15M QRM 1532Z

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15M broadband interference at 4/20/2015 1532Z. This just popped up out of no where this morning.  Never seen/heard anything like this one.  It's a buzzing noise and covers almost 20Mhz of spectrum.  It's S5 on my meter and my hexbeam is pointed at 35 degs.  When I move it to 180 degs it drops to an S3.  S3 at 325 degs.  I don't think it's local but who knows.  Just throwing it out there to see if anyone else's seen/heard something like this on 15M.  Maybe a wall-wart has just failed?  I live in a very RF quiet residential neighborhood and my noise floor is usually less than -120db all the time.  Any thoughts?

Thanks.

Tom - WQ5O
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Tom - WQ5O

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Posted 3 years ago

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George Molnar, KF2T, Elmer

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See similar signals from time to time. I suspect they are "real' signals, as opposed to noise sources, given their apparent structure. There are a LOT of weird things on the HF bands these days. Probably have been there a while, but we never noticed without our new tools.

I hear it here in Las Vegas, so it's definitely not a bad wall wart at your end.
(Edited)
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Tom - WQ5O

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Yeah, it's gone now.  1722Z.  As a retired comms guy (ex-Coast Guard) we heard all kinds of things like this when I was working the merchies CW back in the 70s and 80s.  I caught the CG transmitting fax in the extra class band of 20M a month or more ago.  I managed to notify them that they seems to be off freq - should have been on a 12Mhz freq vice 14Mhz.  So this signal could have been anyone, pretty much anywhere. Heck of a broadband signal, though.  Maybe it was a spread-spectrum transmission or maybe Singars?  Just a guess.   Having the Flex does make it easier to see what's going on for a large slice of the spectrum.  I would have killed for a receiver like the Flex back when I was working the WX OBS skeds at NMR or NMO.  Would have been easier to pick out guys calling than the old Collins R651s receivers we had then.  They were state of the art at the time but compared to the Flex they were bricks.  We did have some really great antennas, though.  Discones, RLPAs, Rhombics.  Ah, those were the days.
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George Molnar, KF2T, Elmer

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Tom - that brings a huge smile to my face. I was the other end of your circuit back in the late 80's and early 90's. Did a fair bit of merchant marine CW over time. Had fun restoring a bunch of Collins receivers while holed up in Diego Garcia. Racal preselectors. Tubes. Knobs.  Romantic, but wow, I'm glad not to have to use them now.
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Tom - WQ5O

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George - I was no longer on the circuits in the late 80s.  I made warrant and left the fun stuff to the new kids as I did MLE out of the 7th CG District in Miami.  Sitting the circuits was fun though.  Shipboard we used the R-1051s with the large hard to turn knobs.  You surely couldn't just spin from one freq to the next with those things.  They were good receivers and were reliable as heck.  Yeah, I don't miss using them compared to the Flex.  Sat a lot of 500khz and the 8-16 Mhz, what we called the AMVER bands.  Down at NMR we did nothing but CW.  The 651 was our only receiver at most shore side stations.  They didn't go to a better receiver until later in my career.  I had moved up to SATCOM by that time using the WSC-3s, DAMA, etc. That was different to say the least!  LoL!  We even used the old NarrowBand stuff with KG-34 encryption.  It worked about 1/2 the time.  DAMA was better.  It was reliable when you could get access to a Navy Satellite.  You're taking me back, George!  LoL! 
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Walt - KZ1F

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I am guessing that's a legit signal, just not a narrow one, like TV
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Bill W2PKY

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Have seen this on other bands as well. I'm in the Tampa. Fl area and my noise level is low too.
Suspect that radios like ours with Panadapters will discover a lot of interesting signals since we can easily see them. Have no idea what they are but sometimes last for 30 minutes. One episode on 17 meters took out the whole band. Perhaps several radios with directional antennas around the country could triangulate the source of the signal?
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George Molnar, KF2T, Elmer

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Sounds like a job for WAN-connected Flex radios! Think of the DF-ing, DQRM, and general cool things coming once we get that capability...
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Stu Phillips - K6TU, Elmer

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Tom,

If the transmission was continuous, I would suspect that it is an Over The Horizon Radar system - likely from somewhere in Russia or perhaps Iran.

If you record the audio using Audacity and then zoom in, you can measure/see the repetition rate - if its around 50 sweeps per second, then the OTHR theory is strongly supported.

You will also see this interferer on 20m - often around 14.180 - 20 KHz wide.

Its often S6 to 7 here on the West Coast.

These transmissions get reported to the IARU Intruder Watch (of which ARRL is a strong supporter) - sometimes they are able to get the interferer to move out of the dedicated ham bands.

The IARU Intruder Watch report can be found here:

http://www.iarums-r1.org/iarums/latest.pdf

Stu K6TU
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Tom - WQ5O

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Hi Stu ... It didn't sound like OTHR to me but I remember the old Soviet OTHR-B transmissions back in the 80s - the notorious Woodpecker - when I was stationed in Hawaii.  They would literally kill the band on 20 meters.  Today's transmission was just a buzzing noise in USB.  It was 20mhz wide.  Didn't sound like it was sweeping from low to high or vice versa.  Just a steady buzzing sound.  The amplitude did seem to change but that could have been due to propagation or me moving my hex.  Hopefully I won't hear it again (yeah, right). Next time I'll capture the audio and see what I can see. 

Thanks.

Tom
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KY6LA - Howard, Elmer

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Thank you Stu...

I have been seeing that interference a lot on 20M around 14.140 and 14.180.. I thought it was local because it was so strong (-50dBm)  and it came from the direction of the TV Towers.... But now that i think about it --that is also the direction of Russia...
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Stu Phillips - K6TU, Elmer

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Yep, this thing is a frequent varmint on the bands.  You will also see a different culprit...  usually 10 KHz wide and with a transmission a few second long - often you will see a "reply" to this little devil further up the band.

For me these peak towards Asia...  I've seen the transmissions on both 20m and 15 - if you zoom in, you will see multiple FSK sub-carriers - these are burst data transmission of some flavor.

Stu K6TU

PS: Got a good laugh at the irony of you winning the 6300 at Visalia yesterday! ;-)
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KY6LA - Howard, Elmer

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Me too... everyone has been ribbing me about the 6300... just what I need .. another Flex.. Hi Hi..  

The real irony would be winning yet another one at Dayton or Friedrichshafen...

Unless someone makes me an offer I can't refuse, it is currently destined as an alpha test machine and later it will be deployed as a Mult-Machine for NX6T contest station...

Loved your talk on remote stations - Heard several very positive comments about your talk from my friends...
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Stu Phillips - K6TU, Elmer

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Thank you!  Always appreciate feedback - presentations particularly at conferences often feel a little one way...

It was good to see you and a bunch of other Flex'ers at the IDXC

Stu K6TU
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Tom - WQ5O

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20 Mhz ... not 20 mhz ... 20 khz.  Jeeze ... I'm getting old. I just can't read my display worth a hoot anymore.  If it was 20mhz it would have been a little more noticeable I guess, huh?  Doh!
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Stu Phillips - K6TU, Elmer

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mHz is milli-hertz - thousandths of a hertz!  If it had been 20 mHz, I don't think you would have noticed it! LOL!

G - giga
M - mega
K - Kilo
m - milli
u - micro
n - nano
p - pico

:-)

Stu K6TU
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Al K0VM, Elmer

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That is likely a high rate digital data transmission that is/has been developing/deployed for military use..  Hard to tell if its them or us that intruded.  Likely to hear more of it on HF in the years to come.

AL, K0VM
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That is a Wideband HF signal that Collins and Harris have been working. They are sending full motion video on HF, really cool stuff. Their license allows them into the corners of several of the Ham Bands.
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Joe, KQ1Q

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See the wide range of RFI types at my location. It fluctuates greatly in type and intensity, goes far outside the ham bands, and is more common on weekend afternoons. It is not isolated to just one ham band but happens notably on 80, 40, 20, and 10. 

It's definitely not coming from my house as it happens when running the Flex on a battery and using a directly-connected laptop, with the AC mains to the house turned off. I have an MFJ-856 which is designed for power line noise. It doesn't find anything. I am working with our local ARES group to track it down:
http://joema.smugmug.com/Hobbies/Ham-Radio2/RFI-163-Heathersett-Drive/48523970_ZBr6HG
(Edited)
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Stu Phillips - K6TU, Elmer

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Joe,

Looking at the pan adaptor captures, I would guess that this is a Variable Speed Motor controller - these are increasingly used on pool pumps, well pumps as well as washing machines, dryers...

Hard to tell for sure from Google Earth but looks like the AC power distribution near your house is underground?  If so, tracking this to a home may be tricky - its most likely getting radiated from a transformer cabinet.

These VSC can create RFI havoc if not correctly installed and filtered - I had one that killed 160 and 80 near me... took several months to find and get fixed.

Full details are here:

http://1vc.typepad.com/ethergeist/2010/02/rfi-hunters.html

The best way to track this down is with a portable receiver and a DF antenna - National RF makes an excellent unit that I use regularly for tracking down noise sources - both my own and other hams who have issues.  Its not inexpensive but you can also make your own loop if you don't mind some home brew effort.

http://www.nationalrf.com/type_hfdf_vector.htm

Good luck in the hunt!  Its endless...  after 3 years of relative peace RFI wise, I'm currently waiting on my utility power company to fix two different power poles and am about to report another issue to the cable company.


Stu K6TU
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Stan - VA7NF

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I agree that the National RF DF loop is excellent, use it frequently.

For general looking use it with a Grundig Satellit 750 portable radio (it has a BNC SW connector) and for accurate readings I carry my 6700 in a shoulder rack case with lithium battery and notebook.

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Joe, KQ1Q

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Stu, thanks very much for the detailed reply, and thanks for taking the time to document your RFI hunt on your blog.  Yes utilities are underground in my subdivision. Similar to your case, on 80m the RFI bands are composed of "sub carriers" 60Hz apart.

I have already ordered the National RF HF DF kit.  BTW for some reason your blog didn't have a link from part VI to part VII. I found it via Google, which is: http://1vc.typepad.com/ethergeist/2010/04/rf-hunters-vii-we-close-in.html

This has been a problem in my area for a long time. It was only recently when I got a Flex 6300 that it gave sufficient detail to characterize the RFI. It's amazing the amount of data an SDR shows, esp. the direct RF sampling type.  When resolved I'll post the conclusion. It could take a while.

Joe, KQ1Q
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Stu Phillips - K6TU, Elmer

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Joe,

Hope you found it useful!  Yes, the articles aren't linked together - they are just in chronological order on my blog as they were written.

I think you will be able to DF the signal to either its source or to the transformer cabinet feeding the area/house from which the signal is radiated.  If each home has a utility access cover, you may be able to isolate to the house...  use a coil on the end of a coax lead and check over the cover associated with each house.  DO NOT REMOVE THE COVER plate to do this...  you shouldn't need to as even if the cover is metal, the box underneath is likely concrete and no where close to noise proof.

Getting the interference fixed could be difficult depending on the owner of the property - you may have to file a complaint with the FCC in order to get action.

Good luck!
Stu K6TU
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Javier, KC2QII

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It looks to me like a DRM signal.  The commercial DRM broadcasts are 20 KHz wide.

Javier, KC2QII
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Tom - WQ5O

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Something new this afternoon.  It's about 500khz wide; 17.640 to 18.100 or so.  The 17.854Mhz transmission is Radio Havana.  It's on the side of my hex with a steady 30 over S9 signal.  It's amazing what I see almost daily working from home and keeping the flex operating.  I don't know when this one started but I'd not be surprised if it was associated with Radio Havana.  Interesting. 
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Tom - WQ5O

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RH went off the air and the interference went the same way as soon as their carrier dropped.
(Edited)
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Walt - KZ1F

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My first thought was it was TV, some of the new digital modes or perhaps even slow scan.
On a related note, I've noticed a lot of very loud AM signals in the low end of 10m. What was that business phone that would chip when you unkeyed the mic? The other day I switched to AM on like 28.004 and it was some guy talking about getting pissed with his trucking company and quit and left the 18 wheeler under an overpass and walked away.

There seems to be way more non-ham signals in our space than there used to be.
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Bill W2PKY

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I hear a lot of AM from the islands on the low end of 10 meters here in Fl.
It's the same operators all the time. Read there are transceivers made that can operate up into our 10 meter band. Guess they are looking for a clear spot. I also see signals between the CB band and 10 meters. Blame the radio manufactures from the Pacific Rim that make the radios.
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Larry - W8LLL

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This was sweeping through the 20 meter band last night, once in a while it would straighten out but mainly sweeping through on an angle like in the image.

 

 

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John

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I have noticed a lot of military stations making noises on HF bands and they usually return to 60m band, where they cam be seem operating
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Larry , W8LO

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Tom -  I too have the same interference, only mine is located at 21.240 -21.270.  It is on 24/7/365, and has been for many months.  Stronger sigs coming from due North, around S5.  Pattern on Waterfall has edges very ragged, as compared to yours which look smooth.  Wouldn't think it would be arching with such a narrow signal.  Take off antenna, it goes away.