5G Interference

Scanners, antennas, coax, filters, amplifiers, demodulators...you get the idea. Scanning equipment questions, answers, and discussion belongs here!
Post Reply
User avatar
W1KNE
Owner-Webmaster
Posts: 5350
Joined: 19 Aug 2005 12:00
Location: Taunton, MA
Contact:

5G Interference

Post by W1KNE »

So as many of you know, I work for a local broadcast station, and get to spend some occasional time up at our Cedar Street tower in Needham. For years, it's always been a great spot to monitor and log UHF catches in and around the Boston/Metro West area. This past spring, I noticed that almost all my good UHF reception had tanked. I went to a semi local channel (Medford Police) and what was normally strong and clear, was noisy!
What I noticed then was the signal meter was 5 bars full strength, despite the noisy signal. So on a whim, I went to a random frequency in the 470 MHz range, and opened the squelch. Same thing, the signal meters are pegged. To see how wide spread this is, it wasn't until I got down to the 450 range that I noticed it dropped out. Figuring it to be a scanner issue, I brought up my SDS100 with me. Same exact thing!
Started to wonder and then it dawned on me. Around May 1st, TMobile fired up their brand new 5G fill in cell site up there. Only 130 feet off the ground. (And now joined with AT&T). When I am down in the Needham-Newton commercial district (Near the old Exit 19/Highland Ave), it's not pegged bad but it's still very strong. It isn't until I am several miles away from there that it goes away. Before it is asked, it's not the UHF TV stations there, we all went full power up there in June of 2020, and there haven't been any further changes. This all failed in the spring, around the time mentioned above.

Has anyone else seen this or experienced it yet? TMobile's running very wide band 600 MHz, at quite a bit of power. Maybe I need a low pass filter that cuts off from 550MHz up.
Mike Fitzpatrick
Broadcast Engineer - RF Enthusiast - Municipal Fire Alarm Collector
Owner: Scan New England - NECRAT.US
Issues with Scan New England can be privately addressed to me.

jack103x
Posts: 161
Joined: 29 Aug 2005 18:24
Location: Tewksbury MA

Re: 5G Interference

Post by jack103x »

Have you tried using an older style scanner with the same results , like a Pro 2006 or a AOR 3000A with the same results?

MrSvenSven
Forums and Wiki Moderator
Posts: 786
Joined: 24 May 2007 10:27
Location: Rt 225 @ 495

Re: 5G Interference

Post by MrSvenSven »

Scanners certainly don't have a good front end for rejecting strong signals (which is unavoidable given that their goal is to receive DC to daylight). I drive around with both a real 800MHz radio and a Uniden BCD996P2 scanner. I find that when I am within 1000 feet or so of a cell site, the scanner gets noisy or completely stops receiving the 800MHz trunk system, while the radio has little to no problem ar all.

Now that T-Mobile is expanding down to 600MHz, I'm not surprised that it would be causing problems into the UHF band.

You're right that the TV stations probably aren't a problem. TV stations have their antennas pointed at the horizon for maximum range.The cell stuff uses downtilted antennas pointed at the ground, and they intentionally want to limit their range.
57446

User avatar
W1KNE
Owner-Webmaster
Posts: 5350
Joined: 19 Aug 2005 12:00
Location: Taunton, MA
Contact:

Re: 5G Interference

Post by W1KNE »

MrSvenSven wrote:
06 Oct 2021 19:14
Scanners certainly don't have a good front end for rejecting strong signals (which is unavoidable given that their goal is to receive DC to daylight). I drive around with both a real 800MHz radio and a Uniden BCD996P2 scanner. I find that when I am within 1000 feet or so of a cell site, the scanner gets noisy or completely stops receiving the 800MHz trunk system, while the radio has little to no problem ar all.

Now that T-Mobile is expanding down to 600MHz, I'm not surprised that it would be causing problems into the UHF band.

You're right that the TV stations probably aren't a problem. TV stations have their antennas pointed at the horizon for maximum range.The cell stuff uses downtilted antennas pointed at the ground, and they intentionally want to limit their range.
Our antenna is equivalent to 14 bays at 1,300 feet above ground. The elevation pattern does have a null fill and electrical beam tilt (0.75), so it's somewhat pointed to the horizon, but at my location the amount of RF coming off of it is pretty low. The side mounted UHF for WNEU is actually putting more down, but still quite a ways off. There's more RF where I am coming from the two way radio antennas and these new crappy 5G transmitters. There's more RF from the FM antenna over on the American Tower in Newton where 94.5 and 98.5 are than anything. That antenna just blankets the area with FM because of how low gain it is.

What I really need to do is take a spectrum analyzer and look at it on that, to determine just how much SNR there is. (and so I know what size filter to get)
Mike Fitzpatrick
Broadcast Engineer - RF Enthusiast - Municipal Fire Alarm Collector
Owner: Scan New England - NECRAT.US
Issues with Scan New England can be privately addressed to me.

jbella
Posts: 330
Joined: 12 Oct 2005 11:24
Location: Gardner

Re: 5G Interference

Post by jbella »

If you're vaccinated, obviously that's part of the problem. You're actually repeating and boosting the signal as a carrier. :t

ChrisP
Posts: 83
Joined: 19 Aug 2011 19:47
Location: Poland, ME

Re: 5G Interference

Post by ChrisP »

That's a really interesting theory. My UHF reception really seemed to go over a cliff about a year and a half ago on both of my base scanners, with no perceived deterioration on VHF. I've been trying everything I can think of with my antenna/coax/splitter/notch filter/amplifier system, and nothing really seemed to help all that much. I'm probably over a mile to the nearest cell site, but like everywhere else, they've been busy building out 5G up here.

I'm not saying 5G is definitely my problem, but it's something I hadn't considered, and your post is making me think...
Chris
Poland, ME

Post Reply