Category: Other

Elektor SDR Hands-on Book + Arduino Shield HF SDR

Elektor is a popular electronics magazine and hobbyist kit store. Recently they have published a book titled "SDR Hands-on Book" written by Burkhard Kainka. The book is intended as a companion to their Arduino SDR shield kit, which is a low cost module that allows you to turn an Arduino into a 150 kHz to 30 MHz capable SDR. It is based on the G8JCFSDR, which is an RF front end downconverter that allows a PC soundcard to be used as an SDR analog to digital converter.

Kainka's book goes over introductory topics such as shortwave reception, explains signal to noise ratio and interference, different types of antennas, software, digital modes, SDR measurements, receiving and finally WSPR and QRP transmission. If you're interested Jan Buiting also recently reviewed the book on the Elektor website.

Elektor are currently running a promotion and are selling the book + Arduino shield for a reduced price of €49.90.

The Elektor Arduino Shield HF SDR Kit.
The Elektor Arduino Shield HF SDR Kit.

The 2019 New England Workshop for SDR

The New England Workshop on Software Defined Radio (NEWSDR) is a yearly conference that hosts multiple SDR related talks. Previously we posted a selection of our favorite 2018 talks which involved topics such as remote sensing of space with SDR, wireless deep learning and multi-objective SDR optimization.

This years NEWSDR event will been held on Jun 13 and 14 at the University of Massachusetts in Boston. They are currently offering pre-registration for free, and are looking for poster presentations.

This year is the 9th iteration of NEWSDR and it will be held at the University of Massachusetts Boston campus on June 13 and 14. Registration is free and we are also accepting submissions for poster presentations and elevator pitches. The event is an excellent networking opportunity and includes technical presentations as well as demonstrations from industry sponsors (Ettus/NI, MathWorks, Analog Devices, and MediaTek).

NEWSDR 2019 Poster
NEWSDR 2019 Poster

SignalsEverywhere Podcast EP2: Common SDR Mistakes and How to Resolve Them

Corrosive from the SignalsEverywhere YouTube channel has recently released episode two of his new podcast. This episode is titled "Common SDR Mistakes and How to Resolve Them". In the podcast Corrosive discusses some tips like how to ensure that the gain on your SDR is set correctly, how to set the sample rate, how to optimize the waterfall display, and what antennas to use. Later he goes on to talk about our RTL-SDR Blog V3 dongles, and discusses some posts from our blog.

Creating an EMC Probe using an RTL-SDR and Semi-Rigid Coax

Thank you to Dimitris for submitting his article on creating an RTL-SDR based EMC probe. An EMC probe is a device that can be used to detect electromagnetic interference leaking from areas on electronic devices. For example an electronic PCB might have problems with RF leaking into other components. With the probe you could determine where the leak is coming from.

To create the probe he uses a 30cm semi-rigid coax cable and an RTL-SDR dongle. The semi-rigid coax is cut in half, the center conductor stripped back, then looped around on itself and soldered to the shield. Dave from EEVBlog did a video on this previously which is what inspired Dimitris. The next steps are simply to connect the probe to an RTL-SDR, put it into direct sampling mode and probe around for signals. Note that an RTL-SDR with direct sampling like our V3 model, or an RTL-SDR with upconverter is required to receive signals below 24 MHz.

His results show that he was able to successfully probe an OCXO oscillator, by seeing the 10 MHz signal in SDR#. The rest of his post goes on to discuss the limitations of this method, and compares it against professional EMC probes available on the market.

RTL-SDR Based EMC Probe
RTL-SDR Based EMC Probe

Reaching Across Europe with a Raspberry Pi Zero and WsprryPi

Over on YouTube user Techminds has uploaded a video that shows how he is using a Raspberry Pi Zero to transmit WSPR. To do this he uses the WsprryPi software which allows you to transmit WSPR by connecting an antenna directly to a GPIO pin on the Pi Zero. With this no extra hardware is required, although a filter is highly recommended to reduce spurious emissions from harmonics.

In his test Tech Minds directly connected the Pi Zero to an unun and HF wire antenna and ran WsprryPi. His results showed that even with the tiny 10mW output power of the Pi Zero's GPIO port his WSPR messages were able to reach several receivers halfway across Europe, and even to Iceland and Morocco from his home in the UK.

WSPR is an amateur radio digital HF mode designed to be decodable even if the signal is transmitted with very low power and is very weak. It can be used to help determine HF radio propagation conditions as WSPR reception reports are typically automatically uploaded to wsprnet.

WSPR - Weak Signal Propagation Reporter - From A Pi Zero ?

GNU Radio Conference 2019: Registration Open + Call For Papers

GNU Radio Conference is a yearly conference based around the GNU Radio project and the surrounding community. GNU Radio is an open source digital signal processing (DSP) toolkit which is often used to implement decoders, demodulators and various other SDR algorithms.

GRCon is the annual conference for the GNU Radio project & community, and has established itself as one of the premier industry events for Software Radio. It is a week-long conference that includes high-quality technical content and valuable networking opportunities. GRCon is a venue that highlights design, implementation, and theory that has been practically applied in a useful way. GRCon attendees come from a large variety of backgrounds, including industry, academia, government, and hobbyists.

The 2019 GNU Radio Conference will be held on September 16-20 at the Marriot at the Space & Rocket Center in Huntsville, Alabama.

Registration and a call for papers and posters is currently open, see gnuradio.org/grcon/grcon19.

Othernet Dreamcatcher On Sale for Only $49

Over on the Othernet website the Dreamcatcher hardware is currently on sale for only US$49. This is the lowest we've ever seen it for sale.

If you weren't already aware, the Othernet project aims to bring live data such as news, weather, video, books, Wikipedia articles and audio broadcasts to the world via a free satellite service and cheap receivers. Although an internet connection provides the same data, Othernet's satellite broadcast is receivable in remote areas, will continue working in disasters, and costs nothing to continually receive roughly 200MB of data a day. The trade off is that the service is downlink only, so the data that you get is only what is curated by the Othernet team.

Currently the public service is in a test period and is only available in North America. Europe has come online recently too, however they write that the current version of Dreamcatcher that is for sale may not be optimal for receiving the EU signal.

While currently active, they write that the Othernet satellite service is not guaranteed to continue long term. However even if the service discontinues, the Dreamcatcher can still be used as a TX/RX capable LoRa radio. In a previous post we demonstrated a fun application with two Dreamcatchers and a LoRa chat application.

Othernet Dreamcatcher
Othernet Dreamcatcher

A Vacuum Tube Based Shortwave Software Defined Radio

Vacuum tubes are not typically found in software defined radios, but this interesting mix of old and new technology by Mirko Pavelski uses one in it's front end. The way it works is that the analogue radio circuit receives a small range of spectrum, and then the tube acts as a mixer, converting that spectrum down into audio frequency range which can be heard by a computer sound card.

The sound card acts as the ADC, digitizing the signal, and then the "SDRadio" software performs the final filtering and demodulation of a narrowband signal in software. This is the same concept used by other HF sound card SDRs such as the Softrock, although those of course do not use tubes in their design. Mirko writes:

Simple to build receiver made according to the instructions of Burkhard Kainka : http://www.b-kainka.de/bastel100.htm. I made it with EF80 tube instead EL95 and it works great. It is powered by a 7.4V lithium-ion battery followed by a 7806 stabilizer, so we get 6v for tube heating and there are no problems with 50 Hz hum. Тhe resonant circuit is made of strong coil with 20 turns of 1.5 mm thick wire wound on a PVC tube with 18 mm diameter. At the cold end of the resonant circuit is an antenna coil with two turns. At the output of the radio, I connecт 2 transistor preamplifier and cheap amplifier module in D class. So we get battery powered tube АМ radio. Using the potentiometer we can select between AM or SDR mode of operation.

In SDR mode, we need to connect the output of the radio to "line in" in sound card of the computer. Then we use some of the free software for example "SDRadio" from Alberto I2PHD. Тhe receiver has very good frequency stability which drifts less than 1 Hz per minute. Тhis is important if we want to decode DRM signals. In good HF propagation conditions I receive BBC World service DRM radio (3995MHz) with 16dB SNR here in Ohrid (41.1231° N, 20.8016° E). This little radio, with a long wire antenna and good grounding, gives us a lot of fun.

Hackaday also recently posted an article about this build.

DIY one tube shortwave + SDR radio