Wideband RFI that skips ham bands?

[brandon]

Today I am noticing a wideband RFI source that appears to skip the amateur radio bands. Whatever this is, it appears to affect the upper freq ranges the most. Seems too odd for this to be a coincidence, and suspect its something man-made that intentionally notches out the ham bands.

Here are a couple screenshots.

Avoids 20 meter band.

Avoids 17 and 15 meter bands.

Has anyone ever seen this? And more importantly have any idea what it could be?

*fingers crossed* this goes away.

 

[SCPD]

Very likely powerline networking. To satisfy ARRL legal threats they filtered out ham bands.

 

[n4yek]

Is the radio you are using with this software an actual ham radio rig?
If so, then it is possible that for the 'ham bands' there is a lot more filtering than on the bands outside of amateur allocations.

 

[majoco]

If the filtering was to allow the ham bands to be received, then the noise would be in the ham bands and filtered out on other frequencies - the very opposite of what Brandon is displaying.

Look like a G33DDC SDR receiver anyway, not a ham bands only - many of which have broadband receivers anyway.

 

[prcguy]

Where are you located? Do you have a directional antenna available to point at or away from power lines etc to see if it might be BPL? In my case I have an NTIA licensed HF marine shore station and other govt stuff at my home, so I would do some research to drop a bomb on a BPL provider causing that much interference.
prcguy

Today I am noticing a wideband RFI source that appears to skip the amateur radio bands. Whatever this is, it appears to affect the upper freq ranges the most. Seems too odd for this to be a coincidence, and suspect its something man-made that intentionally notches out the ham bands.

Here are a couple screenshots.

Avoids 20 meter band.

Avoids 17 and 15 meter bands.

Has anyone ever seen this? And more importantly have any idea what it could be?

*fingers crossed* this goes away.

 

[SCPD]

If the filtering was to allow the ham bands to be received, then the noise would be in the ham bands and filtered out on other frequencies - the very opposite of what Brandon is displaying. Look like a G33DDC SDR receiver anyway, not a ham bands only - many of which have broadband receivers anyway.

What??? The noise is broadband across HF. They use notch filters to filter out the noise of the ham bands.

You can read about it here:

Broadband Over Powerline (BPL)

This has sometimes been done successfully within the BPL industry. Some access BPL providers have installed systems that applied spectral masks (notching) on all HF and VHF amateur bands. This was a successful model (before the utilities involved shut down the BPL systems for other financial and technical reasons). ARRL staff has evaluated several of these notched access BPL systems and has determined that state-of-the-art spectral notching for the amateur bands provides a good general solution that prevents most interference problems.

Industry groups, such as HomePlug and the HomeGrid Forum have implemented industry specifications that also have spectral notches for the amateur bands. This is a successful model, because with millions of in-premise modems deployed, ARRL has not received reports of harmful interference involving HomePlug or HomeGrid Forum products. These groups realize that for BPL to achieve its potential, its proponents and regulators must proactively address interference problems through good rules and industry standards and practices.

Brandon has the G31.

 

[n4yek]

What??? The noise is broadband across HF. They use notch filters to filter out the noise of the ham bands.

You can read about it here:.....

His response was to my statement, not the OP's statement and since I had a 'brain fart', he is correct.

 

[SCPD]

His response was to my statement, not the OP's statement and since I had a 'brain fart', he is correct.

Ah okay that makes more sense but it helps to stay focused on the specific topic guys.

 

[brandon]

WinRadio Excalibur G31DDC is what I am using.

@prcguy I am located in Riverside County, California. I am not aware of any BPL here all of our Internet is Verizon FiOS, which has been very quiet for me. All underground utilities in this area.

I asked my neighbors but they did not install anything. However did have some new folks move in up the street. Am starting to suspect it may be coming from them. Probably be a little weird for me to go over there and tell them their home networking is messing up my radio reception as their first welcome to the neighborhood lol, but it may come down to it eventually.

So far the noise blanker works pretty good, when there isn't much data being transmitted, although the crap still shows up visually. But when the powerline network is in full Netflix or porn mode, the noiseblanker stands no chance. Guess I'm going to connect up the Timewave ANC-4 noise canceller and see how it works. I've had very good luck with that unit in the past on other RFI sources.

Here is another wideband view of it. It starts to become a problem around 12 MHz up through 25 MHz or so. Easy to spot the amateur radio bands

Zoomed in view. Also notice how it briefly stops.

Recording of how it sounds in AM and SSB mode.

Heavy usage? - Audio Clip
Light or Idle usage? - Audio Clip (noise blanker can kill this)

 

[prcguy]

It sure follows the pattern of BPL, what else would block out just the ham bands? You might check into a provider called Suddenlink who might be a BPL provider and they show as active in Riverside, CA.
prcguy

 

[K5MPH]

I thought they were only using BPL out in the country areas of the usa........

 

[n4yek]

Ah okay that makes more sense but it helps to stay focused on the specific topic guys.

We were...

 

[ab3a]

Has anyone ever seen this? And more importantly have any idea what it could be? *fingers crossed* this goes away.

Like everyone else, I'm nearly certain that this is Broadband over Power Line, known as BPL.

BPL is sometimes used by lazy homeowners who don't want to set up wifi or snake some CAT5 cable through the house. It is also suggested as a possible media for smart grid use. I haven't heard of many using it, but there are always a few test cases...

In any case, if you're in the near field of this signal, you could try an electrostatically shielded loop antenna to see if that reduces the noise. If you're outside the near field, then perhaps a directional noise cancellation antenna would be appropriate.

This is what happens when lawyers and lobbyists run amok, while engineers are relegated to the broom closets of the FCC. I wish I could say this is a unique "never could have seen this coming" sort of event, but it isn't.

 

[nanZor]

In any case, if you're in the near field of this signal, you could try an electrostatically shielded loop antenna to see if that reduces the noise. If you're outside the near field, then perhaps a directional noise cancellation antenna would be appropriate.

I have been battling this very same thing for years with neighbors on both sides of me running BPL. Basically killed all SWL from about 5 mhz and upwards, with only the amateur bands steeply notched out. In some cases, it seems like heavily attenuated rather than a steep notch at the amateur band edges.

The problem is that since the noise is basically radiated all along power lines, there is no point-source for which even a small directional loop does any good. Nor does a phase-canceller for the most part, like the MFJ units.

Real bummer. At least they fought for these notches! Still, I can't believe they exist especially when all that noise gets fully radiated on aeronautical frequencies. Just amazingly dumb, but I guess money talks and common-sense and safety take a back seat.

 

[dsalomon]

I agree with all, it is obviously BPL with notched out amateur frequencies. Re: the suggested loop, I've used small magnetic amplified loops to help with exactly this type of situation. In a previous QTH, I was in an area that had BPL with amateur notched out. Using a Pixel PRO 1A loop (the predecessor to the current version, the 1B PRO, I think), I was able to rotate it using the "armstrong" rotator to avoid the interference. These types of amplified magnetic loops, like the Pixel 1B PRO and the Wellbrook antennas have a very rounded reception pattern, with a very deep, sharp null so you can rotate the antenna the practically eliminate a signal entirely. A couple of things have to be working in your favor for this to be a solution. Namely, the BPL must be coming from a single direction/area. If you're surrounded by it, your toast and nothing will help other than noise blankers and/or noise filters, as noted previously. Plus, these antennas are expensive ($500 range last I looked). However, I can attest to the fact that they work extremely well. I've used both the Pixel and Wellbrook brand magnetic loop amplified antennas in the past. They receive great, often outperforming all but the best directional yagi antennas, can be mounted low to the ground. Higher is better, but not by a margin that's worth the effort to get it mounted higher if it would take a lot of effort/cost. And, as I previously noted, they have a pattern with that great null that's very useful for getting rid of interference. My last one was mounted on a 10 foot pole that was just strapped to a fence post. I didn't even have a rotator on it. If/when I really needed to deal with an issue, I'd just run outside and rotate the mast the antenna was mounted on. I just recently sold my Pixel PRO 1A, and I'm now sorry I did. I have a horizontal loop around my entire property (roughly 800 feet of wire, mounted mostly at about 70 feet), which hears better than the Pixel did. However, it hears EVERYTHING better, including all the man made noise. So, the moral of the story...if you can get your hands on one of these amplified magnetic loop antennas for cheap, or borrow one to try it out, it might help resolve your issue.

 

[wb6uqa]

wide band noise

Powerful wideband routers can make interference .

 

[wb6uqa]

noise ID

The ARRL has a full time noise guy. Let him hear it and he will ID it.

 

[KQ6XA]

It appears to be a common Power Line Modem. The spectrum signature shown is typical of the HomePlug Alliance specifications for suppressing emissions in the amateur radio HF bands. Unfortunately, the HomePlug spectrum mask specs were developed prior to USA's 5 MHz (60 meter band) becoming well known. So, there isn't a gap in the HomePlug spectrum mask for 5 MHz.

 

[kc4jgc]

Still, I can't believe they exist especially when all that noise gets fully radiated on aeronautical frequencies. Just amazingly dumb, but I guess money talks and common-sense and safety take a back seat.

If you're talking about HF aero, I'm surprised as well, although HF is normally used for intercontinental flights. (someone correct me if I'm wrong) I'm almost certain though on the VHF aero spectrum is notched out. I seem to recall reading this in QST a few years back.

In the Manassas VA, the local city owned power company gave up on BPL when local radio amateurs kept hounding them with so many complaints to the FCC the city decided the notching was costing to much money and data speeds were negatively affected.

 

[KQ6XA]

It is likely that this is a power line modem in a nearby building. It is unlikely to be a BPL system.