Listening to Radio Prague via WRMI with the Xiegu GSOC
Many thanks to SWLing Post contributor, Tim R, who writes:
First of all thank you so much for the all of the energy you put into the SWLing Post. When crazy things are happening in the world it’s a very welcome sanctuary! Sending you some coffee money.
I plan to become a ham radio operator next year. Bought the book last week and once I finish a large project for work, I’m on it. Of course, the Tech license will only give me limited exposure to HF, but I’m already plotting an HF radio purchase because I can’t WAIT do do some SWLing with it. Up to this point, I’ve only owned portable radios and never really have used external antennas other than some cheap wire.
I’ve been considering grabbing a Xiegu G90 because it seems to be a nice comprehensive beginner’s HF rig and is very affordable. I read your review and understand your caveat that there’s no way to completely disengage the transmit so that it can’t be accidently hit if connected to an RX only antenna. I’m not worried about that because I’m going to hang a G5RV wire antenna and use it both for TX and RX. No problem if RF is accidently sent through it.
Of course, there’s a lot of buzz in the Xiegu community about the new GSOC controller. I had not planned to exceed $600 for my radio purchase, but I love the idea of the controller. But when I add $550 for the controller and $450 for the radio, all the sudden I’m at $1,000.
After some deep soul-searching (and let’s be frank here, a blessing from my wife and CFO) I’ve decided to raise my budget to $1,000.
All of this to ask, if you had $1,000, would you buy the G90 and GSOC controller, or would you get something else keeping in mind I want to use this as much for shortwave listening as for future ham radio work?
Any advice would be appreciated.
Thanks for your question, Tim! And thanks for giving me a complete picture of your budget/radio requirements and the antenna you plan to use.
I’ll try to answer your question here, but understand this is more what I would do if I were in your shoes. This is a pretty simple question, but not simple to answer because there are so many options on the market.
Xiegu GSOC and G90 combo option
Keeping in mind, I feel like the GSOC is a work in progress at the moment and not fully developed–check out my initial review. Once the next firmware update is available it could certainly solve a number of small issues I found with the unit. It works, but it’s not a refined product yet.
It’s ironic, actually. When I received your message this morning, Tim, I was SWLing with the GSOC and G90–listening to Radio Prague on WRMI. In the end, though, the GSOC is primarily an enhanced interface for the G90. While it does add some extra functionality (and should, over time, add much more) it doesn’t really change the performance characteristics of the G90. I’d check out my G90 review for more info about performance.
Would I purchase the G90/GSOC combo if I were in your shoes? Again, it’s early days, so I don’t feel comfortable making a recommendation call yet. The G90 is, without question, a great value at $450 (often even less) investment. I like it primarily as a field radio, though, and once you add the GSOC to the mix, it’s a little less portable because it’s two units with quite a few interconnect cables. Of course, you can swap the GSOC unit for the G90 control head at any time, but that involves attaching and re-attaching the control head each time (there’s no accessible serial port on the back of the G90, for example)
If you’re a huge fan of the G90, the GSOC should eventually be a worthy addition. At present, for your use as a new ham and for SWLing, I’d perhaps consider other options too.
The Icom IC-7300
The Icom IC-7300 SDR transceiver
Since you’ve raised your budget to $1,000, I’d consider adding the Icom IC-7300 to your list. At present, via Universal Radio you can buy a new IC-7300 for a net price of $1039.95 after rebates. Sometimes, the price will go even lower although during the C-19 pandemic, I think that’s less likely to happen since supplies are lower than normal for many items.
The IC-7300 has better performance specs than the G90 and can output a full 100 watts if you like. The display is touch sensitive rather than capacitive like the GSOC. The display is also much smaller than that of the GSOC. The IC-7300 has a lower noise floor than the G90.
I would include the new Icom IC-705 as a recommendation here, too, but it’s $300 over your budget.
A PC-connected SDR and separate transceiver
This might be the option I’d take if I were in your shoes.
Get the 20 watt Xiegu G90 ($450) as planned or consider a radio like the 100 watt Yaesu FT-891 ($640), Both of these radios are general coverage and would serve you well for SWLing and ham radio activities. I’d personally invest the bit extra and get the FT-891 since it would also give you 100 watts output and even has advanced features like memory keying.
The AirSpy HF+ Discovery and a new era of portable DXing
I admit it: I used to be a bit of an old-fashioned radio curmudgeon. One of those, “I like my radios with knobs and buttons” likely followed by, “…and no other way!”
However, about fifteen years ago, many of my DXing friends started turning to the world of software defined radios (or in common parlance, “SDRs”). I staunchly opposed ever following in their footsteps. One of the reasons I for this––a good one––is that, since I spend the bulk of my day in front of a computer, why would I ever want to use a computer when I’m playing radio?
But then…gradually, I found myself playing around with a few SDRs. And I quickly learned that third-generation SDRs were capable of doing something very impressive (and fun), indeed: making spectrum recordings. Using this tool, I found I could record not only the audio of one individual signal, but the audio of entire swathes of radio spectrum. And even more impressive, I learned that you could later load or “play back” the spectrum recording and tune through the bands as if in real time. Any time you want. Before long, I was hooked: SDRs had become my portal into radio time travel!
I quickly found that I loved many of the other advantages of using an SDR, as well, including visual ones––like the ability to view spectrum. The interactive interface allows one to actually see radio signals across the band in real time. I also found incredible value in waterfall displays, which show signals changing in amplitude and frequency over time. Cool stuff.
I purchased my first dedicated SDR in 2012, a WinRadio Excalibur. It was––and still is––a benchmark receiver, performing circles around my tabletop receivers and general coverage transceivers.
And today, although I own and love a number of legacy radios and still listen to them in the good old-fashioned manner to which I became accustomed, I find I’m now spending the bulk of my time DXing with SDRs.
And then, more recently, two amazing things happened in the world of SDRs. Strong market competition, together with serious innovations, have come into play. Thus, for less than $200 US, you can now purchase an SDR that would have easily cost $1,000 US only ten years ago. And now, in many cases, the $200 SDR of today will outperform the $1,000 SDR of yesteryear. We are, indeed, living in good times.
And now––no more a radio curmudgeon––I’m comfortable with my SDR-user status and time at the computer, and glad I was just curious enough about SDRs to let them into my radio (and computer) world.
Since I initially dived into the world of SDRs, I’ve tried to think of a way to take them into the field.
But first, let’s get an obvious question out of the way:
Why would you want to drag an SDR into the field, when a traditional battery-powered radio is so much easier to manage?
After all, you may say, portable and even mobile tabletop receivers require no computer, no hard drive, and are likely more reliable because there are less components to manage or to cause problems for you.
In answer, let’s look at a few scenarios where heading to the field with an SDR system might just make sense. (Hint: Many of these reasons are rooted in the SDR’s ability to record spectrum).
Good Reason #1: Your home location is not ideal for playing radio.
Photo by Henry Be
My good friend, London Shortwave, lives in the middle of London, England. He’s an avid radio enthusiast and DXer, but his apartment is almost a perfect storm of radio interference. Listening from his home is challenging, to say the least: he can only use indoor antennas and RFI/QRM simply inundated his local airwaves.
Many years ago, he discovered that the best way to DX was to go to an area that put urban noise and radio interference at a distance. He found that by visiting large local parks, he could play radio with almost no RFI.
Being a computer guru, he started working on a portable SDR setup so that he could go to a park, set up an antenna, and record radio spectrum while he read a book. His systems evolved with time, each iteration being more compact less conspicuous that the previous. Later, he could head back home, open the recorded spectrum files, and tune through these “time-shifted” recordings in the comfort of his flat. This allowed London Shortwave to maximize the low-RFI listening experience by reliving the time in the park.
Over the years, he tweaked and adapted his setup, often writing his own code to make small tablets and portable computers purpose-built portable-spectrum-capture devices. If you’re curious, you might like to read about the evolution of his systems on his blog.
Clearly, for London Shortwave, an SDR is the right way to capture spectrum and thus likely the best solution for his DX listening.
Good Reason #2: Weak-signal workarounds.
Typically radio enthusiasts turn to field operation to work in a lower-noise environment and/or where there are no antenna restrictions, often to log new stations and DX.
SDRs afford the DXer top-shelf tools for digging weak signals out of the muck. SDR applications have advanced tools for tweaking AGC settings, synchronous detectors, filters, noise reduction, and even to tailor audio.
The WinRadio Excalibur application even includes a waterfall display which represents the entire HF band (selectable 30 MHz or 50 MHz in width)
On top of that, being able to see a swath of spectrum and waterfall gives one an easier way––a visual way––to pinpoint weak or intermittent signals. This is much harder to do with a legacy radio.
Case in point: I like listening to pirate radio stations on shortwave. With a spectrum display, I can see when a new station may be tuning up on the band so can position the receiver to listen in from the beginning of the broadcast, and never miss a beat.
Or, in another example, the visual aspect of spectrum display means I can easily locate trans-Atlantic DX on the mediumwave bands by looking for carrier peaks on the spectrum display outside the standard North American 10 kHz spacing. The signals are very easy to spot.
Good Reason #3: DXpeditions both small and large.
Mark Fahey, scanning the bands with his WinRadio Excalibur/Surface Pro 2 combo at our 2015 PARI DXpedition
Whether you’re joining an organized DXpedition or you’re simply enjoying a little vacation DXpedition, SDRs allow you to make the most of your radio time.
Indeed, most of the organized DXpedition these days heavily incorporate the use of SDRs specifically so DXers can record spectrum. Much like example #1 above, doing this allows you to enjoy the noise-free optimal conditions over and over again through spectrum recordings. Most DXpeditioners will have an SDR making recordings while they use another receiver to DX in real time. Later, they take the recording home and dig even more weak signals out of the mix: ones that might have otherwise gone unnoticed.
Good Reason #4: Sharing the spectrum with like-minded listeners.
Earlier this year, Mark gave me this 8TB hard drive chock-full of spectrum recordings.
One of the joys I’ve discovered in making field spectrum recordings is sharing them with fellow DXers. Most of the time when I go to shortwave radio gatherings (like the Winter SWL Fest), I take a couple hard drives to exchange with other SDR enthusiasts. My friend, Mark Fahey, and I have exchanged some of our favorite spectrum recordings this way. I give him a hard drive chock-full of terabytes of recordings, and he reciprocates. Back home (or on the train or airplane) I open one of his recordings and, boom! there I am in his shack in Freeman’s Reach, Australia, tuning through Pacific stations that are not easily heard here in North America, maybe even turning up some gems Mark himself may have overlooked…just as he is doing with my recordings from the southeast US.
I’ve also acquired DXpedition spectrum recordings this way. It’s great fun to “be there” through the recordings and to enjoy some of the benefits of being on the DXpedition in times when I couldn’t actually make it there in person. For a DXer with a consuming job, busy family life, or maybe health problems that limit their travel, an SDR recording is the way to go.
Good Reason #5: Family time
Photo by David Straight
I’m a husband and father, and no matter how much I like to play radio when we’re on vacation, my family comes first, and our family activities take priority.
Having a field-portable SDR setup means that I can arrange a “set it and forget it” spectrum capture device. Before we head out the door for a family visit, tour of the area, or a hike, I simply set my SDR to record spectrum, then listen to what I “caught” after I return, or after I’m home from vacation.
This practice has allowed me to enjoy radio as much as I like, without interrupting our family adventures. Can’t beat it!
With all of these benefits, one might wonder why many other DXers haven’t been using portable SDRs in the field for a while now? That’s a good question.
The WinRadio G31DDC, like many SDRs of the era, has separate data and power ports
In prior years, DXers and listeners might have been reluctant to lug an SDR and its requisite apparatus out with them. After all, it’s only been in the past decade or so that SDRs haven’t required a separate custom power supply; some legacy SDRs either required an odd voltage, or as with my WinRadio Excalibur, have very tight voltage tolerances.
Originally, taking an SDR to the field––especially in places without grid mains power––usually meant you also had to take a pricey pure sine wave inverter as well as a battery with enough capacity to run the SDR for hours on end.
Having spent many months in an off-grid cabin on the east coast of Prince Edward Island, Canada, I can confidently say it’s an ideal spot for DXing: I can erect large wire antennas there, it’s on salt water, and there are literally no locally-generated man-man noises to spoil my fun. Of course, anytime we go to the cottage, I record spectrum, too, as this is truly a honey of a listening spot.
The view from our off-grid cabin on PEI.
The first year I took an SDR to the cabin, I made a newbie mistake: it never dawned on me until I arrived and began to put it to use that my Goal Zero portable battery pack didn’t have a pure sine wave inverter; rather, I found it had a modified sine wave inverter built into it. The inverter could easily power my SDR, sure, but it also injected incredibly strong, unavoidable broadband noise into the mix. It rendered my whole setup absolutely useless. I gave up on the SDR on that trip.
Both the Airspy HF+ (top) and FDM-S2 (bottom) use a USB connection for both data transfer and power. Photo by Guy Atkins.
Today, most SDRs actually derive their power from a computer or laptop through a USB cable, one that doubles as a data and power cable. This effectively eliminates the need for a separate power system and inverter.
Of course, your laptop or tablet will need a means of recharging in the field because the attached SDR will drain its battery a little faster. Nowadays it’s possible to find any number of portable power packs/banks and/or DC battery sources to power laptops or tablets, as long as one is cautious that the system doesn’t inject noise. This still requires a little trial and error, but it’s much easier to remedy than having two separate power sources.
Even a Raspberry Pi 3B has enough horsepower to run SDR applications.
An SDR is nothing without a software application to run it. These applications, of course, require some type of computer.
I the past, SDR applications needed some computing horsepower, not necessarily to run the application itself, but to make spectrum recordings. In addition, they often required extra on-board storage space to make these recordings sufficiently long to be useful. This almost always meant lugging a full-sized laptop to the field, or else investing in a very pricey tablet with a hefty amount of internal storage to take along.
Today we’re fortunate to have a number of more portable computing devices to run SDR applications in the field: not just laptops or tablets, but mobile phones and even mini computers, like the eminently affordable $46 Raspberry Pi. While you still have to be conscious of your device’s computing horsepower, many small devices are amply equipped to do the job.
64-128 GB USB flash/thumb drives are affordable, portable storage options.
If you’re making spectrum and audio recordings in the field, you’ll need to store them somehow. Wideband spectrum recordings can use upwards of 2GB of data per minute or two.
Fortunately, even a 64GB USB flash drive can be purchased for as little as $7-10 US. This makes for quick off-loading of spectrum recordings from a device’s internal memory.
My portable SDR setup
It wasn’t until this year that all of the pieces finally came together for me so that I could enjoy a capable (and affordable!) field-portable SDR setup. Two components, in particular, made my setup a reality overnight; here’s what made the difference.
The AirSpy HF+ Discovery
Last year, AirSpy sent me a sample of their new HF+ Discovery SDR to test and evaluate. To be fully transparent, this was at no cost to me.
I set about putting the HF+ Discovery through its paces. Very soon, I reached a conclusion: the HF+ Discovery is simply one of the best mediumwave and HF SDRs I’ve ever tested. Certainly, it’s the new benchmark for sub-$500 SDRs.
In fact, I was blown away. The diminutive HF+ Discovery even gives some of my other benchmark SDRs a proper run for their money. Performance is DX-grade and uncompromising, sporting impressive dynamic range and superb sensitivity and selectivity. The noise floor is also incredibly low. And I still can’t wrap my mind around the fact that you can purchase this SDR for just $169 US.
The HF+ Discovery compared in size to a DVD
In terms of portability, it’s in a class of its own. It’s tiny and incredibly lightweight. I evaluate and review SDRs all the time, but I’ve never known one that offers this performance in such a tiny package.
Are there any downsides to the HF+ Discovery? The only one I see––and it’s intentional––is that it has a smaller working bandwidth than many other similar SDRs at 768 kHz (although only recently, Airspy announced a firmware update that will increase bandwidth). Keep in mind, however, that the HF+ series SDRs were designed to prevent overload when in the presence of strong local signals. In fairness, that’s a compromise I’ll happily make.
Indeed, the HF+ Discovery maximum bandwidth isn’t a negative in my estimation unless I’m trying to grab the entire mediumwave band, all at once. For shortwave work, it’s fine because it can typically cover an entire broadcast band, allowing me to make useful spectrum recordings.
The HF+ Discovery is so remarkably tiny, that this little SDR, together with a passive loop antenna, can fit in one small travel pouch. Ideal.
My homebrew NCPL antenna
Speaking of antennas, one of the primary reasons I’m evaluating the HF+ Discovery is because it has a very high dynamic range and can take advantage of simple antennas, in the form of passive wideband magnetic loop antennas, to achieve serious DX.
AirSpy president and engineer, Youssef Touil, experimented with several passive loop antenna designs and sizes until he found a few combinations ideally matched with the HF+ Discovery.
My good buddy, Vlado (N3CZ) helped me build such an antenna per Youssef’s specifications. Vlado had a length of Wireman Flexi 4XL that was ideal for this project (thanks, Vlad!). The only tricky part was penetrating the shielding and dielectric core at the bottom of the loop, then tapping into both sides of the center conductor for the balun connections. Being Vlado, he used several lengths of heat shrink tubing to make a nice, clean, snag-free design. I’ll freely admit that, had I constructed this on my own, it wouldn’t have been nearly as elegant!
Youssef also sent me a (then) prototype Youloop passive loop antenna. It’s incredibly compact, made of high quality SMA-fitted coaxial cables. It can be set up in about 30 seconds and coiled to tuck into a jacket pocket. The AirSpy-built loop has a lower loss transformer than the one in the homemade loop, which translates into a lower noise figure for the system.
Let’s face it: SDR kit simply doesn’t get more portable than this.
My Microsoft Surface Go tablet on a hotel bed.
In the past, I used an inexpensive, circa 2013 mini Windows laptop with an internal SSD drive. Everything worked beautifully, save the fact that it was challenging to power in the field and the internal capacity of the hard drive was so small (16GB less the operating system). In addition, it was a few years old, bought used, so the processor speed was quite slow.
This year, on the way back from the Huntsville Hamfest, I stopped by the Unclaimed Baggage Center in Scottsboro, Alabama. This center has a wide variety of used portable electronics at discount prices. I felt pretty lucky when I discovered a like-new condition Microsoft Surface Go tablet and keyboard with original charger for $190. The catch? The only data port on the tablet is a USB-C. But I grabbed a small USB-C to standard USB 3.0 dongle (for $2!) and took a risk that it would work with the HF+ Discovery.
Fortunately, it did! Score!
While the Surface Go is no powerhouse, it’s fast enough to run any of my SDRs and make spectrum recordings up to 2 MHz in width without stuttering. The only noise it seems to inject into the mix is a little RFI when I touch the trackpad on the attached keyboard.
One of my LiFePo batteries
The HF+ Discovery draws power from the Surface Go tablet via the USB port. With no additional power supply, the Surface Go may only power the HF+ Discovery for perhaps an hour at most. Since I like doing fully off-grid operations and needed to avoid RFI from inverters, I needed a portable power solution.
Fortunately, the Surface Go has a dedicated power port, so I immediately ordered a DC power cable with a standard car lighter plug.
The LiFePo battery is small, lightweight, and can power the tablet /SDR combo for hours on end. Moreover, I have noticed no extra noise injected when the DC power is applied.
My HF+ Discovery-based portable SDR kit
My portable SDR kit on a hotel balcony.
Now I have this kit, I couldn’t be more pleased with it. When all of the components of my SDR system are assembled, they work harmoniously. The entire ensemble is also incredibly compact: the loop antennas, SDR, Surface Go tablet, battery, and distribution panel all fit in a very small travel pack, perfect for the grab-and-go DX adventure.
The entire kit: SDR, cables, Youloop antenna, connectors and adapters all fit in my Red Oxx Lil’ Roy pack.
In November, I took the kit to the coast of South Carolina and had a blast doing a little mediumwave DXing from our hotel balcony. We were very fortunate in that I had two excellent spots to hang the homemade loop antenna: on the main balcony, and from the mini balcony off the master bedroom. Both spots yielded excellent results.
What impressed me most was the fact that the SDR# spectrum display and waterfall were absolutely chock-full of signals, and there was very little noise, even in the popular resort area where we were staying. I found that my portable radios struggled with some of the RFI emanating from the hotel, but the HF+ Discovery and passive loop combo did a much better job mitigating noise.
Check out the AM broadcast band on the spectrum display.
But no need to take my word for it. If you would like to experience it first hand, why not download an actual spectrum recording I made using this setup?
At the top left corner of the SDR# screen, choose “IQ File (.wav)” as the source, then point it to where you downloaded the file.
Press the play button, and experience a little radio time travel!
This particular recording was made on the mediumwave band on November 17, 2019, starting at around 01:55 UTC.
My portable SDR kit capturing spectrum during a hike in Pisgah National Forest.
I’ve also taken this setup to several parks and remote outdoor locations, and truly enjoyed the freedom of taking spectrum recordings back home to dig through the signals.
I finally have a portable SDR system that allows me the flexibility to make spectrum recordings while travelling. The whole setup is compact and can easily be taken in a carry-on bag when flying.
The glory of this is, I can tune through my spectrum recordings in real time and DX when I’m back home, or even on the way back home, in the car, train, or airplane. It’s simply brilliant.
If you don’t already own an SDR, I can highly recommend the AirSpy HF+ Discovery if you’re primarily interested in HF and MW DXing. If you need a wideband SDR, I could also recommend the recently released SDRplay RSPdx, although it’s slightly heavier and larger than the AirSpy.
Thankfully, I am now an SDR enthusiast that can operate in the field, and this radio has had a lot to do with it. I’ll be logging many hours and miles with the AirSpy HF+ Discovery: its incredibly compact footprint, combined with its brilliant performance, is truly a winning combo.
Many thanks to SWLing Post contributor, Ivan (NO2CW), who writes:
The new RSPdx has what they call “High Dynamic Range: (HDR) mode below 2 mHz. I tested a day after receiving the new unit by turning HDR mode on and off. It seemed to make quite a difference when receiving Non Directional Beacons.
As far as Medium Wave itself, I did see some difference but it was harder to make conclusions there as propagation of weak signals on medium wave can change up and down in the course of a minute and some additional testing on Medium Wave will be done in the future. Overall for anyone interested in the world below 2 mHz HDR mode is definitely something to explore!
For over two weeks now, I’ve had an early production model of the RSPdx here in the shack operating on a beta version of the SDRuno application.
In the spirit of full disclosure, SDRplay is a long-time supporter of the SWLing Post and I have alpha- and beta-tested a number of their products in the past. This early production RSPdx was sent to me at no cost for a frank evaluation, and that’s exactly what I’ll offer here. To be clear, while I am using beta software, this is not a beta SDR, but one from a first limited production run.
And thus far, I must say, I’m impressed with the RSPdx.
The RSPdx has been introduced as a replacement for the RSP2 and the RSP2pro receivers. It has been updated and upgraded, with a completely new front-end design.
Here are the highlighted improvements and changes:
Performance below 30 MHz has been enhanced when compared to the RSP2/RSP2pro.
Performance below 2 MHz has been substantially upgraded. Through the use of the new HDR mode, both dynamic range and selectivity have been considerably improved.
There is now a BNC antenna connector on antenna C position instead of a HiZ port. Both A and B antenna ports are SMA like other RSP models.
Let’s face it: those of us interested in low-cost SDRs are spoiled for choice these days. The market is chock-full of sub-$200 SDRs, especially if you include all of the various RTL-SDR-based SDRs and knock-off brands/models one can find on eBay.
Personally, I invest in companies that support radio enthusiasts for the long haul…those that do their own designs, innovations, and production. SDRplay is one of those companies.
SDRplay’s market niche has been providing customers with affordable, high-performance wideband receivers that cover an impressive 1 kHz to 2 GHz.
Wideband coverage can come at a cost. Unless you pay big money for a commercial-grade wideband receiver, you’re going to find there’s a performance compromise somewhere across the spectrum. On the RSP2 series, those compromises would have been most apparent on frequencies below 30 MHz.
That’s not to say HF, MW, and LW performance was poor on the RSP2 series–indeed, it was quite impressive and well-balanced; it just didn’t stack up to the likes of the similarly-priced AirSpy HF+ and HF+ Discovery, in my humble opinion. Both little Airspy SDRs have wooed DXers with their impressive dynamic range and overall ability to work weak signals in the HF portion of the spectrum.
Neither of the AirSpy HF+ models are wideband receivers, but still offer a generous range: 9 kHz to 31 MHz and from 60 to 260 MHz––about 11.5% of the frequency coverage of RSP models. (Note that the Airspy R2 and Mini do cover 24 – 1700 MHz.) For shortwave radio listeners that also want to venture into the UHF and SHF regions, a wideband SDR is still required.
It’s obvious SDRplay’s goal is to make the wideband RSPdx into a choice receiver for HF and, especially, for MW/LW DXers. But have they succeeded? Let’s dive in…
As I say in most of my SDR reviews: doing comparisons with receivers that have so many features and adjustments is never easy. In other words, we want an apples-to-apples comparison, but it can be difficult to achieve, especially with new products.
The RSPdx, Excalibur, and HF+ Discovery all used the same antenna in my tests––a large, horizontal delta loop antenna, via my ELAD ASA15 amplified antenna splitter. I’ve used this antenna splitter for years and can vouch for its equitable, lab-grade distribution of signal.
The RSPdx is not in full production at time of posting, thus application options are limited. Typically, I’d load comparison SDRs in SDR Console or HDSDR and test them with identical settings as well. At present, the RSPdx is only compatible with a beta version of SDRplay’s own application, SDRuno (which will come out of beta rior to the first major production run). The benefit of using SDRuno is that you unlock the full potential of the RSPdx, plus signal and noise numbers are incredibly accurate.
For each SDR in this comparison, I used their native/OEM application to give them the best possible performance.
I also matched filter settings and made an effort to match AGC and volume settings as closely as I could.
Additionally, I resisted the temptation of comparing my RSP2 with the new RSPdx because I didn’t want to run two simultaneous instances of SDRuno on the same computer––especially considering one was in beta.
Is this comparison perfect? Probably not, but I did the best with the time I had available. I do intend to make further comparisons in the future.
Via the RSPdx’s new “HDR” mode, both dynamic range and selectivity have been considerably improved with frequencies below 2 MHz. While I’ll fully admit that I’m not much of a longwave DXer, my very first listening session with the RSPdx started in this region of the spectrum.
In fact, the first evening I put the RSPdx on the air and confirmed that I was, indeed, in HDR mode, I noticed a small carrier via the spectrum display on 171 kHz. I clicked on it and quickly discovered it was Medi 1. The signal was faint, but I could clearly ID at least one song. This truly impressed me because I believe this was the first time I had logged Medi 1 on longwave from the shack.
I didn’t connect the Excalibur at that point to see if it could also receive the faint Medi 1 signal, but I imagine it could have. I’m pretty sure this would have been outside the reach of the RSP2, however.
I tried to explore more of the longwave band, but due to local RFI (I suspect an appliance in my home), most of the LW band was inundated with noise. With that said, I did grab three of my benchmark non-directional beacons.
Obviously, the RSPdx is a capable LW receiver. I would like to spend more time on this band once I’ve tracked down the source of my local RFI.
In the past two weeks, I’ve spent many hours with the RSPdx on mediumwave.
We’re heading into the winter months in the northern hemisphere, and that’s normally when my listening habits head south on the bands.
In short: I find the RSPdx to be quite sensitive and selective on the mediumwave bands while the HDR mode is engaged. A major improvement over its predecessor.
I primarily compared the RSPdx with my WinRadio Excalibur on mediumwave since I consider the Excalibur to be a benchmark MW receiver. And, as you’ll hear in the screencasts below, the RSPdx truly gives the Excalibur a run for its money:
Note that my horizontal delta loop antenna is omni-directional, hence the tug-of-war you hear between stations in the clips above.
In truth, I could have done more to stabilize the signal on both of these fine SDRs, but I wanted to keep the comparison as fair as possible.
You might have noticed that both were running AM sync mode. It seems the sync lock on the RSPdx may have also improved––though I would need to do a direct comparison with the RSP2 to know for sure––but in terms of stability, I still found that the WinRadio Excalibur was superior. Mind you, the Excalibur is a $900 – $1,000 receiver and has the strongest synchronous detector of any radio I’ve ever owned.
SDRplay notes on the preliminary specifications sheet that the RSPdx has been “enhanced” when compared with the RSP2 series.
And, after having spent two weeks with the RSPdx on the shortwave bands, I would say this is a bit of an understatement. For although I haven’t compared the RSPdx directly with the RSP2 yet, I do feel HF performance is substantially better than its predecessor. Indeed, in my comparisons, I often found it gave the Excalibur some serious competition. Overall, the Excalibur had an edge on the RSPdx, but the gap has closed substantially. That’s saying something.
For the comparison videos below, I also included the excellent AirSpy HF+ Discovery.
As you can see and hear, the RSPdx is now in the league of some of the finest HF receivers in my arsenal.
But I’m curious to know what you think after listening to these comparisons. Please comment!
For those of you living in areas with DAB/DAB+ broadcasters nearby, you’ll be happy to note that the RSPdx has a DAB filter to help mitigate any potential overloading.
Also, if you live near a blowtorch mediumwave station, you’ll be quite pleased with the MW notch filter. It’s so effective at filtering out the mediumwave band, my local blowtorch on 1010 kHz is barely visible on the spectrum once the notch filter is engaged. (Note: I should add that neither the DAB nor the mediumwave notch filter was engaged during any of my previous comparisons above.) Check out the screen shots below showing the mediumwave band before and after the MW notch filter is engaged:
For those of you looking for a budget wideband SDR with solid performance below 30MHz, look no further.
For $199 US, you’re getting a quality UK-designed and manufactured SDR in a proper metal housing. The OEM application, SDRuno, is one of my favorite SDR applications and can fully take advantage of the RSPdx’s new HDR mode. No doubt, with a little more time, most third-party SDR applications will also support the RSPdx.
Frankly, I was expecting classy mediumwave and longwave performance as this was the most touted upgrade of the RSPdx. SDRplay certainly delivered.
In my experience, SDRplay doesn’t oversell their products. Their preliminary product sheet mentioned improved performance on HF, but their press release didn’t even mention the HF upgrades. And this is where I, in particular, noticed significant improvement. Perhaps this is because I am primarily an SWLer, thus spend a larger portion of my time in the HF region.
SDRplay products also have a mature, robust SDR application via SDRuno. Day to day, I tend to use Simon Brown’s SDR Console as my primary SDR application, since it’s compatible with so many of my SDRs and also offers some of the best recording functionality for those of us who do audio and spectrum archiving. Each time I beta test or review an SDRplay SDR, however, I’m more and more impressed with SDRuno. It’s evolved from being a rather cluttered application to one with a thoughtful, cohesive user interface that’s a joy to use––a product of true iterative agility.
Indeed, after having used SDRuno exclusively these past two weeks, I believe I would consider it as my primary SDR application…if only it had audio recording in addition to spectrum recording, and could run multiple instances with multiple SDRs. Again, given a little time, I wouldn’t be surprised if some of this functionality is eventually integrated.
Since many SWLing Post readers already own an SDR, I’m sure some of you will have questions. Let’s address a few of those right now.
Question: “I have an RSP2/RSP2pro. Should I upgrade to the RSPdx?”
My recommendation: If you are a shortwave, mediumwave, or longwave DXer, I would indeed recommend upgrading to the RSPdx. If you primarily use your RSP2 series SDR on frequencies above 30 MHz and only occasionally venture below for casual listening, then I’d keep the RSP2.
Question: “I have an RSP1a. Should I upgrade to the RSPdx?”
My recommendation: If you’ve been enjoying your RSP1a and would like to take your listening/monitoring to the next level, then, yes, I would upgrade. Not only can you take advantage of the RSPdx’s enhanced performance, but the RSPdx affords you three antenna ports, and has a more robust front end.
Question: “I have an RSPduo. Should I buy the RSPdx?”
My recommendation: I’m a big fan of the RSPduo. Unless you’re a dedicated mediumwave/longwave DXer, or you’d just like to add another separate SDR to your radio arsenal, I wouldn’t rush out to buy the RSPdx.
And while I’m offering advice, I’d like to offer my standard two cents on the subject of performance optimization: a radio is only as good as its antenna!If you have a compromised antenna, invest in your antenna before upgrading your radio. You’ll be glad you did.
Happily, I can recommend the SDRplay RSPdx without hesitation. This latest iteration of the RSP series SDR is a proper step forward in terms of performance and functionality––obviously implementing years of customer feedback.
SDRplay also has a proven track record of innovation and customer support. Their documentation, video tutorials, and community are among the best in the industry. Purchase with confidence.