Tag Archives: Noise

Steve tracks down the source of persistent radio interference and gets it addressed

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Photo via Unsplash

Many thanks to SWLing Post contributor, Steve Allen (KZ4TN), who shares the following guest post:

Tracking Down Radio Frequency Interference

by Steve Allen, KZ4TN

I first noticed the RFI in late November 2019 as a steady buzz at around S9. It was present over most of the high frequency spectrum. I waited until the second week of December to see if you would end on its own, no such luck. I put an HF rig in my truck and started driving around the area to see if I could find a potential source. About a quarter mile from my home is a 161 KVA substation operated jointly by the Tennessee Valley Authority and my local electrical utility. When I parked in the driveway outside of the gated substation the sound of the interference was very strong and blanked the HF spectrum. I called the phone number on the gate and after an explanation of why I was calling I was connected to a fellow radio operator. I explained the situation and he said he would bring the issue to someone’s attention and get back to me.

A week went by and I didn’t hear back from the TVA. I called the person I spoke with previously and he said that the individuals that he spoke with questioned the validity of my findings. He was very helpful but said he didn’t have much clout with the TVA, RFI investigations were not his area of responsibility. I told him I would be happy to meet with someone from the TVA and show them what I had found. I also said I would contact my local electric utility and see if they had an RFI detector so we could eliminate their equipment. My initial contact at the TVA said he would keep trying to get someone to take this issue on and work with me to investigate. I said I would call him back next week.

I then called the local utility company and talked to someone there who was familiar with these kinds of issues. The local utility company owns the output side of the equipment at the substation. He told me he was going to perform an infrared (heat) inspection of their equipment at the substation mid January as part of their annual maintenance and will also check the low voltage utility lines near the substation. I told him that I didn’t notice this RFI until after they had a power outage nearby. He said he would try and get over earlier and check the power lines that run along the streets and look into the power outage history for this area.

All during this time I kept a daily log of the RFI including time of day, frequency effected and S unit level. I also logged the weather conditions. To eliminate the electronics in my house as a possible source I connected my transceiver to a 12 VDC battery and shut off the mains circuit breaker, the RFI did not change at all. I also visited the ARRL webpage that provide information on RFI including recordings of known RFI:

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

The ARRL is the best source I have found in finding and fixing RFI.

By December 27th,  no word back from anyone. I assumed that they were off for Christmas but decided to write a letter to the TVA as a follow up to what had happened so far. In early January I received and email from one of the TVA engineers who said he would contact a field engineer who would contact me. The next day I received an email from the field engineer who said he was going to be in the area on another job but would meet me at the substation.

So, of course as soon as I am making headway with finding the problem the RFI diminished to the point of not being a problem. By this time here in Northeast Tennessee the winter temps are in the 40s and the humidity is lower. For whatever reason, the RFI ended. I met with the field engineer and we agreed that if there is no RFI there is nothing to search for.

Fast forward to August, 2020. In June and July I had been operating digital, mostly FT8. I usually had the volume control at zero and as it was summer I was doing no shortwave listening. One day I decided to tune around the bands and found that the RFI was back as strong as it was during December at S4-S9 from 2-30 MHz. I emailed the principal engineer I had previously been in contact with at the TVA and he told me he would contact another field engineer and that he would come to my house with an RFI locator and start a thorough investigation. The next day I received an email from the field engineer and we scheduled a time for him come over.

Upon his arrival he connected his RFI locator to my vertical antenna and tuned across the spectrum. The locator immediately displayed the signal. He captured an electronic image and said that he could now drive around the area and try and find a match. A hour and a half later he called and said he was unsuccessful and wanted to come back  and make sure the signal was still present. Sure enough, it still displayed on his locator and he was puzzled why he could not find a similar signal while driving the area. He said he would send a copy of the recording to the TVA engineer and get back to me.

A few days later I heard back from him and he wanted to come over again and make another recording. I believe after discussing this issue with his supervisor he was going to use a different method of searching the area. After a couple of hours I received a phone call from the field engineer telling me that he thought he had found the source of interference. Using a parabolic antenna he had found two different utility poles that appeared to have defective lightening arrestors on them. Both are within a quarter mile of my QTH. These poles are the responsibility of the local electrical utility not the TVA. He said he would contact them and follow up with me in a few days.

In a couple of days the interference was very low to nonexistent. Shortly thereafter the engineer contacted me saying the local utility company had completed the repairs and wanted to know if the interference was still present. I said I hadn’t hear it in a couple of days and I would get back to him if it returned. A couple of weeks later I received an email from the field engineer detailing the incident, what he had done to locate the interference, and what was done to repair it. In his email he stated the service was provided at no cost by the TVA Right of Way and Elizabethton Electric Department through TVA’s Comprehensive Services Program (CSP). I am so appreciative of the Tennessee Valley Authority. The airwaves are now free of manmade interference and I am looking forward to another winter of operating and listening to shortwave radio. Here in the 21st century there are so many electronic devices that are capable of causing RFI. I am very thankful that my station is RFI free (for the time being).

Steve Allen, KZ4TN
Elizabethton, TN

Thank you so much for sharing your story, Steve. Only recently, we posted Emilio’s article about tracing interference to poorly made switching power supplies. Thank you for sharing how you approached your local utility company, in your case, to resolve your RFI!

Very encouraging! Readers note that you don’t always have to live with persistent RFI. If you know the source isn’t coming from within your home, sometimes it’s simply a matter of getting your local utilities company to investigate.

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Post-storm power outage leads Emilio to find the RFI-spewing source of his problems

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Storm with lighteningMany thanks to SWling Post contributor, Emilio Ruiz, who shares the following guest post:

Apprehending an RFI-generating monster!

At the beginning of the year, I was sad because, at home, an awful RFI noise appeared. The next few months the noise increase until S9!!. Day and night my receivers and my feelings were so dampened with this terrific RFI–only the lower Broadcast Band (900 to 540 Khz) was relatively immune to it.

Yesterday, we had a storm and the mains electricity service went off, so I connect a 12 volt battery to my RT-749b military surplus transceiver and the received signals were very clean like the “good old days”.

(Above: Listen W1AW loong distant from my QTH in Chiapas Mexico).

When the power electricity come back on, so did the RFI too!!

(Above: W1AW gone)

Remembering the recently publish post in SWLing Post about RFI, I did some testing by
cutting the electricity to my home (the main switch) and the RFI was gone!! So I discovered the RFI lives in my house–not in the outside wires!!

I put batteries in my old shortwave portable radio and searched (like Ghostbusters) all outlets contacts, one by one, connect and disconnected each device.

And I found the guilty party!

Exhibit A: The Mitzu laptop power supply

On December 2019, the power supply of my son’s laptop broke, so I bought a cheap substitute.

The RFI produced by this little monster could be heard at a distance of about 200 meters from my QTH!!! (Much like an old transmitter spark gap–!)

Even this cheap power supply apparently featured ferrite toroids on the wire but turns out it is fake!! It was only a plastic ball!

Exhibit B: Fake toroids!

The wires were also not shielded. No doubt one of the worst switched-mode power supplies I could have purchased.

Exhibit C: The Mitzu RFI generator wire without shield, only pair wires!

I found a old Acer power supply with same specs and I replaced out the RFI monster one.

And now? The shortwave bands are clean again.

(Video: Testing my Kenwood R-600 rx with Radio Exterior de España… plugging and unplug the Mitzu monster RFI generator).

So I wanted to share what happened to me, so perhaps it can be useful for other SWLing Post blog friends.

Watch these little switched mode power supplies from all devices in your home. Replace them if you detect RFI levels that harms SWLing. Consider disconnect all devices (vampire consumption–or phantom loads) if not in use; the radio waves and electric bill will be grateful to you!

WOW! What a difference! Emilio, that was great investigative work on your part. It’s as if that switching power supply was specifically designed to create RFI! No shield and fake toroids? That’s just criminal in my world! 

Thank you so much for sharing your story. Hopefully, this might encourage others to investigate and apprehend their own local RFI monsters!

(And by the way, Emilio, I love that RT-749b military transceiver!)

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Can you help Bruce identify this shortwave noise?

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Many thanks to SWLing Post contributor, Bruce (VE6XTC), who is trying to identify noises he’s hearing on the HF bands. Perhaps readers can help.

By request, Bruce has provided me with two recordings via his Kenwood TS-440S:

Recording 1: 7,335 kHz at 0500 UTC on September 13, 2020

Recording 2: 7,405 at 0500 UT on September 13, 2020

Post readers: If you can help Bruce by identifying these HF noises, please comment!

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Can’t receive anything on your new shortwave radio–? Read this.

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This morning, I received a question from Andrew, an SWLing Post reader in the UK.  Andrew writes:

May I ask a question please? I am very much a newbie to this. I am not really interested in FM, but I would like to listen to international stations on SW, utilities stations, amateur broadcasts and if possible, local airports, aircraft on air band.

I have just purchased a Tecsun PL-680 and have tried it inside my home with the telescopic and wire aerial that came with it, plugged into the antenna port and clipped to a point near the ceiling. All inside the house and the wire aerial did improve the reception, but I get hardly and channels either during the day or night.

Grateful for your detailed advice on what I need to do exactly to improve the number of stations I can receive.

Kind regards
Andrew

Thank you for your question, Andrew, and I hope you don’t mind that I share it here on the SWLing Post as I receive this question so frequently from new shortwave radio enthusiasts.

Of course, a number of things could be affecting your shortwave radio reception and there is, of course, the possibility the receiver is faulty–however, this is very unlikely. Let’s talk about what is most likely the culprit:

Radio Frequency Interference (RFI)

RFI is quite often the elephant in the listening room. It’s not always immediately obvious–especially if you’re new to shortwave listening.

RFI (also known as QRM) is radio noise that is created locally and often concentrated in our homes and neighborhoods. RFI deafens our shortwave radios by overwhelming the receiver with strong spurious signals. Even if you can’t hear the noise, it could still be overwhelming your receiver from a different portion of the band.

RFI can emanate from most any modern electronic or digital device in your home: televisions, power supplies, dimmer switches, smart appliances, and even computer hard drives. Honestly, most any device could be the culprit.

These “Wall Wart” type adapters can create a lot of RFI

RFI can also be caused by power line noises outdoors which have a much larger noise footprint and typically require intervention from your local utilities company/municipality.

In all likelihood, though, it’s a noise inside your home.

There’s a quick way to determine if RFI is the culprit:

Take your radio outdoors, away from the noise

Depending on where you live, this might only require walking with your radio to the far end of your garden/yard, or it might require hopping in your car and visiting a local park. The idea is to find a spot far removed from houses and buildings, outdoor lighting, and even power lines if possible.

Once you find a listening spot, turn on your portable and tune through some of the popular shortwave radio bands.

If in the late afternoon or evening, I like tuning through either the 31 meter band (9,400–9,900 kHz), 41 meter band (7,200–7,450 kHz) and, if late evening, the 49 meter band (5,900–6,200 kHz). Jot down the frequencies where you hear stations and perhaps even make notes about the signal strength. Then go back home and see if you can receive as many stations. Shortwave stations change frequencies often, but if you listen from home at the same time the following evening, the radio landscape should be similar.

My guess is that you’ll hear many more stations in the field than you can from within your home.

Living with RFI

Sadly, RFI is just a fact of life in this century. It’s very hard to escape, especially for those of us living in dense urban areas. This is one of the reasons I’m such a big fan of taking radios to the field.

There are things you can do to improve reception and I would encourage you to read through this post from our archives (the first two points in the article directly address RFI). Do your best to track down sources of noise and eliminate them.

If you find that, even in the field, your shortwave receiver can’t receive stations with the antenna fully extended, then it may indeed be an issue with the radio itself and you might need to send it back to the manufacturer or retailer if it’s within the return window.

Post readers: If you have other suggestions, feel free to comment!

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Your support makes articles like this one possible. Thank you!

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myNoise: possibly the best ambient sound generator on the planet

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My wife has an amazing ability: when she’s deep into research, writing, editing, or creating something, she has a laser-focus like none other: she can tune out the world around her to the point that it’s honestly hard to get her attention. She can work in almost any environment, and tune out (nearly!) all distractions. It’s quite impressive. She credits this ability to focus in distracting surroundings to our children, who at a young age developed the less-rare ability to generate noise, both wide in variety and sometimes quite intense in volume.

Me? Completely the opposite.

When I’m writing or working on a project––indeed, whenever I need to concentrate––I either have to work in a controlled environment where I have few interruptions, or I have to artificially create that controlled environment.  I usually do this through the use of an ambient noise or instrumental (non-vocal) music. It’s rare that I’m working in an environment with no interruptions, so being able to manufacture my own audio space is important for my productivity.

When I’m here at SWLing Post HQ, I’ll often tune to an HF frequency that has no signal occupying the space. In other words, I’ll listen to shortwave radio static that might include the odd ionosonde sweep and occasional static crash….it creates a white noise that, in essence, nulls out everything else around me. Plus, as a radio geek, I confess to feeling quite at home in that static.

To help me catch some zzzs when I travel, I’ll often do the same: simply tuning to an unoccupied HF frequency and letting it play through the night. I find that it nulls out hotel hallway traffic, like doors banging and loud talking, allowing me to get some needed rest.

Photo by Jp Valery

I also turn to noise generators and numerous YouTube channels that specialize in long ambient field recordings, because finding a reliable (unoccupied) radio frequency doesn’t always work due to garrulous local radio interference or simply a lack of free space on the FM band.

Introducing myNoise

This year at the Winter SWL Fest my friend, David Goren, recommended a website––and accompanying application––called MyNoise.net. As an audio engineer and radio producer, David has a finely-tuned ear and can notice looped sounds, audio irregularities, and poorly-made recordings. So I knew if David Goren was impressed with this collection of ambient noises, they would be first-class.

MyNoise.net is the product of Dr. Stephane Pigeon, a man with an impressive CV that includes consultant work for Roland Corporation and numerous audio websites and applications.

What makes his site so unique is: 1) the sheer number and variety of ambient soundscapes, and 2) the ability to finely-tune and customize each sound in a remarkable number of ways.

Want to travel to a pebble beach, a primeval forest, a Japanese garden, or fall asleep on the bridge of a starship? Yeah, you’re covered––really. And not with, as is typical, short hiccuping loops with background muck imbedded: the MyNoise collection (at time of this post) contains over 200 customizable sound generators, with lengthy live field recordings, and they’re clean. The real deal…high fidelity at its best.

If you like ambient audio, his site provides an incredibly rich deep-dive…

But don’t take my word for it.  Listen for yourself!

Radio Soundscapes

myNoise slider controls allow you to change the level of audio tracks and loops.

When David first introduced me to myNoise, he pointed out two soundscapes in particular: one was called “Shortwaves,” the other, “Numbers Stations.” (Now that’s what I’m talking about!) Every night of the SWL Fest, I listened to these two noise machines as I slept. It was wonderful.

With permission, I have made a couple one-minute audio recordings of the two radio-specific soundscapes from myNoise.net. Keep in mind that these recordings were set at a preset level and left alone; in other words, I did not move the control sliders during the recording. In reality, the sounds can be tailored to your listening pleasure via the sliders and generous array of controls. By the way, I suggest wearing headphones.

Sample of “Shortwaves”

Sample of “Numbers Stations”

While I love these two radio sound generators, I have to say, I’ve truly enjoyed exploring the more than 200 sound generators also available on myNoise.

How to listen

MyNoise.net is a free website supported by user donations.  (Donations, by the way, can unlock an array of extra features and sounds.) Even though I have the app (see below), I still sent a bit of extra support though their website; after all, this is just the sort of project I love supporting.

MyNoise is also available as an iOS or Android app. If you have a mobile device or tablet, I highly recommend downloading the app and purchasing the full set of recordings for a mere $10.

A screenshot of the myNoise app running on my iPad

Stephane also has a YouTube Channel with a number of soundscapes.

Click here to check out myNoise.net.

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Indoor shortwave antenna options to pair with a new SDR

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Many thanks to SWLing Post contributor, Chris Freitas, who writes:

“I am thinking of the new RSP1A SDR. Would you know of a good indoor antenna that would work well with it?”

Your antenna question is simple, but the answer is complex!

First off, I think the RSP1A is a great choice as it’ll give you proper exposure to the world of SDR (1 kHz to 2 GHz!)  at a modest price.

Unlike a portable radio of course, your SDR must be connected to a PC, laptop, tablet or some sort of mini computer like Raspberry Pi. This limits your ability to easily try different antenna locations within your home compared to, say, a battery-powered portable radio. It might take some dedicated experimentation and patience.

Indoor antennas are so vulnerable to the radio noise within your home.

If you live in an off-grid cabin with no radio interference nearby, even a simple $1 random wire antenna hooked up to RSP1A’s SMA connector would yield results. I occasionally spend my summers in an off-grid cabin and it’s simply amazing what you can do with a modest setup when there are no man-made radio noises around.

Listening to the final broadcast of Radio Netherlands in an off-grid cabin on Prince Edward Island in 2012.

But how many radio enthusiasts live in an off-grid cabin? Answer: very, very few! Most of us only get to experience off-grid life during natural disasters when the electrical grid has been damaged in our neighborhoods.

The reality of indoor antennas

You’ve told me previously that you live in an apartment in an urban setting, hence you probably cope with a lot of RFI.

When an antenna is indoors, it is forced to function within this RFI-dense environment. Your telescoping whip or wire antenna doesn’t discern between radio noise and your target broadcast signal. Thus, noise can overwhelm your receiver, essentially deafening it to all but the strongest shortwave broadcasters.

And simple, inexpensive portable amplified shortwave antennas? I’ve expressed my opinions about them before. They amplify the RFI as effectively as they do broadcasters.

This is why if you had a means to put a small random wire antenna outside–even if it was simply draped outside a window–it would likely perform better than an indoor antenna. I’m guessing this isn’t an option for you, Chris.

Think loops

A broadband loop antenna (image courtesy of wellbrook.uk.com)

Magnetic loop antennas are a popular topic here on the SWLing Post for a reason: they’re one of the best frontline tools for fighting urban noise. (Here’s a great tutorial/presentation [PDF] describing how mag loop antennas work.)

The compact Bonito Mega Loop FX

While you can build an amplified mag loop antenna (like our buddy, TomL) it’s not a simple project.  Passive single turn loop antennas, on the other hand, are quite easy to build but are narrow in bandwidth (here’s a very cheap, simple passive loop project). You would likely design a single passive loop to serve you on a specific brodcast band and would have to retune it as you make frequency changes. You could build a passive loop antenna for less than ten dollars if you can find a good variable capacitor. Here’s another tutorial.

Commercially produced amplified wideband magnetic loop antennas are not cheap, but they are effective. If you’re a serious SWL, a good mag loop antenna is worth the investment.

Here are a few of my favorites starting with the most portable:

PK Loops

The PK Loop

The most affordable and portable mag loop antenna I own is the PK Loop.  I have the more compact PK Loop C-LOOP-HDSW6-18 (6 – 8 MHz), but Guy Atkins also touts the slightly larger Ham Loop which he finds tunes beyond the advertised 3.5 – 14.5 MHz range.

PK Loops are not as broad in bandwidth as the other antennas I mention below. You will have to retune the loop with any band changes and sometimes even within a specific meter band.

Click here to check out PK Loop offerings on eBay.

W6LVP Loops

The W6LVP Loop Antenna

To my knowledge, the W6LVP is one of the most affordable larger diameter amplified wideband mag loop antennas. We’ve published positive reviews of this antenna in the past.

W6LVP sells two versions of the antenna–since you’re not operating a transmitter, this $250 model would be all you need. indeed, if I were in your shoes, this would likely be the loop I purchase–very cost effective.

Wellbrook Loops

Wellbrook antennas are the staple magnetic loop antenna for many DXers.

Wellbrook loops are manufactured in the UK and have been on the market for a very long time. Their re-engineered Active Inoor Loop Antenna LA5030 would serve you well. At £240.00 (roughly $330 US) plus shipping, it’s one of the most affordable in the Wellbrook line, but over a $250 budget.

Wellbrook makes a number of loops, but since you have no plans to mount this outside, I believe their indoor model would suffice.

Other loop options

There’s no shortage of magnetic loop antennas on the market, but most are pricer than the models I mention above and I know you have a tight budget. Here’s are some models we’ve mentioned on the SWLing Post in the past:

I have the RF Pro-1B and am very impressed, but it’s overkiil for your application (and twice the price of the W6LVP loop).

Fighting urban noise

Even if you build or purchase a magnetic loop antenna, you still need to eliminate as much RFI as you can on your own.

A couple years ago, our friend London Shortwave wrote a brilliant guest post about fighting urban noise. Read through his piece and try to implement as much of his advice as you can.

I hope this helps, Chris! This post is by no means comprehensive, so I hope others will chime in and comment with their experiences. Good luck fighting urban noise and I hope you enjoy your journey into the world of the SDR!

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Can you help Luke identify this radio noise?

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Many thanks to SWLing Post contributor, Luke Perry, who writes:

I am experiencing a issue with my shortwave reception at my part-time home. I have been helping out my mother so I have brought over my Sony portable, along with the Sony active antenna. I have a constant ‘clicking’ sound starting at about 5 kHz or thereabouts that make listening unbearable. As the video shows the problem is non-existent below 4 kHz. I tried moving the radio throughout the house thinking it could be something in the room and still get the same interference.

I was hoping that the filter on the active antenna would help but it does little to remedy the problem. I have no issues with MW or FM reception at all.

I have made a short YouTube video to document the problem in the hopes that one of the blog readers can identify it. I looked online at other instances of RFI and I could not find one that is similar. Hope that someone can help me!

Click here to view on YouTube.

After listening to the first few seconds of your recording, I thought it sounded a bit like an electric fence controller. However the interval between pops is nearly random, which suggests a different source. I suppose it’s possible a faulty fence controller could do this. I believe the only way you could defeat this noise (without shutting it down at the source) would be to use a radio with a durable noise blanker. Of course, I know of no portable radios with an NB function (though most SDRs and tabletop receivers include an NB).

Post readers: Can help Luke ID the source of this noise?  Does it sound familiar to you? Please comment!

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