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View Full Version : Garage door opener in RF saturated environment


NoCoolUserName
02-05-2011, 10:12 AM
We live near the radio/TV broadcast towers (a couple of hundred yards away). The garage door opener sometimes works and lately hasn't, not even from 8 feet away--apparently they've changed something at the towers. I ran a wire from the antenna inside the garage to outside the garage (under the eaves) but that didn't help. What, if anything, can I do to get the opener working again so we don't have to get out of the car in the freakin' snow to open the garage door?

Dog80
02-05-2011, 10:28 AM
I believe the tv tower and your remote control operate at entirely different frequencies. In addition, remote openers usually employ some kind of spread spectrum transmission technique so they can operate in extremely noisy environments.

So there's something else broken with your garage door and the tv tower is not to blame.

Turble
02-05-2011, 10:50 AM
You did try putting a new battery in the remote, right?

johnpost
02-05-2011, 11:21 AM
We live near the radio/TV broadcast towers (a couple of hundred yards away). The garage door opener sometimes works and lately hasn't, not even from 8 feet away--apparently they've changed something at the towers. I ran a wire from the antenna inside the garage to outside the garage (under the eaves) but that didn't help. What, if anything, can I do to get the opener working again so we don't have to get out of the car in the freakin' snow to open the garage door?

running a wire outside the garage, extending the antenna, would make the situation worse in a number of ways. you would need to mount the antenna on RF coax cable which would go to outside the garage. though i don't think that will cure your problem., if the strong signals are causing it trouble inside the garage it will do so outside the garage. strong signals will overload the receiver no matter what technology it uses.

if the towers are from a direction other than the front of the garage then you might place a grounded metal screen around all sides of the antenna but the front.

make sure the remote works.

NoCoolUserName
02-08-2011, 12:34 PM
You did try putting a new battery in the remote, right?I did, in fact, with no improvement.

The remote works, and it's slightly better with the garage door open (works from 6-8 feet away), hence my attempt to run a wire outside the garage.

The "antenna" on the opener is simply a bit of wire hanging off the back of the case--there's no co-ax that I can see. Maybe inside the unit?

I have an old CB-band antenna...I could mount that near the street and run co-ax out to it. I hate to put in that much effort but my minimal attempts so far have been miserable failures. Maybe it's time to put in the extra work.

beowulff
02-08-2011, 12:49 PM
You can't just use any old antenna. You need an antenna that is tuned to the frequency of your remote, which means it needs to be a specific length. Putting an antenna of the wrong length is just going to make things worse.

Harmonious Discord
02-08-2011, 12:53 PM
Try one of the other channels if your system has it.

Todderbob
02-08-2011, 01:18 PM
Have you tried and made sure the receiver isn't broken?


You say apparently they've changed something at the towers near your home, do you have concrete evidence of this or is it something you believe because you've seen a change in your garage? If the former, you're suffering from the common logical fallacy post hoc ergo propter hoc, if the latter, you're suffering from the same logical fallacy, while lacking the evidence even of a change that was made.

I'd like to know a little more about what you think the problem is, and why it's causing a problem at all?

Do your neighbors have similar problems? If not, it's unlikely it's related to your geographic location, if so, it's possible it's caused by localized phenomena but you still haven't pinpointed the root cause, only that there is a localized (or there is likely a localized) root cause.

engineer_comp_geek
02-08-2011, 01:21 PM
Sticking a CB antenna on the end of some coax is probably going to make things worse, not better.

As beowulff said, an antenna tuned to the frequency of your remote would help.

Using a directional antenna would also probably help, assuming that the RF interference isn't coming from the same direction relative to the receiver as the remote would be while you are in the driveway.

A few well placed grounded copper screens could block out a lot of the RF interference, although again you won't be able to block out anything coming from the same direction as the garage remote. A transmitting tower that close is also likely to reflect signals off of nearby homes and other objects which is going to make it more difficult to block it.

johnpost
02-08-2011, 02:02 PM
running a wire outside the garage, extending the antenna, would make the situation worse in a number of ways. you would need to mount the antenna on RF coax cable which would go to outside the garage. though i don't think that will cure your problem., if the strong signals are causing it trouble inside the garage it will do so outside the garage. strong signals will overload the receiver no matter what technology it uses.

if the towers are from a direction other than the front of the garage then you might place a grounded metal screen around all sides of the antenna but the front.

The "antenna" on the opener is simply a bit of wire hanging off the back of the case--there's no co-ax that I can see. Maybe inside the unit?

what you would have to do is remove the antenna (maybe need to unsolder) from the unit, then attach radio coax and put the wire antenna on the other end of the coax. this would take some soldering and good radio methods and techniques. this won't necessarily cure the problem and could make it worse.

if the towers are to the sides or rear of the garage i would try shielding with screens or panels.

NoCoolUserName
02-10-2011, 08:57 AM
Have you tried and made sure the receiver isn't broken?The transmitter and receiver function when the door is open if the transmitter is within 8 feet of the open door. There might be a more subtle problem--i.e. transmitter is weak, receiver is intermittent, etc.--but I don't have knowledge of how to test that.

Do your neighbors have similar problems? If not, it's unlikely it's related to your geographic location, if so, it's possible it's caused by localized phenomena but you still haven't pinpointed the root cause, only that there is a localized (or there is likely a localized) root cause.Yes, in fact just last week I was chatting with a neighbor who was grouching that his electric gate opener* was displaying the same behavior--only works from a few feet away.

I'd like to know a little more about what you think the problem is, and why it's causing a problem at all?Reasons for thinking it's the towers:
1) Other neighbors have similar problems, see neighbor with gate.
2) Other electronics also have problems--wireless router has VERY limited range (wired network works fine), wireless mouse is always giving trouble (and wired mouse is not), wireless phones--I had to try about 5 different phones on different frequencies before finding one that didn't pick up radio and/or had general background noise, car remote has limited range when here (like 10 feet) but works fine elsewhere (50-100 ft. range in grocery store parking lot which is miles from the towers).

Reason for thinking it's a change made at the towers: the car remote still works fine when away from our area, but has a more limited range recently than it used to.

Note: we have two garage doors with separate mechanisms, on different frequencies, and both display the same behavior (same remote, different receivers).

Thanks for all youse's input, and hoping for more.

* No we don't live in a posh neighborhood. He's the only one with a fence, much less a gate.