and then the signal doesn’t reach the car from your remote.
Just a guess though.

cartan

This is typical jamming. The remote control signal is the desired signal and anything in the background is noise. The receiver needs the signal to be a certain level above the background noise to be able to properly recognize it. In the jamming case, the signal level doesn't change, but the background noise has increased. By increasing the background noise, the receiver can no longer pick out the desired signal.

An analogy is talking. When you are three feet away from your friend in a quiet room, you don't have to talk very loud to carry on a conversation. But if you crank up the stereo really loud (excessive background noise) and you try to speak at the same level as when it was quiet, your friend may no longer be able to understand you over the background noise. You can compensate by shouting (increasing the signal to noise ratio). But in the case of the car remote, it doesn't know to "talk louder" when it is jammed.

ccannizz11

^^Ya, what he said!^^