Tag Archives: Software Defines Radios

Sneak peek of the Apache Labs Andromeda 100 watt SDR transceiver

Many thanks to Apache Labs who share the following announcement:

Sneak peek at the Andromeda 100W Transceiver……

10th GEN Intel 6 Core i7, 7 inch built in touch screen and an option to add up to two External HD Monitors.

Windows 10 Powerful PC and an Ultra High performance 100W SDR with PureSignal Goodness in a single compact Box!

Run FT8 and other Digital Modes out of the box!

Coming Soon!

We will post more information about the Andromeda transceiver when we have solid details.

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Radio Waves: Libre Space Foundation Reviews SDRs, ARRL VEC Statement, Pandemic Pastime, and Former CEO of RadioShack Now C-19 ER doctor

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 Ron, Paul, Marco Zennaro, and Richard Langley for the following tips:

The Libre Space Foundation reviews software defined radios (Hackaday)

If you want to go to the next level with software defined radio (SDR), there are a lot of choices. The RTL-SDR dongles are fine, but if you get serious you’ll probably want something else. How do you choose? Well, your friends at the European Space Agency Libre Space Foundation have published a paper comparing many common options. True, they are mostly looking at how the receivers work with CubeSats, but it is still a good comparison.

The devices they examine are:

  • RTS-SDR v3
  • Airspy Mini
  • SDRPlay RSPduo
  • LimeSDR Mini
  • BladeRF 2.0 Micro
  • Ettus USRP B210
  • Pluto SDR

They looked at several bands of interest, but not the HF bands — not surprising considering that some of the devices can’t even operate on HF. They did examine VHF, UHF, L band, S band, and C band performance. Some of the SDRs have transmit capabilities, and for those devices, they tested the transmit function as well as receive.

The review isn’t just subjective. They calculate noise figures and dynamic range, along with other technical parameters. They also include GNURadio flowgraphs for their test setups, which would be a great place to start if you wanted to do these kinds of measurements yourself.[]

ARRL VEC Issues Statement on Video-Supervised Online Exam Sessions (ARRL News)

Very few ARRL Volunteer Examiner teams have successfully conducted in-person exam sessions (following social distancing guidelines) and video-supervised exam sessions using fillable PDF exams and documents. So far, we have found that both types of sessions take volunteer teams two to three times longer to conduct and accommodate fewer candidates than sessions conducted prior to the COVID-19 pandemic. So far, the video sessions have included only one examinee per session.

We ask the community to be patient with our volunteer teams as they navigate uncharted territory. Please remember with the introduction of significant new processes such as these, that there should be proof of concept, establishment of protocols and procedures, and beta testing before expanding to a larger audience. Video-supervised exam sessions require a different skillset than in-person exam administration. Not all teams will be equipped to deliver video exams right away.

The ARRL Volunteer Examiner Coordinator (VEC) has been investigating options for an online examination system.

Fillable PDFs are cumbersome within a video-supervised exam session process. We recognize that online testing would represent a large-scale solution for our thousands of VEs and would make session procedures easier for our teams, but this will not happen overnight.

The ARRL VEC will continue to adapt and respond to the evolving crisis as we search for viable and easy-to-use online examination system solutions and conduct exam sessions in innovative ways.[]

Pandemic Pastime – Shortwave Radio (KFGO)

Ever since I was a little kid, I was fascinated that at night you could listen to radio stations from all over the country. My little Heathkit radio, which I built myself, could pick up stations in Minneapolis, Chicago, St. Louis, Denver, Little Rock, Pittsburgh to name a few. West coast stations were rare because it was tough getting a signal over the Rocky Mountains.

Then there was shortwave radio. A buddy of mine had one and he showed me a list of all the countries he was picking up. England, France, Germany, Latin American countries, numerous stations on the shortwave bands in America. Even Radio Havana coming out of Cuba. Anything from religion to hard edge rock and roll. He also noted he picked up Radio Free Europe and the Voice of America.

Well years later I would stop by my local Radio Shack and decided it was my turn to take up this hobby of monitoring shortwave radio. This particular radio also had a built in cassette player so you could record your found stations as well. It was really interesting to hear the news from other countries and get their take on what was happening in America.

One of the first frequencies I tuned in was WWV a shortwave radio station out of Fort Collins Colorado, that broadcasts the time via the atomic clock. The seconds tick off until the top of the hour when you hear a voice announce the time, followed by a tone that hits the top of the minute exactly on the nose. Great way to set the clock.

Now I know you can probably find all these shortwave stations on the internet, but what fun is that right?

With the covid-19 pandemic, this is a little something different than binge watching television, or building that 10th jigsaw puzzle or cleaning out that closet again and again.

Have a chair on the patio, a glass of your favorite beverage, extend the antenna, and start turning up and down the dial and see what you can find. I had a little notebook that I kept track of my searches. Don’t have it now though…lost it.

I’ll start a new one.

Stay safe everyone![]

Former CEO of RadioShack now an ER doctor (National Post)

‘I am just one of those people who was very fortunate, where things worked out, and where I could do not just do one thing I really enjoyed in life, but two’

Brian Levy loved science as a kid. He had a microscope, read up on stuff in the encyclopedia and messed around with home experiment kits. During his high school years, he took every science credit possible. By his own admission, he was a “geek,” one with an equally strong passion, alongside science, for electronics.

Levy knew how to operate a shortwave radio. Weekend teenage heaven, in his mind, was hanging around the local RadioShack store, a warehouse of gizmos where he scored his first part-time job in 1974, earning US$1.40 an hour at a shop in downtown Atlanta. He was 15, which, alas, was too young to be working for the company, according to the folks at corporate headquarters in Texas, who fired him upon receiving his paperwork.

The dismissal didn’t sit well with Levy.

“I actually called the vice president of human resources in Texas,” he says. The executive was impressed by the moxie of the kid. On the day he turned 16, Levy was hired back.

[…]Levy did not foresee the premature end to his business career. When it came, rather than being crestfallen, he felt liberated, and free to pursue an “itch” that he had always felt the need to scratch. So he applied to medical school at McMaster University in Hamilton, ON. (Levy came to Canada in the first place after relocating RadioShack HQ north of the border as CEO. He is now a dual citizen, although his soft, buttery accent betrays his roots in the American south.)[]

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Radio Kahuzi Comparison Between Sweden and Switzerland KiwiSDRs

Many thanks to SWLing Post contributor, Dan Robinson, who recently took advantage of a rainy Sunday in Maryland to put together the following video.

Dan notes that the video/screencast demonstrates, “reception of the low power Radio Kahuzi, the religious station in Democratic Republic of Congo, via two of the best KIWI SDR sites, in Sweden and Switzerland. The video shows how the signal of Radio Kahuzi propagates the 9,000 + kilometers from DRC into Europe.”

Fascinating!  Thank you for sharing this, Dan!

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Video: Comparing the SDRplay RSP1A and Airspy HF+ on HF & MW

Many thanks to SWLing Post contributor, Ivan Cholakov, who shares the following video where he compares the SDRplay RSP1A and the AirSpy HF+ software defined radios on shortwave and mediumwave:

Click here to watch on YouTube.

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SDRplay announces the RSP1A software defined radio

(Source: SDRplay Press Release)

15/November/2017, Wakefield UK:

SDRplay announces the RSP1A

SDRplay Limited has today announced the launch of a new Software Defined Radio product – the RSP1A.

The SDR-play RSP1A is a major upgrade to the popular RSP1 and is a powerful wideband full featured 14-bit SDR which covers the RF spectrum from 1 kHz to 2 GHz.

Due to its exceptional combination of performance and price, the RSP1 has proved to be a very popular choice as an “entry level” SDR receiver. Since launching the RSP1, we have learned a great deal about what people are looking for in SDR receivers, and where possible, we have incorporated these improvements and new features into the RSP1A.

The RSP1A therefore delivers a significant number of additional features which result in benefits to amateur radio enthusiasts as well as significant benefits for the scientific, educational and industrial SDR community.

Here are the main additional features of the RSP1A compared to the original RSP1:

  • ADC resolution increased to 14-bit native for sample rates below 6 MHz, increasing to 16 bits with decimation.
  • Enhanced RF pre-selection (greater filter selectivity plus 4 additional sub-bands compared to the original RSP1) for reduced levels of spurious responses
  • Improved LNA architecture with variable gain. The RSP1 had just a single gain step.
  • Improved intermodulation performance • Performance extended to cover 1kHz to 2 GHz with a single antenna port.
  • Bias-T facility • Improved frequency stability incorporating a 0.5ppm TCXO (software trimmable to 0.01ppm)
  • Selectable broadcast AM/FM/DAB notch filters
  • RF shielding within the robust plastic casing

When used together SDRplay’s own SDRuno software, the RSP1A becomes a high performance SDR platform. The benefits of using the RSP1A with SDRuno include:

  • Highly integrated native support for the RSP1A
  • Calibrated RF Power Meter with more than 100 dB of usable range
  • Calibrated S-Meter including support for IARU S-Meter Standard
  • The ability to save power (dBm) and SNR (dB) measurements over time, to a CSV file for future analysis
  • The IQ output wav files can be accessed for 3rd party applications

SDRplay has also worked with developers of the popular HDSDR, SDR-Console and Cubic SDR software packages to ensure compatibility. As with the RSP1, SDRplay provides multiplatform driver and API support which includes Windows, Linux, Mac, Android and Raspberry Pi 3. There is even a downloadable SD card image available for Raspberry Pi3 which includes Cubic SDR.

The RSP1A is expected to retail at approximately £76 (excluding taxes) or $100 (excluding taxes)

For more information visit our website on www.sdrplay.com

About SDRplay:

SDRplay limited is a UK company and consists of a small group of engineers with strong connections to the UK Wireless semiconductor industry. SDRplay announced its first product, the RSP1 in August 2014

Email: [email protected]

Introductory video:

Click here to view on YouTube.

Click here to check out the RSP1A at SDRplay.com.

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Review of the SDRplay RSP2 software defined radio

The SDRplay RSP2

The SDRplay RSP2

This morning, SDRplay Limited announced the release––and availability––of their second generation software defined radio, the RSP2.

Regular SWLing Post readers will note that I’m a pretty big fan of SDRplay’s first SDR, the RSP, or “RSP1,” as I’ll now call it (I published a review of the RSP1 in July 2015). To me, the $129 RSP1 has been the best wideband receiver you can buy under $200 US. Its HF performance, in particular, is sincerely impressive at this price point.

Introducing the RSP2


So what’s the RSP2, and how does it differ from the original RSP?

In a nutshell, here’s how SDRplay describes the difference between the two:

“The RSP2 delivers a significant number of additional features which result in a higher spec for specialist amateur radio users as well as benefits for additional scientific, educational and industrial SDR applications.”

In a sense, the RSP2 gives the enthusiast and experimenter access to more receiver parameters and control, opening it to a wider array of possible applications. The RSP2 will also cover a broader range, from as low as 1 kHz to as high as to 2 GHz, and is designed with better selectivity across the spectrum. Enhanced selectivity will certainly benefit amateur radio operators and SWL DXers who might seek weak signals in crowded portions of the band.


The following list outlines the primary additional features of the RSP2 (via SDRplay’s press release):

  • 10 built-in, front-end pre-selection filters, with substantially enhanced selectivity
  • Frequency coverage extended down to 1 KHz
  • Software selectable variable gain Low Noise Preamplifier
  • 2 x SMA Software Selectable 50? RF ports (1.5 MHz – 2 GHz)
  • 1 x High Impedance RF port (1 kHz – 30 MHz)
  • Built-in software selectable MW /FM notch filters
  • Highly stable 0.5PPM TCXO trimmable to 0.01PPM
  • 24MHz Reference clock input / output connections
  • 4.7V Bias-T option (on one of the software selectable antenna inputs)
  • RF screening within a strong plastic case for the standard RSP2
  • A Rugged metal box version –  the ‘RSP2pro’
The RSP2 has a total of three antenna ports: two SMA and one Hi Z for optimal LW/MW/SW performance

The RSP2 has a total of three antenna ports: two SMA and one Hi Z for optimal LW/MW/SW performance

For the moment, the RSP2 only works with SDRplay’s own application, SDRuno. But SDRplay is already working with developers to make the RSP2 compatible with HDSDR, Gnu Radio, CubicSDR, and SDR Console. I appreciate that although the RSP series has an excellent free proprietary application (SDRuno), it was nonetheless developed with many open-source applications, also free, as well. This level of compatibility and support makes SDRplay rather unique among SDR manufacturers.

SDRuno running the RSP2.

SDRuno running the RSP2 (click to enlarge).

Of course, SDRuno is a great application in its own right, and pairing it with the RSP2 will provide you with out-of-the-box calibrated RF and S meters. So far I’m very pleased with native SDRuno features like virtual receivers, embedded time code, spectrum display options, and streamlined design.

Current SDRuno users will note the different antenna and filter options with the RSP2 which works natively with the latest versions of SDRuno

Current SDRuno users will note the different antenna and filter options with the RSP2 which works natively with the latest versions of SDRuno (click to enlarge).

SDRuno installs very easily and provides a plug-and-play experience. It does have a modest learning curve, but SDRplay has an excellent owner’s manual and “cookbook” available to help you set everything up the first time.

Preliminary impressions of the RSP2

SDRplay sent me a pre-release RSP2 (the base model, not the metal box “Pro” version) to evaluate and provide the company with feedback.

I installed SDRuno and put it on the air only this past week. In truth, as I’ve been traveling and must be on the road again this coming week, I prefer not to comment, at least in depth, on the SDRplay’s performance as I’ve had comparatively little dedicated time with the unit.

Yet I have had the RSP2 on the air a few hours of casual listening, and find that it performs as I would expect: low noise characteristics and sensitivity that seems to be at least as good as the RSP1, if not a bit better.  I’m looking forward to a side-by-side with the RSP1 running an install of SDRuno on my laptop!

I must say that I’m very pleased with the RSP2’s Mediumwave/FM notch filter. It happens that a local daytime 45kW AM broadcaster in our area is having transmitter issues which send wideband spurs across the entire HF spectrum; but at night, when the station lowers its power levels, the RSP2’s MW notch filter effectively mitigates the noisy signal. I imagine this filter will be a welcome addition for listeners living in RF-dense environments.

When the RSP1 was first introduced, it retailed for $149. As the economies of scale worked in their favor, SDRplay lowered the price to $129. The new RSP2, meanwhile, is expected to retail at approximately £130 (excluding taxes), or $169 US (excluding taxes). Quite a value, in my opinion: at $169, you’re getting a lot of SDR for the price––and an effective SDR application, to boot.

But if you already own an RSP1, I wouldn’t necessarily rush out and grab the RSP2 just yet.  Of course, if you like the added features mentioned above, or if you’d like an inexpensive SDR with no less than three switchable antenna ports and a MW/FM notch filter, $169 is a bargain and about the same level of investment as a good modern shortwave portable.

As for myself, I’m happy to see a mom-and-pop community-supported company like SDRplay continuing to innovate for our hobby. I’m pleased to support them, and am truly appreciative that they also support our SWLing Post. This is a win-win, in my view; I’d be pleased to support more such companies.

Again, check back here as I plan to compare the RSP2 with the RSP1 and several of my other SDRs.


Click here to read SDRplay’s full announcement and press release.

I plan to take the RSP2 with me on my travels this week. Time permitting, I might even pair it with my recently acquired PK magnetic loop antenna for some spectrum gathering and testing.

In the coming weeks, as my schedule permits, I’ll post updates here on the SWLing Post, including audio comparisons with some of my SDRs. If interested, bookmark the tag RSP2.

For more information about RSP2 pricing and availability, check out SDRplay.com.

Update: Check out RTL-SDR.com’s assessment of the RSP2.

SDRplay has also posted the following video:

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A review of the Elad FDM-S2 software defined receiver


The following review originally appeared in the November 2014 issue of The Spectrum Monitor magazine.

At the Dayton Hamvention this year, I made it a special point to check out the Italian radio manufacturer, Elad.

Although I’ve known about Elad and their products for some time, and often found them intriguing, I hadn’t yet investigated Elad’s offerings simply because I was under the impression they sold and warrantied their equipment only within Europe. Indeed, this was the case…until just recently. Elad has now begun shipping–and supporting–their products within the US, via their division Elad-USA. Thus my renewed interest in Elad at the Hamvention.


At their Hamvention booth in the East Hall of Hara Arena, the Elad staff gave me a superb table-tour of their array of products. Indeed, I was completely unaware of the broad scope of Elad’s product offerings, which include antenna switches, antenna splitters, test equipment, and, of course, software defined radios (SDRs). Their current SDR offerings are as follows: the Elad FDM-S1, the FDM-S2, and the newly released FDM-DUO. The FDM-DUO is actually a transceiver, while the “S” line is receive-only.


Among Elad’s SDRs, I found myself most interested in the FDM-S2 receiver; a quick demo at their booth caught my interest, as I instantly liked the GUI (graphical user interface), the features, and the specifications of this model. I requested that Elad provide the loan of this SDR for review, and they kindly complied.

Unboxing and installing the Elad FDM-S2


Contents of the FDM-S2 box are few and simple: the FDM-S2 receiver, a black cloth carrying bag, and a 4GB USB drive with installation software and documentation are enclosed. A standard USB cable was also included in the shipping box.


I found installation of the S2 to be fairly straightforward. I would encourage new owners to follow the included guide, since installation is a two-part process:

  • First, you install a C++ package on your Windows PC. When complete, this triggers the actual Elad software installation, a two-part installation that you initiate only once.
  • Secondly, you install the USB driver for the FDM-S2, found in the installation folder of the supplied software. Note: at present, the USB driver cannot be automatically discovered and installed by your PC–you must initiate this installation via the device manager. However, this is very easy: the guide takes you through the process step-by-step.

On the back of the FDM-S2 you’ll find an HF and VHF SMA antenna ports, a USB port, serial interface, and on/off switch.


The FDM-S2 derives its power from the same USB cable that is used for data; no separate external power supply is required–a huge plus, for those of us who like to travel.

Once I installed the software and driver, I hooked up my antenna to the HF SMA connector on the back, turned on the FDM-S2, and launched the application. The FDM-S2 clicked to life, and the application ran on the first go–very nice!

Scope of this review: application

Reviewing an SDR is challenging, especially with a third-generation SDR like the FDM-S2. There are nearly an infinite number of setting combinations for gain control, filters, demodulation, audio, even color schemes; covering all of these is beyond the scope of a basic review such as this, or indeed, virtually any review. In addition, the FDM-S2 can be used with several third-party SDR applications. Therefore, for the sake of this review, I decided to limit myself to evaluating the Elad application that ships with the FDM-S2. In addition, in this evaluation I attempted to retain many of the settings that come as defaults in the Elad application, to support new users. Finally, I limited myself to evaluating the shortwave bands.

After installing the Elad application, I spent a good hour or so familiarizing myself with the software. It’s quite a departure from the WinRadio Excalibur, SDR-IQ, and Microtelecom Perseus applications with which I’m most familiar. There is a modest learning curve involved with using the Elad FDM-S2–it took a good hour with the application to feel relatively comfortable with its functionality. But the trade-off is much more customization and functionality than one can achieve with the Perseus or WinRadio software, for example.

First impressions


First, let me begin by saying that new users will greatly benefit from reading the owners manual and join the Elad Yahoo group. If you’re attempting something that the owner’s manual does not cover, most likely someone in the Elad forum has already posted the answer. Elad’s engineer, Franco, also actively monitors and responds to requests on the Yahoo group.

Once on, the FDM-S2 defaults to the frequency of 0 Hz. Indeed, the Elad software uses Hz as the unit of measure for frequency, so any frequency entered must be in Hz: for example, to enter 9,420 kHz, you must key in 9420000, then press “Enter.” As a shortcut, you can enter 9420 and the “+” key on your number pad which will automatically add the trailing “000.” I found that a bit unusual in the beginning as most SDR software defaults to kHz, but after using the FDM-S2 for a few minutes, it became second nature.

There are several ways of tuning the FDM-S2:

  • Frequencies can be directly keyed in (as described above)
  • You can click on a frequency in the spectrum and waterfall windows (if the center frequency isn’t locked)
  • You can use the scroll wheel on your mouse like a tuning wheel, to scan up or down
  • You can use the arrow keys on your keyboard (left/right are defaults with up/down controlling tuning steps)
  • With your mouse pointer, you can click and drag one of the three horizontal tuning bars at the bottom of the window

Tuning Bars: Click to enlarge

I find it easiest to tune by using the horizontal tuning bars to move to a particular meter band, then locking the center frequency and use the scroll wheel on the mouse to scan in 1 or 5 kHz increments. This makes tuning feel like the experience I’m most used to with other SDRs. I must say that I really like the horizontal tuning bars; these make it quite easy to quickly center on a meter band.

I would also note that I’m favorably impressed with the S2’s waterfall and spectrum display; not only can you customize the colors via the settings window, but you also have the options to embed timecode in the waterfall and to display broadcaster information from the frequency database in the spectrum.


The FDM-S2 has a total of four “virtual receivers,” labeled RX1, RX2, RX3 and RX4. Depending on the receiver configuration and bandwidth you’ve chosen in the S2’s device configuration (see below), you can use each virtual receiver simultaneously. Each receiver can have its own filter settings and modes selected–your only limitation is that each of the four receivers must be tuned within the FDM-S2’s bandwidth.

FDM-S2 receiver bandwidth configurations

The S2 currently has seven receiver configurations:

  • 1 Channel 192 kHz bandwidth
  • 1 Channel 384 kHz bandwidth;
  • 1 Channel 768 kHz bandwidth;
  • 1 Channel 1,536 kHz bandwidth;
  • 1 Channel 3,072 kHz bandwidth;
  • 1 Channel 6,144 kHz bandwidth; and
  • 2 Channels 384 kHz bandwidth.

If you set the S2 to a total bandwidth of 192 kHz in one channel, all four of your virtual receivers are limited to that 192 kHz area. This is a great configuration if you plan to listen to a single broadcaster at a time, and don’t need to see so many signals within the spectrum display. It’s also an excellent configuration to save storage space if you wish to record a relatively small chunk of IF spectrum.


If you choose the 6,144 kHz bandwidth, you can use each of the four virtual receivers simultaneously within the bandwidth. For example, on Saturday evenings I could tune RX1 to the Voice of Greece on 9,420 kHz; RX2 to The Mighty KBC 7,375 kHz; set RX3 to search for pirates around 6,925-6,975 kHz; and listen to the 40 or 30 meter ham radio bands on RX4. All at once! [Note: in the screenshot above, each virtual receiver is marked in the spectrum with a green, yellow, red or blue vertical marker.]

The two-channel 384 kHz option is also a powerful and unique feature of the S2. With this configuration selected, you can have two completely independent receivers with 384 kHz of bandwidth, each. Though this may be more radio than you need, each receiver has four virtual receivers of its own. That’s a whopping 8 virtual receivers!

Most of the time, I keep the configuration set to 1,536 kHz, unless I want to listen in two different meter bands at once. At 1,536 kHz, I can record spectrum and capture a full broadcast band to play back later. I’ve even recorded 6,144 kHz of spectrum, and played it back with no hiccups on my Intel i5 PC, although it did chew through a lot of storage space (roughly 2 GB of data per minute of recording). That equates to 120 GB per hour–but the result is a recording of everything between, say, 4 and 10 MHz. For shortwave radio archiving this is a most impressive capability!


While Digital Radio Mondiale (DRM) is not the most popular mode on the shortwave broadcast bands, DRM is built into the FDM-S2; there is no need to purchase a separate license or plugin as with most SDRs. If you’ve never listened to DRM, you might be surprised by the impressive listening results.

Within the first few days of using the FDM-S2, I was simply blown away by the DRM signal lock I achieved with Radio New Zealand International. Indeed, I’ve found that the FDM-S2 provides the most stable DRM decoding locks of any other receiver I’ve tested to date.

Here is a two hour audio sample of the FDM-S2 recording RNZI DRM:

[On a side note: It simply boggles my mind when I realize that this RNZI broadcast originates from a transmitter some 8,400 miles (13,518 km) from my receiver. Regardless of what one thinks about the future or utility of DRM, this is nothing short of magical in my book.]

Note that only the first virtual receiver, “RX1,” employs the DRM mode. This is important to note, as I find I’ve sometimes finished listening to a DRM broadcast, turned off the FDM-S2, then when I turned it back on later, initially wondered why I was hearing no audio on strong AM signals. I had inadvertently left the DRM mode engaged–user error only, in this case. Just something to be aware of.


But finding a DRM broadcast is very easy with the Elad software; there is a dedicated button that appears when the DRM mode has been selected. When you press the schedule button, it will load all of the DRM broadcasts from the HFCC schedule. You can simply scroll through this list and click on a frequency to find an audible DRM broadcast. So far, on the FDM-S2, I’ve decoded RNZI, Radio Exterior de Espana, and even All India Radio from my QTH in eastern North America. Not bad!


One of the reasons I latched onto the FDM-S2 at the Dayton Hamvention this year was that I immediately saw the potential of the S2 as a recording receiver. Besides posting recordings on the SWLing Post, I also actively make recordings for the Shortwave Radio Audio Archive, so no surprise that one of the first functions I evaluated on the FDM-S2 was its recording capability.

There are two recording modes: AF and Full Span Input Spectrum. You switch between modes in the Recording tab of the Settings window. After the settings have been saved, you simply locate the broadcast or chunk of HF spectrum you wish to record, and press the red record button located on the screen’s bottom left quadrant.

The Elad application also gives you a great degree of control for automatically naming the recorded files; mine is currently set up to embed the frequency, date, time, and device in the filename.

There are few things I’ve reported to Elad as possible improvements for recording:

I do wish that it wasn’t necessary to open the settings window to switch between bandwidth configurations and recording modes (IF or AF); my Excalibur has all of this on the front panel, which is more convenient. While there is a more direct way of opening the recording settings window–simply right click on the red record button–I think it would be preferable to at least have the option of including the information on the main user interface. Also, when you stop a recording, the receiver turns itself off; this obviously needs to be corrected. Fortunately Elad has noted these concerns and plans to address them in future software updates.

Additionally, I’ve noted that while one can record either IF or AF, both can’t be recorded at the same time, a lacking shared, incidentally, by the Microtelecom Perseus. While I probably do more recording than most SWLs, I frequently record both spectrum and an individual broadcast simultaneously on the WinRadio Excalibur. I hope Elad will consider adding this to their software, as well.


Features are always nice to play with, and the FDM-S2 is chock-full of them–but most important are your receiver’s ability to detect faint signals, block adjacent ones, as well as cope with unpredictable conditions.


The FDM-S2 has a wide frequency coverage: 9 kHz-52 MHz, 74-108 MHz, and 135-160MHz. It’s one of the few SDRs on the market that doesn’t need a module or add-on for FM and VHF coverage. It has separate SMA connectors for HF and VHF antennas. While I have not thoroughly tested beyond the HF bands as of this writing, but many experienced FM DXers tout the S2’s abilities in their own reviews, and I don’t doubt them.

On the shortwave bands, the S2’s performance has impressed me: this SDR has remarkably excellent sensitivity and selectivity. Indeed, its performance is on par with my WinRadio Excalibur, and surpasses that of my RFSpace SDR-IQ, no mean feat. I have made many A/B comparisons with my Excalibur on weak signals; the two receivers are nearly indistinguishable. I’ve conducted blind-listening tests on weak signals (much like those described here) and found that the two recordings were nearly identical. On occasion, I might favor one receiver’s AGC over the other in a recording, but a slight tweak to the AGC settings could readily fix any discrepancies.

Herein lies the difficulty of reviewing an SDR’s performance–the user has so much power to control variables and thus shape the receiver’s function, that it’s hard to make an “apples-to-apples” comparison. But clearly, the Elad holds its own.

Noise reduction

While I’m not a great fan of digital noise reduction, the Elad software has a variable noise reduction feature that I admit to have used on several occasions. I found that by increasing it to approximately 10-20%, audio characteristics of an AM signal were mostly preserved while noise was effectively mitigated. This is where the S2 has a distinct advantage over the Excalibur which has no noise reduction feature.

AM Synchronous detection

With that said, the Excalibur has an edge on the S2 when it comes to blocking adjacent signals. At the time of review, I’m using version 1.12 of the Elad software, which lacks a selectable AM sync detector–a powerful tool to block noise, which may only be present in one sideband of an AM broadcast. Elad engineering tells me that they have this feature planned for a future software update.


Remarkably enough, the FDM-S2 can actually be used with a number of third-party SDR applications. The FDM-S2 comes with Winrad EXTIO Dlls compatible format: all software based on Winrad derivatives (like HDSDR and Studio1) work, and have been tested by S2 users. So if I really need sync detection, for example, I can simply find and use another SDR application to run the S2.

Indeed, flexibility may be among the most powerful features of the S2. If for any reason you don’t like the Elad application, you can simply use another one.


Invariably, all radios have strengths and weaknesses; here is a list of my notes from the moment I put the S2 on the air:


  • Beautiful, rich audio fidelity via headphones or my amplified speakers
  • Excellent sensitivity
  • Excellent selectivity (which would be enhanced with USB/LSB selectable sync–see con)
  • Low noise floor
  • Four virtual receivers: RX1, RX2, RX3, and RX4
  • Superb DRM decoding built-in, no additional license key or plug-in purchase required
  • Noise reduction is quite effective with few digital artifacts, even at low levels
  • Tasteful waterfall and spectrum displays
  • Wonderfully rapid tuning via horizontal tuning bars
  • Power derived from USB port (no external power supply needed)
  • Separate HF/VHF antenna ports
  • Ability to embed and record UTC time in waterfall display
  • Can display schedule information in waterfall and spectrum
  • ES2 supported by third-party OEM and open-source SDR applications; not confined to Elad application (as tested)
  • Small form factor/footprint, convenient for travel or limited shack space
  • Networking features for remote receiver control (not tested)
  • Iterative agility: application/firmware updates influenced by customer feedback
  • Great value–$300 less than most of its competitors


  • Recording cannot be fully controlled from the front panel; to adjust most settings, you must do so via a separate settings window
  • Receiver turns off completely after stopping a recording (Elad plans to fix this)
  • AM sync currently lacks USB/LSB selectivity
  • Elad application has steeper learning curve than other OEM SDR applications
  • Though highly customizable (see pro), changing color schemes requires patience and practice
  • Some reports from users indicate that sensitivity may be compromised if you live near a blowtorch AM station
  • IF and AF recordings cannot be made simultaneously; AF recordings cannot be made from an IF spectrum recording without a virtual audio cable application (similar to the Microtelecom Perseus)


While the Elad FDM-S2 has some growing to do, I expect many of these concerns may be addressed in updates over time, and I look forward to trying the S2 with other SDR applications. I’m fairly confident that Elad is serious about their products’ iterative agility, which is to say, software development based on customer input. They’ve been responsive to email and active on the Elad Yahoo email discussion group, which indicates promise. I believe they’re serious about supporting the North American market as well as they even attended the 2014 Dayton Hamvention.

Frankly, at $580 US (via Elad USA) I think the FDM-S2 is quite reasonably priced, especially considering this SDR’s performance and features. After all, it’s only $80 more than the RFSpace SDR-IQ, while it is $300-400 less than the Microtelecom Perseus and WinRadio Excalibur. That’s good value, in my book.

But with each review, I always ask myself: “Would I buy it?”

For the Elad FDM-S2, the answer is, unhesitatingly, Yes! I intend to purchase the FDM-S2 from Elad immediately following the publication of this review. I believe it will make a fine addition to the shack–I can see myself using it often for travel, future DXpeditions, and, of course, shortwave radio archiving.

As always, the proof is in the pudding: look for my Elad FDM-S2’s coming contributions to the Shortwave Radio Audio Archive in the near future. And listen for yourself.

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