Tagged: sdrplay

NOAA using the SDRplay RSP2 and RTL-SDR for Receiving Weather Balloon Data

NOAA RSP2 setup for Receiving Radiosonde Data
NOAA RSP2 setup for Receiving Radiosonde Data

Over on the SDRplay forums there has been a post by a NOAA engineer showing how they are using SDRplay RSP2 units in the field for tracking their radiosonde weather balloons. A radiosonde is a small sensor package and transmitter that is carried high into the atmosphere by a weather balloon. It gathers weather data whilst transmitting the data live back down to a base stations. You can get data such as temperature, pressure, humidity, altitude and GPS location.

Bobasaurus' coworker launching a weather balloon.
Bobasaurus' coworker launching a weather balloon.

The NOAA engineer on the forum (handle 'bobasaurus') wrote SkySonde, which is the software used by NOAA to decode and plot data from the radiosondes. SkySonde is freely available for public download on the NOAA website. A PDF file showing how to use the SkySonde software with an RSP2 or RTL-SDR can be found here, and the full SkySonde manual is available here. The software consists of a client and server, with the server connecting to the RSP2 or RTL-SDR, and then sending data to the client. Both server and client can run on the same PC.

The hardware setup consists of an RSP2 (can be interchanged with an RTL-SDR), an Uputronics Radiosonde Filtered preamp and a Yagi antenna. Presumably a Yagi and LNA is not completely required, although the receivable range will be less. The RSP2 bias tee is used to power the preamp, and on a V3 RTL-SDR the bias tee should also work.

NOAA appears to use the iMet brand of radiosondes which transmit a Bell 202 signal. Bobasaurus writes that they transmit in the 401-405 MHz range. This video shows an example of such a signal. If you are in the US near an area that launches these iMet weather balloons you should be able to receive them. An alternative piece of software that supports iMet radiosondes is RS. For other radiosondes we have a tutorial that uses SondeMonitor available here.

SkySonde Radiosonde Software
SkySonde Radiosonde Software

Several new SDRPlay RSP1A Reviews

Like the HF+ mentioned in the previous post, the RSP1A SDR was also recently released and has now had enough time in the wild to gather up a few online reviews. If you didn't already know, the $99 US SDRplay RSP1A is a revision of the RSP1. Compared to the RSP1 it significantly improves the filtering and front end design. We have our own review of the RSP1A unit here, and we mentioned some early reviews from other bloggers in this linked post. Below we post some of the new reviews that we are aware of which have come out since our last post.

Robert Nagy

In his video Robery Nagy does a full review of the RSP1A including a 15 minute primer on SDRs. This is great if you want a brief introduction to understanding how SDRs actually work, and what performance measures are important for comparing them. In the second half of the video Robert shows how to use SDRuno and shows the RSP1A in action.

Mile Kokotov

In this video Mile Kokotov demonstrates the HF+ receiving a CW contest in his home country of Macedonia with the RSP1A and a full-size half wave resonant dipole antenna. He writes:

CQ World Wide DX Contest (CW) receiving in Macedonia with SDRplay RSP1A SDR-receiver and SDRuno software on 80m-Band with full-size half-wave (40 meters long) resonant dipole antenna.

Contest conditions are always big challenge to any receiver dynamics. Here you can see only 60 kHz wide frequency spectrum fulfilled with many competitor stations "fighting each other". In addition, there are local radio-station (only 1 km from my place) with huge signal...

The Radio Hobbyist

In The Radio Hobbyist's video on YouTube Rick (VE3CNU) unboxes his RSP1A and shows the setup and download of SDRuno. He then goes are demonstrates reception on various signals.

icholakov

In icholakov's video on YouTube he compares the older RSP1 with the newer RSP1A on medium wave and shortwave reception using a dipole in a noisy suburban RF setting. Differences are hard to detect as the signals he tests with are not likely to cause any overloading issues, but the RSP1A does seem to have a slightly less noise.

Leif Compares various SDRs including the RSP1, Airspy with SpyVerter, Airspy HF+, FDM-S1, IC706, Perseus

Over on YouTube Leif 'sm5bsz' has uploaded a video that does a lab comparison of various SDRs on the market now including the new Airspy HF+. Leif is known for providing excellent lab based technical reviews of various SDR products on his YouTube channel.

The first video compares the Airspy HF+ with the Perseus SDR. The Airspy HF+ is a new high performance yet low cost ($199 USD) HF/VHF specialty SDR. The Perseus is an older high performance direct sampling HF only SDR, although it comes at the high price of about $1000 USD.

In his tests Leif tests both units at 14 MHz and finds that the HF+ has about 15 dB better sensitivity compared to the Perseus (NF = 7dB vs 22dB). On the other hand the Perseus has about 23 dB better dynamic range compared to the HF+ (Dynamic Range = 127 dBc/Hz vs 150 dBc/Hz), although he notes that a blocking transmitter needs to have a very clean signal to be able to notice this difference which would be unlikely from Amateur transmitters. 

In the next two videos Leif compares multiple SDRs including the SDRplay RSP1, FUNcube Pro+, Airspy with Spyverter, Airspy HF+, Afedri SDR-Net, ELAD FDM-S1, ICOM IC-706MKIIG and Microtelecom Perseus at 7 MHz.

In the RX4 video Leif compares each SDR on dynamic range at 7 MHz. If you want to skip the testing parts, then the discussion of the results in the RX4 tests start at 1:03:00. A screenshot of the results is also shown below. The SDRs are ranked based on their average results over multiple measurements at different times which is shown in the last column. A lower value is better, and the value represents how much attenuation needed to be added to prevent the SDR from overloading and causing interference in his setup.

Dynamic Range Test Rankings
Dynamic Range Test Rankings

In the RX5 video the results start at 54:20:00. In this video he compares the SDRs with real signals coming in from his antenna at 7 MHz. He tests with the antenna signal wide open, with a 4.5 MHz LPF (to test out of band blocking performance), and with a bandpass filter at 7 MHz. Again lower values are better and the values indicate the amount of attenuation required to prevent overload. The Perseus is used as the reference benchmark. He also tests reciprocal mixing later in the video.

RX5 Results
RX5 Results

TempestSDR: An SDR tool for Eavesdropping on Computer Screens via Unintentionally Radiated RF

Thanks to RTL-SDR.com reader 'flatflyfish' for submitting information on how to get Martin Marinov's TempestSDR up and running on a Windows system. If you didn't already know by definition "TEMPEST" refers to techniques used by some spy agencies to eavesdrop on electronic equipment via their unintentional radio emissions (as well as via sounds and vibrations). All electronics emit some sort of unintentional RF signals, and by capturing and processing those signals some data can be recovered. For example the unintentional signals from a computer screen could be captured, and converted back into a live image of what the screen is displaying.

TempestSDR is an open source tool that allows you to use any SDR that has a supporting ExtIO (such as RTL-SDR, Airspy, SDRplay, HackRF) to receive the unintentional signal radiation from a screen, and turn that signal back into a live image. This can let you view what is on a screen without any physical connections. If a high gain directional antenna is used then it may be possible to receive images from several meters away as well.

TempestSDR showing what's on the screen via unintentional RF radiation from the monitor.
TempestSDR showing what's on the screen via unintentional RF radiation from the monitor.

Although TempestSDR has been released now for a number of years it hasn't worked properly in Windows with ExtIO interfaces. In his email flatflyfish showed us how to compile a new version that does work.

1. You need to install a 32-bit version of the Java runtime. The 64-bit version won't work with extio's possibly because they are all 32-bit. Also install the JDK.

2. You need to install MingW32 and MSYS and put their bin folders in your Windows PATH.

3. Then when compiling I was seeing a lot of CC command unknown errors. To fix that I just added CC=gcc to the top of all makefiles. I also removed the Mirics compilation line from the JavaGUI makefile to make things easier as we're not using that sdr.

4. Originally my JDK folder was in Program Files. The makefile didn't like the spaces in the folder, so I moved it to a folder without spaces and it fixed the errors.

5. Lastly to compile it you need to specify the ARCHNAME as x86 eg "make all JAVA_HOME=F:/Java/jdk1.7.0_45 ARCHNAME=X86"

After doing all that it compiled and I had a working JAR file. The extio's that are used normally with HDSDR work fine now and I get some images from my test monitor with an rtlsdr.

We tested compilation ourselves and were successful at getting a working program. To help others we've just uploaded a fork of the code with the makefile changes done, as well as a precompiled release ZIP available on the releases page so no compilation should be required to just use it. Note that to use the precompiled JAR you still need to install MingW32, and also don't forget to install the MingW /bin and msys /1.0/bin folders into the Windows PATH. You also do need to have the 32-bit Java runtime installed as the 64-bit version doesn't seem to work. On at least one Win 10 machine we also had to manually add a 'Prefs' folder to the Java path in the registry.

We've tested the software with the ExtIO for RTL-SDRs (available on the HDSDR downloads page) and confirmed that it works. Images from one of our older DELL monitors using DVI are received nicely, although they are a bit blurry. We also tried using an Airspy or SDRplay unit and this significantly improved the quality of the images a lot due to the larger bandwidth. The quality was good enough to make out large text on the screens. ExtIO's for the Airspy are available on this page, and for the SDRplay on the official SDRplay website. Note that for the SDRplay we were unable to go above 6 MHz, and on the RTL-SDR 2.8 MHz was the limit - anything higher on these SDRs did not produce an image possibly due to dropped samples.

To use the software you should ideally know the resolution and refresh rate of your target monitor. But if you don't there are auto-correlation graphs which actually help to predict the detected resolution and frame rate. Just click on the peaks. Also, you will need to know the frequency that your monitor unintentionally emits at. If you don't know you can browse around in SDR# looking for interference peaks that change depending on what the image of the screen is showing. For example in the image below we show what the interference might look like. A tip to improving images is to increase the "Lpass" option and to watch that the auto FPS search doesn't deviate too far from your expected frame rate. If it goes too far, reset it by re-selecting your screen resolution.

Unintentionally radiated RF signal from computer screen shown in SDR#
Unintentionally radiated RF signal from computer screen shown in SDR#

The best results were had with the Airspy listening to an older 19" DELL monitor connected via DVI. A newer Phillips 1080p monitor connected via HDMI had much weaker unintentional signals but images were still able to be recovered. A third AOC 1080p monitor produced no emissions that we could find.

Clear images were obtained with an antenna used in the same room as the monitor. In a neighboring room the images on the DELL monitor could still be received, but they were too blurry to make anything out. Possibly a higher gain directional antenna could improve that.

An example set up with RTL-SDR antenna and monitors
An example set up with RTL-SDR antenna and monitors

Below we've uploaded a video to YouTube showing our results with TempestSDR.

If you want to learn more about TEMPEST and TempestSDR Martin Marinovs dissertation on this software might be a good read (pdf).

SDRplay RSP1A Reviews from Other Sites

Moments ago we posted our own review of the RSP1A. But other radio bloggers, YouTubers and websites have also recently released reviews. Below is a summary of those other reviews.

SWLing Post Blog

In his post on the SWLing.com blog Thomas has nothing but positive words for the RSP1A, an excerpt reads:

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.

NN4F.com

In his post NNF gives a quick review of the new unit from the perspective of an average user. He notes that spurious signals that were visible on HF with the RSP1 as now gone, at that the RSP1A is on par with the RSP2, if not better.

HamRadioScience

Here the author of hamradioscience.com compares his RSP1A with the RSP1 and RSP2. He notes better sensitivity with the RSP1A compared to the RSP1, but comparable performance with the RSP1A vs the RSP2. He has also uploaded a video demonstrating a comparison between the RSP1 and RSP1A.

Laboenligne.ca

Over on YouTube user Laboenligne.ca (aka Pascal Villeneuve VA2PV) has uploaded an interview that he did with Jon Hudson of SDRplay. The interview discusses the RSP1A product as well as the development around it.

A Review of the SDRplay RSP1A

Yesterday the SDRplay team released the $99 US RSP1A, which is a revision of the RSP1A. In this post we present a review comparing its performance against the older RSP1 and the currently selling $169.95 US RSP2. We aim to mainly show demonstrations of improvements that we've found on the RSP1A in areas where we discovered problems on the RSP1 or RSP2.

Discussion of Improvements 

First we present a discussion on the improvements made.

TCXO: The first noticeable improvement is that the RSP1A now comes with a 0.5PPM TCXO. This was one of the main criticisms of the RSP1 as the RSP1 only came with a standard oscillator which can drift as the temperature changes. But as mentioned in our previous review that included the RSP1, the drift was fairly small after warmup due to the good heat dissipation of the large PCB, and the relatively low power usage and thus less heating of the Mirics chips used on RSP units. Nevertheless, a TCXO is a good upgrade and brings it back in line with most low cost SDRs on the market now.

Enhanced RF Preselectors + Notches: Strong out of band signals can overload an SDR causing problems like imaging and reduced sensitivity. Preselectors are RF filters which help to filter out unwanted signals for the band that you are listening to. 

The RSP1 had 8 preselector bands and the RSP1A brings this number up to 12, which is even more than the 10 preselectors on the RSP2. 

In testing we found that the new preselectors certainly do help out a lot. The new 2 MHz low pass and 2 - 12 MHz certainly help to reduce interference from the MW broadcast AM band. Changes in the VHF filters reduce problems from strong broadcast FM and DAB stations. The filters have also been sharpened considerably making the existing filters even more effective. The RSP-1 in some cases suffered quite severely from out of band signal interference, and the RSP-2 made it a bit better, but the RSP-1A solves the interference problem much more.

The new FM/AM and DAB notch filters also do a good job at notching out these often problematic very strong signals.

Preselectors on the RSP1, RSP1A and RSP2
Preselectors on the RSP1, RSP1A and RSP2

Improved LNA Architecture: In the RSP1 the front end LNA could only be turned on or off. Turning it on reduces the noise figure and improves performance, especially at UHF frequencies. The single gain step was problematic as often the LNA could overload on strong signals if turned on. The RSP1A introduces a gain control block which allows the LNA to have variable gain steps.

This new architecture helps to maximise the dynamic range of the RSP1A, thus reducing overloading.

Extended frequency coverage down to 1kHz: The lower limit of the RSP1 was 10 kHz, so really low LF reception is now available on the RSP1A.

Bias-T: Just like with the RSP2, the bias-t allows you to power external devices over the coax cable. Such as remote LNAs, switches etc. Running a good LNA next to the antenna is optimal, as this helps push signals through the coax cable losses.

RF Shielding: Like the RSP2 the plastic case is now spray painted with metallic paint on the inside. This works almost as well as a full metal case to shield from unwanted signals entering directly through the PCB, instead of through the antenna. We do still notice some leakage making its way in through the coax shield, but it is relatively minor with the shielding.

ADC Resolution Increased to 14-bits: The RSP1A uses the same ADC chip as the RSP1, but now has unlocked 14-bit ADC capability for bandwidths below 6 MHz thanks to onboard decimation and oversampling. So now 14-bit data comes directly into the PC if using a bandwidth below 6 MHz. Further decimation can still be achieved within software like SDRuno.

A higher bit ADC can improve dynamic range, meaning that strong signals are less likely to overload the SDR.

We asked SDRplay how 14-bits was achieved with the same chips used by the RSP1 and they explained that it is through oversampling and decimation onboard the chip. They also wrote the following technical reply which is a very good read (collapsed as the reply is quite long, click on "Read the Reply" to expand):

READ THE REPLY

The ADCs on the MSi2500 use a sigma-delta topology where a highly oversampled multi-bit ADC uses decimation filtering to provide the desired resolution. As the original spec for the MSi2500 called for 12 bit resolution, the fact that the converter was capable of delivering 14 bits for final sample rates of less than 6.048 MHz was ignored. Working with the Mirics team, we have been able to unlock the extra two bits of resolution that the MSi2500 was always capable of delivering. Using sample rates above 6.048 MHz, the ADC defaults back to 12 bit resolution.

They also explained:

If we take an 8 bit ADC for example, we can expect around 48 dB of instantaneous dynamic range. This will most likely be far lower than that achievable from the RF front end whose dynamic range will be influenced by factors such as noise figure, intermodualtion, cross modulation and synthesizer phase noise (reciprocal mixing). A decent tuner front end should be capable of delivering 65-70 dB of instantaneous dynamic range, which is also roughly what you can expect from a 12 bit ADC. In other words, we believe that in the RSP1, the instantaneous dynamic range of the tuner and ADCs were approximately the same. The limitation that the RSP1 had was because of the single gain step in the LNA, it was not always possible to utilise the available dynamic range in the most effective way. The RSP1A gives much greater (and finer) control over the RF gain and this allows for better alignment of the signal level into the tuner to better exploit the available dynamic range. In our tests in the broadcast FM band, we believe that the RSP1A gives around 10 dB more ‘usable’ dynamic range than the RSP1. In other words, if we combine multiple controlled modulated signals (for RF signal generators), with real weak off-air signals, the RSP1A is capable of handling interferers that are around 10 dB greater than the RSP1. Benchmarking against other products, in our tests, the RSP1A seems to give better performance now than anything else in the same price range, both in terms of sensitivity and in terms of in-band overload performance.

The RSP1 always gave very good sensitivity but in optimising it in this way, we gave up some performance in terms of in-band overload performance. Our objective with the RSP1A was to address this without sacrificing sensitivity. 

Now, going back to the issue of 14 bits vs 12 bits and instantaneous dynamic range. If we increase the ADC dynamic range from 12 to 14 bits, then the ADC dynamic range should no longer influence the performance of the receiver. Indeed, it is our view, that for any receiver that needs to use a tuner as part of the front end (and any receiver that operates across the frequency range of the RSP will have to use a tuner for the foreseeable future), there is little benefit to be gained with ADC resolutions in excess of 14 bits, as to utilise the extra dynamic range that a higher resolution ADC can give, a much higher performance tuner would be required. Tuner technology has come a very long way in the last 10-15 years and the performance of modern integrated devices is actually very good. To get 12 dB of better dynamic range from a tuner is extremely difficult and can really only be achieved by using very much greater levels of power and esoteric semiconductor technologies. One possible area where you might see better performance is where you have multiple strong interfering signals to the extent that the RF gain needs to be turned down to such a level that the ADC quantisation noise effectively limits the noise floor of the receiver. In this case, you ought to see improved performance in 14 bit mode when compared to 12 bit mode, but please note that the improvement may only be a few dBs in the weak signal reception. If the noise floor of the receiver is still limited by the external LNA, then improved ADC dynamic range will give no perceptible improvement whatsoever.

A direct sampling receiver that does not use a tuner should in principle allow greater dynamic range than one that does, but in practice any direct sampling ADC needs some form of external low noise amplification to ensure a reasonable noise figure and the dynamic range (noise, intermodulation performance etc) of this external amplification block becomes a limiting factor. This is certainly true at VHF and above. At HF, as you will be well aware, the receiver noise figure is not really very important because the atmospheric noise floor is so high. In principle, you might therefore think that our best approach would be to bypass the tuner and use the decimated 16 bit performance of our ADCs. This would still give an effective receiver bandwidth of 375 kHz with 16 bit performance. The reality though is that the real dynamic range of signals coming into the antenna is limited by propagation conditions and atmospheric noise. It is rare to find signals that are above the atmospheric noise floor that vary by more than 60 dB. In practical terms, we believe that equivalent performance can be achieved, simply by the addition of RF pre-selection and AM-band notch filters and in this way we avoid some of the other compromises of direct sampling systems.

So, in a nutshell, when transitioning from 12bit mode to 14 bit mode, don’t expect to see 12 dB more dynamic range. In the real world, it doesn’t work this way. This is why 12 bit devices can give quite favourable performance to higher end 16 bit SDRs such as the Elad FDM-S2, particularly when you consider the difference in cost. We fully expect the Elad to be better, but the difference will not be 24 dB or anything close to it.


Without wishing to labour the point about myths and misunderstandings, it is worth adding a bit of clarification regarding the term ‘dynamic range’. This is a much misunderstood term which can mean very different things depending upon the circumstances and type of signal being received. There is also a difference between ‘dynamic range’ and ‘instantaneous dynamic range’. If you ask 10 different radio engineers what they mean by the term dynamic range, you are sure to get more than one different answer! Another important point to note is that ADC dynamic range is NOT the same as receiver dynamic range. When referring to ADCs, the term dynamic range generally refers to the Spurious Free Dynamic Range (SFDR). This is measured using a CW tone and refers to the ratio between the maximum RMS signal that the ADC can handle and the largest spur or level or quantisation noise within the ADC bandwidth. This is a measure of both noise and linearity of an ADC. As a case in point, it is worth noting that a 16 bit ADC may not necessarily have a higher SFDR than a 12 bit ADC despite having a greater resolution. The greater resolution will generally result in a lower level of quantisation noise, but not necessarily a lower level of harmonic distortion and spurs. In a multi-channel/multi-signal SDR system a lower level of quantisation noise is generally helpful, even if the SFDR is not better, but is not guaranteed to give better performance if the weak signal of interest happens to fall on top of an ADC spur. Where a single signal occupies the entire ADC bandwidth, it is ONLY the SFDR that matters and not the resolution or quantisation noise. Sometimes you will hear people refer to the Effective Number Of Bits ENOB. ENOB is related to the SFDR in that it is a measure of the maximum SINAD that can be attained with an ADC at a give sample rate and so is also a measure of both linearity and noise performance. ENOB is actually = (SINAD – 1.76)/6.02
In the ADC subsystem used in the RSP, whilst the ADCs are 12 bit at 8 MHz sampling the ENOB is 10.4 (for both I and Q). At lower sample rates, the ENOB improves and gets closer to the idealised performance of the converter.

In a receiver system as a whole, the term dynamic range will generally be interpreted to mean the difference (in dB) between the minimum discernible signal and the maximum level of signal that can be handled. But this is different from the term instantaneous dynamic range, which generally refers to the difference between the minimum discernible signal in the presence of the largest signal that can be handled at the same time. What this ‘number’ is in each case will depend upon the type of signal. So for example, a receiver with a given noise figure and linearity performance will have a different instantaneous dynamic range when receiving a 8 MHz wide 256-QAM CATV signal than when receiving a FM signal that is a few kHz wide. This is simply because the SINR (Signal to Interference + Noise Ratio) requirement for a given BER for a 256-QAM signal is very different than that required for a FM signal and also the peak to average ratio of the two signals is very different.

PCB Photos

Compared to the RSP1 the RSP1A PCB is significantly more populated due to the additional filter banks.

RSP1A PCB Top

RSP1A PCB Top

RSP1A PCB Bottom

RSP1A PCB Bottom

RSP1A PCB Bottom

RSP1 vs RSP2 PCBs

Testing the RSP1A

Below we show some screenshots of tests that we made to compare the three RSP units. We focused on bands where the RSP1 or RSP2 had issues, and try to show how much improvement you can get from the RSP1A.

Medium Wave Broadcast AM Band

In the screenshots below we compare the three SDRs on the broadcast AM band which has some very strong signals. The RSP1 definitely shows signals of overloading and turning the gain down did not reduce the interference shown between 0 - 500 kHz. 

The RSP1A on the other hand does not overload that easily. In the third screenshot we turn the MW notch on half way through the waterfall. The notch does not cover the entire AM band and signals at around 500 - 700 kHz are attenuated less. But turning it on does seem to do enough to solve most imaging problems as will be seen in the next tests.

SDRplay RSP1

SDRplay RSP1

SDRplay RSP1A

SDRplay RSP1A

SDRplay RSP1A (MW Filter ON Halfway Through)

SDRplay RSP1A (MW Filter ON Halfway Through)

SDRplay RSP2

SDRplay RSP2

Continue reading

NOAA using the SDRplay RSP2 and RTL-SDR for Receiving Weather Balloon Data

NOAA RSP2 setup for Receiving Radiosonde Data
NOAA RSP2 setup for Receiving Radiosonde Data

Over on the SDRplay forums there has been a post by a NOAA engineer showing how they are using SDRplay RSP2 units in the field for tracking their radiosonde weather balloons. A radiosonde is a small sensor package and transmitter that is carried high into the atmosphere by a weather balloon. It gathers weather data whilst transmitting the data live back down to a base stations. You can get data such as temperature, pressure, humidity, altitude and GPS location.

Bobasaurus' coworker launching a weather balloon.
Bobasaurus' coworker launching a weather balloon.

The NOAA engineer on the forum (handle 'bobasaurus') wrote SkySonde, which is the software used by NOAA to decode and plot data from the radiosondes. SkySonde is freely available for public download on the NOAA website. A PDF file showing how to use the SkySonde software with an RSP2 or RTL-SDR can be found here, and the full SkySonde manual is available here. The software consists of a client and server, with the server connecting to the RSP2 or RTL-SDR, and then sending data to the client. Both server and client can run on the same PC.

The hardware setup consists of an RSP2 (can be interchanged with an RTL-SDR), an Uputronics Radiosonde Filtered preamp and a Yagi antenna. Presumably a Yagi and LNA is not completely required, although the receivable range will be less. The RSP2 bias tee is used to power the preamp, and on a V3 RTL-SDR the bias tee should also work.

NOAA appears to use the iMet brand of radiosondes which transmit a Bell 202 signal. Bobasaurus writes that they transmit in the 401-405 MHz range. This video shows an example of such a signal. If you are in the US near an area that launches these iMet weather balloons you should be able to receive them. An alternative piece of software that supports iMet radiosondes is RS. For other radiosondes we have a tutorial that uses SondeMonitor available here.

SkySonde Radiosonde Software
SkySonde Radiosonde Software

Several new SDRPlay RSP1A Reviews

Like the HF+ mentioned in the previous post, the RSP1A SDR was also recently released and has now had enough time in the wild to gather up a few online reviews. If you didn't already know, the $99 US SDRplay RSP1A is a revision of the RSP1. Compared to the RSP1 it significantly improves the filtering and front end design. We have our own review of the RSP1A unit here, and we mentioned some early reviews from other bloggers in this linked post. Below we post some of the new reviews that we are aware of which have come out since our last post.

Robert Nagy

In his video Robery Nagy does a full review of the RSP1A including a 15 minute primer on SDRs. This is great if you want a brief introduction to understanding how SDRs actually work, and what performance measures are important for comparing them. In the second half of the video Robert shows how to use SDRuno and shows the RSP1A in action.

Mile Kokotov

In this video Mile Kokotov demonstrates the HF+ receiving a CW contest in his home country of Macedonia with the RSP1A and a full-size half wave resonant dipole antenna. He writes:

CQ World Wide DX Contest (CW) receiving in Macedonia with SDRplay RSP1A SDR-receiver and SDRuno software on 80m-Band with full-size half-wave (40 meters long) resonant dipole antenna.

Contest conditions are always big challenge to any receiver dynamics. Here you can see only 60 kHz wide frequency spectrum fulfilled with many competitor stations "fighting each other". In addition, there are local radio-station (only 1 km from my place) with huge signal...

The Radio Hobbyist

In The Radio Hobbyist's video on YouTube Rick (VE3CNU) unboxes his RSP1A and shows the setup and download of SDRuno. He then goes are demonstrates reception on various signals.

icholakov

In icholakov's video on YouTube he compares the older RSP1 with the newer RSP1A on medium wave and shortwave reception using a dipole in a noisy suburban RF setting. Differences are hard to detect as the signals he tests with are not likely to cause any overloading issues, but the RSP1A does seem to have a slightly less noise.

Leif Compares various SDRs including the RSP1, Airspy with SpyVerter, Airspy HF+, FDM-S1, IC706, Perseus

Over on YouTube Leif 'sm5bsz' has uploaded a video that does a lab comparison of various SDRs on the market now including the new Airspy HF+. Leif is known for providing excellent lab based technical reviews of various SDR products on his YouTube channel.

The first video compares the Airspy HF+ with the Perseus SDR. The Airspy HF+ is a new high performance yet low cost ($199 USD) HF/VHF specialty SDR. The Perseus is an older high performance direct sampling HF only SDR, although it comes at the high price of about $1000 USD.

In his tests Leif tests both units at 14 MHz and finds that the HF+ has about 15 dB better sensitivity compared to the Perseus (NF = 7dB vs 22dB). On the other hand the Perseus has about 23 dB better dynamic range compared to the HF+ (Dynamic Range = 127 dBc/Hz vs 150 dBc/Hz), although he notes that a blocking transmitter needs to have a very clean signal to be able to notice this difference which would be unlikely from Amateur transmitters. 

In the next two videos Leif compares multiple SDRs including the SDRplay RSP1, FUNcube Pro+, Airspy with Spyverter, Airspy HF+, Afedri SDR-Net, ELAD FDM-S1, ICOM IC-706MKIIG and Microtelecom Perseus at 7 MHz.

In the RX4 video Leif compares each SDR on dynamic range at 7 MHz. If you want to skip the testing parts, then the discussion of the results in the RX4 tests start at 1:03:00. A screenshot of the results is also shown below. The SDRs are ranked based on their average results over multiple measurements at different times which is shown in the last column. A lower value is better, and the value represents how much attenuation needed to be added to prevent the SDR from overloading and causing interference in his setup.

Dynamic Range Test Rankings
Dynamic Range Test Rankings

In the RX5 video the results start at 54:20:00. In this video he compares the SDRs with real signals coming in from his antenna at 7 MHz. He tests with the antenna signal wide open, with a 4.5 MHz LPF (to test out of band blocking performance), and with a bandpass filter at 7 MHz. Again lower values are better and the values indicate the amount of attenuation required to prevent overload. The Perseus is used as the reference benchmark. He also tests reciprocal mixing later in the video.

RX5 Results
RX5 Results

TempestSDR: An SDR tool for Eavesdropping on Computer Screens via Unintentionally Radiated RF

Thanks to RTL-SDR.com reader 'flatflyfish' for submitting information on how to get Martin Marinov's TempestSDR up and running on a Windows system. If you didn't already know by definition "TEMPEST" refers to techniques used by some spy agencies to eavesdrop on electronic equipment via their unintentional radio emissions (as well as via sounds and vibrations). All electronics emit some sort of unintentional RF signals, and by capturing and processing those signals some data can be recovered. For example the unintentional signals from a computer screen could be captured, and converted back into a live image of what the screen is displaying.

TempestSDR is an open source tool that allows you to use any SDR that has a supporting ExtIO (such as RTL-SDR, Airspy, SDRplay, HackRF) to receive the unintentional signal radiation from a screen, and turn that signal back into a live image. This can let you view what is on a screen without any physical connections. If a high gain directional antenna is used then it may be possible to receive images from several meters away as well.

TempestSDR showing what's on the screen via unintentional RF radiation from the monitor.
TempestSDR showing what's on the screen via unintentional RF radiation from the monitor.

Although TempestSDR has been released now for a number of years it hasn't worked properly in Windows with ExtIO interfaces. In his email flatflyfish showed us how to compile a new version that does work.

1. You need to install a 32-bit version of the Java runtime. The 64-bit version won't work with extio's possibly because they are all 32-bit. Also install the JDK.

2. You need to install MingW32 and MSYS and put their bin folders in your Windows PATH.

3. Then when compiling I was seeing a lot of CC command unknown errors. To fix that I just added CC=gcc to the top of all makefiles. I also removed the Mirics compilation line from the JavaGUI makefile to make things easier as we're not using that sdr.

4. Originally my JDK folder was in Program Files. The makefile didn't like the spaces in the folder, so I moved it to a folder without spaces and it fixed the errors.

5. Lastly to compile it you need to specify the ARCHNAME as x86 eg "make all JAVA_HOME=F:/Java/jdk1.7.0_45 ARCHNAME=X86"

After doing all that it compiled and I had a working JAR file. The extio's that are used normally with HDSDR work fine now and I get some images from my test monitor with an rtlsdr.

We tested compilation ourselves and were successful at getting a working program. To help others we've just uploaded a fork of the code with the makefile changes done, as well as a precompiled release ZIP available on the releases page so no compilation should be required to just use it. Note that to use the precompiled JAR you still need to install MingW32, and also don't forget to install the MingW /bin and msys /1.0/bin folders into the Windows PATH. You also do need to have the 32-bit Java runtime installed as the 64-bit version doesn't seem to work. On at least one Win 10 machine we also had to manually add a 'Prefs' folder to the Java path in the registry.

We've tested the software with the ExtIO for RTL-SDRs (available on the HDSDR downloads page) and confirmed that it works. Images from one of our older DELL monitors using DVI are received nicely, although they are a bit blurry. We also tried using an Airspy or SDRplay unit and this significantly improved the quality of the images a lot due to the larger bandwidth. The quality was good enough to make out large text on the screens. ExtIO's for the Airspy are available on this page, and for the SDRplay on the official SDRplay website. Note that for the SDRplay we were unable to go above 6 MHz, and on the RTL-SDR 2.8 MHz was the limit - anything higher on these SDRs did not produce an image possibly due to dropped samples.

To use the software you should ideally know the resolution and refresh rate of your target monitor. But if you don't there are auto-correlation graphs which actually help to predict the detected resolution and frame rate. Just click on the peaks. Also, you will need to know the frequency that your monitor unintentionally emits at. If you don't know you can browse around in SDR# looking for interference peaks that change depending on what the image of the screen is showing. For example in the image below we show what the interference might look like. A tip to improving images is to increase the "Lpass" option and to watch that the auto FPS search doesn't deviate too far from your expected frame rate. If it goes too far, reset it by re-selecting your screen resolution.

Unintentionally radiated RF signal from computer screen shown in SDR#
Unintentionally radiated RF signal from computer screen shown in SDR#

The best results were had with the Airspy listening to an older 19" DELL monitor connected via DVI. A newer Phillips 1080p monitor connected via HDMI had much weaker unintentional signals but images were still able to be recovered. A third AOC 1080p monitor produced no emissions that we could find.

Clear images were obtained with an antenna used in the same room as the monitor. In a neighboring room the images on the DELL monitor could still be received, but they were too blurry to make anything out. Possibly a higher gain directional antenna could improve that.

An example set up with RTL-SDR antenna and monitors
An example set up with RTL-SDR antenna and monitors

Below we've uploaded a video to YouTube showing our results with TempestSDR.

If you want to learn more about TEMPEST and TempestSDR Martin Marinovs dissertation on this software might be a good read (pdf).

SDRplay RSP1A Reviews from Other Sites

Moments ago we posted our own review of the RSP1A. But other radio bloggers, YouTubers and websites have also recently released reviews. Below is a summary of those other reviews.

SWLing Post Blog

In his post on the SWLing.com blog Thomas has nothing but positive words for the RSP1A, an excerpt reads:

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.

NN4F.com

In his post NNF gives a quick review of the new unit from the perspective of an average user. He notes that spurious signals that were visible on HF with the RSP1 as now gone, at that the RSP1A is on par with the RSP2, if not better.

HamRadioScience

Here the author of hamradioscience.com compares his RSP1A with the RSP1 and RSP2. He notes better sensitivity with the RSP1A compared to the RSP1, but comparable performance with the RSP1A vs the RSP2. He has also uploaded a video demonstrating a comparison between the RSP1 and RSP1A.

Laboenligne.ca

Over on YouTube user Laboenligne.ca (aka Pascal Villeneuve VA2PV) has uploaded an interview that he did with Jon Hudson of SDRplay. The interview discusses the RSP1A product as well as the development around it.

A Review of the SDRplay RSP1A

Yesterday the SDRplay team released the $99 US RSP1A, which is a revision of the RSP1A. In this post we present a review comparing its performance against the older RSP1 and the currently selling $169.95 US RSP2. We aim to mainly show demonstrations of improvements that we've found on the RSP1A in areas where we discovered problems on the RSP1 or RSP2.

Discussion of Improvements 

First we present a discussion on the improvements made.

TCXO: The first noticeable improvement is that the RSP1A now comes with a 0.5PPM TCXO. This was one of the main criticisms of the RSP1 as the RSP1 only came with a standard oscillator which can drift as the temperature changes. But as mentioned in our previous review that included the RSP1, the drift was fairly small after warmup due to the good heat dissipation of the large PCB, and the relatively low power usage and thus less heating of the Mirics chips used on RSP units. Nevertheless, a TCXO is a good upgrade and brings it back in line with most low cost SDRs on the market now.

Enhanced RF Preselectors + Notches: Strong out of band signals can overload an SDR causing problems like imaging and reduced sensitivity. Preselectors are RF filters which help to filter out unwanted signals for the band that you are listening to. 

The RSP1 had 8 preselector bands and the RSP1A brings this number up to 12, which is even more than the 10 preselectors on the RSP2. 

In testing we found that the new preselectors certainly do help out a lot. The new 2 MHz low pass and 2 - 12 MHz certainly help to reduce interference from the MW broadcast AM band. Changes in the VHF filters reduce problems from strong broadcast FM and DAB stations. The filters have also been sharpened considerably making the existing filters even more effective. The RSP-1 in some cases suffered quite severely from out of band signal interference, and the RSP-2 made it a bit better, but the RSP-1A solves the interference problem much more.

The new FM/AM and DAB notch filters also do a good job at notching out these often problematic very strong signals.

Preselectors on the RSP1, RSP1A and RSP2
Preselectors on the RSP1, RSP1A and RSP2

Improved LNA Architecture: In the RSP1 the front end LNA could only be turned on or off. Turning it on reduces the noise figure and improves performance, especially at UHF frequencies. The single gain step was problematic as often the LNA could overload on strong signals if turned on. The RSP1A introduces a gain control block which allows the LNA to have variable gain steps.

This new architecture helps to maximise the dynamic range of the RSP1A, thus reducing overloading.

Extended frequency coverage down to 1kHz: The lower limit of the RSP1 was 10 kHz, so really low LF reception is now available on the RSP1A.

Bias-T: Just like with the RSP2, the bias-t allows you to power external devices over the coax cable. Such as remote LNAs, switches etc. Running a good LNA next to the antenna is optimal, as this helps push signals through the coax cable losses.

RF Shielding: Like the RSP2 the plastic case is now spray painted with metallic paint on the inside. This works almost as well as a full metal case to shield from unwanted signals entering directly through the PCB, instead of through the antenna. We do still notice some leakage making its way in through the coax shield, but it is relatively minor with the shielding.

ADC Resolution Increased to 14-bits: The RSP1A uses the same ADC chip as the RSP1, but now has unlocked 14-bit ADC capability for bandwidths below 6 MHz thanks to onboard decimation and oversampling. So now 14-bit data comes directly into the PC if using a bandwidth below 6 MHz. Further decimation can still be achieved within software like SDRuno.

A higher bit ADC can improve dynamic range, meaning that strong signals are less likely to overload the SDR.

We asked SDRplay how 14-bits was achieved with the same chips used by the RSP1 and they explained that it is through oversampling and decimation onboard the chip. They also wrote the following technical reply which is a very good read (collapsed as the reply is quite long, click on "Read the Reply" to expand):

READ THE REPLY

The ADCs on the MSi2500 use a sigma-delta topology where a highly oversampled multi-bit ADC uses decimation filtering to provide the desired resolution. As the original spec for the MSi2500 called for 12 bit resolution, the fact that the converter was capable of delivering 14 bits for final sample rates of less than 6.048 MHz was ignored. Working with the Mirics team, we have been able to unlock the extra two bits of resolution that the MSi2500 was always capable of delivering. Using sample rates above 6.048 MHz, the ADC defaults back to 12 bit resolution.

They also explained:

If we take an 8 bit ADC for example, we can expect around 48 dB of instantaneous dynamic range. This will most likely be far lower than that achievable from the RF front end whose dynamic range will be influenced by factors such as noise figure, intermodualtion, cross modulation and synthesizer phase noise (reciprocal mixing). A decent tuner front end should be capable of delivering 65-70 dB of instantaneous dynamic range, which is also roughly what you can expect from a 12 bit ADC. In other words, we believe that in the RSP1, the instantaneous dynamic range of the tuner and ADCs were approximately the same. The limitation that the RSP1 had was because of the single gain step in the LNA, it was not always possible to utilise the available dynamic range in the most effective way. The RSP1A gives much greater (and finer) control over the RF gain and this allows for better alignment of the signal level into the tuner to better exploit the available dynamic range. In our tests in the broadcast FM band, we believe that the RSP1A gives around 10 dB more ‘usable’ dynamic range than the RSP1. In other words, if we combine multiple controlled modulated signals (for RF signal generators), with real weak off-air signals, the RSP1A is capable of handling interferers that are around 10 dB greater than the RSP1. Benchmarking against other products, in our tests, the RSP1A seems to give better performance now than anything else in the same price range, both in terms of sensitivity and in terms of in-band overload performance.

The RSP1 always gave very good sensitivity but in optimising it in this way, we gave up some performance in terms of in-band overload performance. Our objective with the RSP1A was to address this without sacrificing sensitivity. 

Now, going back to the issue of 14 bits vs 12 bits and instantaneous dynamic range. If we increase the ADC dynamic range from 12 to 14 bits, then the ADC dynamic range should no longer influence the performance of the receiver. Indeed, it is our view, that for any receiver that needs to use a tuner as part of the front end (and any receiver that operates across the frequency range of the RSP will have to use a tuner for the foreseeable future), there is little benefit to be gained with ADC resolutions in excess of 14 bits, as to utilise the extra dynamic range that a higher resolution ADC can give, a much higher performance tuner would be required. Tuner technology has come a very long way in the last 10-15 years and the performance of modern integrated devices is actually very good. To get 12 dB of better dynamic range from a tuner is extremely difficult and can really only be achieved by using very much greater levels of power and esoteric semiconductor technologies. One possible area where you might see better performance is where you have multiple strong interfering signals to the extent that the RF gain needs to be turned down to such a level that the ADC quantisation noise effectively limits the noise floor of the receiver. In this case, you ought to see improved performance in 14 bit mode when compared to 12 bit mode, but please note that the improvement may only be a few dBs in the weak signal reception. If the noise floor of the receiver is still limited by the external LNA, then improved ADC dynamic range will give no perceptible improvement whatsoever.

A direct sampling receiver that does not use a tuner should in principle allow greater dynamic range than one that does, but in practice any direct sampling ADC needs some form of external low noise amplification to ensure a reasonable noise figure and the dynamic range (noise, intermodulation performance etc) of this external amplification block becomes a limiting factor. This is certainly true at VHF and above. At HF, as you will be well aware, the receiver noise figure is not really very important because the atmospheric noise floor is so high. In principle, you might therefore think that our best approach would be to bypass the tuner and use the decimated 16 bit performance of our ADCs. This would still give an effective receiver bandwidth of 375 kHz with 16 bit performance. The reality though is that the real dynamic range of signals coming into the antenna is limited by propagation conditions and atmospheric noise. It is rare to find signals that are above the atmospheric noise floor that vary by more than 60 dB. In practical terms, we believe that equivalent performance can be achieved, simply by the addition of RF pre-selection and AM-band notch filters and in this way we avoid some of the other compromises of direct sampling systems.

So, in a nutshell, when transitioning from 12bit mode to 14 bit mode, don’t expect to see 12 dB more dynamic range. In the real world, it doesn’t work this way. This is why 12 bit devices can give quite favourable performance to higher end 16 bit SDRs such as the Elad FDM-S2, particularly when you consider the difference in cost. We fully expect the Elad to be better, but the difference will not be 24 dB or anything close to it.


Without wishing to labour the point about myths and misunderstandings, it is worth adding a bit of clarification regarding the term ‘dynamic range’. This is a much misunderstood term which can mean very different things depending upon the circumstances and type of signal being received. There is also a difference between ‘dynamic range’ and ‘instantaneous dynamic range’. If you ask 10 different radio engineers what they mean by the term dynamic range, you are sure to get more than one different answer! Another important point to note is that ADC dynamic range is NOT the same as receiver dynamic range. When referring to ADCs, the term dynamic range generally refers to the Spurious Free Dynamic Range (SFDR). This is measured using a CW tone and refers to the ratio between the maximum RMS signal that the ADC can handle and the largest spur or level or quantisation noise within the ADC bandwidth. This is a measure of both noise and linearity of an ADC. As a case in point, it is worth noting that a 16 bit ADC may not necessarily have a higher SFDR than a 12 bit ADC despite having a greater resolution. The greater resolution will generally result in a lower level of quantisation noise, but not necessarily a lower level of harmonic distortion and spurs. In a multi-channel/multi-signal SDR system a lower level of quantisation noise is generally helpful, even if the SFDR is not better, but is not guaranteed to give better performance if the weak signal of interest happens to fall on top of an ADC spur. Where a single signal occupies the entire ADC bandwidth, it is ONLY the SFDR that matters and not the resolution or quantisation noise. Sometimes you will hear people refer to the Effective Number Of Bits ENOB. ENOB is related to the SFDR in that it is a measure of the maximum SINAD that can be attained with an ADC at a give sample rate and so is also a measure of both linearity and noise performance. ENOB is actually = (SINAD – 1.76)/6.02
In the ADC subsystem used in the RSP, whilst the ADCs are 12 bit at 8 MHz sampling the ENOB is 10.4 (for both I and Q). At lower sample rates, the ENOB improves and gets closer to the idealised performance of the converter.

In a receiver system as a whole, the term dynamic range will generally be interpreted to mean the difference (in dB) between the minimum discernible signal and the maximum level of signal that can be handled. But this is different from the term instantaneous dynamic range, which generally refers to the difference between the minimum discernible signal in the presence of the largest signal that can be handled at the same time. What this ‘number’ is in each case will depend upon the type of signal. So for example, a receiver with a given noise figure and linearity performance will have a different instantaneous dynamic range when receiving a 8 MHz wide 256-QAM CATV signal than when receiving a FM signal that is a few kHz wide. This is simply because the SINR (Signal to Interference + Noise Ratio) requirement for a given BER for a 256-QAM signal is very different than that required for a FM signal and also the peak to average ratio of the two signals is very different.

PCB Photos

Compared to the RSP1 the RSP1A PCB is significantly more populated due to the additional filter banks.

RSP1A PCB Top

RSP1A PCB Top

RSP1A PCB Bottom

RSP1A PCB Bottom

RSP1A PCB Bottom

RSP1 vs RSP2 PCBs

Testing the RSP1A

Below we show some screenshots of tests that we made to compare the three RSP units. We focused on bands where the RSP1 or RSP2 had issues, and try to show how much improvement you can get from the RSP1A.

Medium Wave Broadcast AM Band

In the screenshots below we compare the three SDRs on the broadcast AM band which has some very strong signals. The RSP1 definitely shows signals of overloading and turning the gain down did not reduce the interference shown between 0 - 500 kHz. 

The RSP1A on the other hand does not overload that easily. In the third screenshot we turn the MW notch on half way through the waterfall. The notch does not cover the entire AM band and signals at around 500 - 700 kHz are attenuated less. But turning it on does seem to do enough to solve most imaging problems as will be seen in the next tests.

SDRplay RSP1

SDRplay RSP1

SDRplay RSP1A

SDRplay RSP1A

SDRplay RSP1A (MW Filter ON Halfway Through)

SDRplay RSP1A (MW Filter ON Halfway Through)

SDRplay RSP2

SDRplay RSP2

Continue reading

SDRplay Release the RSP1A: A $99 14-bit 1 kHz to 2 GHz Revision of the RSP1

Today SDRplay have released the RSP1A, a revision of the popular $99 USD RSP1 with some significant improvements. The press release is pasted below: 

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

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

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

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

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

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

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

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

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

The RSP1A is expected to retail at approximately £76 (excluding taxes) or $100 (excluding taxes) For more information visit our website on www.sdrplay.com

About SDRplay:

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

The datasheet is available here (pdf), and a the full technical information is available here (pdf).

We've had a RSP1A beta preproduction unit for a few weeks now and will be releasing a full review comparing it against the RSP1 in a day or so. For a quick review conclusion we note that we've noticed that the filters are significantly more effective on the RSP1A compared to the RSP1, and the inclusion of the MW/FM and DAB notch filters help a lot in certain situations. The increased ADC resolution is due to decimation on board the MSi2500 chip and is noticeable in some situations, but does not seem to cause a huge improvement. Overall compared to the RSP1 some overloading problems are still present with strong signals, but intermodulation and imaging is reduced significantly and in some cases the RSP1A even outperforms the RSP2.

Also, Mike Ladd KD2KOG a member of the SDRplay technical support team has uploaded a video announcing and demoing the RSP1A. 

SDRplay RSP1A
SDRplay RSP1A

 

A Tutorial on Receiving HRPT Weather Satellite Images with an SDRplay RSP2

RSP2user's HRPT equipment

Over on the SDRplay forums user 'RSP2user' has put up a quality post describing how he receives HRPT weather satellite images with his SDRplay RSP2. HRPT stands for 'High Resolution Picture Transmission' and provides a much higher resolution image compared to the APT weather satellite images typically downloaded from NOAA satellites. Somewhat confusingly the picture quality of HRPT is similar to LRPT (low rate picture transmission) which is used on the Russian Meteor M series weather satellite. HRPT provides 1.1 km resolution, whilst LRPT provides 1 km resolution.

Currently there are multiple satellites broadcasting HRPT signals including NOAA 19, NOAA 18, NOAA 15, Meteor M2, Fengyun 3B, Fengyun 3C, Metop A and Metop B.

The difference in difficulty of receiving APT and LRPT versus HRPT transmissions typically occur in the L-band at about 1.7 GHz, and requires a directive high gain antenna with tracking motor to track the satellite as it passes over. This makes these images many times more difficult to receive compared to APT and LRPT which only require a fixed position antenna for reception at the more forgiving 137 MHz.

Over on his post RSP2user shows how he uses a repurposed Meade Instruments telescope tracking mount and controller to drive the tracking of a 26 element loop Yagi antenna. A 0.36dB noise figure LNA modified with bias tee input is used to boost the signal and reduce the noise figure. The signal is received by a SDRplay RSP2 and processed on a PC with USA-satcoms HRPT decoder software, which is available for purchase by directly contacting him. The HRPT signal bandwidth appears to be about 2.4 MHz so possibly an RTL-SDR could also be used, but it might be pushing it to the limit.

If you are interested, RSP2user also uploaded an APT weather satellite image reception tutorial on another post. This tutorial shows how to build a quality quadrifilar helix antenna as well.

Receiving the HRPT signal on USA-Satcoms' HRPT decoder.
Receiving the HRPT signal on USA-Satcoms' HRPT decoder.