Tag Archives: SDR

A “knobs and switches” oldster investigates the SDRplay RSPdx . . . Wow!

By Jock Elliott, KB2GOM

It is hard to imagine a less spectacular looking piece of radio gear than the SDRplay RSPdx. It is literally a black box. Aside from the printing on top of the box, the most exciting thing about the RSPdx are the two red plastic covers on the antenna connectors on the side. There are no switches, no knobs . . . you can’t do anything to it except connect an antenna (or antennas) on one side and a USB cable on the opposite.

But once you connect the USB cable to your laptop and fire up the SDRuno software (that you have previously downloaded and installed), you are now in command of a listening post that covers from 1 kHz to 2 GHz.

We’ll get to the important stuff in just a minute, but first a little background.

For an oldster retrocrank like me, a proper radio has knobs and switches . . . preferably a knob or switch for every job. Lately, however, I have noticed that a lot of DXers and ordinary listeners are reporting good success with SDRs – software-defined radios. So I started to wonder about them.

There are three elements to a software-defined radio like the SDRplay RSPdx:  the SDR box itself, which is the part of the system that actually receives the radio signals; a Windows computer (laptop or desktop), which provides the command and control for the SDR; and whatever antennas are required to receive the signals that the listener would like to hear. And, just to be absolutely clear, you need all three elements for the SDR system to work at all.

With my curiosity about SDRs rising, I inquired of Thomas, SWLing’s Maximum Leader, whether SDRplay – one of SWLing Post’s sponsors – might like me to take a look at one of their SDRs. Their answer was an emphatic Yes, and I had an RSPdx in my hands just a couple of days later at no cost to me or the SWLing Post.

I have to admit I had some trepidation about the process of bringing the RSPdx online because any time you have three different elements from three different sources that must work together for a system to function properly, there is always the possibility that some of the elements might not “play well together.”

Installation is easy and fast. Connect the RSPdx to the computer using a USB A-male to B-male cable (which the user must supply; often called a printer cable), then connect the antennas using the appropriate cable. In my case, I connected an MFJ 1886 Receive Loop to the Antenna C connector and an off-center fed dipole to the Antenna A connector.

To SDRplay’s great credit, they have produced an excellent video for first-timers and folks not familiar with SDRs — https://youtu.be/Oj_-dOLVzH8 . I recommend watching it, perhaps a couple of times, before you get started.

When you first fire up the SDRuno software, you will see the main panel:

Click on the “RX” button, and the Receive panel will be displayed. After you slide it over, it will look something like this:

Click on SP1 or SP2 in the main panel, and one of the peak displays will appear:

Finally, click on the PLAY button in the main panel, and whatever frequency you have selected will begin to play. Continue reading

Spread the radio love

Radio Waves: Shively Labs Broadcast Antennas, Fedora SWL, F-150 Lightning AM, and Young Listeners on the Decline

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!

Many thanks to SWLing Post contributor Dennis Dura for the following tips:


Public radio engineers await fate of major antenna maker (Current)

The potential sale of one of the country’s only major manufacturers of high-power FM broadcast antennas is causing concern among public radio engineers who have long depended on the company for challenging projects such as directional antennas and multistation combiner systems.

Antennas and combiners made by Shively Labs carry the signals of many major stations, from Boston’s WBUR to Dallas’ KERA/KXT to Seattle’s KUOW. Shively’s headquarters in Maine boasts one of the few test ranges needed to fully prepare complex directional antenna systems for real-world performance.

Founded in 1963 by former RCA engineer Ed Shively, the company has been owned since 1980 by Howell Laboratories, an engineering firm that now has a wide range of product lines. Those include water purification systems, dehydrators and an increasing amount of contract work for the U.S. Navy.

While its military and commercial marine business has grown, broadcast antennas have become a smaller piece of the company’s portfolio, said Shively VP Angela Gillespie. [Continue reading…]

How to become a Shortwave listener (SWL) with Fedora Linux and Software Defined Radio (Fedora Magazine)

Catching signals from others is how we have started communicating as human beings. It all started, of course, with our vocal cords. Then we moved to smoke signals for long-distance communication. At some point, we discovered radio waves and are still using them for contact. This article will describe how you can tune in using Fedora Linux and an SDR dongle.

My journey

I got interested in radio communication as a hobby when I was a kid, while my local club, LZ2KRS, was still a thing. I was so excited to be able to listen and communicate with people worldwide. It opened a whole new world for me. I was living in a communist country back then and this was a way to escape just for a bit. It also taught me about ethics and technology.

Year after year my hobby grew and now, in the Internet era with all the cool devices you can use, it’s getting even more exciting. So I want to show you how to do it with Fedora Linux and a hardware dongle. [Continue reading…]

Did AM Radio Just Get Hit By “Lightning”? (Radio World)

There’s something missing from the newest F-150 Lightning truck

These days, the auto industry is as disrupted as broadcast radio. Like the radio companies – a group of independent operators, each moving down a different pathway – automakers are highly individual companies. Continue reading

Spread the radio love

Radio Waves: Radio Martí, SDRs for Ukraine, Military Morse Code Innovation, and RFE/RL Opens Riga Bureau

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!


Radio Martí news: Migrants land by Keys broadcasting tower promoting Cuban democracy (Miami Herald)

Washington maintains a waterfront radio tower in the Florida Keys to broadcast programming aimed at encouraging democracy and press freedom in Cuba, and on Sunday that area in Marathon was the landing spot for a group of migrants fleeing the island. A boat of 25 migrants arrived on the shores of Sister Creek, home to a Radio Martí transmission station on Sunday morning, said Adam Hoffner, assistant chief patrol agent for U.S. Customs and Border Protection’s Miami operations. The landing was one of two known migrant arrivals in the Keys on Sunday, with another 28 Cubans arriving on private property in Key Largo. While the government-run broadcasting agency targets Cuban listeners with Spanish programming, Radio Martí reports typically discourage the kind of voyage that reportedly landed some Cubans on or near Martí property, said Tomás Regalado, the former Miami mayor who also recently ran the agency that oversees Radio and TV Martí. “Historically, the migrant situation was something that was treated as news,” Regalado said. “But with the caveat that it’s a very dangerous trip and not recommended.” [Read more here…]

Ukraine Uses Off-The-Shelf Electronics To Target Russian Communications (Forbes)

A nonprofit organization based in the U.S. is supplying Ukrainian forces with advanced electronic warfare gear assembled from simple off-the-shelf components. The secret is a new technology known as Software Defined Radio (SDR) which can locate Russian radio emitters, from command centers to drone operators. Previously this sort of capability required expensive, high-grade military equipment.

Serge Sklyarenko says his organization, American Ukrainian Aid Foundation, based in New York, is supplying Ukrainian intelligence with a number of the versatile SDR radio kits.

“The beauty of them is they are software defined, meaning they can be reprogrammed in the field to suit a multitude of use cases,” Sklyarenko told me.

In a traditional radio set, the signal from an antenna is processed by dedicated hardware – amplifiers, filters, modulator/demodulators and other components. This means that each radio set is dedicated to one particular type of radio signal, whether it is a 5G cellphone, AM radio, digital television or WiFi. In Software Defined Radio, the only dedicated hardware is the antenna. All the signal processing is carried out digitally with a computer. Simply by changing the programming, an SDR can extract the signal for cellphone, radio, Bluetooth, or any other defined waveform. One device can do everything. [Continue reading…]

Innovation on Morse Code for the US Military (SOFREP)

On January 10, 1991, the U.S. Army Intelligence School Devens (USAISD) introduced the Basic Morse Mission Trainer to the 98H Morse intercept operator and 98D emitter identifier/locator advanced individual training courses. This system revolutionized the training of Morse code copying skills for both students and instructors, reducing course attrition, and turning out better trained operators faster. Continue reading

Spread the radio love

Radio Waves: Splinter Cell Audio Drama, On-The-Go Antenna Mount, Antique Radio Collection, and HAARP to Asteroid Bounce

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!


Splinter Cell: Audio drama, gaming’s next frontier? (BBC)

Whether it’s World of Warcraft, Uncharted or the upcoming Super Mario movie – games characters have been all over our cinemas in recent years.

The Last of Us is coming to television screens, where shows based on Resident Evil and Halo have found audiences.

Now, BBC Radio 4 is getting in on the act.

Sam Fisher, leading man from the Splinter Cell game series, can call the radio station home, thanks to a first-of-its-kind adaptation that producers say no-one had thought possible.

Radio 1 film critic Ali Plumb says that with so much competition for audiences these days it’s no surprise that commissioners are giving the green-light to projects with a “built-in audience”.

He argues that we live in a world that is dominated by content: “From podcasts to music, TV, movies, games and audiobooks – frankly its tricky for anyone to cut through the noise.

“The art of finding intellectual property, using the built-in fan base of that property and engaging with them in something you want to say about the world is the trick that many creative people are trying to do.”

Splinter Cell: Firewall is an eight part dramatisation of a novel based on the famous video game franchise. Sam Fisher, the series’ main protagonist, is a covert special agent who excels at sneaking around military bases at night, silently killing terrorist guards and generally saving the world.

Listen to Splinter Cell: Firewall on BBC Sounds

Bringing the gaming revolution to audio drama makes perfect sense to actor Andonis Anthony, who plays Sam in the Radio 4 drama, which is also available on BBC Sounds. He argues that with more people turning to “non-music audio”, it’s a good time for BBC radio to tell stories that offer a “cinematic experience”.

“Given the rise in podcasts, and audiobooks being so popular – more and more people are getting used to listening to audio as a story experience. Everyone’s going out and about with their air pods on these days and listening in a different way to before.” [Continue reading…]

Antenna Mount Designed For On-The-Go SDR (Hackaday)

Software-defined radio is all the rage these days, and for good reason. It eliminates or drastically reduces the amount of otherwise pricey equipment needed to transmit or even just receive, and can pack many more features than most affordable radio setups otherwise would have. It also makes it possible to go mobile much more easily. [Rostislav Persion] uses a laptop for on-the-go SDR activities, and designed this 3D printed antenna mount to make his radio adventures much easier.

The antenna mount is a small 3D printed enclosure for his NESDR Smart Dongle with a wide base to attach to the back of his laptop lid with Velcro so it can easily be removed or attached. This allows him to run a single USB cable to the dongle and have it oriented properly for maximum antenna effectiveness without something cumbersome like a dedicated antenna stand. [Rostislav] even modeled the entire assembly so that he could run a stress analysis on it, and from that data ended up filling it with epoxy to ensure maximum lifespan with minimal wear on the components. [Continue reading…]

Tour of a Spectacular Antique Radio Collection….Primarily Majestic Radios from the 1930’s (YouTube)

Click here to view on YouTube.

HAARP to bounce signal off asteroid in NASA experiment (University of Alaska Fairbanks)

An experiment to bounce a radio signal off an asteroid on Dec. 27 will serve as a test for probing a larger asteroid that in 2029 will pass closer to Earth than the many geostationary satellites that orbit our planet.

The High-frequency Active Auroral Research Program research site in Gakona will transmit radio signals to asteroid 2010 XC15, which could be about 500 feet across. The University of New Mexico Long Wavelength Array near Socorro, New Mexico, and the Owens Valley Radio Observatory Long Wavelength Array near Bishop, California, will receive the signal.

This will be the first use of HAARP to probe an asteroid.

“What’s new and what we are trying to do is probe asteroid interiors with long wavelength radars and radio telescopes from the ground,” said Mark Haynes, lead investigator on the project and a radar systems engineer at NASA’s Jet Propulsion Laboratory in Southern California. “Longer wavelengths can penetrate the interior of an object much better than the radio wavelengths used for communication.”

Knowing more about an asteroid’s interior, especially of an asteroid large enough to cause major damage on Earth, is important for determining how to defend against it.

“If you know the distribution of mass, you can make an impactor more effective, because you’ll know where to hit the asteroid a little better,” Haynes said.

Many programs exist to quickly detect asteroids, determine their orbit and shape and image their surface, either with optical telescopes or the planetary radar of the Deep Space Network, NASA’s network of large and highly senstive radio antennas in California, Spain and Australia.

Those radar-imaging programs use signals of short wavelengths, which bounce off the surface and provide high-quality external images but don’t penetrate an object.

HAARP will transmit a continually chirping signal to asteroid 2010 XC15 at slightly above and below 9.6 megahertz (9.6 million times per second). The chirp will repeat at two-second intervals. Distance will be a challenge, Haynes said, because the asteroid will be twice as far from Earth as the moon is.

The University of Alaska Fairbanks operates HAARP under an agreement with the Air Force, which developed and owned HAARP but transferred the research instruments to UAF in August 2015.

The test on 2010 XC15 is yet another step toward the globally anticipated 2029 encounter with asteroid Apophis. It follows tests in January and October in which the moon was the target of a HAARP signal bounce.

Apophis was discovered in 2004 and will make its closest approach to Earth on April 13, 2029, when it comes within 20,000 miles. Geostationary satellites orbit Earth at about 23,000 miles. The asteroid, which NASA estimated to be about 1,100 feet across, was initially thought to pose a risk to Earth in 2068, but its orbit has since been better projected by researchers.

The test on 2010 XC15 and the 2029 Apophis encounter are of general interest to scientists who study near-Earth objects. But planetary defense is also a key research driver.

“The more time there is before a potential impact, the more options there are to try to deflect it,” Haynes said.

NASA says an automobile-sized asteroid hits Earth’s atmosphere about once a year, creating a fireball and burning up before reaching the surface.

About every 2,000 years a meteoroid the size of a football field hits Earth. Those can cause a lot of damage. And as for wiping out civilization, NASA says an object large enough to do that strikes the planet once every few million years.

NASA first successfully redirected an asteroid on Sept. 26, when its Double Asteroid Redirection Test mission, or DART, collided with Dimorphos. That asteroid is an orbiting moonlet of the larger Didymos asteroid.

The DART collision altered the moonlet’s orbit time by 32 minutes.

The Dec. 27 test could reveal great potential for the use of asteroid sensing by long wavelength radio signals. Approximately 80 known near-Earth asteroids passed between the moon and Earth in 2019, most of them small and discovered near closest approach.

“If we can get the ground-based systems up and running, then that will give us a lot of chances to try to do interior sensing of these objects,” Haynes said.

The National Science Foundation is funding the work through its award to the Geophysical Institute for establishing the Subauroral Geophysical Observatory for Space Physics and Radio Science in Gakona

“HAARP is excited to partner with NASA and JPL to advance our knowledge of near-Earth objects,” said Jessica Matthews, HAARP’s program manager.


Do you enjoy the SWLing Post?

Please consider supporting us via Patreon or our Coffee Fund!

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

Spread the radio love

Mario shares a short review of the Airspy HF+ Discovery SDR

Many thanks to SWLing Post contributor, Mario Filippi (N2HUN), who shares the following guest post:


Author’s Airspy HF+ Discovery (small black box to the left of the laptop)

A Short Review of the Airspy HF+ Discovery SDR

by Mario Filippi (N2HUN)

I recently purchased an AirSpy HF+ Discovery.  As a SWL for over 60 years who’s owned many shortwave radios by manufacturers such as Drake, Yaesu, Icom, Zenith, Kenwood, Panasonic, Sony, Radio Shack, Grundig, CountyComm, MFJ, Sears, AOR and have used a number of different SDRs such as the RTL-SDR.com, HackRF, NooElec and many other rudimentary inexpensive first generation SDR dongles, I feel the AirSpy was an excellent choice. It cost $169 plus shipping.

For LW/MW/HF reception, I use a 30’ ground mounted vertical with about 50 buried radials in different stages of decomposition hihi. For VHF, a roof mounted 2m/70cm SlimJim antenna is used, but I haven’t done much listening in that portion of the spectrum yet except for occasional foray into the aero, 2m ham, NOAA satellite and public service bands.  Note that the AirSpy also covers 60 – 260MHz.

An older Dell Inspiron laptop and SDR# are used in conjunction with the AirSpy.  For decoding, MultiPSK, FLDigi, MTTY, Yand (for NAVTEX), along with VB cable are the accompanying software to make the digital modes intelligible.

So far I’ve logged a few local LF aeronautical beacons and some DGPS beacons on longwave but will be in a better position to judge its performance when winter sets in.  As for the medium (520 – 1710 kHz) wave AM broadcast band, the AirSpy easily brings in both local stations during daytime and distant stations at night with no adjacent channel interference whatsoever.  Even low powered community Emergency Alert Stations in the 1600 – 1710 kHz portion of the band can be heard daily from this QTH. A rotatable loop would certainly improve reception though.

As for shortwave listening the AirSpy HF+Discovery is, in my opinion, great for listening to both shortwave broadcasts and utility stations though I tend to concentrate on UTES mostly such as VOLMET, WEFAX, RTTY (the few that remain unencrypted), CW marker stations (e.g. XSG and XSQ from China) NAVTEX (519 kHz), aero/maritime SSB, time signal stations (WWV, CHU) and many of the other esoteric digital utility signals populating the band.  As for SW broadcast stations, WRMI, Radio Exterior, RFI, R. Marti,  BBC, WWCR and Radio Algerienne, to mention a few have been received.  The Frequency Manager (memory storage) in SDR# has quickly filled up with intercepts using the AirSpy.

As a ham and CB operator (yes, the two can mutually coexist in the same human body), I’ve found the AirSpy HF+ Discovery to be a trouper on all the HF ham and CB bands. One of my favorite hangouts is the 28.100 – 28.300 MHz slice of 10m where domestic and international low power CW beacons transmit their callsigns (and at times their grid squares and power output) into the ionosphere and achieve great distances.  Recently, beacons from 5, 6 and 7 land in the US along with DX prefixes ED4, PY4 and XE1 were logged.  If you’re into 10m FM operation you can also tune the AirSpy to hear local and distant repeaters on 29.62 – 29.68 MHz.  When the band is open, .62 and .64 seem to be the most active here in Central NJ.

If you’re a CB (aptly named the Citizen’s Band) op, the AirSpy HF+ Discovery does a stellar job on Channels 1 – 40 which is especially exciting when the band’s open.  While domestic (USA)  CB’ers are limited to frequencies from 26.965 – 27.405 MHz you’ll nonetheless hear DX ops below our (USA) channel 1 and above channel 40 conversing in French, Spanish and German in LSB/USB.  Add to this mix the fact that the FCC dropped the 150 mile limit for US ops a few years back and now the advent of the FM mode operation in the US, you’ll find the AirSpy won’t disappoint.  In my opinion the AirSpy HF+Discovery was an excellent choice and I’m more than satisfied with its performance.

In the matter of honesty and full disclosure, I purchased the AirSpy HF+ Discovery completely on my own in an effort to upgrade my station.  My choice was based on information gathered from the Internet and YouTube video reviews.  The performance of this receiver was based on my experience using the vertical antenna described earlier, the hours spent at my QTH (location) listening to stations of interest to me and my six decades experience as a SWL.  No test equipment to assess sensitivity, selectivity or other empirical methods to measure performance was used. That information can be found on the Airspy website.  The main purpose of this article was to craft a rudimentary review for those interested with the caveat that reception will vary depending on many factors such as location, antenna, ionospheric conditions, feedline quality, computer/software variations, QRN, QRM, and operator experience.  The results presented in this article are typical for my location; others may experience different results.  Thanks very much.

Spread the radio love

Radio Waves: Insomnia-Fueled Pirate, Cold War & High-Tech Tactics for Russia, PL-660 Panadapter, Women-Run Radio in Somalia, and Building an SDR Transceiver

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!


Meet the 68-year-old ‘bad-boy nerd’ behind this North Side pirate radio station (WBEZ)

If you’re driving through the greater Ravenswood area and tune your radio dial to 87.9 FM, you might just enter a sort of radio twilight zone. On tap? Old timey, crime-thriller radio dramas, complete with sleuthy melodramatic music, damsels in distress and classic radio sound effects – footsteps, doors slamming, the gun going off.

There are no call letters or DJs, just “audio noir” floating out over a two-square-mile sweet spot on Chicago’s North Side.

It’s all broadcast illegally out of a nondescript two-flat on a residential block. There’s a spindly antenna on the roof, visible mainly from the alley, and a 50-watt transmitter in the upstairs apartment. And there’s Bill, a retired computer and audio engineer who’s been operating this illegal station for some 15 years. He asked us not to use his last name for fear of “FCC prison.”

“People on the lakefront up in the high rises can hear it,” said Bill. “And they used to listen at Lane Tech somewhere on an upper floor. So it gets out a little ways, but not that far.”

Bill got into noir not because it’s gripping radio, but rather because it’s not. He has insomnia, and the plot lines from Dragnet and Yours Truly, Johnny Dollar help him fall asleep. [Continue reading and listen to this piece at WBEZ.]

U.S. and Ukrainian Groups Pierce Putin’s Propaganda Bubble (NY Times)

U.S.-backed news outlets and Ukrainian activists use Cold War techniques and high-tech tactics to get news about the war to Russians.

WASHINGTON — Using a mix of high-tech and Cold War tactics, Ukrainian activists and Western institutions have begun to pierce the propaganda bubble in Russia, circulating information about the Ukraine war among Russian citizens to sow doubt about the Kremlin’s accounts.

The efforts come at a particularly urgent moment: Moscow appears to be preparing for a new assault in eastern Ukraine that could prove devastatingly bloody to both sides, while mounting reports of atrocities make plain the brutality of the Kremlin’s tactics.

As Russia presents a sanitized version of the war, Ukrainian activists have been sending messages highlighting government corruption and incompetence in an effort to undermine faith in the Kremlin.

Radio Free Europe/Radio Liberty, a U.S.-funded but independent news organization founded decades ago, is trying to push its broadcasts deeper into Russia. Its Russian-language articles are published on copies of its websites called “mirrors,” which Russian censors seek out in a high-stakes game of whack-a-mole. Audience numbers have surged during the war despite the censorship. Continue reading

Spread the radio love

Guest Post: An Introduction to DXing the MF Marine Bands

Many thanks to SWLing Post contributor, Don Moore–author of  Following Ghosts in Northern Peru–for the following guest post:


Monitoring the MF Marine Bands

By Don Moore

For me, DXing has always been about the challenge of receiving difficult-to-hear radio stations, regardless of the type of station or frequency range. In my five decades in the radio hobby I’ve logged a lot of different kinds of stations – shortwave broadcast, medium wave, shortwave utility, longwave beacons, etc. But some of my favorite catches have been in the upper end of the medium frequency range.

Technically speaking, medium frequency (MF) is the range from 300 to 3000 kHz and includes the standard medium wave (AM) broadcast band. The upper end of the MF band, from 1600 to 3000 kHz (except for a small portion reserved for amateur radio),  has always been assigned to various types of utility uses including broadcasts and other voice communications from regional maritime stations. And while digital modes and satellites have done a lot to change the nature of communication with ships at sea, there is still a lot of good human-voice DX to be heard.

Several dozen stations, mostly in Europe and North America, broadcast regularly scheduled marine information broadcasts in the MF range. These broadcasts are usually between five to ten minutes in length and include weather forecasts, navigational warnings, and other notices to keep ships at sea safe. On occasion it’s possible to hear two-way voice communication here between ships and shore stations, although that’s much less common today.

The Equipment

Nothing special is needed to DX the marine MF band other than a receiver that covers the frequency range and can receive USB mode (which all these broadcasts are in). However, for reasons explained below, I highly recommend using an SDR to make spectrum recordings of the entire band to go through later. Continue reading

Spread the radio love