RFI- Anyone recognize this?

[k4kyv]

Hello All!

     Sounds to me like one of the neighbors is growing pot to me.

Then you would be lucky.  He would most likely be co-operative and willing to correct the problem as quickly and with as little hassle as possible.

[W8IXY]

The only real CURE is for every ham operator to start filing complaints with the FCC every time & every day there is RFI heard on the station's receivers.

Craig,

Well, that would be nice if the FCC actually acted on the complaints.  I brought up the problem of interference from power lines, part 15 devices, etc., to Bill Cross at the FCC forum at Dayton earlier this year.  Bill deferred to one of the FCC field engineers from Chicago to answer that question.  Oddly enough he was sitting right next to me.  His answer was basically that the FCC doesn't have the facilities or manpower to investigate most complaints directly.  I asked why the FCC hasn't appeared to be vigilant about enforcing interference limits on Part 15 devices before as well as after manufacture.  Same answer, not enough manpower. 

As we watch the circus of Congress proceed through its everyday squabbling, I doubt the FCC will ever be empowered to have any "clout" again, except for the most egregious offenses.

The FCC will spend a lot on resources to shut down some bootleg broadcaster which may interfere with a couple of dozen (or less) licensed stations in a geographical area as small as several hundred square yards, but will allow manufacture of substandard equipment which affects millions of people in thousands of locations. 

73
Ted  W8IXY

[WD8KDG]

The only real CURE is for every ham operator to start filing complaints with the FCC every time & every day there is RFI heard on the station's receivers.

Craig,

Well, that would be nice if the FCC actually acted on the complaints.  I brought up the problem of interference from power lines, part 15 devices, etc., to Bill Cross at the FCC forum at Dayton earlier this year.  Bill deferred to one of the FCC field engineers from Chicago to answer that question.  Oddly enough he was sitting right next to me.  His answer was basically that the FCC doesn't have the facilities or manpower to investigate most complaints directly.  I asked why the FCC hasn't appeared to be vigilant about enforcing interference limits on Part 15 devices before as well as after manufacture.  Same answer, not enough manpower. 

As we watch the circus of Congress proceed through its everyday squabbling, I doubt the FCC will ever be empowered to have any "clout" again, except for the most egregious offenses.

The FCC will spend a lot on resources to shut down some bootleg broadcaster which may interfere with a couple of dozen (or less) licensed stations in a geographical area as small as several hundred square yards, but will allow manufacture of substandard equipment which affects millions of people in thousands of locations. 

73
Ted  W8IXY

As long as amateur radio ops only p&m on the internet and never file complaints with the FCC; then Part 15 is working as intended......there is no interference.

Craig

[Jim/WA2MER]

Although this doesn't sound exactly like your interference, here's what plagued me for months until I found the time to chase it.  Open the attached file to see the waveform and hear the noise.  It turned out to be the built-in battery charger of one of those Scooter motorized wheelchairs at my next door neighbor's house.

The noise was coming in on the power line.  I used a portable AM radio to poke around the house before venturing outside.  I cut the main breaker to the house and there was no change in the noise level or characteristics.  There were hot spots all around the inside the house near electrical outlets and along wire routes inside the walls.  The biggest hot spot was near the breaker panel.  I figured that since the noise was present in the house with the breaker off that the noise was coming in on the neutral, confirming that the power line was acting as an antenna for whatever the source was.

I walked the street and saw that the noise pretty much followed the power line, with a very slight amplitude peak coming from my neighbor's house.  A quick walk through the house with the radio found the culprit.

I hope this is somewhat helpful.  Good luck with your hunt.

73,
Jim
W2BVM

[Carl WA1KPD]

Found-

It is from the Arris WBM760A modem Comcast sent me as an upgrade several months ago. It is located in the shack but I hear it in receivers all over the house. Google product and I get hits all about it. Time to deal with Comcast.

I unplug it and the lower bands drop down to the normal nise I have had here for 17 years.

I appreciate all the help

Carl

[flintstone mop]

Congrats on that one. Cable modem geesh...They'll make it good. I wonder how far it was radiating into the neighborhood?

[Carl WA1KPD]

I have to say Comcast was a pleasure to deal with. The woman I dealt with was a real pleasure, knew her stuff and is sending me a different make/model modem. Said there was no need for me to have that one since I do not have telephone with them.

This was an "upgrade" they provided this summer and I just have not been on that much to really notice it.

[Steve - K4HX]

Would it be useful for us to catalog these "noisemakers?" We could have a sticky thread or even a forum section just for people to post known RFI generators. The make and model would be listed along with RFI info like freq ranges, type of noise (pulsed, steady, warbling, etc) and of course, recordings and spectrum shots.

Or is there something like this already on the Web?

What say?

[Carl WA1KPD]

Steve
I think that is a great idea
Carl

[W0BTU]

Would it be useful for us to catalog these "noisemakers?" We could have a sticky thread or even a forum section just for people to post known RFI generators. ...

Good idea, Steve.

There was thread about plasma TVs on either eHam or QRZ some time ago, that listed some that were quiet, and other that were notorious, incorrigible RFI generators. If you decide to start such a thread, let me know and I'll see if I can find it.

[KA2DZT]

Doesn't sound like power line noise,  more like something running, could be almost anything.  Check your QTH by using a portable receiver outside and then shut off everything including all your electronics in the shack.  This is what you should start with.

Fred

Not unusual for a noise like you had to be coming from something nearby, especially with all the junk electronics, light bulbs, chargers, etc. that we all use or have to use.

Fred

[Steve - K4HX]

I'm looking around to see if any such listing or catalog already exists. The ARRL has a good section on RFI on their website.

http://www.arrl.org/radio-frequency-interference-rfi


One part of the RFI info includes recording which may be of use in tracking down or determining the cause of interference.


http://www.arrl.org/sounds-of-rfi

[W1AEX]

Would it be useful for us to catalog these "noisemakers?"

Steve,

I think it would be very useful. There is information all over the web, but much of it is not terribly useful and to be honest, there's a lot of misinformation and monkey-see-monkey-do myths everywhere. It would be great to have a section where users here could list problematic appliances and hardware they have encountered and effective resolutions for issues they have run into. I will always be grateful for one post in this forum several years ago that mentioned RFI from Philips DVD players. I had put up with that weak but incessant mosquito-like whine on 75 meters for 2 years and had no clue it was my own DVD player causing it!

There is a lot of expertise floating around in this forum that might help others to mitigate the onslaught of noise that is growing daily. We are all at the mercy of what our neighbors pick up off the shelves at Walmart and plug into the grid.

Rob

[KM1H]

The voice and data modem here from Comcast is a RCA (by Thomson) Model DHG536C.  With just the lines wrapped around FT-240-77 or -31 toroids its quiet in an old Zenith tube radio 5' away from BCB-18MHz using a 20' hunk of hookup wire on the floor.

Carl

[ke7trp]

Glad you found the problem.  Every once in a while, I have an RFI "HUNT".  I use a SW radio tuned to 6.5 to 7mhz. 

You will find that most modern consumer gear blasts out RFI.  The latest culpret here was a Neighbors Cell phone charger.  It took out the 40 meter band.

C

[WA1GFZ]

It would be interesting to know what caused the noise. My guess rectificers.

[KD6VXI]

Gotta love those switching power supplies.


--Shane
KD6VXI

[Carl WA1KPD]

I have to say Comcast was a pleasure to deal with. The woman I dealt with was a real pleasure, knew her stuff and is sending me a different make/model modem. Said there was no need for me to have that one since I do not have telephone with them.

This was an "upgrade" they provided this summer and I just have not been on that much to really notice it.

They may have been a pleasure but they screwed up. The "new" modem arrived today. Exact same model, exact same noise. After all the discussion about sending me a different make and model

The good news is I have been cleaning the shack today and I found the old modem. I thought i had lost it and they had billed me for it. I swapped that out, noise is gone and my speed test produces better results. Interesting the new modem was supposed to be part of a speed increase and at the time did show better speeds. Go figure. Maybe the modem just needed a rest  

So I'm returning both of the Arris WBM760A modems using the older and now faster one and having the rental charge removed.

It all worked out

[W1AEX]

Hi Carl,

There are so many layers of bureaucracy in cable companies that simple things like a cable modem swap can be bungled easily.

The Arris WBM760A is a Docsis 3.0 modem that supports multiple channel bonding on the downstream and the upstream. My guess would be that the old modem is probably a Docsis 2.0 modem that utilizes a single channel for downstream and another single channel for upstream. You really should stay on them to get the alternate Docsis 3.0 modem sent to you. You will typically have much more downstream bandwidth, less packet loss, and lower pings with the Docsis 3.0 modem assuming the cable company's infrastructure has been upgraded to take advantage of it. Most cable companies are preparing to also deploy multiple upstream channel bonding to allow greater uploading performance within the next 2 - 3 years. I have Cox Cable at my location and have a Motorola SB6120 (Docsis 3.0) sitting 3 feet from the operating position that is RF silent and it doesn't flinch when I run full legal limit on any band.

Rob W1AEX

[Carl WA1KPD]

Rob
I respect your opinion and will do so. But why do the speed tests on line show much faster downloads?

[W1AEX]

Rob
I respect your opinion and will do so. But why do the speed tests on line show much faster downloads?

It's possible that the power level and SNR of one or more bonded channels might be off a bit. They refer to this as "tilt" but all it means is that the lower frequencies typically have more gain than the upper frequencies. There could be other factors involved as well. If you can access the diagnostics page of the modem you can see what's going on and bring it to their attention. They should be able to view your modem diagnostics page remotely and send someone out if it needs attention. Once it's set up correctly a Docsis 3.0 connection is far more robust than the older standard.

The picture below shows the frequency, signal to noise, and power level of each bonded downstream channel on my connection. The SNR and power level should not vary by a value greater than 2 between any of the channels. They have been out here all week getting it right and have pretty much nailed it.