Category Archives: QRM

Hamvention Highlights: Affordable diversity reception with the SDRplay RSPduo

Each year at the Dayton Hamvention I enjoy checking out the latest radio products and services. This year (2019) I found an exceptional number of innovations and will share these in Hamvention Highlights posts. If you would like to check out 2019 Hamvention Highlights as I publish them, bookmark this tag: 2019 Hamvention Highlights

Diversity reception with the SDRplay RSPduo

Last year, during the 2018 Hamvention, SDRplay announced the RSPduo, a 14bit dual-tuner SDR. We posted a review of the RSPduo on the SWLing Post.

At the time, SDRplay mentioned that the RSPduo could eventually be used for diversity reception.

Diversity reception is the ability to combine or select two signals, from two (or more) antenna sources, that have been modulated with identical information-bearing signals, but which may vary in their fading/noise characteristics at any given instant.

In short, diversity reception gives one a powerful tool to mitigate fading and noise, and to improve a signal’s overall integrity.

Andy and Mike with SDRplay demonstrated SDRuno’s diversity reception functionality and noted that it will soon roll out as a free upgrade to SDRuno, SDRplay’s open SDR application.

I should note here that the SDRplay booth at the 2019 Hamvention was incredibly busy—no doubt, because the RSPduo must be one of the least expensive, most accessible, ways to experiment with diversity reception. Case in point: the new Elecraft K4D transceiver will support diversity reception, but the price is about $4,700 US; the RSPduo can be purchased for $280 US.

Based on the demonstration, this feature will be quite easy to use and I love how it has been implemented in the SDRuno GUI (graphical user interface).

To learn more about the RSPduo, check out SDRplay’s website or read our review. Of course, when SDRplay releases the diversity reception upgrade to SDRuno, we will make an announcement!

If you would like to follow other Hamvention Highlights, bookmark the tag: 2019 Hamvention Highlights

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Arcing can produce nasty broadband radio interference

On this trip to Québec, indoor listening has been more productive than listening from our balcony.

I mentioned in a previous post that, this year, QRM levels here at the condo in Québec are higher on our balcony than they are inside the building.

I think I found the source.

A couple weeks ago, on my morning walk, I passed underneath some high voltage power lines about 1 km from the condo. I noticed the sound of arcing coming from a pole nearby. No doubt, something metal–a staple, a cable, a pin, etc.–is the culprit.

I pulled out my smart phone and made this short video. If you turn up the volume, you might hear the noise especially at the end of the clip.:

I took a portable radio back to the site later and heard the same broadband noise I heard from the condo.

Although we only rent this condo a couple months a year, I’ll try to report the noise to the Hydro Québec. I know that our utility company in the States must follow up with requests like this and do their best to eliminate unintentional sources of RFI. These issues can also be an indication of something in the system failing, so power companies can actually be quite grateful for the feedback.

If you have persistent broadband noise at home, check out some of the trouble shooting tutorials at K3RFI’s website for a little guidance.

Despite all of this noise, I’m pleased I can still receive a few of my favorite shortwave stations. And, of course, escape to the KiwiSDR network and hit the field from time to time!

No worries, though, I’ll be back at my home station soon and can once again enjoy a relatively RFI-free radio space!

Post readers: Have you ever been plagued with power line noise? What did you do about it? Any tips? Please comment!

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LED QRM jams maritime Automatic Identification System

(Source: Southgate ARC)

LED lights jam shipping Automatic Identification System

VERON report investigators from the Netherlands Radiocommunications Agency have discovered RF Pollution emitted by LED lights caused the loss of AIS shipping signals around 162 MHz

A Google English translation of the Radiocommunications Agency article reads:

In the mouth of the Waalhaven in the Nieuwe Maas in Rotterdam, ships from the electronic map have been missing for some time. The Port of Rotterdam Authority and skippers were completely in the dark about the cause of this.

In the busy Rotterdam port area, of which the Waalhaven is a part, it is important that you know where everyone is. A ship that automatically sends its position and data via AIS – and is therefore visible on the electronic navigation chart – not only increases safety, but also shortens the waiting times for the berths and waiting areas. And what about ships loading and unloading dangerous goods or passenger ships? These are continuously monitored. If such a ship is dropped, dangerous situations can arise.

During an investigation the inspectors of the Radiocommunications Agency quickly discovered that the frequency band for AIS signals was disturbed. And after several polls in the surroundings of the Waalhaven they came to a work of art. In an atelier near the mouth of the Waalhaven, an artist had made a work of art with the help of LED lights. All these lights appeared to be the key to the solution together with the power supply.

Because LED lights are indeed economical, but if you do not buy the right one or install them incorrectly, they cause a lot of problems. In this case, the frequencies of the AIS band were therefore disturbed. After the power of the lighting was switched off, the disruption was resolved. In retrospect, it appeared that the lighting and the power supply exceeded the interference limits. To prevent new failures, a solution is sought for the artist together with the business community.

The agency also regularly receives reports of disruptions of AIS reception from the Amsterdam port area. Here, too, we conduct an investigation. If something interesting comes out of this, you may read more about this in the next newsletter. To prevent disruptions, we regularly monitor frequency use (preventively). Especially in areas with busy shipping traffic.

Source Netherlands Radiocommunications Agency
https://magazines.
agentschaptelecom.nl/
ontwikkelingenindeether/2018/03/
schepen-verdwenen-van-de-elektronische-kaart

VERON in Google English
http://tinyurl.com/NetherlandsVERON

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DARC asks that you send RF polluting LED bulbs to Elektor Magazine

Photo By Trung Pham Quoc

(Source: Southgate ARC via Mike Hansgen)

LED Bulb RF Pollution – Elektor Magazine investigates

DARC, the German national amateur radio society, are requesting amateurs to send LED bulbs which pollute the RF spectrum to the magazine Elektor for investigation

A Google English translation reads:

Elektor-Verlag GmbH calls all readers and especially all radio amateurs to send non-compliant LED bulbs including power supplies. Elektor wants to investigate this EMC-technical and then forward it to the competent market surveillance of the BNetzA.

The reason for the action: As a result of a press release of the DARC in September 2017 on the significantly increasing interference of radio communications, other radio services and the DAB reception by non-EMC compliant LED bulbs Elektor had investigated such lamps (as well as LED strips). The result showed a progressive electromagnetic pollution.

The Federal Network Agency as competent authority for market surveillance in accordance with the EMVG has welcomed the call for the submission of suspicious copies. In addition, the Federal Agency would like to be informed if disturbing lamps attract attention. She then wants to investigate this situation and take the products out of the market, if they are still offered.

Please send suspicious copies

Elektor-Verlag GmbH
Kackertstr. 10
52072 Aachen

Please enclose a note with the words “EMC LED lamp” so that everything runs correctly in the inbox. You can also announce your submission via e-mail to redaktion@elektor.de with the subject “EMC-LED-Lamp”. Elektor Verlag GmbH then checks the lamp, publishes an update if necessary and informs the Federal Network Agency.

Here the link to the Elektor article from 23.04.2018
https://www.elektormagazine.de/news/bundesnetzagentur-zu-schicken-sie-uns-verdachtige-led-lampen

Source DARC http://darc.de/

2017 RF pollution from LED bulbs in Elektor Magazine
http://www.southgatearc.org/news/2017/september/rf-pollution-from-led-bulbs-in-elektor-magazine.htm

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RSGB presentation on RF Interference

Digital-Frequency-DialMany thanks to SWLing Post contributor, Gary (W4EEY), who writes:

I want to recommend an excellent presentation on RF Interference from
the Radio Society of Great Britain (RSGB) Convention in 2015. The
presenter is Ian White, GM3SEK, who has a Blog website here:

https://gm3sek.com/

You can find the presentation video on YouTube here:

Click here to view on YouTube.

The presentation runs for about one hour and contains some valuable
information to help you fight noise and interference in your shack.

Thanks for the tip, Gary!

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Can you help Luke identify this radio noise?

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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Exotic shortwave DX copied in Rio Capim, Northern Brazil

The beautiful Capim River in a land of Jaguars, Tarantulas and occasionally, wonderful shortwave DX

Hi there, I returned from my third trip to the Rio Capim area of Pará, Northern Brazil about 5 weeks ago, having been out there for exactly a month. Now, whilst this was strictly a business trip I always make time to tune around the bands, mostly shortwave, in the hope of copying some interesting DX. My previous two trips were reasonably successful; however, I didn’t really hear anything new – just lots of Tropical Band – and tropical stations with much greater signal strength and clarity. Part of the problem is one of which most of us suffer from – the dreaded local QRM. Even in the depths of the rain forest noise is present from building electrical systems (particularly lighting) and other equipment. In my first attempt to escape the noise on this trip I ventured out of my accommodation building (basically a very large hut) to the wire fence that separates us and the larger fauna (although having said that, the monkeys and everything else that lives in the area appears to have no difficulty scaling a 6 foot fence – funny that! ). Anyway, ultimately, you’ve really got to want to hear something special quite badly to venture out. I suppose it could be the definition of hard-core DX! I tried this only once because as I was copying a very nice signal from Radio Guinea on 9650 kHz, I found myself about 2 feet from a Tarantula Hawk Wasp dispatching a very large spider (check out the very brief video on my YouTube channel). That was me done for alfresco DXing in the jungle.

Bonito’s USB-powered MegActive MA305 E-field antenna up a tree…performed superbly in Brazil

Fortunately, I was lent a 4-wheel drive truck for the duration of my visit and so I decided to find a quiet location to park up and listen to the radio – therefore only having to venture outside (at night) to place my antenna. One evening after dinner I got in the truck and drove around the site for a while until I found a location, effectively on the edge of the jungle that was mostly very quiet. Perfect…as long as I didn’t end up as something else’s dinner. I took the super-compact USB-powered Bonito MegActive MA305 antenna with me on this trip because I’d already tested it at home on DXpeditions and in Crete and thus I was confident as to how superbly well it would perform in a quiet location. To supplement my antenna choices, during the first weekend, I made the 90 km drive to the nearest town and bought, amongst other supplies, a 40 metre length of speaker wire and a 3.5 mm jack connector to make a temporary long-wire antenna.

In my experience, there are roughly 3 tiers of Tropical and Tropical Band DX on short wave. There’s the bottom tier of stations which with a decent portable and a few metres of wire can be readily heard in the UK on a Dxpedition – and at home with a magnetic loop antenna, for example and a good quality table-top receiver or SDR. Amongst this group of signals I would include Rádio Clube do Pará, Brazil on 4885 kHz,  Radio Difusora Roraima on 4875.3 kHz, Emisoras Pio XII 5952.5 kHz, Radio Santa Cruz, 6134.8 kHz etc. etc. On the next tier are tropical stations that are really difficult to hear in the UK – but can be heard with good propagation and good equipment. This group includes Radio Aparecida  on 6135.2 kHz particularly, Rádio Educação Rural on 4925.2 kHz, Radio Tarma Internacional on 4774.9 kHz, Rádio Evangelizar (formerly Radio RB2) on 6040.7 kHz etc. There are many more examples from these two groups I could use, but you get the picture. Lastly, there is a tier of stations that are very rarely or never heard in Europe, irrespective of equipment or propagation. Often these stations operate with low TX power which makes them extremely difficult to copy anyway – and that leads to ambiguity farther as to whether they are even on-air. Furthermore, some of these stations broadcast very irregularly, which makes copying them even more of a lottery.

My mainstay travel receiver, the brilliant Eton Satellit..two-time veteran of South American DXing

In this context, a month in Northern Brazil was a useful timescale for surveying the Tropical Bands and geographically tropical stations for the presence of very rare signals. Fortunately, over many hours of listening in Rio Capim with the Eton Satellit and mostly the Bonito MegActive MA305 antenna, I manged to record six signals that are very rarely heard outside of South America. The list of stations follows below, complete with the antenna arrangement. Further below you will find embedded reception videos and text links to the same videos on the Oxford Shortwave Log YouTube channel. Please take the time to watch the videos and note the comments made by some of my subscribers with local knowledge. In particular, Rádio Gaúcha and Rádio Canção Nova on 4825 kHz are very irregular broadcasters and therefore I was fortunate to be in the right place, at the right time to copy their signal. More luck came my way with the reception of Radio Sora de Congonhas on 4775 kHz – made possible because of a total power cut on site, reducing noise effectively to zero (I was indoors at the time). I, personally, never heard anything else other than Radio Tarma, Peru on or around 4775 kHz – itself something of a rarity, except when conditions are very good.

In conclusion, I have to say, once again, the DXing credentials of the Eton Satellit and the Bonito MegActive MA305 USB-powered antenna are clearly demonstrated here. The perfect travelling companions for the serious DXer and broadcast band listener alike, I had no issues getting through security at any of the airports and their combined weight is unnoticeable in a fully loaded backpack. I definitely recommend both products. It’s also worth noting that if you’re travelling to a relatively remote location, even with modest equipment, you might be able to copy rare signals that will provide good information to the rest of us trying to hear those same signals from 1000’s of km away. I will be returning to Rio Capim early in 2018 and I’m seriously considering taking my Perseus SDR with me. A superbly sensitive and selective receiver with noise reduction that actually works, it opens up the possibility of even more exotic DX on that trip.

As always, thanks for watching/listening/reading and I wish you all excellent DX and Season’s Greetings. 73!


   The list of exotic catches and antennas utilised:

  • Radio Apintie 4990 kHz, Suriname – Bonito MegActive MA305
  • Radio Cançao Nova 9675 kHz Sao Paulo – 20 metre long-wire
  • Radio Verdes Florestas 4865 kHz, Cruzeiro do Sul – Bonito MegActive MA305
  • Rádio Gaúcha 11915 kHz, Porto Alegre – Bonito MegActive MA305
  • Radio Sora de Congonhas 4775 kHz, Congonhas – Bonito MegActive MA305 antenna
  • Rádio Canção Nova 4825 kHz, Cachoeira Paulista – Bonito MegActive MA305

 

Click here to watch on Oxford Shortwave Log YouTube channel

 

Click here to watch on Oxford Shortwave Log YouTube channel

 

Click here to watch on Oxford Shortwave Log YouTube channel

 

Click here to watch on Oxford Shortwave YouTube channel

 

Click here to watch on Oxford Shortwave YouTube channel

 

Click here to watch on Oxford Shortwave Log YouTube channel

 


Clint Gouveia is the author of this post and a regular contributor to the SWLing Post. Clint actively publishes videos of his shortwave radio excursions on his YouTube channel: Oxford Shortwave Log. Clint is based in Oxfordshire, England.

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