Garage Door question - Rotating Codes

[Beachcomber]

From the Internet and other sources, I think I have a partial understanding about how rotating code remote controls (like garage door openers) work.

I understand that multiple remotes must be registered to the central receiver and the codes advance according to a pre-programmed algorithm.

What happens though if the remote control button is advanced multiple times when it is out of range of the receiver? I would think it would get out of synch and eventually cease to function.

Does the receiver accept a range of codes? (Say the last 10 codes or is it some other number).

How does the receiver stay in sync with the transmitters?

Beachcomber

[buffalobill]

[Tony Hwang]

Hi, Don't need to worry. Things like that is designed to include your worries. If you keep pushing remote button more than once, door will stop/reverse/stop/reverse..... Right? Tony

[trader4]

"Hi, Don't need to worry. Things like that is designed to include your worries. If you keep pushing remote button more than once, door will stop/reverse/stop/reverse..... Right? Tony "

Not if you're pushing it when out of range, which is the interesting question he was asking.about rotating codes. From the link, it looks like the door will accept any one of the next 256 codes. If you push it more than that, it will be out of synch with the opener and will require re-initializing it.

[Beachcomber]

Then if someone like a parking lot attendent had access to a sophisticated storage ocilliscope/spectrum analyzer/function generator, couldn't they just press the button once and have their device learn a valid code?

As long as they used it before the owner went back home (say by telephoning the code to an accomplice), then they would have access to the garage, right?

Not that your average Joe thief would have access to this kind of equipment, but the rotating code scheme doesn't seem to provide the degree of security that it promises....

Beachcomber

[trader4]

"Then if someone like a parking lot attendent had access to a sophisticated storage ocilliscope/spectrum analyzer/function generator, couldn't they just press the button once and have their device learn a valid code?

As long as they used it before the owner went back home (say by telephoning the code to an accomplice), then they would have access to the garage, right?

Not that your average Joe thief would have access to this kind of equipment, but the rotating code scheme doesn't seem to provide the degree of security that it promises.... "

Yes, I believe that would work. If they pressed the button on your transmitter while they had access to your car, captured the transmitted digital code, went to your house and retransmitted that code to the opener before you returned and used the transmitter yourself, it should work. Of course to do that would take a hell of a lot of fairly sophisticated equipment and there are much easier ways to gain entry to garages. Most alarm systems don't even cover the garage area. Plus, if you allow someone access to the transmitter, they could also just use that by taking it over to the house and skip all the hitech stuff!