Category: SDRplay

SDR-J Now Compatible with the Raspberry Pi 2

The popular software DAB (Digital Audio Broadcast) decoder SDR-J has recently been updated and can now run on the Raspberry Pi 2. In addition the author has also added experimental DRM decoding capabilities to his shortwave receiving software. The author writes about the Raspberry Pi 2:

The Raspberry PI 2 has a processor chip with 4 computing cores. By carefully spreading the computational load of the handling of DAB over these cores it is possible to run the DAB software on the Raspberry PI 2.

In my home situation the – headless – Raspberry PI 2 is located on the attic and remotely controlled through an SSH connection using the home WiFi on my laptop in my “lazy chair”. To accomodate listening remotely, the DAB software on the Raspberry PI 2 sends – if so configured – the generated PCI samples (rate 48000) also to an internet port (port 100240). On the laptop then runs a very simple piece of program reading the stream and sending it to the soundcard

DAB is a digital audio protocol that is used in some countries as a digital alternative to broadcast FM (music stations). SDR-J is a suite of programs that includes the ability to decode DAB, FM, and several shortwave modes such as AM, USB, LSB, PSK, RTTY, WeatherFax, SSTV, BPSK, QPSK, CW, NavTex (Amtor-B), MFSK, Domino, Olivia, Hell, Throb and now DRM. It can directly connect to RTL-SDR receivers as well as other hardware such as the Airspy and SDRplay.

Screenshot of SDR-J running on the Raspberry Pi 2.
Screenshot of SDR-J running on the Raspberry Pi 2.

Another L-Band Antenna Build and comparing L-Band reception on the RTL-SDR, HackRF and SDRplay

Over on Reddit user killmore231 has made a post showing his comparison of L-Band reception with RTL-SDR, HackRF and SDRplay software defined radios. killmore231 built the L-band patch antenna which Adam 9A4QV showed how to build on his YouTube channel late last month.

When testing the antenna on his RTL-SDR he saw no reception of any L-band signals at all. The RTL-SDR requires an external LNA to properly receive signals at this frequency range, which he did not have. Next he tried it on his HackRF and saw that some signals were weakly visible. When he tried it on his SDRplay the L-band satellite signals were clearly visible, probably due to the SDRplay’s good sensitivity at this frequency range and the fact that it has a built in LNA. His results show that the SDRplay is a good SDR for receiving L-band satellites as it does not need an external LNA for decent reception. An external LNA may still be needed if a long run of coax cable is used however.

SDRplay reception of L-band satellite signals with no external LNA.
SDRplay reception of L-band satellite signals with no external LNA.
L-band patch antenna
L-band patch antenna

Demonstrating the Dynamic Range on the SDRplay RSP

The SDRplay radio spectrum processor (RSP) is a $150 USD software defined radio that can be considered as a next stage level up from the RTL-SDR dongle. We also consider it a competitor to the $199 USD Airspy SDR.

Over on YouTube the SDRplay designers have posted a video that demonstrates the dynamic range that is possible with their SDR. Dynamic range is a measure that defines the range between the strongest and weakest signal that can be received. So for example, if you have two signals near to each other on the frequency spectrum, dynamic range defines how much stronger can one signal be compared to the other before the weaker signal disappears into the noise.

In the experiment they use two frequency generators to generate a simulated wanted signal at 98.4 MHz and an unwanted blocking interferer at 98.7 MHz. They show that by reducing the IF bandwidth in their configuration screen and thus tightening the internal filters that the dynamic range can be increased to about 70 dB.

Previously Leif sm5bsz performed some similar tests, comparing many SDRs against one another, but did not utilize the programmable IF filters in the SDR Play RSP perhaps undervaluing the best possible dynamic range by about 5-10 dB.

SDRplay RSP FM Dynamic Range Demo

HAMSPIRIT.DE’s Review on Airspy vs SDRPlay

Over on the hamspirit.de blog author January has just uploaded his latest review comparing the Airspy with the SDRPlay (article in German, so use Google Translate if necessary). These are two mid price range RX only software defined radio receivers that many people see as a first upgrade from an RTL-SDR dongle. Currently, the Airspy sells for $199 USD and the SDRPlay sells for $149 USD.

In his review January uses the SDR# to compare both devices on a wide range of signals include a beacon in the 10M band, broadcast FM stations, another beacon in the 2M band, TETRA signals and trunked radio in the 70cm band. He ran the SDRPlay at a bandwidth of 1.536 MHz and the Airspy at a bandwidth of 2.5 MHz, with decimation set to 2 in order to get comparable bandwidths.

From the results it appears that overall the two SDR’s are quite comparable to one another. But the SDRPlay has the advantage that it’s frequency range covers shortwave frequencies and his results show that the SDRPlay had better SNR in the FM broadcast band (although these results may be incorrect as it appears that his gain settings were not set properly, as the Airspy guide recommends that Airspy gains be adjusted to keep the noise floor near -80 dBFS). On the other hand the Airspy was much better when strong FM overload was present as shown in his TETRA results. In his conclusion he writes (translated from German to English):

If one value to a SDR, which covers with the short wave, it is running out on the SDRplay.

If one is interested in the field below the 70cm amateur radio bands, is in my view the Airspy front.

The Airspy software defined radio    The SDRPlay software defined radio

New drivers for the SDRPlay released: No more frequency gap

The SDRPlay is a $149 USD software defined radio with a 12-bit ADC, 8 MHz of bandwidth and a 100 kHz to 2 GHz tuning range. It is a good upgrade to the RTL-SDR and can be considered as a competitor to the Airspy SDR. 

One of the initial cons of the SDRPlay was that it had a tuning gap from 380 MHz to 420 MHz. The gap was due to hardware limitations and had nothing to do with censorship. However, now the SDRPlay team have released a new API which fixes these limitations and can fully close the gap.

Along with this update they have also released a new EXTIO driver file with the following improvements:

  • Implementation of a selectable 1st LO frequency for the block converter. This will apply to frequencies below 60MHz (up-converted) and between 250MHz and 420MHz (down-converted). This allows full coverage between 100kHz and 2GHz in AUTO mode or the re-position of interferes at the expense of coverage range 

  • Added a down conversion routine to convert Low IF modes to Zero IF modes for compatibility in SDR interfaces. IF bandwidths below 1.536MHz supported choice of IF Frequency and sample rate are restricted. 

  • Added Options to control the DC offset compensation mode used by the tuner. Available modes are Static, Periodic, One-Shot and Continuous 

  • Improved robustness when dynamically changing between IF modes and sample rates

The new drivers can be downloaded from sdrplay.com/platforms.html.

SDR Play Radio Spectrum Processor
SDR Play Radio Spectrum Processor

 

A Review of the SDRPlay Software Defined Radio

In the May 2015 issue of The Spectrum Monitor magazine, the SDRPlay was reviewed in an article by Thomas. Now the article has been released for free over on the swling.com blog. The SDRPlay is a $149 USD software defined radio with a tuning range of 100 kHz – 380 MHz and 430 MHz – 2 GHz, a 12-bit ADC, and up to 8 MHz of bandwidth. We consider it as a decent upgrade to those wishing for something better than the RTL-SDR and a good competitor to the Airspy SDR.

In the review Thomas unboxes the unit, installs the software and reviews the HF DX performance comparing it to the more expensive Elad-FDM S2. While the performance isn’t as good as the Elad, Thomas writes that for the price it performs very impressively. In his conclusion he writes:

[The] SDRplay RSP really impressed me from the beginning with its low noise floor, variable IF bandwidth options, and relative ease of installation. Since the RSP only requires one USB cable for both data and power, it’s also an ideal portable SDR.

SDR Play Radio Spectrum Processor
The SDR Play Radio Spectrum Processor

SDRPlay Price Reduced to $149 USD

The Radio Spectrum Processor (RSP) by SDRPlay is a receive only software defined radio with a 100 kHz to 2 GHz range (with a small gap at 380 MHz to 430 MHz), a 12-bit analogue to digital converter (ADC) (~10.4 ENOB), 8 MHz bandwidth and a bank of several switched front end filters.

Previously the SDRPlay RSP was priced at $299 USD, however they have just halved this price down to $149 USD plus tax and shipping. At this price point we think the SDRPlay is a very good competitor to the Airspy SDR which seems to be the more popular option priced at $199 USD, especially if you are interested in listening to the HF bands without the need for an upconverter.

Recently we posted about some SDRPlay reviews which are all favourable.

The Radio Spectrum Processor (RSP) by SDRplay.
The Radio Spectrum Processor (RSP) by SDRplay.

Highlighting some SDRPlay Reviews

Update: Note that we also now have our own comprehensive review available here which compares the Airspy, SDRplay RSP and HackRF.

The Radio Spectrum Processor (RSP) by SDRplay is a receive only software defined radio with a 100 kHz to 2 GHz range (with a small gap at 380 MHz to 430 MHz), a 12-bit analogue to digital converter (ADC) (~10.4 ENOB), 8 MHz bandwidth and a bank of several switched front end filters. It currently costs $299 USD and with these specs and price range we consider the RSP to be a competitor to the Airpsy and Funcube Dongle software defined radio offerings.

Recently several reviews of the SDRplay RSP have been written online and in magazines. The first review comes from the pages of the UK based Radio User magazine (pdf warning) which goes through the specs, design, install and operation of the device. A more recent review shows an unboxing and there’s also this review submitted to the SDRplay team which demonstrates some FM dxing results. There are also several more reviews collected by the SDRplay team linked on the SDRplay website at http://www.sdrplay.com/reviews.htm.

We also note that we recently posted about some in depth measurements that Leif (programmer of Linrad) recently made to multiple SDR’s, including the SDRplay.

The Radio Spectrum Processor (RSP) by SDRplay.
The Radio Spectrum Processor (RSP) by SDRplay.