Garage Door question - Rotating Codes
 

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

Garage Door question - Rotating Codes
 

http://electronics.howstuffworks.com/remote-entry2.htm

Garage Door question - Rotating Codes
 

Beachcomber wrote:

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


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

Garage Door question - Rotating Codes
 

"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.

Garage Door question - Rotating Codes
 

On 19 Nov 2005 10:28:48 -0800, wrote:

"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.


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

Garage Door question - Rotating Codes
 

"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!