The SDRplay is a $149 USD RX only software defined radio with a 12-bit ADC and up to 8 MHz of bandwidth that can tune from 10 kHz – 2 GHz. We consider it and it’s competitors the Airspy R2/Mini to be the best next step up from an RTL-SDR. See our previous post for a review comparing the Airspy and RSP.
One of the main drawbacks of the RSP has been that it does not have any official software associated with it. The closest competitor, the Airspy has the free official SDR# software, but the RSP relied only on third party programs like HDSDR and SDR-Console.
That is set to change today as SDRplay have announced the release of their SDRuno software, a free general purpose software defined radio program for the RSP. SDRuno is a customized version of the Studio1 software which SDRplay acquired the rights to last April. The full press release is quoted below:
SDRplay is pleased to announce the official release of SDRuno for the RSP. SDRuno is the new name for the RSP compatible version of Studio1, the rights to which we obtained and announced on 28th April. SDRuno contains native support for the SDRplay RSP and no extra plugins are required. Third party hardware can also be supported via the ExtIO interface, but with reduced functionality.
SDRuno provides a rugged and flexible, high performance SDR receiver capability and boasts some excellent features:
Multiple ‘Virtual Receivers’ which allow for simultaneous reception and demodulation of different types of signals within the same receiver bandwidth.
A selectivity filter with an ultimate rejection greater than 140 dB.
A unique distortion-free double stage AGC with fully adjustable parameters.
Multiple notch filters with BW adjustable down to 1 Hz, Notch Lock feature.
A unique synchronous AM mode with selectable/adjustable sidebands, dedicated PLL input filter, and selectable PLL time constants.
SNR (stereo noise reduction), featuring a proprietary noise reduction algorithm for stereo broadcast.
AFC for FM signals.
Calibration for receiver frequency errors.
Over time, we plan to add many more features to SDRuno to enhance the user’s experience of this very powerful piece of software. This software runs on Windows and we don’t yet know how easy it will be to migrate it to other platforms but this is something we will be investigating.
SDRuno will be made freely available to all current and future users of the RSP – to download a copy – simply go to http://www.sdrplay.com/windows.html
Our support for SDRuno in no way lessens our commitment to support HDSDR, SDR Console, Cubic SDR or ANY other software solution where the authors are willing to work with us. We fully recognise that many people have strong preferences for particular pieces of software and we do not want to do anything to undermine the options that people have to use their favoured software packages. Indeed, our view is quite the opposite. Our objective remains aim to have our hardware platforms support any and every SDR package out there. This of course may not be possible, but it is our philosophy and part of the ethos of our company.
About Studio 1:
Studio1 was developed in Italy by SDR Applications S.a.s. and has hundreds of happy customers around the world.
Studio 1 is known for its user friendly stylish GUI, CPU efficiency and advanced DSP capabilities, including features not available on other SDR software packages.
SDRplay limited is a UK company and consists of a small group of engineers with strong connections to the UK Wireless semiconductor industry. SDRplay announced its first product, the RSP1 in August 2014
The software can be downloaded at http://www.sdrplay.com/windows.html. SDRuno comes with a full manual (pdf) and SDRplay fans and beta testers of SDRuno have also released a free SDRuno cookbook guide (pdf). From the cookbook it appears that SDRuno is also compatible with any SDR that supports ExtIO modules, like the RTL-SDR, although as noted in the press release functionality for other radios may be reduced. We look forward to being able to test the software out, and post a review within the next few days.
Over on YouTube user Mile Kokotov has uploaded a video showing him using the SDRplay on the recently released official software SDRuno. In the video he first shows reception of some HF signals, then goes on to show how he can characterize some HF filters using a noise source.
Mile also wrote in to use to expand on his video. We quote:
“SDRuno” is new specialized software for SDRplay – RSP1 receiver. Besides many others excellent features, the new one is 10 MHz spectrum span on the window screen. The 10 MHz frequency span you can use it for characterize the HF Band-pass, Low-pass, High-pass or Notch filters. All you need is one noise source (noise generator) which you can find on eBay for about 20 USD.
With addition of directional coupler (for another 20$ USD), you can using SDRplay and SDRuno for HF antenna analyzer, measuring SWR like poore-man`s HF Vector Network Analyzer!
An RF filter is an electrical circuit designed to have specific characteristics with respect to the transmission or attenuation of various frequencies that may be applied to it.
There are three general types of RF filters:
1. A high-pass filter (HPF) similarly has a cut-off frequency, above which there is little or no loss in transmission, but below which there is considerable attenuation. Its behavior is the opposite of that of the low-pass filter.
2. A low-pass filter (LPF) is one that will permit all frequencies below a specified one called the cut-off frequency to be transmitted with little or no loss, but that will attenuate all frequencies above the cut-off frequency.
3. A band-pass filter (BPF) is one that will transmit a selected band of frequencies with substantially no loss, but that will attenuate all frequencies either higher or lower than the desired band.
The Filter connected in the front end of the receiver can be very much useful and it can improve the reception of the weak signals rejecting all others unwanted signals that can produces interference, intermodulation and as a results, the weak signals can not be copied !
With bandpass filter for particular frequency band, Receiving weak signals on that band is much easier, without problems from out of band strong sugnals.
Over on his ‘SDR4Everyone’ blog author Akos has recently uploaded a new post that reviews the HackRF One, and also compares it against the SDRplay RSP and RTL-SDR. In his review he discusses his first impressions of the HackRF, his concerns about it being labelled as a transceiver, and some of its various features. He also does a screenshot comparison of the HackRF, RSP and RTL-SDR on shortwave reception and image rejection performance. Akos also notes that there are not many applications in the high gigahertz range that cannot be done with cheaper or more specialized equipment. Finally he concludes that the HackRF is not very sensitive or good at RX in general, but still has enough features to make it a worthwhile purchase for some people.
Over on his sdr4everyone blog author Akos has uploaded a tutorial that shows how to set up the recently released SDRUno with the RTL-SDR. SDRuno is a spin-off of the (recently acquired by SDRplay) Studio1 software. Although designed and tailored for the SDRplay, SDRuno also supports any radio with an ExtIO interface available, such as the RTL-SDR. The one limitation is that the maximum bandwidth of radios other than the SDRplay is locked to 1 MHz at most.
Akos’ post shows where to download and add the required ExtIO file (it’s the same one used for HDSDR) and how to start the RTL-SDR in SDRuno, as well as a quick tutorial on changing some settings and tuning.
We note that the fact that you need to install the ExtIO dll file to the documents folder seems to be a bug in the latest version at the moment. In future updates they may fix this, and then the ExtIO dll will go back to needing to be added to the C:\Program Files (x86)\SDRplay\SDRuno folder, as it was in previous versions. We’ve also heard one or two reports of users stating that they needed to add in the libusb-1.0.dll file as well, but we can’t confirm if this is actually required as none of our test PC’s have needed it.
Also, a recent post on Nobu’s blog shows how to get rid of the center DC spike in SDRuno by adjusting the Channel Skew Calibration. The post is in Japanese, but the gist of it is that you just need to adjust the fine tuning DC offset slider in the Channel Skew Calibration settings. Nobu also points out that a handy shortcut to getting the ExtIO window to display is to simply press the ‘H’ key.
Over on YouTube user Mile Kokotov has uploaded a video showing his reception of the SAQ very low frequency (VLF) signal. The SAQ transmitter is based in Grimeton, Sweden and transmits at 17.2 kHz, which is well below the frequency of most radio communications. SAQ only transmits its beacon on certain days, and last Sunday July 3rd 2016 the SAQ beacon activated to celebrate Alexanderson day, which is named after Swedish radio pioneer Ernst Frederick Werner Alexanderson.
In the video both the Airspy + Spyverter and the SDRplay RSP appear to receive the SAQ VLF signal equally well. In the video description Mile writes:
“SAQ”- Radio Station at Grimeton is a VLF transmission facility at Grimeton, Sweden. It has the only working Alexanderson alternator rotating armature radio transmitter in the world and is classified as a World Heritage Site.
The transmitter was built in 1922 to 1924 to operate at 17.2 kHz. The antenna is a 1.9 km wire aerial consisting of eight horizontal wires suspended on six 127-metre high freestanding steel pylons in a line, that function as a capacitive top-load to feed energy to six grounded vertical wire radiating elements.
Until the 1950s, the Grimeton VLF transmitter was used for transatlantic radio telegraphy to Radio Central in Long Island, New York, USA. From the 1960s until 1996 it transmitted orders to submarines in the Swedish Navy.
The Alexanderson transmitter became obsolete in 1996 and went out of service. However, because it was still in good condition it was declared a national monument and can be visited during the summer.
On July 2, 2004, the Grimeton VLF transmitter was declared a World Cultural Heritage site by UNESCO. It continues to be used on special occasions such as Alexanderson Day to transmit Morse messages on 17.2 kHz. Its call sign is SAQ.
Recent transmissions from SAQ on 17.2 kHz with Alexaderson 200 kW alternator, was on Alexanderson day (Sunday, July 3rd 2016) at 09:00 UTC.
Distance between SAQ transmitter in Grimeton, Sweeden and Macedonia where the signal was received is about 1850 km.
Receiving with: 1. AIRSPY R2 – SDR + Spyverter and SDRsharp software. 2. SDRplay RSP1 and SDRuno software.
Both SDR receivers settings were previously set for maximum S/N ratio.
Antenna is Mini-Whip 10cm homemade active antenna on 6.5 meter plastic pole.
Decimation of the sample rate for improved noise performance
Improved performance
Better function support for developers
Callbacks used for stream data and gain updates
Tuner AGC function moved to the API
The major changes for users appears to be the the 10 MHz sampling rate and the addition of decimation. The 10 MHz sample rate increases the visible spectrum, however it appears that the maximum IF Bandwidth is still only 8 MHz, meaning that the outer edges of the spectrum won’t show any signals. However,. but the IF filter roll off is not super sharp, meaning that the full 10 MHz should still be usable, with only minor attenuation at the edges. However, we note that in our testing we noticed some roll off at the edges, giving us about 9 MHz of usable spectrum. There should also be an improvement in SNR by using the higher sampling rate thanks to decimation.
Edit: Jon Hudson from SDRplay wrote in to let us know that our assumption of the outer edges being useless was incorrect (the crossed out text). He writes:
I noted one error in what you wrote there…..you suggest that the 10 MHz of visible B-W is worthless because the IF bandwidth is only 8 MHz max and hence you can’t see any signals beyond that 8 MHz window. This isn’t true. The IF filters start to roll off at 8 MHz, but they are not brick wall filters. The actual roll off is at +/- 5 MHz (10 MHz of bandwidth) so within that 10 MHz, at the edges, there are only a few dB of attenuation, and because the CNR has been defined by the front end circuits ahead of the IF filter, any filter attenuation will be applied equally to the signal and the noise leaving the Carrier to Noise ratio unaffected. As a consequence, whilst the user may seem some roll off, the ability to see and receive signals that may lie at the outer edges of the 10 MHz bandwidth is unaffected.
In this update they also added visual decimation controls. This is useful as this allows you to zoom into a signal without loosing resolution whilst maintaining a high sample rate. The decimation controls only appear to activate in the lower IF Bandwidth settings.
The SDRplay RSP is a $149 USD software defined radio with 10 kHz to 2 GHz tuning range, 12 bit ADC and up to 8 MHz of visible bandwidth.
The new RSP EXTIO control panel showing decimation and 10 MHz sample rate.
rtl_fm / rx_fm: Allows you to decode and listen to FM/AM/SSB radio. rtl_sdr / rx_sdr: Allows you to record raw samples for future processing. rtl_power / rx_power: Allows you to do wideband scans over arbitrarily wide swaths of bandwidth by hopping over and recording signal power levels over multiple chunks of spectrum.
rx_tools is based on SoapySDR which is an SDR abstraction layer. If software is developed with SoapySDR, then the software can be more easily used with any SDR, assuming a Soapy plugin for that particular SDR is written. This stops the need for software to be re-written many times for different SDR’s as instead the plugin only needs to be written once.
rx_power scan with the HackRF at 5 GHz over 9 hours.
Radio-Sky Spectrograph is a radio astronomy software program that integrates data over long periods of time and displays it as a waterfall. It is described by the author:
Radio-Sky Spectrograph displays a waterfall spectrum. It is not so different from other programs that produce these displays except that it saves the spectra at a manageable data rate and provides channel widths that are consistent with many natural radio signal bandwidths. For terrestrial , solar flare, Jupiter decametric, or emission/absorption observations you might want to use RSS.
In previous posts we showed how some amateur radio astronomers were able to capture noise bursts from the sun and from Jupiter with an RTL-SDR. In the SDRplay software release post and documentation that comes with the software Nathan shows how he was able to capture solar emissions and Jupiter bursts with the SDRplay.
SDRPlay2RSSSolar emissions received with the SDRplay and Radio-Sky Spectograph.Jupiter Noise Bursts with the SDRPlay and Radio-Sky Spectrograph.
Over on on the HamRadioScience blog, the author has uploaded an article that makes the case on why Apple iMac PC’s may be the best choice for SDR receivers (at least for HF frequencies). In the testing he uses an SDRplay and Elad FM-Duo to show that the plastic case of the SDRplay does not affect the picked up RFI. He shows that when the SDR’s are connected to an iMac the interference from RFI on HF frequencies is minimal. However when connected to a Core i5 PC, there is significant amounts of CPU and monitor noise generated.
The differences in generated noise probably come from the fact that the iMac is probably much better shielded with an aluminum case and that they have high build quality standards for their monitors. The author suggests that an alternative to using an iMac could be to build your own PC, ensuring that dual chamber metal enclosures are used, which ensures that the power supply is isolated in its own separate steel compartment.
RFI is visible with the SDRplay in SDRuno when using the PC. But no RFI is seen with the iMac.
The SDRplay RSP is a software defined radio with a 10 kHz to 2 GHz tuning range, 12 bit ADC and up to 8 MHz of visible bandwidth. Usually the RSP costs buyers $149 USD, but thanks to good exchange rates they have now reduced this price down to $129 USD. This price is only for purchases coming directly from their website at www.sdrplay.com, and it appears that their local US resellers at HRO are keeping the original price (though it is still on sale until 30/09/2016 for $139 USD). SDRplay writes:
Thanks to the weakening of the GB Pound, the dollar exchange rate has changed significantly over the past few months. We have decided that we would like to pass on the benefit of this to our customers and so have reduced the price for which we sell the RSP to those customers who buy directly from us in US Dollars down to $129.
SDRUno, the official software for the SDRplay has recently been updated to version 1.03. SDRUno is the free SDRplay specific version of Studio1, and also supports other SDR’s like the RTL-SDR, with an artificial 1MHz bandwidth limit. The change log is shown below:
Bug Fixes
High DPI resolution issue.
Various minor bug fixes and typos
Updates
Reworked filter cutoffs
Separate out EXTIO functionality
RSP Ready indicator in Main Window/SETT/Input
Rename FM Stereo Noise Reduction button and slider to FMS-NR to avoid confusion with SNR (Signal Noise Ratio)
Improvements to tuner AGC scheme
Improvements to DC offset scheme
Removed unused buttons in SP1/SP2 windows
LO display in RSP advanced window and the SP1 window
Over on YouTube two new videos comparing the reception on the SDRplay and Airspy have been uploaded. The first is by Mile Kokotov and he compares the reception on a very weak broadcast FM station, with several strong signals surrounding it. He writes:
In this video I am presenting Airspy+SDR# vs SDRplay+SDRuno in the real world, receiving very weak FM broadcast station in the terrible conditions, with very strong signals around. The Weak signal was in the lower edge of the FM broadcast spectrum, with very strong local signals close to the weak one, in the upper frequencies of the FM broadcast spectrum. The antenna for the both SDR receivers was the same – Vertical Dipole for FM BC band.
Both SDR receivers were tuned to maximum possible signal to noise ratio (SNR) of the weak FM broadcast signal.
In SDRuno RSP control panel (for SDRplay receiver) ZERO IF and 0.3/0.6 bandwidth were chosen, and the weak signal of interest was placed on the right edge of IF filter, so that the strong signals from other FM broadcast radio stations were placed right from the weak one in order to minimized the negative influence to the our weak signal. LNA was switched off. When the LNA was on, there where high distortion level because LNA was overloaded from the strong signals, and SNR was deteriorated regardless of gain reduction. The best results were achieved with gain reduction set to “0”, without LNA.
In SDR# software (for Airspy SDR receiver) 10 MSPS and Decimation was used. From the version 1480, in SDR#, when decimation is choosed, there is tracking filter which allow better selectivity, so you can use more gain, increasing the SNR to maximum possible level depending of concrete situation.
The overall receiving conditions was extremely bad. The signals from local FM radio stations were too strong so the weak signal from this video can not be received at all, with many expensive FM tuners which I tried: Pioneer VSX 527, Denon AVR-1802, Marantz SR6300. I was tried RTL-SDR just for fun, but it can not receive weak signal too :-), not because SDR-RTL is not sensitive enough, but because its dynamic range is not so high and it is overloaded by too strong local signals.
The very sensitive receiver is not problem to design and produce. Much more difficult is to design a high dynamic range receiver. which will be able to receive very weak and very strong signals at the same time without overloading.
Overloaded receiver front end means that it is not linear any more, and produces many signals by itself, increasing its noise level. Very strong signals at the receiver front end makes Desensitization of the receiver, so it could not receive weak signals any more. We should not forget that the receiver front end “looks” all signals from the wide frequency range even if we want to receive only one signal at the time. The more wideband the receiver is, the higher dynamic range it has to be, for not been overloaded…
In the second video Leif sm5bsz compares the Airspy+SpyVerter with the SDRplay RSP on HF reception. He concludes that the difference between the two radios on HF is small. However, Youssef from Airspy has contested the result, noticing that Leif ran the Airspy at 2.5 MSPS, resulting is significantly less decimation being used. In response Leif updated his video adding an A/B comparison on HF with the Airspy correctly running at 10 MSPS in the last 8 minutes of the video. The results seem to show that the SDRPlay and Airspy+Spyverter have similar HF performance, but when comparing maximum decimation on the Airspy and the smallest bandwidth the SDRplay to obtain similar bandwidth’s, the results seem to show that the Airspy+SpyVerter is about 5 dB more sensitive at receiving weak signals.
Moon Bounce or “Earth Moon Earth” (EME) is an amateur radio activity where people attempt to transmit a signal towards to the moon, and listen to the reflected signal. In some cases a separate transmitter is not needed, as an already powerful constant transmitter like the GRAVES radar in France can be used.
Over on his YouTube channel user cqpy2rn has uploaded a video showing his moon bounce reception of the GRAVES radar using an eleven element yagi antenna. He compares the reception with an RTL-SDR, FunCube PRO Plus and SDRplay. He writes:
+++ Nooelec model NESDR Smart (RTL-SDR) +++ GOODs: Price $20, frequency stability 0.5ppm tcxo, aluminum case, firm sma antenna connector, better dynamic range than regular-cheaper RTL dongles. Easy gain adjustment. BADs: No pass filters, freq coverage from 24MHz to 1.7GHz, poor dynamic range (moderate de-sense with near strong signals)
+++ FunCube PRO PLUS – FCDPP +++ GOODs: freq coverage from 150KHz to 2GHz, pass saw filters, frequency stable 0.5ppm tcxo, easy gain adjustment, acceptable dynamic range. BADs: Plastic case, fragile sma connector, just 192KHz wide spectrum view, price $160.
+++ SDRPlay +++ GOODs: Frequecy coverage from 10KHz to 2GHz, firm SMA connector, pass saw filters, up to 8MHz wide spectrum view, acceptable dynamic range. BADs: Plastic case, legacy printer USB connector, frequency drift during warm up, difficult gain adjustment
CONCLUSION: In essence all these have the same “DNA”, they were made from digital TV tuner chips, comparisons produce very similar RX practical results, the RTL suffers due the lack of internal filtering which can be a little remediated adjusting the gain carefully through your SDR software or adding external filters. FCDPP and SDRPlay are vey similar, although the freq drift for SDRPlay is a bit annoying to me.
Over on YouTube Jon from SDRplay has uploaded a video showing how he’s used the knobs and interface from a 75 year old Marconi CR100 analogue radio to completely control an SDRplay SDR. This allows you have the feeling of tuning a vintage radio with the old fashioned knobs, whilst enjoying the features of a modern SDR.
Within the old radio enclosure they’ve managed to fit in a full Acer mini computer which runs the RSP on HDSDR. To allow the main tuning knob on the Marconi to tune the SDRplay they’ve used an Arduino controller, and an optical shaft encoder. As they intend for their hybrid to be completely keyboard-less, they’ve also added two UP/DOWN buttons to jump up and down the spectrum, buttons to choose the demodulation mode, and a new knob to control the zoom setting in HDSDR.
The project was sponsored by RS components and is intended to be used in the November 2016 Electronica event in Munich as an exhibit that celebrates the 80th anniversary of the expo. The idea is that the SDRplay-Marconi hybrid combines radio technology which would have been around during the first Electronica expo’s as well today’s modern SDR technology. There is a write up of the project available on the RS components designspark website.
One very useful page he’s put together is his explanation of the “dynamic range” concept, which is probably the most important characteristic when it comes to a radio. According to Miles description dynamic range measures the ability of a radio to “receive very weak and very strong signals at the same time, without overloading”. His page also explains how decimation in software can help improve the dynamic range without needing to improve the hardware.
Mile’s page is not yet 100% finished, so we advise you to keep an eye on it for new information.
In addition they’ve also now increased the previous 0.96 MSPS sample rate limit which was enforced for all third party radios running via EXTIO drivers. The new limit is 2.5 MSPS (with 2.4 MSPS being the limit for the RTL-SDR). This is great news for RTL-SDR users as SDRuno for the RTL-SDR is now almost as functional as in other SDR software like SDR#, HDSDR and SDR-Console. The change log is pasted below:
Version 1.1 (11th November 2016) Bug Fixes
1.04.1 – fixed issue where highlighted filter wasn’t always the one loaded.
Waterfall in combo mode now flows the same direction as other modes
Updates (RSP only V1.1)
Tighter integration of RSP controls
Calibrated power measurement
Automatic S-Meter calibration
SNR meter
dBm scale for both SP1 and SP2 windows
Automatic frequency calibration
Support for IARU S-Meter standard
Zoom to VFO button in SP1 window
More improvements to AGC scheme
More improvements to DC offset compensation scheme
Reversed default mouse wheel scroll direction
Waterfall in combo mode direction can be reversed in the same way as other modes
Added extra frequency step sizes
LSB / USB filter presets back to being the same
USER filter preset renamed to DIGITAL
Support for both gain and gain reduction displays
Updated hardware driver – now reports as SDRplay device
Over on YouTube Leif SM5BSZ has uploaded two new videos. The first video shows a set up that compares the Airspy and the SDRplay RSP on several lab tests that test for dynamic range performance at various frequency offsets. The Airspy definitely shows better results, but Leif notes that the differences are fairly small. The Airspy and SDRplay are two SDRs that compete in the mid range SDR price bracket.
Smaller is better. Each value represents the amount of attenuation used (in dBm) that causes a 3dB loss from reciprocal mixing
As lab tests can only approximate real world performance, in the next video Leif does a HF reception comparison on a real world antenna. In this video he compares our RTL-SDR.com V3 in the special direct sampling HF mode, a Funcube Pro+, SDRplay RSP, Airspy+Sypverter, Afedri Net, and an FDM-S1. The test injects an artificial signal and combines signals from a real antenna via an adjustable attenuator. Leif adjusts the attenuator to increase the antenna signals until the test signal strength is degraded by 3dB from reciprocal mixing/overload. That attenuation setting is then recorded.
The results for the daytime and nighttime results results rank the SDR’s in order from best to worst: FSM-S1 ($400 + shipping), Afedri ($259 + shipping), Airspy+Spyverter ($218 + shipping/$149 + shipping (mini)), SDRplay ($129 + shipping), Funcube Pro+ ($155 + shipping), RTL-SDR.com V3 direct sampling ($20 incl shipping). Interestingly the performance seems to correlate nicely with the unit cost. Of course the V3 in direct sampling mode can be significantly improved by using filtering on the front end, or just by using an upconverter and quadrature mode instead.
At the end of the video Leif also shows a final ranking of the HF performance of all radios tested in his previous videos.
Night time reception SDR rankingDaytime reception SDR rankingFinal Ranking
Today SDRplay have just released their newest software defined radio – the Radio Spectrum Processor 2 (RSP2) which is the successor of the RSP1. The RSP2 costs $169.95 USD, and the older RSP1 is still for sale at $129.95 USD. There is also the “RSP2pro” model which is an RSP2 in a metal enclosure, and this sells for $192.95 USD.
The RSP2 has nearly the same base specifications as the RSP1 (12 bit ADC, 10 MHz bandwidth, 10 kHz – 2 GHz range), but now comes with additional features and enhancements such as a software switchable BCFM and BCAM notch filter, TCXO, multiple antenna ports, HF optimized Hi-Z antenna port, clock in and out ports, better shielding and can also now tune down to 1 kHz.
SDRplay Limited has today announced the launch of a second Software Defined Radio product – the RSP2.
Building on the popularity of our first product, the RSP1, we have now launched the RSP2. The RSP2 delivers a significant number of additional features which result in a higher spec for specialist amateur radio users as well as benefits for additional scientific, educational and industrial SDR applications.
Here are the main additional features of the RSP2:
10 built in front-end pre-selection filters, with substantially enhanced selectivity
Frequency coverage extended down to 1 KHz
Software selectable variable gain Low Noise Preamplifier
2 x SMA Software Selectable 50Ω RF ports (1.5 MHz – 2 GHz)
1 x High Impedance RF port (1 kHz – 30 MHz)
Built in software selectable MW /FM notch filters
Highly stable 0.5PPM TCXO trimmable to 0.01PPM
24MHz Reference clock input / output connections
4.7V Bias-T option (on one of the software selectable antenna inputs)
RF screening within a strong plastic case for the standard RSP2
A Rugged metal box version – the ‘RSP2pro’
When used together SDRplay’s own SDRuno software, the RSP2 becomes a high performance SDR platform. The benefits of using the RSP2 with SDRuno include:
Highly integrated native support for the RSP2 professional grade software based upon class leading ‘Studio 1’, free of charge
Calibrated S-Meter including support for IARU S-Meter Standard
Calibrated RF Power Meter with in excess of 100 dB of usable range
Best in class audio quality
Currently the RSP2 requires the use of SDRuno software, but in the coming weeks we plan to provide support for HDSDR, Gnu Radio, CubicSDR and we are working with Simon Brown to get support within SDR Console.
We believe that the RSP1 will continue to prove very popular as the lowest cost 12-bit SDR for general applications such as Short Wave Listening or for use as a panadapter and we pleased that we can now offer more choice to the growing community of RSP users.
The RSP2 is expected to retail at approximately £130 (excluding taxes) or $169 (excluding taxes)
For more information visit our website on www.sdrplay.com
The new RSP2
The table below shows a comparison of the RSP1, RSP2 and RSP2pro. A datasheet can be found on SDRplay’s new RSP2 webpage.
Thanks to the generosity of the SDRplay team we were fortunate enough to receive an early pre-production review model of the standard (not pro) RSP2 unit. The unit arrived a few days ago, and here we give it an initial review. In a previous review we did a comparison of the Airspy SDR, SDRplay RSP1 and HackRF. We found that the RSP1 and Airspy had similar overall performance, but that the Airspy would be better for those people who needed high dynamic range performance in strong signal environments, and that the SDRplay RSP1 would be best for people who wanted a low cost all-in-one unit with performance better than an RTL-SDR.
The Inside
We decided to take a look inside and see how much the PCB has changed from the RSP1 to the RSP2. Judging from the two photos we can see that there is quite a significant increase in the number of components used. What was once a sparse PCB is now populated much more heavily with additional filter banks and several new switches. However, the core design of the RSP2 remains similar to the RSP1. The RSP2 uses the same Mirics MSi001 tuner chip and MSi2500 ADC chips.
The standard plastic enclosure is also now spray painted on the inside with conductive metal paint which helps by acting as a Faraday cage. This prevents interference from getting through and should be almost as good as a metal enclosure.
The conductive paint seems to be working well, as in our tests the RSP2 does not receive any signals with the antenna disconnected, whereas the RSP1 does weakly receive some very strong pager signals.
RSP1 & RSP2 PCBsConductive paint on the plastic case inside.
Continue reading for the rest of our review
New Antenna Ports
The RSP1 was simple and had one RF port for the antenna. In comparison the RSP2 now has three antenna ports and two clock ports.
Ports A & B are standard 50 Ohm SMA female ports, with port A tunable from 10 kHz – 2 GHz, and port B tunable from 1.5 MHz – 2 GHz. Port B can also be used with the 4.7V bias tee. Having two antenna ports is useful as this means that switching between two different antennas made for different bands is made much easier.
The Hi-Z port operates from 10 kHz – 30 MHz and is used for high impedance HF antennas such as long/random wires and loop antennas. More on this port later in the review.
There are also now two clock ports available. One “in” port and one “out” port. The “in” port allows you to connect a highly stable external 24 MHz clock reference if desired. The “out” port allows you to connect two RSPs together for experiments that require clock sharing. Hopefully we’ll start to see coherent receiver projects with the RSP2, such as passive radar and direction finding experiments.
TCXO (Temperature Compensated Crystal Oscillator)
The RSP2 comes with a very stable 0.5 PPM TCXO. The RSP1 did not use a TCXO and this was one of the most requested upgrades. Use of a TCXO means that you won’t have to do any initial calibration to get the frequencies to show up where they should be and it also means that the frequency of signals on the display won’t drift over time as the ambient and internal PCB temperature changes. This makes the RSP2 much more usable at L-band frequencies where the apparent drift is much larger.
In our tests we found that the frequency calibration was spot on without the need for any adjustments, and no drift was noticeable over a period of time. If you want to calibrate the TCXO perfectly, SDRuno has an autocalibrate mode now. Simply select the “SAM” mode, tune to an known accurate signal, then click on the “Autocal” button in the RX settings menu.
New Preselectors
The RSP2 has two additional preselectors which appear to be aimed at improving reception on the milsat bands around 250 MHz, as well as signals between 300 – 380 MHz. Previously we’d seen reports that the RSP1 has problems with milsat reception, so this may be a fix for that.
It’s not mentioned in their release documents, but we’ve heard that the preselectors have also been tweaked to be much tighter, meaning less roll off, and so they should give better rejection of out of band signals. They have probably increased the filter order which means more components. This may be partially why the PCB looks to be so much more filled out.
RSP2 Switched Preselectors
RSP1 Switched Preselectors
0 – 12 MHz (LPF)
12 – 30MHz (BPF)
30 – 60MHz (BPF)
60 – 120MHz (BPF)
120 – 250MHz (BPF)
250 – 300MHz (BPF)
300 – 380MHz (BPF)
380 – 420MHz (BPF)
420 – 1000MHz (BPF)
1000 MHz+ (HPF)
0 – 12 MHz (LPF)
12 – 30 MHz (BPF)
30 – 60 MHz (BPF)
60 – 120MHz (BPF)
120 – 250 MHz (BPF)
250 – 420 MHz (BPF)
420 – 1000 MHz (BPF)
1000 MHz+ (HPF)
Bias Tee
The RSP2 includes a 4.7V bias tee on the SMA-B port. This is very useful for powering remote low noise amplifiers. Generally, you’ll want to place an LNA close to an antenna placed up high, say on the roof. The LNA will then help overcome any losses that come from using coax cable.
The problem is that it may be difficult to find a power source for an LNA when it is in an inaccessible location like up on a mast or on the roof. The solution is to use a bias tee, which allows you to inject DC power onto the coax cable. The coax cable itself can then be used to power the LNA. To activate the bias tee simply click on the “BIAS-T” button in the Main SDRuno window.
We tested the RSP2’s bias tee with SDRuno and found that it worked as expected. We didn’t see a current limit rating for the bias tee, but it seems to work just fine with a PGA-103 based LNA that draws about 100 mA of power. We also tested the bias tee together with the Outernet LNA and we were able to receive L-band signals with no trouble. Finally it was also tested with a Chirhiro Miniwhip HF active antenna, and the bias tee powered it up with no problems.
Note that just like with other SDRs that have bias tees, if you use a long USB cable the voltage you get out might be lower than the specified 4.7V. With a long 10m USB cable the RSP2 put out 4.2V, which was still sufficient to power all the LNA and devices.
The RSP2 receiving L-band signals with an Outernet bias tee powered LNA and Patch Antenna.
FM and MW Notch Filter
One problem with the RSP1 was that it seemed susceptible to overloading and non-linear mixing from broadcast FM (BCFM) stations. This could cause desensitization and images of BCFM signals to appear on top of other signals. This happens because BCFM stations tend to be local and thus extremely strong in many locations which can cause the RSP1 to overload. The solution is to filter it out, or to somehow improve the dynamic range of the receiver with higher bit size ADCs or other design improvements. (If you don’t understand overload think of someone trying to talk to you in a noisy bar with a live band. The loud sounds from the band will make you unable to listen to your friends voice. The same happens with radio – the strong BCFM signals make it difficult to hear weaker stations)
The RSP1 and RSP2 use an array of automatically switched band pass filters to reduce interference and overloading problems. The filters near the BCFM band are 30 – 60 MHz, 60 – 120 MHz, and 120 – 250 MHz. Signals between 60 – 120 MHz are most likely to experience problems because the BCFM band is between 88 – 108 MHz, and so between 60 – 120 MHz there will be no reduction of the BCFM signal strength. Signals between 30 – 60 MHz and 120 – 250 MHz can also experience problems because the filters are not perfectly rectangular, meaning that attenuation of the BCFM band may not be strong enough to prevent overload.
To help fix any problems related to BCFM overload the RSP2 has included a software switchable BCFM band stop filter. This does the same job as the BCFM bandstop filter that we sell, but it is built in to the RSP2 itself. This filter attenuates (reduces) the signal strength in the BCFM band (between 88 – 108 MHz), thus preventing the signals from being too strong and overloading the RSP2. The filter can be turned on and off easily by clicking on the “MW/FM Notch” button from within the main control screen in SDRuno. We did notice some small insertion losses of about 1-2 dB’s on other signals when this filter was turned on, but it is certainly worth it to use if you are experiencing BCFM overload. If you are not experiencing overload then it is best to keep this off.
The same button also turns on a MW (AM broadcast band (BCAM)) filter when SDRuno is tuned to 30 MHz or lower. Again the same problem as with BCFM can occur on HF. Signals from the often local BCAM band are so strong and this can cause the receiver to overload. The MW notch filter attenuates this band significantly, eliminating any overload problems caused by the BCAM band. The BCAM notch filter is only available in the SMA-A and SMA-B ports and cannot be used on the Hi-Z port.
See the image below for a comparison with the notch turned off and on.
BCFM Notch OFF
BCFM Notch ON
High Impedance (Z) Input
One useful addition to the RSP2 is the High Z input port. This input has an impedance of 1 kOhm and is only active when the unit is tuned to frequencies between 1 kHz – 30 MHz. This port is now intended to be the main port for connecting to HF antennas.
Normally radio input impedance is 50 Ohms, and the antenna should also be designed and matched to be as close to 50 Ohms for the frequencies you are interested in. Normally if an antenna has a high impedance characteristic an impedance transformer is used to reduce it to something closer to the typical 50 Ohms.
The idea with the High-Z input port is that these high impedance antennas can be connected directly to the radio, eliminating the need for any impedance transformers. Good impedance matching typically results in stronger signals and less noise.
Examples of high-Z antennas include the simple “random wire” or “long wire” antenna and balanced loop antennas. Random wire antennas should be connected to the “P” (leftmost) input on the high-z connector with the “N” (middle) input connected to the GND (rightmost) input.
The SDRuno Ports with HI-Z connections shown.
The video below explains the ports including the High-Z port in more details.
We tested the Hi-Z port and had no trouble getting good HF reception with a simple random wire antenna. It definitely did seem to give better reception compared to the SMA ports. However, we wish that the MW bandstop filter had also been implemented for this port.
See the image below for a test. Both tests were tuned for maximum SNR. The Hi-Z port image shows higher SNR and less noise.
Hi-Z Port with Long Wire
SMA-A Port with Long Wire
We asked SDRplay for some more information about this port and they wrote:
Regarding HF usage: Ports A and B are intended as general purpose RF ports, but the Hi-Z port is really intended as the prime port for HF and below and has been optimised as such. This is one of the major changes in thinking from the RSP1. The reasoning here is that you will never get a single antenna that gives optimised performance from VLF to UHF and so the majority of people will tend to use separate antennas for HF and VHF/UHF. We chose a 1 K ohm impedance for this port, to simplify the connection to a random wire antenna which is the antenna of choice for HF for many of our customers and is also a good choice for frequencies below 1 MHz. Because of the long wavelengths involved at HF, this port also works well for 50 ohm antennas as long as the feed cable is not excessively long, but if someone really did want to us a very long feed cable (say 30m for example), you could simply reverse a 9:1 balun and use it between the Hi-Z input and the end of the feed cable and you would get a perfectly adequate match to 50 ohms for this purpose. When operating below 1 MHz (down to VLF), though, the direct connection will work best, even with a 50 ohm feed as the high impedance termination will deliver the highest terminal voltage at the input to the RSP2 and reflections will really not be a problem because the wavelength is so long.
New Built in LNA’s
We asked SDRplay for more information about the new LNA’s they have used. They wrote:
On the RSP1, the LNA had only 2 states, on/off. In reality it is not strictly true to say the LNA was ever off, but instead it has a fixed 24 dB gain step in HF and VHF bands. This gave the user only two possible settings in which to trade off noise figure for improved intermodulation performance. With the RSP2, we have added many more gain states for the LNA (5 on the Hi-Z port and up to 9 on ports A and B). Each state has a different trade-off between noise figure and signal handling and so this gives the user a lot more flexibility in handling a wider range of signal reception conditions. As a consequence the slider that you now see in the Main Panel adjusts the LNA gain only. The IF gain is controlled automatically and only serves to ensure that the ADCs do not overload.
Software
SDRuno is the official software for the RSP1 and RSP2 and is free of charge. Operation of SDRuno on both units is similar, but there are several new buttons available for the RSP2 which can be used to select between the three antenna ports, and turn on or off the notch filter.
SDRuno Control Screen for the RSP1 and RSP2
At the moment the RSP2 is only compatible with SDRuno but the SDRplay team write that they are working on support for HDSDR, GNU Radio, Cubic SDR and SDR-Console.
SDRplay also have RSP compatible versions of dump1090 available on their website. The RSP2 should be able to perform very well on ADS-B reception now with its bias tee and a remote LNA.
Teething or Actual Problems?
When testing the RSP2 we ran into a few problems. Some of these we’re not sure if they’re actual design faults, or maybe a software bug, or perhaps something was wrong with our unit since we received a pre-production unit. We don’t want to speculate so we’ve informed SDRplay of most of these issues and they are looking into it and we’ll update this part of the post as soon as we get more information.
Notch filter problems
While testing the notch filter we encountered some problems that don’t really make sense. The notch filter appears to work perfectly fine while tuned to or very near 88 – 108 MHz, however, when tuned further away it appears to not work. For example we tuned to 200 MHz and saw heavy BCFM imaging, so we turned the notch filter on. But with the notch on we saw no reduction in image signal strength, in fact the images seemed to get even stronger with the notch turned on. Adding in an external BCFM bandstop filter near the RSP2 completely removed the images. No preamps were used and the antenna was a discone.
To be fair we did test in an environment with very strong BCFM signals, but this should be exactly the environment that the notch filter is supposed to help with. Hopefully this is just a glitch in the software not turning the notch on properly, or perhaps a fault in our pre-production hardware as this behavior doesn’t really make sense for the notch filter.
BCFM Interference on HF
The SMA-A and SMA-B ports appear to have BCFM interference problems on HF. When using a discone to receive the AM broadcast band or other HF frequencies we saw lots of BCFM interference. The same interference does not appear on the RSP1, or if we use the Hi-Z ports. The SDRplay team have indicated that the Hi-Z port is now recommended for HF use, but it is strange that the SMA ports are not working as well as on the RSP1.
The discone is not really a HF antenna, but we do sometimes use it for listening to broadcast AM.
Leakage between Port-A and Port-B
There appears to be some signal leakage between the two SMA ports. For example we connected an antenna to the SMA-B port, and selected the SMA-A port. Even with SMA-A selected and no antenna connected, we received strong BCFM signals. Disconnecting the antenna from the SMA-B port made the signals disappear. This is probably not an issue for most people, but if you have really strong BCFM or other signals leaking through the other antenna it might mean that you will still need to manually disconnect it to avoid possible interference.
Software Bugs
We used SDRuno V.11. The SDRuno software sometimes seems to get confused with the gain settings. Sometimes it seems like the RSP2 is not receiving anything, but simply moving the gain slider up and down, then back to where it was before usually brings the signals back. Sometimes instead switching back and forth between ports A & B fixed it.
UPDATE 24/11/2016: Regarding the issues SDRplay responded
..we have been looking at this in some detail and we do believe that we understand what you are seeing. The RSP2 and the RSP1 before it uses a switched filter matrix in front of the MSi001 to provide front end selectivity. With the RSP1, the front end band-pass response of these filters were fairly gentle and what many users found was that when operating in the air-band, 2m or 4m bands, the front end filters gave insufficient rejection (if the user was operating in an area with very strong BCFM signals) to allow the user to operate the unit with the LNA ‘on’ and thus achieve the best possible sensitivity. This was one of the design constraints of the RSP1 that we were aiming to address with the RSP2. As well as significantly improving the stop rejection of the band-pass filters, we decided to add an FM notch filter as there is a limitation to what rejection of BCFM signals that we can realistically achieve for the lower end of the Air Band when using a band-pass response.
To make these filters software controllable, we have to use the already mentioned front end switching network and necessarily this means the use of semiconductor RF switching elements such as FETs and diodes. What you have observed at 200 MHz is second harmonics being generated within this switching network, which is why you have seen that the notch filter has no effect on them, but does have a very beneficial effect in the Air Band. In other words, it is not the MSi001 that is generating these images, but given the very large BCFM signals in your area, you are seeing harmonics being generated in front of the notch filter which appear as low level images.
Whenever you are operating in an area of high RF interference, you would always ideally place your pre-selection filters right at the antenna. To avoid the effect that you have observed completely, it would be necessary to go to a completely mechanical switching arrangement such as swapping cables or using RF mechanical relays. Software Defined Radios always involve a degree of compromise as there is always a trade-off between size, cost and performance. The key, we believe is to maintain flexibility so that users retain as many options as possible for dealing with the various situations that confront them. In this case, the option to swap cables and use an external notch filter remains in the cases where the internally switched notch response doesn’t provide sufficient protection.
We will do a little bit more assessment of the differences in the pre-production design that we sent you and the final production design. As I have already mentioned, we did tweak the input match for the production units to improve the intermodulation performance on ports A and B and so it is possible that this may have some bearing on the levels of harmonics that you are seeing, if not the effect in itself. It will take us a little bit of time, but if we find the production units are different in this regard, we will ship you out an new unit so that you can compare.
Conclusions
The RSP2 is an excellent upgrade to the RSP1 however the core technology of the RSP2 has not changed from the RSP1 so this is more of an evolution of the RSP1 rather than a totally new product. The evolution of the RSP1 to RSP2 does implement several enhancements and new features that will make using the RSP2 much more enjoyable.
Below is a review of the new features and enhancements we’ve found:
Many of the issues that some SDRplay users experienced with overloading should be significantly reduced in the RSP2 thanks to the BCFM and BCAM notch filters and the additional band pass filters.
Users can now use the bias tee to power remote LNA’s like the LNA4ALL in order to overcome coax losses.
The High-Z port provides an easy way to get started on HF with decent performance with a simple random/long wire antenna.
The change to a TCXO increases frequency stability and now brings it in line with most other SDRs in this price range.
The three antenna ports allow you to easily switch between antennas designed for different bands.
Coherent radio experiments are now possible with the CLK IN and CLK OUT ports.
There do seem to be a few issues that we’ve encountered, but we are hopeful that these are mainly issues with our pre-production unit or software problems. We’ll update this post as soon as we receive word from SDRplay.
Two days ago the RSP2 was released for sale as we released a review of a pre-production unit that they sent us. Since then there have been some more review that have come out from other users who had a review unit.
Hamradioscience.com have released a good review of the RSP2 along with a video. The author writes how he’s impressed with the additional shielding, the software switchable antennas and the bias tee. Like in our review he also tested the RSP2 bias tee with the Outernet LNA and found good results. He notes that the RSP1 and RSP2 are very similar in terms of RF performance, but writes that he noticed times when the RSP2 seemed to be more sensitive or exhibit a lower noise floor than the RSP1.
On YouTube user Laboenligne.ca reviews the RSP2 and also has a live Skype interview with Jon the head of marketing at SDRplay. Jon gives a good overview of the new features and some applications that they could be used for.
Over on NN4F.com Paul Jones also reviewed his RSP2. He was very impressed with the performance of the Hi-Z port, the performance of the BCFM notch filters and the stability of the TCXO.
The author of swling.com has also released his review and he too was impressed by the improvements.
Over on YouTube user Mile Kokotov has uploaded two new videos that show both the SDRplay RSP1 and RSP2 receiving VLF, LF and AM BC signals. The SDRplay RSP1 is a 12-bit SDR that can receive from about 10 kHz – 2 GHz. Recently the RSP2 was released which is an upgrade over the RSP1 with additional filters and features. On this blog we did an initial review of the RSP2 and found mostly improved performance over the RSP1.
Mile writes about the signals he receives:
Antenna on RSP2 is connected to its Hi-Z port.
Here are some information about signals in this video:
60 kHz Time signal from NPL is a radio signal broadcast from the Anthorn Radio Station near Anthorn, UK. The signal, also known as the MSF signal is broadcast at a highly accurate frequency of 60 kHz and can be received throughout the UK, and in much of northern and western Europe. (But I am receiving it in Macedonia) The signal’s carrier frequency is maintained at 60 kHz controlled by caesium atomic clocks at the radio station.
77.5 kHz Time signal is German DCF77 longwave time signal and standard-frequency radio station. The highly accurate 77.5 kHz carrier signal is generated from local atomic clocks that are linked with the German master clocks.
On 295 kHz there is NDB (Non directional Beacon) from Alexander The Great Airport near Skopje (about 80 km from my home)
On AM Broadcast Band (530 kHz – 1620 kHz) you can see how many AM stations are on the spectrum display (with 9 kHz raster) receiving here at my home with Mini-Whip antenna which is only 10 cm long!
The first video shows reception with a Mini-Whip, and the second with a Delta Loop. We don’t see much difference in reception between the RSP1 and RSP2 in these videos but viewers with more sensitive ears may be able to tell us if they notice any differences.
