Door Openers QRM'd by DoD

[WA3VJB]

If your garage door opener starts acting strange, this could be how come.

http://www.washingtonpost.com/wp-dyn/content/article/2007/02/25/AR2007022501417_pf.html

[WA1GFZ]

When my XYL lived at home her room was over the garage.
This reminds me of the time we were home alone .......and the door opened......

[k4kyv]

Part 15 devices must accept interference from licensed services.

That was a clever idea helping the neighbour clear up the rfi problem.  I have found it helpful to get their cooperation by allowing them some "ownership" in the radio station.  For example, if you can get them to help you with an antenna in exchange for your helping them with a simple house repair, they will be less likely later on to complain about rfi or your "unsightly" antenna, since they helped you put it up.

The guy across the street, who has always been a good friend and we sometimes give each other a hand with our home projects, had his phone to go out.  I helped him track down the problem; the phone wiring under his house was badly corroded due to excessive moisture.  We fixed the wiring, and then I invited him over and showed him the measures I had taken to eliminate the severe moisture problem I previously had under my house.  He didn't take as drastic measures as I did, but he did open up some vents and lay down some plastic.

He used to always be griping to me about hearing me in the background when he used his phone.  I'm sure he still hears me in the phone (it never was bad enough to keep him from using it, just a nuisance), but he never says anything to me about it any more.

[n3lrx]

When my XYL lived at home her room was over the garage.
This reminds me of the time we were home alone .......and the door opened......

Oooops! Daddy's home!

[WA1GFZ]

Nobody came home ....good thing
The door just decided to open.

[The Slab Bacon]

When my XYL lived at home her room was over the garage.
This reminds me of the time we were home alone .......and the door opened......

Been there done that!!

[WA1GFZ]

OM wouldn't be giving me grapa if he came home that night.

[W1RKW]

When my XYL lived at home her room was over the garage.
This reminds me of the time we were home alone .......and the door opened......

Went through that a couple of years ago here at the new QTH.  I installed 2 new openers. After several months of no problems I came home from work to find my wifes side of the garage wide open to anyone.  She normally leaves for work after me  so I figured she forgot to close the door when she left.  I told her about it but she swore up and down that she saw it close before she drove off.  I believed her since she's far more responsible than I and suspected a problem with the opener.  A couple of months go by, my wife and I are asleep and it's about 2AM.  I hear her opener activate.  I jump out of bed and look out the window, nothing on the street, no cars and everyone elses home are dark, nothing. Now I'm pissed off that I have to screw around with a door openers the following weekend.

So I give her my opener mechanism since my side is hardly ever used and I'll just open my side manually for a while hers is just hanging there disengaged from the door. The one on my side which was hers works fine to this day.  Figuring everying is good, we go about our normal lives.  About a month later I'm by myself working in the garage and her  side door goes up again by itself.  Now I'm really annoyed because I'm thinking the mechanism is OK but something is setting it off.  Just have to figure out what it is. 

Replacing wiring, switches, removing batteries from remotes and trying a different AC circuits didn't solve any of the random self openings on her side.  My side with her opener from the original setup again continued fine.  This continued for almost a year but I was determined to figure it out.

I borrowed a 500mhz scope from a friend and put it on the RF amp and could see all sorts of noise.  I came to the conclusion that something in the house was triggering it.  Tried reorienting the antenna, no luck in noise reduction.

When all was said and done. It was a combination of the microwave oven clock and the storing of to many remote codes stored in the opener. My opener was probably far enough away not to receive this noise, though I never checked it with the scope. 

I eliminated several remote codes from the opener on her side. That seemed to do the trick.   I figured with to many remote codes and the noise, the right combinations of random noise stored in the registers that was enough to trigger the opener.  It's been fine ever since though I still am leary that one day I will again come home to find the garage wide open.  Knocking on wood as I type this.

If we leave the house for more than a day the doors are disengaged and locked.

[Rob K2CU]

Why not just convert the units to IR (THz)?

[The Slab Bacon]

Instead of going through all of the trouble trying to live with outdated crap, convert over to the new 390Mhz digital remotes?? The newer remotes mfr'd within the last few years are many times better than the old ones, and they're relatively inexpensive. They are immune to noise and stray rf signals, they respond to the digital code sent by the transmitter. The codes are field selectable and changable. We use them all of the time here at work and never have any falsing problems.

                                                   the Slab Bacon

[WA1GFZ]

Interesting since the Aircraft UHF band goes to 400 MHz

[WD8BIL]

Interesting since the Aircraft UHF band goes to 400 MHz

225 - 400 Mhz ? Isn't that military only

I know flight ops on carriers run in the 380 to 390 Mhz range.

[KB2WIG]

I think  part 15 devises can go most anywhere.... but I don't know fer sur.. if I wasn't lazzy  I'd check the CFR for the fcc stuff. cant remember what the numbers are... klc

[The Slab Bacon]

Earlier R/C remotes were around 225 Mhz, and not digital, they were interferance prone pieces if s#!#. Later ones were moved to right around 300Mhz they were better but still not great. The newest ones were moved to 390Mhz with digital protacol. These have been just about trouble free.

In some areas they still have some minor problems with the 390s, but I havent seen it around here. There is some chatter now about moving them to somewhere between 433 and 433.5Mhz. I'm sure this will go over like the proverbial "fart in church" being that it is in the UHF amateur band.

                                                The Slab Bacon

[W1RKW]

Hey Frank,
In my case the door openers we have are the new digital types and if I remember right they were in the 390MHz range.  We had 4 digital transmitters.  Each transmitter was used to open both doors.  So each opener had 8 codes programmed into it initially.  The opener closest to the microwave was the one that false triggered, the other opener never false triggered.  Removing most of the codes from each opener stopped the false triggering on the one closest to the microwave oven.  My side of the garage which never gave me trouble only has one code in the receiver, now.  My wifes side has only two at this point in time.  Her side is used most often by the both of us and it's been fine ever since.  I'm not sure exactly what was happening in the decoder that would cause it to trigger but seeing noise coming from the microwave on the rf frontend was enough to convice me that the false triggers were not only coming from there but the noise would have been random enough to "grab" one of the many store codes in the receiver and cause a false trigger.  Don't ask me how, I'm not a digital guru.   But in any event, we haven't had a false trigger in over 3 years.

Instead of going through all of the trouble trying to live with outdated crap, convert over to the new 390Mhz digital remotes?? The newer remotes mfr'd within the last few years are many times better than the old ones, and they're relatively inexpensive. They are immune to noise and stray rf signals, they respond to the digital code sent by the transmitter. The codes are field selectable and changable. We use them all of the time here at work and never have any falsing problems.

                                                   the Slab Bacon

[The Slab Bacon]

Bob,
      They have a very simple encoder / decoder in them it is basically a decade counter ic. I have never bothered to see exactly what they put out. (go figure, I have 4 scopes and a HP spectrum analyser at home). I dont know if the info is sent as a modulated carrier or pulsed like cw. That might tell the tale. We use a lot of them here at work for actuators and remote controls for ADA / handicapped automatic door operators. I know since the change to the 390Mhz units we have had no problems with them. The earlier 225Mhz units were absolutely hateful. The brand that we use is MS Sedco, they also used make them for the "Genie" brand.

the old Multi-Elmac (same as the ham gear) company was still around making 300Mhz units as a few years ago. They sold them under the brand name of "Multi-code". The 225 Mhz units were made by a company called "Telectron". Another company that markets the 390 units is a company called "B.E.A.", theirs are also pretty good. One of the most notable improvements they have done was going to crystal controlled transmitters and receivers instead of the really crude L/C controlled units of the past! (that were NEVER tuned to each others frequency very accurately)

As with everything electronic, as the technology keeps improving they just keep getting better (and cheaper)

                                                      The Slab Bacon

[W1RKW]

Hi Frank,
I'll confess.  Our openers are Sears openers. I'm not sure who made them for Sears but maybe that will be a clue.  I'm sure being the typical consumer junk that is put out on the market that they aren't all that great.  I sure wouldn't rely on them as a security device even though the doors do stay down when I'm not home.  I do lock the garage doors if we go away for more than a day.  Even though they have been trouble free over the last 3 years I still don't trust them.  I have thought about putting them on timers and cutting the power from them based on our schedule here but haven't commited to doing that.  One thing I'm not sure about is how long the stored codes will stay in memory. 

At one point when we were having the trouble I considered cutting the antenna shorter.  I wouldn't have cared if I had to be 10feet away to make the door go up but I didn't go down that road.  Anyway,  all has been fine.

I can only imagine how a homeowner who isn't technically saavy and a bunch of garage door opener technicians would have dealt with this sort of trouble especially the Sears  people.  I wonder if they know what an oscilloscope is.  I'm glad I handled it my way and was able to come up with a solution.

[Steve - WB3HUZ]

There is some chatter now about moving them to somewhere between 433 and 433.5Mhz.

Already there. I have several that operate at 433.