A number of SWLing Post readers have asked about the metal case upgrade for the SDRplay RSP1A. It has been out-of-stock for several months. I just learned via Mike Ladd on Facebook, that the case is back in stock and shipping via eBay. He also noted that it will soon be available via Amazon.com. The price is $24.95 shipped via eBay.
Many thanks to SWLing Post contributor, Dave Zantow (N9EWO), who writes:
Our greatly “Updated” SDRplay RSP1A review is now available (with new number two 2019 manufactured test sample). As usual with our web pages be sure and have pop up blocker on full (allow no pop ups) and browser security settings at default or above.
Thanks for sharing this, Dave!
The following article originally appeared in the July 2018 issue of The Spectrum Monitor magazine:
Welcome back to the world of SDRs
Last month we covered Part One of our three-part primer on software-defined radios (SDRs). While last month’s Part One focused on the nomenclature and components of a functioning SDR system, Part Two will take a look at some affordable SDR station options that will propel you into the world of SDRs for less than $200 US. We’ll cover Part Three in November, and we’ll dive a little deeper into the rabbit hole and cover higher-end SDRs and ham radio transceivers with embedded SDRs.
SDRs are affordable
If there’s one thing I’d like you to take away from this part of our primer, it’s that SDRs are truly affordable. For less than the price of a typical full-featured shortwave portable, you can own an SDR that covers almost all of the listening spectrum, and that does so with excellent performance characteristics.
We’re lucky to live in a time of phenomenal radio innovation. When I first jumped into the world of SDRs, the least expensive SDR that covered any of the bands below 20 MHz was about $500. That was only a few years ago, in 2010 or so.
Yet in the past three years, affordable SDRs have become the dominant radio product on the market. And these modestly-priced products have made the barrier of entry into the SDR world crumble overnight.
Today, even a $100 SDR has more features, more frequency range, and more functionality than a $1000 SDR from just a decade ago. Times have changed dramatically; indeed, the pace of innovation in this craft is simply amazing.
Before we begin looking at some choice sub-$200 SDRs, I’d just like to direct your attention to the first part of our SDR Primer (click here to read). Specifically, I’d like you to note one element I discussed in that article: the vital importance identifying your goals as an SDR owner. In other words, how do you plan to use your SDR? If you’re only seeking an SDR to listen to local ham radio repeaters, track cubesat satellites, or gather ADS-B information from aircraft, a $25 SDR will more than suffice. If you wish to use the SDR as a transceiver panadapter, or you wish to chase weak signal DX on the HF bands, then I’d suggest you invest a bit more.
I’d also like to remind you, as I noted in the previous article, that this primer will be limited in the SDRs I highlight. The reason for this is simple: there now exists a vast ocean of SDRs on the market (just search eBay for “SDR” and you’ll quickly see what I mean) so all models simply can’t be included in this introductory foray. I’ll be focusing here on several SDRs that cover the HF spectrum and above. I’ll also focus on SDRs with which I have personal experience, and which I consider to be “enthusiast” grade among a healthy community of users. Of course, this part of the primer will only include HF-capable receivers that cost a total of $200 or less.
Let’s take a look at what’s on the market in order of price, starting with the most affordable.
$10-$25: The RTL-SDR dongle
No doubt, many of you reading this primer have purchased an RTL-SDR dongle. Over the years, I’ve owned three or four of them and have even purchased them for friends. These dongles originally appeared on the market many years ago as mass-produced DVB-T TV tuner dongles based on the RTL2832U chipset. Very soon, users discovered that with just a little hacking, the dongle was capable of much, much more than its original intended purpose.
The dongle resembles a USB memory stick. On one end, you’ll find a standard USB connector. On the other, you’ll find an antenna port, typically SMA, to which one connects an antenna. Although it goes without saying, here’s a friendly reminder: make sure you’re choosing an antenna to match the frequency range you’re exploring!
Early RTL-SDR dongles couldn’t cover the HF bands or lower, but many models can now cover a gapless 500 kHz all the way to 1.75 GHz.
So, what can you do with an RTL-SDR dongle? In short, quite a lot! Here are a few of this simple device’s many applications and uses in our hobby. It can:
- become a police radio scanner
- monitor aircraft and ATC communications
- track aircraft with ADS-B decoding and read ACARS short messages
- scan trunking radio conversations.
- decode unencrypted digital voice transmissions such as P25/DMR/D-STAR.
- track maritime boat positions like a radar with AIS decoding.
- track and receive weather balloon data
- connect to VHF amateur radio
- decode APRS packets
- receive and decode GPS signals
- utilize its rtl-sdr as a spectrum analyzer
- receive NOAA weather satellite images
- and so much more––! This list is not fully comprehensive by any means. Check out this list of projects at RTL-SDR.com.
And, of course, you can listen to any signals between 500 kHz up to 1.75 GHz––essentially, most of the radio listening landscape.
Is $25 still a little high for your budget? RTL-SDR dongles can be found for as low as $10 US, shipped, on eBay. While the cheapest of these dongles may suffice for some radio applications, I’m partial to the dongle produced by RTL-SDR.com, since they’re built in a tough metal enclosure, have thermal pad cooling, as well as extra ESD protection. Amazon has an RTL-SDR.com dongle starter package with antenna options for about $26. That’s, what, the price of three hamburgers? Two orders of fish and chips? And worth it.
Many third-party SDR applications support the RTL-SDR dongle, but my favorite is SDR# (click here to download).
So, the major pros of this little SDR are 1) obviously, the price; 2) many, many uses; and 3) the fact that it’s the most popular SDR on the market, with a massive online user base.
What about negatives? Well, to be frank––aside from the dongle’s budget-busting versatility––the fact is that “you pay for what you get.” You’re investing just $10-$27 in this receiver, so don’t expect exceptional performance especially on anything lower than 50 MHz. On HF, for example, the RTL-SDR could easily overload unless you employ external filtering.
Indeed, I’ve never used the RTL-SDR for HF DXing, but I currently have three dongles in service 24/7: two as ADS-B receivers, and one as a receiver for the LiveATC network. And these work hard. Indeed, It’s a workhorse of a device!
I suggest you grab an RTL-SDR and use it as an accessible step into the world of SDRs, and as an affordable single-purpose tool to unlock the RF spectrum!
$99: The SDRplay RSP1A
When you invest a modest $99 US (or $120 shipped), and purchase the RSP1A, you take a major step forward in the SDR world.
UK-based SDRplay is an SDR designer and manufacturer that focuses on enthusiast-grade, budget wideband SDRs. SDRplay designs and manufactures all of their SDRs in the United Kingdom, and over the past few years, they’ve developed a robust user community, extensive documentation, and, in my humble opinion, some of the best tutorial videos on the market.
Although the RSP series SDRs are supported by most third-party SDR applications, SDRplay has their own app: SDRuno. Moreover, SDRuno is a full-featured, customizable application that takes advantages of all of this SDR’s performance potential and features. I should mention that installing the RSP1A and SDRuno is a pure plug-and-play experience: just download and install the application, plug in the RSP1A to your computer, wait for the USB driver to automatically install, then start SDRuno. Simplicity itself.
While the RSP1A is SDRplay’s entry-level wideband SDR, it nonetheless plays like a pro receiver and truly pushes the envelope of performance-for-price, and for other SDR manufacturers, sets the bar quite high. The RSP1A is a wideband receiver that covers from 1 kHz all the way to 2 GHz; equally pleasing the longwave DXer, HF hound, tropo-scatter hunter, and even radio astronomer. This affordable SDR really covers the spectrum, quite literally. Not only does the RSP1A cover a vast frequency range, but its working bandwidth can be an impressive 10 MHz wide and via SDRuno, the RSP1A will support up to 16 individual receivers in any 10 MHz slice of spectrum. All this for $99? Seriously? I assure you, yes.
Think of the RSP1A as the sporty-but-affordable compact car of the SDR world. It delivers performance well above its comparatively modest price, and is fun to operate. In terms of DX, it gets you from point A to point B very comfortably, and is a capable receiver which will help you work even weak signals––and very reasonably!
If you’re looking to explore the world of SDRs, would like a capable receiver with great LW/MW/HF reception to do it with, but also want to keep your budget in check, you simply can’t go wrong with the RSP1A.
Check out the RSP1A via:
$167 US (125 GBP): FUNcube Dongle Pro+
Many years ago when I ventured into the world of SDRs, one of the only affordable SDRs which covered the HF bands was the FUNcube Dongle Pro+.
The Funcube Dongle Pro+, which resembles the RTL-SDR “stick” type dongle, was originally designed as a ground receiver for the FUNcube Satellite (cubesat) project initially made possible by AMSAT-UK and the Radio Communications Foundation (RCF). The original Funcube dongle did not cover any frequencies below 64 MHz, but the Funcube Dongle Pro+ added coverage from 150 kHz to 1.9 GHz with a gap between 240 MHz and 420 MHz.
In full disclosure, I’ve never owned a FUNcube Dongle Pro+, but I have used them on several occasions. I believe you would find that it is prone to overloading if you use a longwire antenna that’s not isolated from the dongle. In other words, during such use it seems to be subject to internally-generated noise. In my experience, the Pro+ worked best when hooked up to an external antenna fed by a proper coaxial cable.
To be clear, with the advent of SDRplay and AirSpy SDRs, the FUNcube Dongle Pro+ is no longer the budget SDR I would most readily recommend.
Still, the Pro+ is a very compact dongle that has a great history, and around 2012 really pushed the performance-for-price envelope. It still has many dedicated fans. No doubt, this product has had a huge influence on all of the sub $200 SDRs currently on the market, thus we owe it a debt of gratitude.
$169 US: SDRplay RSP2 & RSP2 Pro ($199):
In 2016, after the remarkable success of the original RSP, SDRplay introduced the RSP2 and RSP2 Pro SDRs. The RSP2 is housed in an RF-shielded robust plastic case and the RSP2 Pro is enclosed in a rugged black painted steel case. In terms of receivers and features, the RSP2 and RSP2 Pro are otherwise identical
The RSP2 and RSP2 Pro provide excellent performance, three software-selectable antenna inputs, and clocking features, all of which lend it to amateur radio, industrial, scientific, and educational applications; it is a sweet SDR for $169 or $199 (Pro version). I know of no other SDRs with this set of features at this price point.
The RSP2 series has the same frequency coverage as the RSP1A. Of course, to most of us, the big upgrade from the SDRplay RSP1A is the RSP2’s multiple antenna ports: 2 x 50-Ohms and one High-Z port for lower frequencies.
As with all of SDRplay’s SDRs, their own application, SDRuno, will support up to 16 individual receivers in any 10 MHz slice of spectrum.
Bottom line? Since the RSP2 has multiple antenna ports––and two antenna options for HF frequencies and below–the RSP2 is my choice sub-$200 SDR to use as a transceiver panadapter. (Spoiler alert: you’ll also want to check out our summary of the recently released $279 RSPduo from SDRplay in this review or in Part 3 of our primer before pulling the trigger on the purchase of an RSP2 or, especially, an RSP2 Pro!)
Check out the RSP2 via:
$199 US: AirSpy HF+
Sometimes big surprises come in small packages. That pretty much sums up the imminently pocketable AirSpy HF+ SDR.
The HF+ has the footprint of a typical business card, and is about as thick as a smartphone. Despite this, it’s a heavy little receiver––no doubt due to its metal alloy case/enclosure.
Not to dwell on its size, but other than my RTL-SDR dongle, it’s by far the smallest SDR I’ve ever tested. Yet it sports two SMA antenna inputs: one for HF, one for VHF.
When I first put it on the air, my expectations were low. But I quickly discovered that the HF+ belies its size, and is truly one of the hottest sub $500 receivers on the market! Its HF performance is nothing short of phenomenal.
The HF+ is not a wideband receiver like the FunCube Dongle Pro+ or RSP series by SDRplay. Rather, the HF+ covers between 9 kHz to 31 MHz and from 60 to 260 MHz only; while this is a relatively small portion of the spectrum when compared with its competitors, this was a strategic choice by AirSpy. As AirSpy’s president, Youssef Touil, told me,“The main purpose of the HF+ is [to have] the best possible performance on HF at an affordable price.”
Mission accomplished. Like other SDRs, the HF+ uses high dynamic range ADCs and front-ends but enhances the receiver’s frequency agility by using high-performance passive mixers with a robust polyphase harmonic rejection structure. The HF+ was designed for a high dynamic range, thus it is the best sub-$200 I’ve tested for strong signal handling capability on the HF bands.
You can very easily experiment and customize the HF+ as well; easy access to the R3 position on the circuit board allows you to make one of several published modifications. “During the early phases of the design,” Yousef explains, “R3 was a placeholder for a 0 ohms resistor that allows experimenters to customize the input impedance.” He goes on to provide in-depth clarification about these mods:
- A 300 pF capacitor will naturally filter the LW/MW bands for better performance in the HAM bands
- A 10µH inductor would allow the use of electrically short antennas (E-Field probes) for MW and LW
- A short (or high value capacitor) would get you the nominal 50 ohms impedance over the entire band, but then it’s the responsibility of the user to make sure his antenna has the right gain at the right band
- A custom filter can also be inserted between the SMA and the tuner block if so desired.”
Since the introduction of the HF+, it has been my recommended sub-$200 receiver for HF enthusiasts. If you want to explore frequencies higher than 260 MHz, you’ll have to look elsewhere. Also, note that longwave reception is not the HF+’s strong suit––although modifications to R3 and future firmware upgrades might help with this! Additionally, the HF+’s working bandwidth is 660 kHz; quite narrow, when compared with the RSP series, which can be widened to 10 MHz.
AirSpy also designed the free application SDR# to take full advantage of their receivers’ features and performance.
Installing the HF+ and getting it on the air is pure plug-and-play. While SDR# is a powerful and fluid SDR application, I actually use SDR Console more often, as it supports most of my other SDRs as well, and offers advanced virtual receiver and recording functionality.
If you’re an HF guy like me, the HF+ will be a welcome addition to your receiver arsenal. It’s a steal at $200.
If you haven’t gathered this already, it’s simply a brilliant time to be a budget-minded radio enthusiast. Only a few years ago, there were few, if any, enthusiast-grade sub-$200 SDR options on the market. Now there are quite a number, and their performance characteristics are likely to impress even the hardest-core weak-signal DXer.
Still, some hams and SW listeners reading this article will no doubt live in a tougher RF environment where built-in hardware filters are requisite to prevent your receiver from overloading. Or perhaps you desire truly uncompromising benchmark performance from your SDR. If either is the case, you may need to invest a little more of your radio funds in an SDR to get exactly what you want…and that’s exactly where I’ll take you November in the final Part Three of this SDR primer series. Stay tuned!
Stay tuned for more in Part Three (November). I’ll add links here after publication.
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Many thanks to SWLing Post contributor, Mike Ladd, who notes that the SDRplay RSP1A aluminum metal enclosure kit is now available on eBay.
The price is $29.95 shipped and the kit includes:
- 1x Black aluminum metal enclosure with two labelled side panels
- 1x Black semi-hardshell carry case
- 1x Thermal pad to keep the RSP1A cool and mechanically stable inside the enclosure
- 1x Accessory set including enclosure screws, GND lug bolt set and 3M anti-slip rubber feet
- 1x Tecsun AN03-L seven meter long wire antenna + 1x Matching SMA Adapter
- 1x 11cm to 48cm portable SMA telescopic antenna
Thanks for the tip, Mike. I’m definitely pulling the trigger. What a great upgrade and price!
Many thanks to SWLing Post contributor, Ivan Cholakov (NO2CW), who shares the following video and notes:
Comparing side to side reception performance on RSP1A vs. RSP1 on medium wave and shortwave using SDR Console 3.
Audio level is uneven because two laptops were used. Antenna is the same, 80m OCF dipole.
The RSP1A joins the SDRplay product line of the RSP2 ($169.95 US), and RSP2 Pro ($199.95 US). The new RSP1A will retail for $99.00 US.
But what of this SDR’s performance? In a nutshell: as of today, I’d contend that the RSP1A will simply be the best SDR value on the market. End of story. There is nothing I know in the $99 price bracket that can beat it.
How do I know this? I can make this statement with confidence because I have been involved with real-world testing and evaluation of the RSP1A Alpha, Beta, and production models since May. I took the RSP1A with me to Canada this past summer for field recordings with my laptop, and I’ve also evaluated the RSP at my home. Like a number of other reviewers, I’ve been intimately involved with putting the RSP1A through its paces. And let’s just say I like what I’ve seen.
I actually do quite a bit of Alpha and Beta testing for manufacturers. While it’s time-consuming volunteer work and requires meticulous attention to minor details, it gives me an opportunity to have meaningful positive impact on an upcoming product. Manufacturers that actively involve enthusiasts in their testing phase tend to produce better-quality products on the first run. Better products, of course, mean a better radio market with options for those only now discovering the mystery––and fun––of radio as well as DXing.
Since the RSP1A is essentially iterative agility on behalf of SDRplay, the RSP1A was surprisingly solid even in its early release. And try as I might, there were very few issues I ever needed to report back to the engineering team. SDRplay took each item of feedback seriously, logged it, and followed-up. Over the course of the evaluation period, SDRplay improved their dedicated SDR application SDRuno, as well.
In essence, the RSP1A hardware now in production and shipping has been thoroughly tested and is ripe-and-ready for your radio adventures.
I have not compared the RSP and RSP1A side by side; running two instances of SDRuno on the same PC has been problematic. To my ear, when I’ve tested one after the other, the RSP1A serves up slightly better sensitivity, perhaps due to a slightly lower noise floor. Also the RSP1A frequency stability is much improved over the RSP1.
Specifically, the following upgrades have been made per SDRplay:
- 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
Suffice to say, this budget SDR delivers, and users will be wooed by its stellar performance.
I’ve spent 95% of my evaluation time on the HF and mediumwave bands and I’ve been impressed with the receiver’s sensitivity, selectivity, and AGC control. The audio fidelity is also highly customizable since it’s pumping audio directly through your PC’s system.
I haven’t spent any time above the aviation bands (higher than 140 MHz); I have, however, tested the RSP1A thoroughly on the FM broadcast bands and found it a solid FM performer. Note, too, that SDRuno’s built-in RDS decoder window provides quite a lot of data.
I’m also pleased that I haven’t noticed any front-end overloading––this, despite the fact that during travel, I’ve used it in the vicinity of some powerful broadcasters.
Comparing to benchmarks
But let’s be clear, here: this is not an “apples-to-apples” comparison since the RSP1A is a fraction of the cost of the others, and is also a wideband receiver (1 kHz to 2 GHz). The only other SDR I own that has VHF coverage is the FDM-S2, which tops out at 160 MHz.
Pricier HF-focused SDRs have distinct hardware advantages––especially in terms of filtering––that give them an edge over budget wideband SDRs. Still, in my comparisons, the RSP1A holds its own quite well.
Compared to the WinRadio Excalibur, for example, this SDR came fairly close in terms of sensitivity. The WinRadio’s synchronous detector––which I consider to be the best in the business––was indeed more stable than that of the RSP1A. The RSP1A sync lock could falter a bit during a weak signal’s QSB dip compared with the Excalibur.
But again, HF SDRs in the league of the FDM-S2, Excalibur, and Perseus have the luxury of designing receiver architecture around a much smaller portion of the spectrum. If you are a hard-core DXer looking for uncompromised performance on the HF/MW bands, then you should invest in one of these benchmark SDRs. I have, and I’d never give one of them up.
With that said, even though I have these amazing benchmark SDRs at my disposal, I still purchased the original RSP1 (then at $159 US) years ago. Why? For one thing, it’s more portable than the Excalibur or Perseus as it requires no external power supply (like the excellent FDM-S2, the RSP derives its power from the USB data cable). Additionally, I do like to play with frequencies above 50 MHz from time to time. The RSP offers up an all-in-one RF toolbox at a very affordable price. I don’t hesitate to throw the RSP in my pack and take it anywhere I’m travelling. If it gets damaged or lost, I’m only out $99––not $1,000.
Again, RSP1A’s bang-for-buck simply blows my mind.
Side note: I do wish someone would develop an accessory outboard filter box that could be implemented with budget wideband SDRs, thus providing, in a sense, a hardware “upgrade.” Something like the Elad SPF-08 preselector box designed for the FDM-S2
This review has been overwhelmingly positive because, frankly, the RSP1A is challenging to find fault with. Of course, if it carried a price tag of $600-900, I’d be much more critical of its performance as compared with my benchmark receivers in that same price class. I’d fully expect a robust preselector system, a bullet-proof front end, and performance that could match or surpass the benchmarks.
But for just $99? You simply can’t get that kind of hardware for that cost. So SDRplay engineering cleverly pulls every bit of performance out of their receiver by focusing on their SDRuno application, which is optimized for this receiver. And for that reason, it’s in a class by itself.
Admittedly, when SDRplay first introduced their application, SDRuno, I wasn’t the biggest fan. I found it rather quirky and a little cumbersome to use. SDRuno has come a long way, though; SDRplay has continuously improved it, and today, I prefer it to HDSDR and SDR console. SDRuno is much less cumbersome to use than it used to be, and the default window arrangement is pleasing (though I’d still like SDRuno windows to lock and act as one window as I flip through programs on my Win 10 PC). I even prefer SDRuno to Elad’s application in terms of ease of use.
If more AF/IQ recording features are added (virtual receivers, for example) it could even become my application of choice.
The great thing about the SDRplay RSP series, however, is that they’re supported by so many third-party SDR apps. If you don’t like the one you’re using, there are numerous others to chose from. SDRplay takes an affirmative stance that their hardware should be usable on as many platforms with as many applications as possible. Kudos to them.
Here’s a question I know I’ll be asked…
“I just purchased the RSP1. Should I upgrade?”
Good question! As you might guess, my answer is fairly simple and depends on your particular needs:
If you’re happy with the RSP1 and see no real benefit in the RSP1A upgrades above, don’t bother upgrading. Seriously…enjoy what you have! The RSP1 is still a sharp, capable, versatile little SDR and fully supported by SDRplay and its community. I’ve worked some incredible DX with mine over the past few years, and love it.
If you like the sound of the RSP1A and would appreciate the upgrades listed above, then go for it! After all, it’s only $99! Consider this: the price is less than that of my recently reviewed Digitech AR-1780 portable and less than the venerable Tecsun PL-660. Even with a modest external antenna, it will perform circles around these rigs.
If you need an excuse to justify the upgrade to the RSP1A, consider doing what I’m planning to do: give your RSP1 to a friend or someone interested in the hobby. Or, donate it to your radio club as a raffle prize. Then too, of course, you can snag a decent price for it by selling it on eBay or QTH.com.
If you can’t tell, I’m most impressed with this latest offering from SDRplay. I can recommend it with confidence because you simply can’t beat the performance and features for the price.
If you’re considering the RSP1A as your first SDR, you’ll be happy to know SDRplay’s Mike Ladd has also amassed a healthy number of SDRuno instructional videos on YouTube as well. If you start with the first video, by the end of the series you’ll be adept at using SDRuno. Couldn’t be easier.
Think of it this way: The RSP1A is the sporty-but-affordable compact car of the SDR world. It delivers performance well above its comparatively modest price and is fun to operate. In terms of DX, it gets you from point A to point B very comfortably––and quite affordably!
With just $99, there’s no reason you can’t join the world of SDR––the RSP1A is a very accessible, very intuitive SDR start your exploration of the radio spectrum.