Tag Archives: SDR

Radio Deals: Airspy Black Friday Sale 2020!

If you’ve been thinking about pulling the trigger on an Airspy product, now’s the time!

Airspy is once again offering huge discounts during their 2020 Black Friday promotion.

For example, their Airspy HF+ Discovery SDR–which I consider to be one of the best HF SDRs on the market–is 30% off ($119 US). This is a phenomenal deal on an amazing SDR!

The YouLoop antenna is only $20.97 US. Click here to read my review of the YouLoop.

That’s such a good deal, I’m contemplating the purchase of a second one.

Both the HF+ Discovery SDR and YouLoop are the major components of my portable SDR DXing kit. During the Black Friday sale, you can purchase both for $141 US! That’s much less than the normal price of the HF+ Discovery alone.

It seems all Airspy distributors are participating in the sale, so click here to find the distributor that ships to your part of the world.

[Just found out the Frugal Radio channel also discovered this sale!]

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Peter demonstrates SDR# Co-Channel Canceller with FM DX

Many thanks to SWLing Post contributor, Peter Wilson, who writes:

Hello Thomas,
I noticed you have included the SDR# AM Co-channel Canceller in your blog, I’ve made a video of the SDR# FM Co-channel Canceller in action.

Es IQ files are from August 2020, received using an Airspy HF+ Discovery using SDR# 1732, near Lobatse, Botswana. Playback
in SDR# 1772.

A couple of people asked me why the SDR# FM Co-Channel Canceller was only cancelling adjacent channel signals in my video above.

This video is for you:

FM Co-Channel Canceller separating two stations 60kHz apart on the OIRT FM band, received by Es in the UK:

Wow!  This is simply amazing! Thank you for the demonstration Peter.

Again, the Co-Channel Canceller is a free upgrade for SDR# users.

Click here to download your copy of SDR#.

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Video: Uncovering a Buried Co-Channel Station with the New AirSpy SDR# Tool

AirSpy’s Youssef Touil shares a video from YouTube author “PY3CRX&PY2PLL” which dramatically demonstrates the extent to which the Co-Channel Canceller tool can uncover a much weaker signal beneath a powerful one:

Youssef commented on the video that It only needs some tweaking to the lock/offset to get a perfect decode. So, presumably the result could be even better than heard here.

For more information on the Co-Channel Canceller, see my original article here, and the follow-up piece.

Guy Atkins is a Sr. Graphic Designer for T-Mobile and lives near Seattle, Washington.  He’s a regular contributor to the SWLing Post.

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SDR#’s Co-Channel Canceller Gets Additional Options

In my earlier article, I introduced the Co-Channel Canceller, a unique feature in AirSpy’s SDR# program for the benefit of medium wave DXers.

Now only a day later, software author and AirSpy founder Youssef Touil expands the toolset of Co-Channel Canceller with I.F. Offset and Channel Bandwidth controls.

To download this latest release, click here to go to AirSpy’s downloads page.

It’s my hope that AirSpy will publish a tutorial or YouTube video(s) with step-by-step examples to help with using this unique feature. Until then, it’s certainly fun to try!

Guy Atkins is a Sr. Graphic Designer for T-Mobile and lives near Seattle, Washington.  He’s a regular contributor to the SWLing Post.

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AirSpy SDR#’s New Killer Feature: the Co-Channel Canceller

An example of an AirSpy SDR# software screen.

A version of AirSpy’s popular SDR# software, showing the dark mode interface introduced in 2019. SDR# is always evolving, and the latest new tool is the Co-Channel Canceller.

It’s easy to take for granted the magical math that happens in Software Defined Radio. Occasionally though a breakthrough occurs which really grabs our attention, thanks to the hard work and bright minds of the designers behind the receivers and the software.

On the software side, the first series of “wow” moments happened for me in 2007-2008 when Nico Palermo of Perseus SDR fame expanded the program’s alias-free bandwidth incrementally from a modest (but impressive for the time) 100 kHz all the way up to the current 1600 kHz coverage.

The top-end 1600 kHz bandwidth was a game changer which allowed  medium wave DXers the opportunity to record IQ-WAV files of the entire band for later review, analysis, and DXing. It’s even more impressive considering this expansion was done without any additional hardware or receiver updates.

What did Nico charge Perseus owners for this incredibly useful expansion of spectrum and waterfall bandwidth? Nothing! The program with its much improved features continued freely available to previous and new Perseus SDR owners.


Now in 2020, Youssef Touil, AirSpy’s hardware and software developer, brings  a “killer feature” to his own SDR program named SDR#, for the benefit of medium wave DXers: the Co-Channel Canceller. The cost for this innovative tool? Yep, it’s a free addition to SDR#.

What are the benefits of the Co-Channel Canceller? This question is best answered by listening to three examples published by Youssef on his Twitter feed.

Read the descriptions below and listen to the brief audio files. In each example the Co-Channel Canceller is turned on and off a few times:


For the first example above, I suspect the 594 kHz station is Saudi Arabia’s Radio Riyadh, and the off-channel 596 kHz signal is Al Idaa Al-Watania from Morocco. It’s impressive that the 50 kw 596 station can be uncovered to any degree, as Radio Riyadh is a whopping 2000 kw!

In the AirSpy Groups.io forum, Youssef clearly illustrates the steps needed to initiate the Co-Channel Canceller. I’ve reproduced his screenshots below:

I’ve only just begun to explore the possibilities of the Co-Channel Canceller tool, but it holds promise of helping to reveal and identify hopelessly buried co-channel or adjacent channel stations. Not only does it work “live” in real time reception, it functions well with recorded IQ-WAV files too! Checkout the newest version of SDR# and give this new feature a try. I can imagine situations where this tool could be highly useful at times for the shortwave DXer also.

Thanks, Youssef, for this brilliant tool, which you’ve included free with the newest SDR# !

I encourage radio hobbyists to support AirSpy’s efforts to advance the state-of-the-art. The diminutive AirSpy HF+ Discovery receiver is not only a reasonably priced SDR to use with SDR#, it’s a top performer and a recipient of the World Radio TV Handbook’s Best Value SDR award for 2020.

Guy Atkins is a Sr. Graphic Designer for T-Mobile and lives near Seattle, Washington.  He’s a regular contributor to the SWLing Post.

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Radio Waves: The “Weird Wide Web” of SW, VOA Whistleblower Complaint, KiwiSDR v RaspberrySDR, and the Portable Operations Challenge this weekend

Radio Waves:  Stories Making Waves in the World of Radio

Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers.  To that end: 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 contributors Steve Lord, Michael Guerin, and the Southgate ARC for the following tips:


Propaganda, Pirates and Preachers: The Weird Wide Web Of Shortwave Radio (The Dork Web)

The world of Shortwave is a world of state-backed propaganda, cults, pirates, and spies. You’ll find every form of freakery and geekery on air. Digital, analogue, even stuff where you can’t tell if it’s digital, analogue, bad music or interference.

[…]In a world of constant connections Shortwave radio may seem anachronistic. But there’s something special in Shortwave and I’d like to show it to you. With a tiny bit of effort and at zero cost you can explore this world from the comfort of your own home.

How Shortwave Shaped Lives

Of all the things I expected to get into, Shortwave radio wasn’t one of them. As a kid I’d listen to my dad’s old valve radio. Strange voices from distant lands floated through the air. Shortwave’s audio quality was terrible even by early 80s standards. There was something magical in hearing distant voices from across Europe and beyond.

I got back into Shortwave listening earlier in the UK lockdown period. Over the past few months I’ve heard stations from as far as Florida, Cuba, Botswana, North Korea and China. I’ve heard signals broadcast from Ascension island in the Atlantic to Tinian island in the Pacific.

Some people will tell you that Shortwave is dead. While it’s passed a 20th century peak there’s plenty happening. In 2002 the National Association of Shortwave Broadcasters estimated that hundreds of millions of households around the world had Shortwave-capable receivers.[]

Six senior Trump admin officials file whistleblower complaint over Voice of America CEO (The Hill)

Six senior Trump administration officials filed a whistleblower complaint with the State Department’s inspector general over allegations that Michael Pack, CEO of the U.S. Agency for Global Media (USAGM), violated federal law and abused his authority, according to a copy of the complaint reported by Politico on Wednesday.

The 32-page complaint includes allegations from six members of the Senior Executive Services at the USAGM accusing Pack, who was confirmed as head of the agency which oversees the state-run network Voice of America in June, of engaging in conduct that “constitutes an abuse of authority and gross mismanagement.”

The six officials who filed the complaint were all placed on administrative leave Aug. 12.

The complaint alleges Pack, who was appointed by Trump, wanted to force out the complainants because they were part of the “Deep State” and had “played a role in the delay” of Pack’s confirmation to his position at the USAGM.

The complaint alleges Pack ordered a close aide to conduct research on the voting history of agency employees, including one of the complainants, Matthew Walsh, the deputy director for operations who was placed on administrative leave. The research “was to be utilized in evaluation of career civil servants’ abilities to carry out the duties of their positions,” the complaint states.[]

KiwiSDR vs RaspberrySDR— a tale of two SDRs (Hackaday via Southgate ARC)

Once you move away from the usual software defined radio (SDR) dongles, you have only a few choices unless you want to drop some serious cash. One common hobby-grade SDR is the KiwiSDR. This popular unit runs Linux and can receive up to 30 MHz. The platform uses a dedicated A/D converter, an FPGA, and BeagleBone computer. Success of course breeds imitators, and especially when you have an open source design like the Kiwi, you are going to find similar devices with possibly different end goals. That’s how the RaspberrySDR came to be. This is a very similar unit to the KiwiSDR but it uses a Raspberry Pi, along with a handful of other differences. What’s different? [KA7OEI] tells us in a recent blog post.

Other than the obvious difference of the computer and all that it entails, the RaspberrySDR has a higher speed A/D (125 MHz vs 66 MHz) and 16-bits of resolution instead of the Kiwi’s 14 bits. This combines to give the Raspberry a wider receive range (up to 60 MHz) and — in theory — better performance in terms of dynamic range and distortion.

[KA7OEI] measures a few key parameters on both devices and arrived at some surprising conclusions. The Kiwi appears to boost signals near its cutoff frequency to compensate for losses in the system. The Raspberry — using adapted software — looks as though it does the same trick, but does it around the Kiwi’s cutoff frequency, which is lower. Probably a software fix could take care of that, of course.

There are also tests of image rejection and front-end overloading. The tests revealed a few problems with signal strength measurement and some other problems with the RaspberrySDR. The biggest issue, though, was that the 16-bit A/D didn’t seem to have better performance. Without proper design, throwing more bits at a problem isn’t always helpful and this appears to be a good example of that.

In the end, the Raspberry looks like a cheap clone of the Kiwi with some benefits, but also some drawbacks. The blog post also covers some open source issues where Kiwi is now saying some parts of their code will only be binary in the future and there has been some difficulty finding all of the Raspberry’s files. If you are looking to buy one, you might not find the name “raspberrysdr” but [KA7OEI] suggests searching for “New 16bit 62M real-time bandwidth network shared SDR receiver” which does turn up some results.

Of course, you can always use a Pi with a more conventional dongle, and that works well enough. If you want to make a Pi just transmit, you can do that with little more than a wire, although the quality might not be perfect.

https://hackaday.com/2020/09/30/kiwisdr-vs-raspberrysdr-a-tale-of-two-sdrs/

Portable Operations Challenge (Southgate ARC)

The final rules for the FMH Portable Operations Challenge are now posted on the POC webpage at foxmikehotel.com/challenge/. N1MM+ users, need to select FMHPOC as the contest and VKContest Logger users just POC.

The organisers wish all other contests taking place this weekend success and lots of fun – the bands will be busy again and we’re hoping propagation plays along.

We hope many amateurs give this new-style contest a go whether from a home QTH station or out portable.

Ed DD5LP


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SDR# upgrades include device sharing and spectrum slicing

Youssef with Airspy has just announced the release of the latest SDR# version. He wrote the following in a tweet:

Check the latest and greatest release of SDR# with device sharing across multiple instances covering different slices of the spectrum.

[…]One master instance can spawn many slices with entirely separate signal paths and displays.

Click here to download SDR#.

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