Your reference to police/military installations tweaked my memory.
I used to find my garage door open some mornings. Changed codes, thinking someone had the same one. Changed to a new controller with rolling codes. Still the occasional problem.
One morning, coming home late from work, I was reaching for the opener on the visor when the garage door opened in front of me, just as a police cruiser went by. They do a circuit through the neighbourhood every night. I flagged then down and asked them to transmit- the door closed! re-transmit- it opened!
Seems that if they were on the radio when they went by, it was enough to trigger the controller. Couldn't figure out why. I eventually bought an entire new system from another manufacturer, with I assume, an RF receiver on a v. different frequency or perhaps better frequency discrimination. No problem now for 5+ years.
Your problem might relate to de-synchronized rolling codes. I had this problem with a weak car battery. Even though the car started (grudgingly, at minus 30), the voltage drop was enough to starve the transmitter and it wouldn't work. Re-synched it and no prob so far.
bob
