I've tried turning off all power to the house and UPS devices. The noise continues.
It is 24/7 so not likely a neighbor's plasma TV
I went portable and operated 3 miles away and the noise was gone
I've used two different antennas in two locations and the noise stays the same.
I've used an RTL dongle on the laptop (with 125Mhz up converter) with same antennas but don't see the noise (I can't explain this one at all). SSB signals come in fine.
I'm thinking about making a Yagi and going out to do some direction finding if there's nothing else obvious. My guess is a power line somewhere. Has anyone else come across this before on a Flex?
A quick test to see whether its power line noise is...
1. Put the slice in AM mode - filter width is not important - this gives an envelope detector
2. Record the noise using Audacity or similar audio tool - Audacity is free, works on Mac & PC
3. Zoom in using the spectrum tool until you are down in the millisecond range
If the noise is power line generated, your will see 8.33 mS between noise spikes - 8.33 mS is 1/120th of a second... power line noise is caused by arcing and there are two voltage peaks per cycle at 60 Hz - so the arc is generated on both positive and negative going AC peaks - hence the 120 Hz rate.
If you use the latest version of SpectrumLab, it has a digital oscilloscope mode that allows you to capture the patter on the arcing... a specific source of power line noise will have a pretty repetitive pattern so it helps as you go hunting to figure out whether you have found the right pole or not.
Whether power line noise or not, DF it at HF and see where it is strongest. If it is power line noise, as you get closer, go UP in frequency. When you find the right pole you will hear the arcing at least to 150 MHz, sometimes even higher. If the pole isn't "hot" on VHF, its NOT the right pole. Keep looking and remember that the noise will set up a standing wave on the power lines which will have its own peaks and nulls.
If you get to a pole and find that all directivity of the noise has disappeared, this is also a clue that its NOT the right pole. Keep walking.
I can't really tell from the video what you are dealing with - between the frame rate of the spectrum display and the frame rate of the video capture/playback, its too jumpy.
Last but not least... its fun to speculate about the likely source, but you will only know when you find it! :-)
Once you have found it, then you need to get it fixed... depending on what it is, I have additional experience in resolving a number of these situations for myself and others - so happy to help as I can.
Another thing to watch is an electronic filter on your furnace. Mine had to be disconnected as it was adding a couple of S units to the noise floor
If you can hear this on the broadcast AM band - I'll bet you can - you might be able to walk around the neighborhood and locate the general area of the noise.
If you believe that it is a power line noise, call your local power company, tell them that you are an amateur radio operator and that you believe that they're causing noise across a wide swath of the Hf Bands. Ask that they send out an RFI investigator.
If it is outside your house, it could be a number of things:
- Failed lightning arrestor on the power line (Large SCR)
- Bad GFCI breaker.
- Someone's electric fence charger
- Invisible fence
- Ballast for halogen or flourescent lignts - anyone growing anything inside?
Locate your local ARRL Technical Specialist for interference help.
ARRL Technical Specialist
I'm headed out to find some stuff to make a inexpensive yagi. Lots of wooded area and hills around here so I think I'm going to try some DF.
And yes it can be heard on AM radio.
When you find the pole on VHF, capture the audio again and compare it with the capture above. If they are reasonable matches, you have the right pole.
Hopefully your power company is more responsive than Pacific Gas & Electric here in NorCal. The only proven way to deal with PG&E is a direct letter to the CEO. Their own internal process is to ignore all RTVI complaints and hope the ham will go away or go SK with old age.
Good luck and let us know what you find!
There are two power lines running along the common ground right next to our house. One is high voltage and goes directly to a coal plant. The other is a residential line that feeds underground wiring to the houses in the neighborhood. The are parallel and about 20 yards apart.
I have an Eton shortwave receiver I picked up years ago. On 1400 AM I walked around the immediate vicinity and the worst noise was actually right at the outside of my house. The noise was quieter when I walked towards and under the power lines. The radio has a whip antenna and a "DX/Local switch" which I assume is an attenuator. That helped localize the noise a little.
The receiver also has an antenna jack. I finally completed a "tape measure yagi" and tried wiring that in. But since it's more for 2M, I didn't really get much from that. (But hey, there's a Fox Hunt next weekend and I've been meaning to complete that project).
I only have a FM (only) transceiver for 2M, I'm assuming that really won't help, even with a directional antenna.
It's suppose to rain later, which may give me another clue.
Other than that, I'm not really sure what to try next. Maybe wait until it gets dark and maybe I can find some arcing on one of the nearby poles ?
I had an odd intermittent noise that bugged me for a while. Turns out there was a loose connection on the outside circuit breaker box. Why in Las Vegas they'd put them outside, on the south-facing wall, is beyond me. Talk about thermal stress. After cutting the mains completely, tightening up the connections and checking for corrosion cleaned up that particular noise.
"I've used an RTL dongle on the laptop (with 125Mhz up converter) with same antennas but don't see the noise "
So if you don't hear it on your dongle then why bother to look elsewhere? Obviously something is wrong with your Flex or the power supply you're using.
Take your Flex somewhere else, a friend's QTH or someplace away from your house and try it.
Do you HEAR the noise?
I will note that with the noise blanker on (on the Flex), I can hear strong signals fairly clear, so kudos there.
That noise doesn't look like power line noise at all. Power line noise has a definite peak at 120 Hz, plus even harmonics.
Again, this looks unique to the immediate environment.
Good luck! I know how annoying it is to track interference!
As already stated, it's a good idea to run the Flex off a battery and laptop and pull the main breaker to your house. Also shut down all UPS units.
In my case I'm waiting to receive this HF Direction Finder: http://www.nationalrf.com/noise_location.htm
See also Stu's excellent blog on RFI hunting:
Parts I through VII: http://1vc.typepad.com/ethergeist/2010/02/rfi-hunters.html
Parts VII and VIII: http://1vc.typepad.com/ethergeist/2010/04/rf-hunters-vii-we-close-in.html
I've appreciated everyone's help, you all have given great suggestions. I'll keep this thread bookmarked for when the noise inevitably starts back up again ...
Part of solving these cases is tracking their behavior over time. IOW what time of day, what day of week, does wet weather affect it, does hot vs cold weather affect it, etc.
Kevin, your panadapter display is very interesting as most noise investigations are with a baseline + noise that follows a frequency based pattern. Yours is reversed with a S5 "steady state" with both frequency and time based removal of noise. I have trouble keeping my mind reminded that I am looking at a frequency based not a scope time based display.
This strikes me as something similar to a bad coax connection where something like power line induced voltage is being rectified/mixed with other signals then intermittently grounded (the ground connection may also be involved). The case I recall gave me BC band images (base + noise/images) but if the main source in this case is a 60Hz strong signal induced and rectified from the HV power lines then the mixing products may produce a high flat-line base.
Techniques offered here are all solid EMI chasing suggestions. Probably will restart as things dry out or you heat things up with high power RF.
73, Stan - VA7NF
Such a different display - Note the horizontal pattern in the waterfall, repeating around 1 per second.
Jump in the car and head towards the coal plant and expect to find something like a variable speed conveyor belt or pump (VFD-Variable Frequency Drive). Also expect a strange look when the geek arrives with a radio and DF antenna.
I did put a call out to the power company thought. I was friendly, told them what I tried, mentioned I cannot listen to broadcast AM stations, as well as not being to operation amateur radio. They sent someone out in less than an hour. They apparently found some issue, and will schedule some work in the future. I'll call in a day or two and see if I can get a timeframe though.
I'm disappointed I was not able to "find it myself", but I'm still new and learning. I now have two yagis for this weekend's foxhunt though.