Category Archives: Articles

Radio Waves: Maverick-603 SDR for FT8, EC-130J Commando Solo Final Broadcast, WRTH Survey, and Railways On The Air

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EC-130J Photo By Staff Sgt. Tony Harp | An EC-130J Commando Solo aircraft from the 193rd Special Operations Wing performs a flyover during Community Days at the Lancaster Airport in Lititz, Pennsylvania, Sept.17, 2022. (Source: DVIDS)

Radio Waves:  Stories Making Waves in the World of Radio

Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

RadioStack’s Maverick-603 Is a Fully-Functional Open-Silicon Software-Defined Radio for FT8 (Hackster.io)

Built using open tools and readied for manufacturing at SkyWater using the Efabless platform, the chip on this SDR is something special.

New Hampshire-based RadioStack is looking to launch a piece of amateur radio equipment with a difference: the Maverick-603 is powered by free and open source silicon, built using the Efabless platform at a SkyWater fab.

“Maverick-603 is the first affordable FT8 receiver board built around an RF receiver chip that was designed using fully open source tools and fabrication,” its creators explain. “It is capable of acquiring FT8 signals between 7MHz and 70MHz. With this frequency range, you will be able to receive signals from around the world with high accuracy. The use of our Low Noise Amplifier (LNA) will also give the chip the ability to amplify very low-strength signals, which is necessary for an effective FT8 receiver.” [Continue reading…]

EC-130J Commando Solo performs final broadcast (DVIDS)

MIDDLETOWN, PA, UNITED STATES
09.17.2022
Story by Master Sgt. Alexander Farver
193rd Special Operations Wing

Airmen from the 193rd Special Operations Wing here, who operate the only flying military radio and TV broadcast platform in the U.S. military, transmitted their final broadcast today to spectators at the Community Days Air Show at Lancaster Airport, Lititz, Pa., bringing to close a 54-year chapter in unit history.

The EC-130J Commando Solo mission has helped keep this Air National Guard unit’s aircraft and its Airmen at the tip of spear for nearly every major U.S. military operation since the Vietnam War. Before bombs dropped or troops deployed in the Global War on Terror following the attacks on Sept. 11, 2001, this specially modified aircraft was already over the skies of Afghanistan broadcasting to America’s enemies that the U.S. military was bringing the fight to them.

“Any world event or crisis that our military has responded to in recent history, our 193rd Airmen – and Commando Solo – were likely key components in that response,” said Col. Eric McKissick, 193rd SOW vice commander. “As we prepare to open a new chapter in our history, we thank those who have enabled us to be among the very best wings in the Air National Guard.”
The genesis for this airborne information operations platform can be traced back to 1968 when the 193rd Tactical Electronics Warfare Group received its first aircraft, called the EC-121 Coronet Solo. In the late 1970s, the aircraft were replaced by the EC-130E before finally being replaced by the current aircraft in 2003. Throughout its history, it was instrumental in the success of coordinated military information support operations, earning the wing the moniker of “the most deployed unit in the Air National Guard.”

These deployments included: Operation Enduring Freedom, Operation Iraqi Freedom, Operations Odyssey Dawn/Unified Protector in Libya, Operation Inherent Resolve, Operation Resolute Support/Freedom’s Sentinel, Operation Secure Tomorrow and Operation Unified Response in Haiti.

Although this unique mission has earned the wing many prestigious accolades, Lt. Col. Michael Hackman, 193rd Special Operations Squadron commander, believes the mission’s success and legacy lies in winning the hearts and minds of adversaries and providing vital information to allies, refugees and victims in times of crisis.

“This capability has been an essential tool in our nation’s inventory, from the battlefields to assisting hurricane and earthquake-ravaged nations,” Hackman said. “During this time, thousands of Pennsylvania Air National Guard volunteers fulfilled their call to duty in this unique capacity, leveraging this capability against U.S. adversaries and supporting allies while always fulfilling the unit tenet of ‘Never Seen, Always Heard.’”

Aside from sporting an impressive operational record, the aircraft holds another distinction with having completed over 226,000 hours of accident-free flying.

“Having that many thousands of hours of accident-free flying is a testament to the excellence of our maintainers, to the operators and anybody who has touched that aircraft. Thank you for leaving that foundation and setting that example that we’re building from,” said Col. Jaime Ramirez, 193rd Special Operations Maintenance Group commander.

McKissick believes the success of the 193rd in operating the Commando Solo mission over the past few decades has led to Air Force Special Operations Command selecting the wing to be the first and only ANG unit to operate the MC-130J Commando II. The Commando II flies clandestine, or low visibility, single or multiship, low-level infiltration, exfiltration and resupply of special operations forces, by airdrop or airland and air refueling missions for special operations helicopters and tiltrotor aircraft, intruding politically sensitive or hostile territories.
“Today we honor the men and women, past and present, who have served this unit and mission with unparalleled distinction,” said McKissick. “The Airmen who came before us created an enduring culture and spirit of hard work, innovation and grit. We thank them for that, and we will do our best to carry this forward.”

The final broadcast of the EC-130J was transmitted to the ground and played at the Community Days Air Show at Lancaster Airport. In the transmission, the wing thanked the local community for their support over the past 54 years before broadcasting the Santo and Johnny song, “Sleepwalk.” The transmission ended with the phrase, “Commando Solo, music off.” [Read the full article here…]

WRTH Reader Survey

The new owners of the World Radio TV Handbook who like your input as readers. Please click on this link and share your opinions with them!

Railways On The Air (Southgate ARC)

The South Eastern Amateur Radio Group (EI2WRC) will be active from The Waterford and Suir Valley Railway station Kilmeaden, Co. Waterford for the ‘Railways On The Air‘ event on Sunday, the 25th of September.

WSVR is a community heritage project. The project has enabled the magic of rails golden age to be brought to life in Kilmeaden. A heritage narrow gauge railway runs along 17 kilometres of the abandoned Waterford to Dungarvan line.

The South Eastern Amateur Radio Group would like to thank the manager Maria Kyte and all the staff of The Waterford and Suir Valley Railway for all their help and allowing us access to the station to do this event again this year. For more information about the WSVR please see www.wsvrailway.ie .

The September meeting of the South Eastern Amateur Radio Group EI2WRC will take place on Monday, the 26th of September 2022 at 8.00 p.m. sharp at The Sweep Bar, Adamstown, Kilmeaden, Co. Waterford, Eircode X91 H588. New members or anyone interested in learning more about amateur radio or the group are as always very welcome to attend.

For anyone that wishes to find out more about the South Eastern Amateur Radio Group and their activities you can drop them an email to southeasternarg /at/ gmail.com or please feel free to go along to any of their meetings. You can check their website www.searg.ie and you can also join them on Facebook and follow them on Twitter.

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How Jake configures SDR# to listen to Encore classical music

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Many thanks to SWLing Post contributor, Jake Brodsky (AB3A), who shares the following guest post:

How I Listen to Encore on Radio Tumbril

Listening to Classical music on shortwave is a challenge. It has loud and soft parts to the music. There may be selective fading. It isn’t a simple thing.

Also, configuring a software defined radio such as the highly configurable SDR# is not trivial. Note to readers: SDR# has been updated a lot recently and the noise reduction features are vastly improved. Kudos to Youssef Touil for all the hard work on this software. He continues to impress me with every update.

So I have some suggestions for those who are interested in listening:

First, get a decent set of over-the-ear headphones. Don’t rely on laptop speakers. They’re usually not designed for audio fidelity.

Set the radio for DSB reception with Lock Carrier and Anti-Fading checked. I also set the bandwidth to cover about 11 kHz or thereabouts.

On the Audio tab I uncheck the Filter Audio option. I’m going to rely on IF filtering to do my work for me.

Next, find an empty channel on the band where you will be listening to the program. Enable the IF Noise Reduction feature, set it to HiFi, and then set the threshold so that the noise floor is reasonably low. If you set the threshold too high, you’ll lose the higher frequency audio and there will be artifacts from the noise floor that I find unpleasant. A little bit of noise reduction is good, but more is not better.

I also enable the IF Filter/notch processing window to handle any stray birdies from switching mode power supplies. However, if not needed, I turn that feature off.

I turn off the AGC. And then I set the volume level to something reasonable, not too loud, not too soft, but just barely able to hear the noise floor.

Then I tune in the program. I was listening to the Sunday Evening (Monday 0200 UTC) broadcast from WRMI on 5950 kHz. There was some fading going back and forth. However, I took the atmospherics in stride, as if it were part of the experience. The broadcast from this evening
ended with the Pastoral Symphony from Beethoven. There were a few fades and there were a few swells, all due to atmospherics as the signal faded to the noise floor and emerged from it. But there was very little distortion. (thanks to the excellent engineers at WRMI).

The experience was actually sublime.

This is why I listen to shortwave broadcasts.

73,

Jake Brodsky, Amateur Radio Station AB3A

Click here for Radio Tumbril schedule and updates.

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Dan reviews the new Chameleon CHA RXL Pro Wideband Magnetic Loop Antenna

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Many thanks to SWLing Post contributor, Dan Robinson, for the following guest post and review:

Photo by Chameleon

The Chameleon CHA-RXL Pro:  Improved Amp Board Raises the Game

by Dan Robinson

Back in 2021 I reviewed the CHA-RXL loop by Chameleon.  This loop antenna is sold by major retailers such as DX Engineering, Gigaparts and Chameleon itself – the company is a well-known name in antennas and other equipment for the amateur radio world.

I compared the CHA-RXL to Wellbrook 1530 and W6LVP loops feeding into a four-position Delta antenna switcher, and then to a Raven 16 port multicoupler which maintains good steady gain.

My Wellbrook is mounted on a telescopic mast about 15 feet above ground level, with a rotor.  The W6LVP (using LMR400 coax) is tripod-mounted with an overall height from ground of about 12 feet. It has special filters to prevent strong medium wave signals from bleeding into HF.

I have since added a UK-made loop (essentially a copy of a Wellbrook loop but smaller diameter and made of metal) combined with a W6LVP amp.  This W6 amp does not have filtering to block strong mediumwave signals.  In all, I have four loops into my Delta switcher, which feeds about two dozen receivers.

There is by the way quite robust discussion at https://groups.io/g/loopantennas about various loops, including the Chameleon.  And this past July, Steve Ratzlaff posted news about the upgraded loop amp board which will ship with what is now the CHA RXL Pro, saying:

“Chameleon has completely redone their CHA RXL loop amp board from the previous poor-performing loop amp that I tested some time back, and sent me one of the new production boards to test. I’m happy to say it tests very well especially for LF sensitivity, and I can now give it my “seal of approval”.  The new board is a version of the LZ1AQ loop amp.”

Photo by Chameleon

It turns out, according to an email from Don Sherman of Chameleon, that Steve is one of the engineers who helped design the new amp board for the CHA RXL Pro, and on the Loop Antenna group he provides a folder in which he placed previous test results with “new files of the new board (sweep of the new RXL Pro loop amp, and a picture of the new amp PCB).”

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Small Unidirectional Loop Antenna (SULA) Part 2: Construction Notes

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Many thanks to SWLing Post contributor extraordinaire, 13dka, who brings us Part Two of a three part series about the new SULA homebrew antenna project. This first article describes this affordable antenna and demonstrates its unique reception properties. This second article focuses on construction notes. The third and final article will essentially be a Q&A about the SULA antenna. All articles will eventually link to each other once published.

This wideband unidirectional antenna is an outstanding and innovative development for the portable DXer. I love the fact that it came to fruition via a collaboration between Grayhat and 13dka: two amazing gents and radio ambassadors on our SWLing.net discussion board and here on the SWLing Post. So many thanks to both of them!

Please enjoy and share Part 2:

Part 2: SULA Construction notes

by 13dka

The drawing [above] has all you need to know. You basically need to put up a symmetrical wire diamond starting with a balun at the one end and terminating in a resistor at the other end of the horizontal boom, the sides are supposed to be 76cm/29.92″ long so you need to make yourself some…

Support structure:

I used 0.63″/1.6cm square plastic square tubing/cable duct profiles from the home improvement market to make the support structure. You can use anything non-conductive for that of course, broom sticks, lathes… The plastic profiles I used had the advantage of being in the house and easy to work on with a Dremel-style tool and everything can be assembled using the same self-tapping screws without even drilling. The profiles are held together with 2 screws, for transport I unscrew one of them and put that into an extra “parking” screw hole on the side, then I can collapse the cross for easy fit into the trunk, a rucksack etc.

These profiles are available in different diameters that fit into each other like a telescoping whip. This is useful to make the support structure variable for experiments and to control the loop shape and tension on the wire. The booms end up at 1.075m each, the profiles come in 1m length, so that’s 4 short pieces of the smaller size tube to extend the main booms by 37mm on each side

On the resistor end of the loop that smaller tube isn’t mounted in the “boom” tube but to the side of it in order to keep the wire running straight from the balun box on the other side.

Mast/mounting:

You can use anything non-conductive to bring it up to height. On second thought that is indeed bad news if you were planning on putting that up on your metal mast…and we have no data on what happens when you do it anyway. I don’t know if the smallest (4m) telescoping fiberglass poles would suffice for portable operation, but I’m a fan of just using the big lower segments of my 10m “HD” mast for the stiffness they give me (3 segments for the height, the 4th collapsed into in the base segment for easy rotation). Telescoping masts also give you easy control over…

Height:

The published patterns are for 3m/10′ feedpoint height over “average” ground. Increasing height further has no expectable advantage, instead it will deteriorate the favorable directional pattern of the loop. Flying it lower, or even a lot lower in windy weather on the other hand is causing a surprisingly moderate hit on performance.

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Introducing the amazing SULA: An affordable unidirectional DX-grade loop antenna that you can build!

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Many thanks to SWLing Post contributor extraordinaire, 13dka, who brings us a three part series about the new SULA homebrew antenna project. This first article describes this affordable antenna and demonstrates its unique reception properties. The second article will focus on construction notes. The third and final article will essentially be a Q&A about the SULA antenna. All articles will eventually link to each other once published.

This wideband unidirectional antenna is an outstanding and innovative development for the portable DXer. I love the fact that it came to fruition via a collaboration between Grayhat and 13dka: two amazing gents and radio ambassadors on our SWLing.net discussion board and here on the SWLing Post. So many thanks to both of them!

Please enjoy and share SULA Part 1:

Introducing the Small Unidirectional Loop Antenna (SULA) 1-30MHz

A small and simple, unidirectional and DX-capable loop “beam” for SWLs!

by 13dka

In early June, Andrew (grayhat), SWLing Post‘s resident antenna wizard suggested a variation of the “cardioid loop” on the SWLing Post message board: The original “cardioid loop” is a small loop receiving antenna deriving its name from a cardioid shaped (unidirectional) radiation footprint. The design is strikingly simple but it has a few downsides: It relies on a custom preamp, it needs a ground rod to work and it is unidirectional only up to 8 MHz.

Andrew’s version had the components all shuffled around and it did not only lose the ground rod, it also promised a nice cardioid pattern over the entire shortwave, from a small, diamond shaped loop. Wait…what? It can be made using parts available on Amazon and your DIY store:

You need some 3m wire and PVC tubes to create a support structure to hold the wire, a 530 Ohm resistor and a 9:1 balun like the popular “NooElec One Nine”. Since it’s a “lossy” design, adding a generic LNA like the NooElec “LANA HF” would help getting most out of it. When you put that all together you have what sounds like an old shortwave listener’s dream: a small, portable, tangible, and completely practical allband shortwave reception beam antenna with some more convenient properties on top, for example, it is a bit afraid of heights.

That sounded both interesting and plain crazy, but the .nec files Andrew posted were clearly saying that this antenna is a thing now. Unfortunately Andrew suffered a little injury that kept him from making one of those right away, I on the other hand had almost all the needed parts in a drawer so I ended up making a prototype and putting it through some of its paces, with Andrew changing the design and me changing the actual antenna accordingly, then mounting it upside down. Let me show you around:

  •  Small, diamond shaped wire loop (with 76cm/29.92″ sides), needing as little space as most other small loops.
  • Unidirectional with a ~160° wide “beam” and one pronounced minimum with a front/back-ratio of typically 20dB over the entire reception range 1-30MHz.
  • Moderate height requirements: It works best up to 3m/10′ above ground, where it gives you…
  • …a main lobe with a convenient flat takeoff angle for DX
  • Antenna is comparatively insensitive to ground quality/conductivity.
  • Wideband design, works best on shortwave and is pretty good up to 70cm.

A functional small beam antenna for shortwave reception that’s just as small and possibly even more lightweight (prototype:~250g/9oz) than your regular SML, that can be easily made out of easy to obtain parts and easily carried around for mobile/portable DXing and due to its cardioid shaped directional pattern also for direction finding, a “tactical” antenna that’s also doing DX? Unlike conventional, Yagi-Uda or wire beams it can achieve a low takeoff angle at only 3m/10ft height or less, the front/back ratio is typically better than that of a 3-element Yagi, with a particularly useful horizontal pattern shape. That it’s rather indifferent to soil quality could mean that more people get to reproduce the good results and being a real wideband antenna is making the SULA an interesting companion for multiband radios and SDRs. Really? A miracle antenna? Is it that time of year again? If I had a dollar for every….

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Radio Waves: DRM Demo in Australia, Decoding the JWST, the ARDC, and EV Makers Dropping AM Radio

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Radio Waves:  Stories Making Waves in the World of Radio

Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Australia Demonstrates DRM on AM, FM (Radio World)

Since September 2020, ABC Radio has been quietly trialing DRM technology in Victoria

The public-service Australian Broadcasting Corp. and its transmission contractor BAI Communications Transmission Network hosted a public demonstration of Digital Radio Mondiale broadcasts on June 29, 2022. ABC highlighted the use of DRM on both AM and FM in Wagaratta, Victoria.

According to the DRM Consortium, the demonstration was the culmination of almost two years of COVID-impacted work to assess the performance of DRM services in Australia’s VHF and medium-wave bands.

Previously, the Australian Amateur Radio Experimenters Group reported that AREG member Steve Adler (VK5SFA) had been monitoring “a very un-publicized Digital Radio Mondiale (DRM) trial” on 747 kHz from Wangaratta in August 2021.

The Australian Communications and Media Authority provided ABC with a license variation to conduct the DRM 30 trials from September 1, 2020, to August 31, 2022.

At the public demonstration, senior representatives from the public, commercial and community radio sectors, along with regulators and other interested parties, were able to hear and see the capabilities of DRM broadcasting on AM from Dockers Plains and on FM from Mount Baranduda. They were also able to review the transmission equipment at Wagaratta.[Continue reading…]

Also check out the DRM Consortium’s article on this same topic.

Decoding James Webb Space Telescope (Daniel Estévez)

The James Webb Space Telescope probably needs no introduction, since it is perhaps the most important and well-known mission of the last years. It was launched on Christmas day from Kourou, French Guiana, into a direct transfer orbit to the Sun-Earth L2 Lagrange point. JWST uses S-band at 2270.5 MHz to transmit telemetry. The science data will be transmitted in K-band at 25.9 GHz, with a rate of up to 28 Mbps.

After launch, the first groundstation to pick the S-band signal from JWST was the 10 m antenna from the Italian Space Agency in Malindi, Kenya. This groundstation commanded the telemetry rate to increase from 1 kbps to 4 kbps. After this, the spacecraft’s footprint continued moving to the east, and it was tracked for a few hours by the DSN in Canberra. One of the things that Canberra did was to increase the telemetry rate to 40 kbps, which apparently is the maximum to be used in the mission.

As JWST moved away from Earth, its footprint started moving west. After Canberra, the spacecraft was tracked by Madrid. Edgar Kaiser DF2MZ, Iban Cardona EB3FRN and other amateur observers in Europe received the S-band telemetry signal. When Iban started receiving the signal, it was again using 4 kbps, but some time after, Madrid switched it to 40 kbps.

At 00:50 UTC on December 26, the spacecraft made its first correction burn, which lasted an impressive 65 minutes. Edgar caught this manoeuvre in the Doppler track.

Later on, between 7:30 and 11:30 UTC, I have been receiving the signal with one of the 6.1 metre dishes at Allen Telescope Array. The telemetry rate was 40 kbps and the spacecraft was presumably in lock with Goldstone, though it didn’t appear in DSN now. I will publish the recording in Zenodo as usual, but since the files are rather large I will probably reduce the sample rate, so publishing the files will take some time.

In the rest of this post I give a description of the telemetry of JWST and do a first look at the telemetry data. [Continue reading…]

Helping Secure Amateur Radio’s Digital Future (Hackaday)

The average person’s perception of a ham radio operator, assuming they even know what that means, is more than likely some graybeard huddled over the knobs of a war-surplus transmitter in the wee small hours of the morning. It’s a mental image that, admittedly, isn’t entirely off the mark in some cases. But it’s also a gross over-simplification, and a generalization that isn’t doing the hobby any favors when it comes to bringing in new blood.

In reality, a modern ham’s toolkit includes a wide array of technologies that are about as far away from your grandfather’s kit-built rig as could be — and there’s exciting new protocols and tools on the horizon. To ensure a bright future for amateur radio, these technologies need to be nurtured the word needs to be spread about what they can do. Along the way, we’ll also need to push back against stereotypes that can hinder younger operators from signing on.

On the forefront of these efforts is Amateur Radio Digital Communications (ARDC), a private foundation dedicated to supporting amateur radio and digital communication by providing grants to scholarships, educational programs, and promising open source technical projects. For this week’s Hack Chat, ARDC Executive Director Rosy Schechter (KJ7RYV) and Staff Lead John Hays (K7VE) dropped by to talk about the future of radio and digital communications. [Continue reading…]

Interference causes EV makers to drop AM radio (Radio World via the Southgate ARC)

Radio World reports the Electromagnetic Interference generated by Electric Vehicles is causing some EV automakers to drop AM (medium wave) radio

The article says:

Some EV automakers are dropping AM altogether due to audio quality concerns, but that’s just one piece of the puzzle as radio continues to fight for space on the dash.

“As carmakers increase electric vehicle offerings throughout their lineups, the availability of AM radio to consumers is declining,” said Pooja Nair, communications systems engineer with Xperi Corp., in a Radio World guest commentary. “This is because the effects of electromagnetic interference are more pronounced in EVs than in vehicles with internal-combustion engines.”

In other words, electromagnetic frequencies generated by EV motors occupy the same wavelength as AM radio signals. The competing signals clash, effectively cancelling each other out. As EV motors grow more powerful, AM static tends to increase.

Read the full story at
https://www.radioworld.com/news-and-business/headlines/why-are-some-automakers-ditching-am-radio

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Ken reverse-engineers the Apollo spacecraft’s FM radio

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Many thanks to SWLing Post contributor, Paul, who shares the following post from Ken Shirriffs’ Blog:

Reverse-engineering the Apollo spacecraft’s FM radio

How did NASA communicate with the Apollo astronauts, hundreds of thousands of miles from Earth? The premodulation processor1 (below) was the heart of the communication system onboard the Apollo spacecraft. Its multiple functions included an FM radio for communication to the astronauts, implemented by the Voice Detector, the module second from the top. In this blog post, I reverse-engineer the circuitry for that module and explain how it worked.

The Apollo communication system was complex and full of redundancy. Most communication took place over a high-frequency radio link that supported audio, telemetry, scientific data, and television images.2 NASA’s massive 85-foot dish antennas transmitted signals to the spacecraft at 2106.4 megahertz, an S-band frequency, giving the system the name “Unified S-Band”. These radio signals were encoded using phase modulation;3 onboard the spacecraft, a complex box called the transponder received the S-band signal and demodulated it.4

The voice and data signals from Earth were combined through a second layer of modulation: voice was frequency-modulated (FM) onto a 30-kilohertz subcarrier while data was on a 70-kilohertz subcarrier, so the two signals wouldn’t conflict.5 One of the tasks of the premodulation processor was to extract the voice and data signals from the transponder’s output. These voice signals went to yet another box, the Audio Center Equipment, so the astronauts could hear the messages from the ground. The data signals were decoded by the Up-Data Link, allowing NASA to send commands to the Apollo Guidance Computer, control onboard relays, or set the spacecraft’s clock.

Many systems worked together for communication, but I’m focusing on a single module: the voice detector inside the premodulation processor that performed the FM demodulation. [Continue reading the full article…]

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