Lehi area garage door opener issues

[kenglish]

KSL has a story about garage door opener RFI in Lehi. Now, I'm hearing comments from Eagle Mountain and Saratoga Springs as well.
Anybody down around Lake Mountain with a spectrum analyzer?
I wonder if it's a harmonic or spur from something up there.

[henry]

Something with Camp Williams or the NSA complex has gone awry, perhaps?

[CAwasinNJ]

For reference, the article is here: www.ksl.com/article/50458455/lehi-neighborhood-wants-to-find-out-whats-interfering-with-garage-door-openers

One big problem is that the article doesn't even mention what frequency range they're talking about, which makes even speculating difficult. However, based on what is does say I would make an educated guess that they're talking about the 433MHz band. There are approximately 1 gazillion unlicensed devices that use that band, like weather stations, car key fobs, car tire pressure sensors, door openers and who knows what else. If Wikipedia is right that's also part of the HAM bands, which opens up a whole world of possibilities. An SDR with a direction-finding antenna should be able to find the source very quickly.

[kenglish]

I read that Genie uses 315/390 band. Several commenters indicated that the problems are pretty widespread, and all started around the same time. 315 would be a third harmonic for the upper part of the FM broadcast band, so I'm wondering if the recent storms might have affected something on Lake Mountain.

Jason says he has arranged for some help from BYU, with a spectrum analyzer and a nice, wide-band directional antenna. I asked him to keep me in the loop.
I meant to ask him if he talked to their radio-astronomy folks, who have a facility near there. Could be, they have a remote analyzer on line.

[kenglish]

I also wonder if the old K43JV is operating now, which would be on channel 16. They've been silent for some time, but now have a CP for some changes...it was modified last week, and expires next month. Maybe there's some sort of beat, or intermod, between that and one of the nearby Provo stations, that just showed up.

[CAwasinNJ]

The only Lake Mountain station with a third harmonic above 300 would be K280GJ/103.9 (311.7).

The K43JV idea is very interesting. It's K16LW-D now. Their latest construction permit modification was granted on Monday, though they might have been doing some work using the old CP for some time. I'm not sure if I'll be able to pick up their broadcasts from my location, but I'm not picking up anything now. It should put a good quality signal up to the Salt Lake area if anyone wants to look.

[kenglish]

I couldn't see a trace of anything on 16 yesterday, but my neighbor got pissy (I had a small antenna sitting on the balcony railing, with it tied down for safety), so I gave up on any more of this "stupid old fool" hobby.
I'll let you guys know if someone finds the Lehi problem. Maybe somebody could do a GoFund Me account, to pay the FCC to come visit 😏 .

[CAwasinNJ]

(The neighbors discussion has been merged into the Old People Suck thread.)

I realize the GoFundMe comment was a joke but for the less techy among us.... I don't think there's much the FCC would be able to do anyway. Garage door openers and similar devices are unlicensed and under Part 15 rules must accept incoming interference. I have a weather station and every once in a while it looses communication with the remote sensor. After a while the signal returns. I'm guessing that the timing of another weather station (and I know there are at least 2 others in the area) will occasionally drift into matching with mine and wipe it out. Over time they drift apart again and all is well. It happens.

[kenglish]

Haven't heard from anyone about whether the problem is solved or not.
No other media (other than aggregators quoting KSL) has picked up on the story.

[kenglish]

They found a signal on 387.45 MHz, coming from the NSA facility. It seems to swamp the receivers on 390.
Now, they are trying to find out how to fix it.
Is NTIA still over government channels?

[CAwasinNJ]

That seems odd. That would mean whatever signal they're putting out would be strong enough to cause an issue 2 1/2 MHz and 10 miles away. Maybe there's a problem with the emissions mask or something, but how much power would they have to be putting out in such a broad pattern southward to be creating that much of a problem? Is it just me or does this raise more questions than it answers?

[kenglish]

I suspect that the NSA signal is strong enough that it just saturates the front-end amplifier of the opener's receiver. The receiver is likely "wide as a garage door" 😋, not expecting such a huge signal close by. I wonder if there is a bandpass filter that could be inserted in line with the antenna, or a trap available for the offending signal. Either way, might be something a homeowner could install himself.