All India Radio DRM: Dan notes two simultaneous feeds

All India Radio (AIR) Headquarters in Dehli, India. Photo courtesy of Wikipedia.

All India Radio (AIR) Headquarters in Dehli, India. Photo courtesy of Wikipedia.

Many thanks to SWLing Post contributor, Dan Srebnick, who writes:

While DRM (Digital Radio Mondiale) has long been pronounced DOA (dead on arrival), All India Radio seems to be taking it pretty seriously. Here’s a screenshot of not one, but two simultaneous feeds going out over the same 10 kHz wide 40 meter frequency (7,550 kHz) at 2027 UTC today. The signal on my Perseus was just a tad under S9+5db using my ham band Alpha Delta DX-CC antenna.

image001So what’s the twist, aside from the 2 feeds on 1 frequency? Even at +5 over S9, the feed was only strong enough to occasionally flutter in with some decoded audio. Mostly, it was silence.

[I had] about a 98% successful decode by 2051 UTC when the signal rose to S9+10 db. I could switch between streams by clicking channel button within Dream!

Dan wrote the message above yesterday, I asked him if he could record AIR  today and he kindly sent the following:

AIR DRM recorded today with announcements @ 1930 UTC. Some dropouts as a
great example of the dropout/echo effect heard on DRM when signals are quite
strong enough. This decode was done at S9 signal strength.

Dan actually calls the DRM dropouts, the Max Headroom Effect.”  That is the best description I’ve ever heard, Dan.  Thanks for sharing your notes and recording!

Alexander reviews the Avion AV-DR-1410 DRM receiver


Many thanks to SWLing Post contributor, Alexander (DL4NO), for the following review of the new Avion DRM receiver:

A review of the Avion DRM receiver

by Alexander von Obert (DL4NO)

The Avion AV-DR-1401 DRM receiver has appeared on the SWLing Post before in a previous review.

Amazon India does not sell the Avion outside of India. As it happens, I found someone who was willing to buy it for me and bring it with him from India to Germany.

The first impressions were quite disappointing. This feels more like a prototype, not a polished product:

  • The power supply produces lots of interference and runs quite hot. Unless I find another power supply, I can either charge the battery or listen to the radio.
  • The handle rattles. Such things often are symptoms for the whole product.
  • The firmware fails in many ways: update errors of the display, very confusing user interface.
  • No acceptable field strength indicator, especially in DRM until a signal is decoded. If you have a selective antenna you need to switch to AM to tune it. And then you tune it by ear or by numbers. No bar of any kind.
Avion AV-DR-1410 DRM

Radio Romania

Radio Romania produced very good signals this evening in southern Germany on 41m. But with the built-in antenna, DRM reception was impossible even in my shack directly under the roof. A Degen 31MS selective active antenna indoors enabled sketchy reception of Radio Romania and All India Radio on 41m. Reasonable reception was only possible with my external antenna.

All India Radio

All India Radio

Just imagine why I took the trouble to get the receiver! It is a far cry from what I really wanted: a modern replacement of my trusty Sony ICF7600D from the 1980s. I had to retire it for mechanical reasons after it travelled with me for 20 years.

In India, they might not have the industrial infrastructure they have in China or Japan, but an intensive firmware update is urgently needed. Software is something they are good at in India. Many problems could be solved that way:

  • The volume knob has no stop and must be pressed for a few seconds to turn the radio on or off. A short press could be used to switch it between volume and tuning.
  • A reasonable field strength indicator should be introduced.
  • The remote control does not work reliably.
  • With the “mode” switch I can select AM, FM, or DRM. But I have not found anything that the “band” switch could be doing.
  • The “scan” switch works on FM and puts all transmitters found into the favorites. But neither is that the function I would expect it to do nor does it work on other bands.

From my preliminary tests I fear the unit has massive large-signal problems. For example, I heard distorted signals of Radio Romania on bands where they were not transmitting at all. I use an active antenna but this is the same I use for the DX Patrol or SDRplay RSP, therefore I know that my antenna is not to blame. I also see this as an indicator about the DRM signal of Radio Romania.

I could not help but open the Avion receiver: [the internal antenna worked so poorly, I wanted to investigate].

I must say that the rattling handle was an accurate indicator of production quality.

Inside the Avion

Inside the Avion

See “Inside the Avion” image above (click to enlarge). The back side on the left was originally covered by an aluminum shield. I had to remove it as the wires are quite short–one cannot put the two parts flat on the bench otherwise. You see that they tried to improve the shielding on the right.

AVION internal antenna preamp

Avion internal antenna preamp

See “Avion internal antenna preamp” above (click to enlarge). The circuit board at the lower left corner of the first picture is the preamp for the internal antennas. In the lower left corner is the telescopic antenna connection. The wire here was extremely short–either it broke before and made contact by chance or I broke it when I dismounted the circuit board. At least I did not force it (still a bad manufacturing practice).

If you examine the circuitry, you see very bad practices: C2 directly connects the antenna to the base of Q2. It must be a bipolar transistor considering R3/R4. At least there is DN1 which seems to be protection diodes. On the whole board I can find no inductivities at all. There is absolutely no band limiting.

AVION broken shilding wire

Avion broken shilding wire

See “Avion broken shielding wire” above. The shielding wire had broken from the soldering. That was definitely not my fault. At the yellow isolation, a second wire is connected. That is the wire routed around the backside without any connection. This doesn’t make sense to me.

Avion crushed battery holder

Avion crushed battery holder

See “Avion crushed battery holder” above. The battery holder is fixed together with the aluminum shielding. The worker crushed the lug of the battery holder while mounting the shield. A few other threads were torn, too. A typical case of too much strength.

Avion seems to know about the inherent RFI problems of this receiver, but could not solve them. No wonder I have to use an external antenna.

Perhaps I will replace the antenna preamp with something reasonable.

Otherwise this radio will gather dust here.

Thank you for your report, Alexander–I’m sorry to hear about your experiences with the Avion, especially after the trouble you went to obtaining it.

So far, I’ve heard no truly positive reviews of the Avion AV-DR-1410. Sadly, it sounds like a radio to avoid.

A review of the new Avion receiver and a few thoughts about DRM


Many thanks to SWLing Post reader, Mike Barraclough, for sharing a link to this review of the new Avion DRM receiver by DRM Radio Forum user PhilipOneL. I’ve pasted his evaluation of the Avion below–you can read this, along with the full discussion thread, on the DRM Radio Forum:

I received my Avion AV-DR-1401 this afternoon and have had it up and running for a couple of hours. There is no instruction booklet with it so I am puzzling over the 41-button remote. It is not as user-friendly as I hoped.

First impression: somewhat cheap feel to it. I have put a small bend already in the thin but long aerial. But that is just the outside (handle, volume control, master power switch, and aerial); I hope it works well anyway. But that cheapness hurts when the price of the radio was fairly high to begin with and I paid more than I wanted for a private company to ship it (Fedex).

The radio arrived with its battery fully charged: nice. (But I need to get an adaptor for the AC adaptor’s mains plug which has tubular prongs rather than the North American blade prongs.) I like a lot the fact that it runs normally with its internal battery rather than plugged into mains. This means I can carry it away from noise sources. And it is very carryable — it reminds me of a small 1965-era beach radio in size.

Turned on, it scanned the local FM spectrum well and registered all the local stations. But I cannot get the Scan function to operate on MW and SW, nor in DRM mode. With an outside antenna (8 metre wire) attached, it was able to get the AIR DRM broadcast on 7550 kHz and decode it. It didn’t seem to be able to get enough signal with just the extending aerial.

I have not figured out yet how to make it register a medium-wave, shortwave, or DRM station in its memory; it does not happen when the button labelled “Delete / Store” is pushed. Among the 41 buttons, there is no other likely candidate for that function.

Shortwave sensitivity in AM mode seems to be poor. I was listening, for instance, to ERT Greece on 9420 on the three receivers now on my desk: Satellit 750, MorphyRichards 27024, and the Avion DR-1401, each in turn connected to the same outdoor antenna. The MR27024 produces the best sound and greatest s/n ratio. It seems far more sensitive than the Avion. But who knows? I may discover I am doing something wrong with the set.

Tuning can be done by inputting a frequency on the remote. Alternatively, the volume wheel can be pushed (this takes two hands) to convert it to a tuning knob. Two problems are apparent. One is that the signal is muted as you tune until you wait on a frequency for four or five seconds. Thus it is a slow and aggravating experience to try to tune across a band looking for signals. Secondly, as soon as a station is tuned and producing audio, the knob goes back to being a volume control. Grrrr. (I think there is a professor at all the design schools who seems to be telling all her/his students to be visually minimalist in design and to give every knob multiple functions. That professor should be publicly shamed until she/he recants and causes all the students to go back to multiple knobs each of which does one thing well.) When the radio gets itself ready to produce audio it seems to ramp itself up to full audio in a series of four steps, each a half-second or so after the last — it is an odd-sounding process. It is like a faulty AGC circuit; perhaps it is.

Sound quality is mediocre at best on AM (both mw and sw). I didn’t listen long enough to the DRM signal from AIR before it signed off to get a good idea of DRM audio quality; I was busy cooking supper. FM audio is mediocre too on the internal speakers but, piped out through the headphone jack to external speakers, it is quite good. When I piped the AM audio out it still seemed mediocre.

Why the AM sound is mediocre seems to be related to two things: the tiny speakers (about 8 cm or 3.3 inches) and the bandwidth at the radio stage. Even comparatively strong (and clean) signals like RHC on 6000 kHz have what may be adjacent signals mixing in — perhaps even internal mixing products? I heard a splash of a local FM station at one point while listening to a shortwave band.

I have written my contact at Avion (Ankit) asking for an instruction booklet, or a pdf of one. I hope I’ll get that early next week (if indeed they have one).

I hope over the next week I will get some chances to check out more DRM signals. I am also hoping that my gradual love affair with the MorphyRichards radio will be replicated here. When I first got the MR27024 I was very cranky about its weird ways of doing things. But once I got a good antenna on it, and got used to its ways, I prefer it to all my other radios as a table-top radio (that is, one useful for listening to specific regular stations). The MR’s radio-stage DSP is quite lovely and makes for good sound. I doubt the Avion will seduce me to quite the same extent, but it may grow on me in other ways.

I understand the problems with DRM but I am still a fan of of the system. I bought this Avion set partly in hopes that I would encourage the manufacturer in some small way. I will use it but I suspect that the minimalist design features (which were also a part of the MorphyRichards design) will turn off users of the Avion.

I’m not terribly surprised by this reviewer’s assessment. Just looking at some of the preliminary info on the Avion receiver last year made me think of previous DRM portables like the Newstar DR111 and the Uniwave Di-Wave 100.

The UniWave Di-Wave/Di-Wave 100.

The UniWave Di-Wave/Di-Wave 100.

I have a hunch all of these designs were fleshed out by engineers and entrepreneurs who had not gotten customer input in advance.

It’s sad, too. While I know DRM (via the shortwaves) was a “cart before the horse” innovation–meaning, broadcasters adopted the technology well before consumer receivers were on the market.

I really wish the medium would’ve gained traction.

While I prefer the rich sonic texture of amplitude modulation, I love listening to DRM broadcasts well. Last year, during my presentation at PARI, I played a recording of a piano concerto I heard on one of Radio New Zealand International’s DRM broadcasts. If memory serves, the audio clip was taken from this recording I made on June 21, 2104:

Through the presentation room’s hi-fi system, the music sounded absolutely brilliant.

To put what this audience was hearing in perspective, I told them:

“We’re listening to a radio station some 8,300 miles away without the use of the Internet, mobile phones, satellites, or any sort of subscription service. We’re hearing FM-quality audio, streamed wirelessly and originating from the other side of our planet.”

I then received a number of questions like: “How is this technology possible?” and “Do they make car radios that can receive these broadcasts?”

There’s magic in DRM. Sadly, I feel its deployment was awkward and its window of opportunity may have already passed. An affordable, effective, and simple DRM receiver (combined with serious, viral publicity) could turn the tide somewhat–but it doesn’t seem like this will happen anytime soon. Each new DRM portable is only a slightly improved iteration of its predecessor and the price tag continues to be too high for effective market penetration.

I want to be proven wrong, though.

Avion DRM Receiver now shipping via Amazon India


The Avion portable DRM receiver is now available on Amazon India (click here to view). It’s being sold for 14,999.00 INR (roughly $230 US).

At time of posting, The Avion DRM receiver only has one review by someone who has (obviously) never used the radio. They give one star then state: “price is very high. so i hate this product.


While I dismiss reviews like this, I must believe that this price is, indeed, high for most Indian consumers; especially when compared with alternate forms of media consumption (smart phones, analog radio, FTA satellite TV, etc.). It would be high for me, too.

I hope, at least, that the Avion performs well. I have no plans to review the Avion DRM receiver at this point simply because it’s challenging for me to find and decode DRM here in North America with my SDRs hooked up to large external antennas. Don’t get me wrong–occasionally, I do get amazing copy–but it’s typically when conditions are favorable. Listeners in Europe, Asia, and Oceana would have better results, no doubt.

Has anyone seen an objective review of the Avion DRM receiver? Please comment.

Click here to view the new Avion DRM receiver on

The Avion AV-DR -1401 DRM receiver to ship in October


Many thanks to several SWLing Post readers who shared this RadioWorld article about the new Avion AV-DR -1401 portable DRM receiver. According to RadioWorld, the AV-1401 will be sold through Amazon India as of October 2015 for approximately $175 US.

Click here to read the full article.

Special DRM broadcast to Europe

drmlogoMany thanks to Mauno Ritola who shares a link to the following schedule from the DRM Consortium via the WRTH Facebook page:

During IBC, Babcock will be transmitting DRM service from the UK, towards Europe.

[Friday September 11, 2015 to September 15, 2015]

  • 1600-1700 local Amsterdam time (1400-1500 GMT), BAB Woofferton, 100 kW, 6040 kHz, 114 degrees (Programme TBA)

  • 1700-1800 local Amsterdam time (1500-1600 GMT), BAB Woofferton, 100 kW, 6040 kHz, 114 degrees (BBC WS English)

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.