Category Archives: Software Defined Radio

SDRplay RSP: now $149 or £99

I just received the following tweet from @SDRplay:

We’ve been able to reduce the SDRplay RSP price to $149 or £99 (approx €149 ) + tax/shipping. See http://www.sdrplay.com

I’ve just started reviewing the SDRplay RSP for the June 2015 issue of The Spectrum Monitor Magazine. Preliminary impressions of this SDR are quite positive–especially for a receiver in this price class. At $149 US, the SDRplay RSP is now less expensive that the Funcube Dongle Pro+. Indeed, the RSP is even less expensive than portables like the Tecsun PL-880 and Sangean ATS-909X.

Over the next two months (as I get to know the RSP better) I will post the occasional broadcast recording using the SDRplay RSP with HDSDR and SDR#.

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Pulling Radio Santa Cruz out of the interference

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I recorded Radio Santa Cruz early this morning around 05:00 UTC on 6,135 kHz using the TitanSDR I currently have under review.

Radio Santa Cruz‘s 10 kW signal from Santa Cruz, Bolivia, was very much audible here in North America, though RSC was competing with another station on-frequency at the time. Actually, Radio Santa Cruz was broadcasting slightly off-frequency–6134.8 kHz instead of 6,135 kHz. In this case, the fact that RSC was slightly below frequency helped me delineate the station’s audio from that of a competing station.

In the screen-grab of the narrowband channel from the Titan SDR (above–click to enlarge) you can see two distinct carriers spaced only .2 kHz apart (represented by the two peaks in the spectrum display and two parallel vertical lines in the waterfall display).

Here is what the audio sounds like in normal AM mode when we center on the Radio Santa Cruz frequency of 6,134.8 kHz:

You hear a hetrodyne and garbled noise from a competing station. Not pleasant audio.

If we change from the AM mode to eLSB mode (essentially, the TitanSDR’s version of synchronous detection on the lower sideband) we are ignoring all of the noise in the upper sideband, allowing the desired signal of RSC to pop out.

You can see in the screen-grab above that now only the lower sideband of the RSC signal is highlighted. Here’s a 21 minute recording:

Makes quite a difference!

It’s easy to see competing signals and interference on an SDR’s spectrum display, but if you hear something similar on your portable, try the techniques above to see if it clears up the signal.

If your receiver lacks a selectable synchronous detector, much of the same results can be gained by zero-beating (tuning in) the desired signal in lower sideband mode. Of course, if you have a receiver that lacks SSB mode, the best you can do is tune slightly below frequency in AM, in which case the results will not be as dramatic.

Conclusion? Listening in single-sideband or with a selectable sync detector might be all you need to dig a signal out of the interference.

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The Quadrus SDR: A New Military-Grade Software Defined Radio Receiver

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Dr. Bertalan Eged of Spectrafold Technologies recently contacted me regarding a new military grade SDR they’ve produced: the Quadrus SDR. Today is the Quadrus official release.

The Quadrus SDR has phase-coherent multi-channel capabilities with up to 16 channels, which means that it can be used for direction finding, diversity reception, as well as MIMO applications.

While the Quadrus line is aimed squarely at government and scientific research markets, the $1490 US Quadrus DRU-244A-1-1-PCI, a four-channel SDR, might appeal to the discerning DXer, amateur radio operator, or radio experimenter.

Below, I’ve posted the full press release from Spectrafold Technologies along with several photos and screen shots.

Since I’m not a radio engineer, I’ve asked a representative of Spectrafold to answer any questions you may have about the Quadrus SDR line and its receiver architecture.

Military-Grade Software Defined Radio Receiver Platform
Now Commercially Available for Building Better Receivers

Phase-coherent, Multi-channel Quadrus Platform Brings New Features to Commercial Market

Spectrafold Technologies today released the Quadrus software defined radio (SDR) platform for commercial use, enabling access to advance, professional-grade platform for signal intelligence, spectrum monitoring communications systems and missions. The long-standing platform has features are still unmatched by other commercially available products, and include four cutting-edge, phase-coherent antenna inputs with 16 bit, 80 MSPS; high-sensitivity, high-dynamic range Analog-to-Digital Converters (ADCs) driven by a low phase noise; and high-stability sampling clock. The input signal chain also contains a Low-Noise pre-Amplifier (LNA) and an input leveling attenuator providing the necessary sensitivity while still maintaining the proper input drive. The architecture provides the capability of using high gain antennas, and standing against the overload by the crowded radio spectrum.

“Today there is strong international community of radio enthusiasts and listeners using SDR technology, looking for platforms that implement advanced radio signal processing algorithms,” said Dr. Bertalan Eged, chief architect of the Quadrus. “Physically and logically phase-coherent multi-channel SDR platforms provide the capability to implement various algorithms and receivers such as diversity reception, interference cancelling, beam forming and correlative receivers. These applications can help to deliver better sensitivity, more stable fading free reception, longer connectivity and collecting more information on the radio signal environment.”

The platform input bandwidth is wide enough to be used up VHF/UHF bands as Direct Digital Receiver (DDR). The samples are fed into an FPGA, where a non-blocking switch matrix is used to forward them to the input of the four on-board receiver signal processors. The on-board processing is capable of forming a 16 multi-channel receiver. The platform also features a standard PCI interface for PC integration, and comes with a Windows®32 bit kernel driver and fully open API, which can be downloaded from the website along with the operating SDR software. The SDR receiver software has remote control capability for system level integration via TCP/UDP/IP links. Further details on these capabilities are available at the Spectrafold website. The system has spectrum recording capability to binary files, some example can be downloaded for evaluation purposes.

The Quadrus API is available as a Windows® DLL, and developers and system integrators may download it from the SUPPORT page on the Spectrafold website. The hardware API is meant for direct hardware access, but a higher level remote control interface API is available as well, which can be used to (i) set up the receiver channel parameters and to (ii) access the IF as a UDP/IP stream. If you prefer to not use any of these methods, it is possible to fall back to a virtual audio card connection between the SDR software and external applications, like decoders and post processors.

Additional information on the performance and usage scenarios is available in the BLOG. Users interested in experimenting with the hardware can gain access to remote access to a computer with SDR hardware digitizer and installed SDR software. Interested parties should contact the team by email: [email protected]

Hardware orders may be placed through the manufacturer’s ORDER page. Standard secure payment option is provided via PayPal. International shipment by UPS is part of the service. The hardware is manufactured in batches with limited stock. Introductory pricing starts at $1490.

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About Spectrafold Technologies

Spectrafold is a dedicated community of professionals, who work tirelessly to invent and create affordable, cutting edge SDR solutions. Together we have decades of hands-on experience delivering working solutions to the toughest missions and environments. Our customers include academic, governmental, and military organizations, but radio enthusiasts as well.

Screen shots

Click to enlarge:

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23 January 2015: A Friday morning 31 meter band scan

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This morning, I tuned around the 31 meter band and was surprised with favorable propagation out of Asia (see spectrum waterfall above–click to enlarge).

I started logging a few stations, but the effort quickly turned into a full band scan/survey. I logged everything I could easily hear between the 9,390-10,000 kHz portion of the 31 meter band.

I logged 52 stations and omitted eight that I considered too weak for good copy.

I used my WinRadio Excalibur SDR connected to a large horizontal delta loop wire antenna.

The number of broadcasts originating in or targeting China is pretty phenomenal: the 31 band is your oyster, if you speak Chinese.

31 Meter Band 1200 – 1300 UTC, all frequencies in kHz

9390 Radio Thailand Malaysian (1200Z) then English (1230Z)
9410 China National Radio 5 Chinese
9430 FEBC Radio Chinese
9440 China Radio International Cambodian
9460 China Radio International English
9475 Radio Australia English
9490 Voice Of America Korean
9500 China National Radio 1 Chinese
9515 China National Radio 2 Chinese
9530 Voice Of America Chinese
9540 China Radio International Chinese
9550 China Radio International Vietnamese (covered by CRI Cantonese distortion)
Note the blowtorch CRI signal on 9,570 kHz which was blanketing the surrounding spectrum with noise.
9570 China Radio International Cantonese (transmitter spewing distortion 50 kHz wide)
9580 Radio Australia English (covered by CRI Cantonese distortion)
9590 China Radio International Russian (covered by CRI Cantonese distortion)
9600 China Radio International English
9620 China National Radio 6 Chinese
9635 Voice of Vietnam 1 Vietnamese (slightly below freq)
9640 Radio Havana Cuba Spanish
9645 China Radio International English
9655 China Radio International Chinese
9660 Radio Taiwan International Chinese
9680 Radio Taiwan International Chinese
9700 Lower Sideband communication (UNID)
9710 China National Radio 1 Chinese
9720 China Radio International Filipino
9730 China Radio International English
9735 Radio Taiwan International Indonesian
9740 BBC English
9745 Guanghua zhi Sheng Chinese
9750 Radio Kuwait Arabic
9730 China Radio International English
9770 KBS World Radio Chinese
9775 China National Radio 2 Chinese (vy weak)
9785 China Radio International Laotian
9790 Voice Of Islamic Republic of Iran Pashto
9810 China National Radio 2 Chinese and All India Radio Telugu
9820 Radio Havana Cuba Spanish
9825 Voice Of America Chinese
9830 China National Radio 1 Chinese
9840 Voice of Vietnam English
9850 Radio Habana Cuba Spanish
9855 China Radio International Chinese
9860 China National Radio 1 Chinese (vy weak)
9880 KSDA-AWR Guam Korean (vy weak)
9900 Radio France International Chinese
9920 FEBC Radio Bahnar (w/Jamming)
9940 Reach Beyond Australia (HCJB) Indonesian
9955 Radio Slovakia International English (via WRMI/WRN)
9975 KTWR Guam Chinese
9990 Radio Farda Persian
10000 WWV Fort Collins English

I recorded two broadcasts during the scan–both at 12:30 UTC: Radio Thailand (9,390 kHz) and Radio Slovakia (9,955 kHz). I will post them soon.

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Excellent website dedicated to the RTL-SDR

Video: Controlling the Elad FDM-S2 SDR with the HP Stream 7 tablet

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Many thanks to SWLing Post contributor, Guy Atkins, who shares the following video demonstrating how the Elad FDM-S2 can be controlled with the $99 HP Stream 7 Windows 8.1 tablet PC:

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Elad FDM-S2: Eric’s method of mitigating strong local signals

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Many thanks to SWLing Post reader Eric Cottrell, who writes:

“Thanks for your excellent review of the Elad FDM-S2. I bought one and received it yesterday.

I tried out the software earlier this week by downloading 4GB of sample files from DK8OK and the Elad software. There are a lot of interesting features.

It is small! I like the use of the USB port for power. I can see how it would be a good receiver to throw into your laptop bag for trips.

I have a harsher Urban RF environment with 5KW and 1KW AM Broadcast transmitters within 2.5 miles. They reduce power at night. The Wellbrook AHA1530 Loop outputs a very high signal level from all the area’s AM stations. I have to use the attenuator on any radio at my QTH below about 2.5 MHz.

The unit having one preselection filter for LW/MW/HF is noticeable as I got ADC Clip warnings when directly connected to the Wellbrook loop. Turning on the 11 dB attenuator took care of the problem and did not seem to affect the weak signals much. It also was not as bad when I connected a Mini-Circuits ZFSC-2-6+ two port splitter between the Elad and the Wellbrook.

The Perseus has multiple preselection filters, but I noticed only one low pass filter for the 0 to 1.7 MHz range. So a MW band reject filter would be useful for Long Wave with both units. I plan on building an external preselector.

The option for multiple receivers and two RF ranges is pretty neat. I was listening to multiple FM stations at once. This morning I set one range to 31 meters and the other to 49 meters. I listened to Radio Australia on 9580 KHz using the right laptop speaker for audio, and could check their other frequencies on 31 and 49 meters using the left laptop speaker for audio.

I do HF Utility monitoring on digital signals, so I want to setup the Elad software with external decoder software. I have seen reports that the Elad can receive Airband pretty good, so I will also try receiving and decoding multiple ACARS frequencies at the same time.

So many experiment to try this Winter!”

Thanks for sharing your experience, Eric! Since I live in such a rural area, I never have to worry much about low pass filters (though I’m sure they couldn’t hurt). I’ve had the FDM-S2 since June this year. I can tell you that there are so many features, settings and possibilities with this radio, you could easily spend the winter and spring experimenting. I have yet to use the WinRad app to drive the S2.

Eric, we welcome any other discoveries you make along the way! Many thanks!

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