Over on his YouTube channel Tech Minds has uploaded a video where he tests out a cheap US$90 automatic antenna switch with DC-160 MHz range that he purchased from Chinese goods retailer Banggood. An automatic antenna switch like this is required when wanting to use an SDR such as an RTL-SDR as a panadapter with a transmit capable radio. The switch will automatically switch the SDR to ground when transmitting, so that high power does not enter the SDR via the shared antenna and destroy it.
In the video Tech Minds shows how to set the switch connections up and then demonstrates the switch in action with a Yaesu FT-991A and SDRplay SDR. He notes that this cheap Chinese version is actually built better than the MFJ-1708 antenna switch which until recently was the only commercial option available. It is also half the price.
PANADAPTER For Any Radio DC - 160 MHz SDR Antenna Switch
SDRplay have recently released a blog post warning potential customers to be wary of the proliferation of fake and imitation SDRplay devices on various online marketplaces. SDRplay warn that these clones may not function with the latest SDRplay software such as SDRUno, and that no technical support for the clones is provided.
Of note is that ICQ Podcast Episode 344 released on Feb 14 also discusses this issue starting at 30:50 in the episode. They note that ethically these clones are problematic as they are ripping off a small company who have sunk a lot of costs into R&D and software development.
SDRplay is a UK based company that designs and manufactures low cost software defined radios which start from $109 + shipping. In the past we've posted a few times about SDRplay clones like the MSI.SDR, and about more elaborate clones of the RSP1A as well as Airspy and RTL-SDR V3 clones. As Mirics, the company manufacturing the main silicon chips used in SDRplay products is owned by most of the same people behind SDRplay it is unclear as to how their chips made it onto the Chinese markets. However, as these Mirics chips were originally used in mass market TV tuners, it is thought that they were probably desoldered from a batch of old USB TV tuners.
DragonOS is a ready to use Ubuntu Linux image that comes preinstalled with multiple SDR program. The creator of DragonOS, Aaron, uploads various YouTube tutorials showing how to use some of the preinstalled software. This month one of his tutorials covers how to use a SDRplay RSP1A or a HackRF to receive and decode FT8 with the preinstalled software WSJT-X or JS8Call. Aaron also notes that an RTL-SDR could also be used as the SDR.
In the video he covers how to set up a virtual audio cable sink in Linux for getting audio from GQRX into WSJT-X, setting up rigctld to allow WSJT-X to control GQRX, configuring GQRX, CubicSDR and WSJT-X, and finally downloading and using GridTracker.
Earlier this year SDRplay updated their SDRuno software to have plugin functionality. This allows third party programmers to implement their own decoders and software which interfaces with SDRuno directly. Recently we've seen some new plugins become public, and in one of their recent blog posts, SDRplay highlights a few new ones.
SDRplay writes the following about three demonstration videos:
The first shows the latest version of FRAN – a FRequency ANnotation programme, developed by Eric Cottrell – it can read SWSKEDS or .s1b memory bank files and display the active stations from the files on the main spectrum window. This is an example of a Community Plugin
Quick Look at the FRAN Plugin (VID558)
FRAN complements the DX Cluster demo plugin provided by SDRplay. This programme displays DX cluster callsigns on the SDRuno spectrum display. A DX cluster is a network of computers, each running a software package dedicated to gathering, and disseminating, information on amateur radio DX activities. With this plugin you can overlay the DX cluster callsigns as they pop up. There’s a choice of how long you let them display and you can control the way in which they appear. Here we show it successfully tuning in to a US station flagged by the cluster. (The receiver was in the UK):
Quick Look at the DXcluster Plugin (VID560)
Finally there’s this new video showing the new plugin for interfacing the software suite from Black Cat Systems to SDRuno enabling DXToolbox, HF WEFAX and Slow Scan TV decodes:
In this week's Tech Minds video Matthew interviews the SDRplay team and also takes a tour of their design lab and PCB manufacturing facility. SDRplay is a manufacturer of low cost wideband software defined radios, with the cheapest starting at US$109.
The video starts with an interview with Jon Hudson from the SDRplay sales team who gives an overview of the entire SDRplay product line up, also explaining how the products have been iterated on over time. Jon also talks about the SDRuno software and team members in the company.
The next interview is with Andy Carpenter who is the head of SDRplay software development. Andy talks about SDRuno and how it came to be acquired and improved by SDRplay. They go on to discuss some recently added SDRuno features such as the plugin environment as well as the upcoming feature roadmap.
The final part of the video is a tour of the equipment used at the SDRplay design lab, and a tour of the UK based PCB manufacturing facility contracted by SDRplay.
The course appears to be intended for University teachers in order to accelerate adoption of SDR based teaching of RF courses. We're unsure if this material will be released to the general public as their signup form appears to ask for University details. They write:
Alton, England; 5th November 2020 – SDRplay Limited announces a new Radio Communications course for under-graduate teaching as part of its SDRplay Educators Programme
“Understanding Radio Communications – using SDRs” includes a rich set of teaching materials and practical exercises to help students understand the key elements of radio communications. This one semester course provides teaching materials and practical workshops that lead students from the first switch-on of a Software Defined Radio (SDR), through to signal reception, demodulation, and finally, successful communications with satellite signals.
As well as guides and set-up instructions for teachers for both the lecture and lab sessions, there are downloadable teaching materials in both PowerPoint and .pdf formats. There are video guides showing the lab activities and there’s a dedicated new forum for teachers to share experiences and to get help from the authors.
The course was created in association with academic partners Sapienza University of Rome, Department of Mechanical and Aerospace Engineering whose intention was to create a practical course that will inspire Science, Technology and Engineering students to nurture their understanding of radio communications.
The course started life as a 12-hour optional course for third-year bachelor students in Aerospace Engineering and has been broadened to make it suitable for all students that have some basic knowledge of signal theory and signal processing. It can either be run as an additional or optional “module” or adapted to be included as materials within a full year radio communications subject.
Robert Owen, University Programme specialist at Essaimage who guided the academic team, says, “I have spent 26 years in global “University Programmes” and across this time I’ve learned two fundamental principles. The first is that teaching materials must fill an essential need in the curriculum, not just be something that business thinks should be taught. And secondly, that the best teaching materials come from academics not commercial trainers. This course, Understanding Radio Communications, fulfils these principles generously, and I am proud to be associated with it!”
Key dates:19th November 2020, 1300 UTC – SDRplay and Course developers, Lorenzo Frezza and Paolo Marzioli from the Department of Mechanical and Aerospace Engineering, (DIMA), Sapienza University of Rome, will host a webinar presenting the programme and taking questions via YouTube chat.
About the SDRplay Educators Program The SDRplay Educators Program provides practical encouragement to teachers around the world so that they can use SDRplay’s SDR receivers in courses and student projects. The focus is on providing the key elements needed to teach a course: a suitable hardware platform at a reasonable price, ready access to SDRplay software, effective technical support, and excellent teaching materials that serve genuine teaching needs. The SDRplay Educators Programme is open to all members of academia, see
Over on the SDRplay blog Jon has posted about the STRATONAV experiment which makes use of the SDRplay RSP1 software defined radio. The STRATONAV experiment uses high altitude balloons to carry the RSP1 as well and a commercial portable receiver. The two receivers were configured to receive aircraft VOR navigation signals in order to test the effectiveness of VOR when used at extreme altitudes of up to 28 km. The VOR navigational data was then compared against GPS tracks, resulting in a measure of how well VOR worked at those altitudes.
VOR (aka VHF Omnidirectional Range) is a navigational beacon that is transmitted between 108 MHz and 117.95 MHz from a site usually at an airport. In the past we have posted about VOR a few times as it can also be decoded with an RTL-SDR, or used for passive doppler aircraft radar.
The results showed that VOR navigation does indeed continue to function at extreme altitudes, proving that it can be used as a back up navigation system for stratospheric platforms. They also note that VOR navigation could also be used as a primary navigation system on smaller stratospheric platforms due to its low cost and low complexity to implement.
Back in April we posted a video from Tech Minds where he showed us how to use special software combined with an SDRplay RSPdx to detect and report VDSL interference on the HF bands. VDSL or Very High Speed Digital Subscriber Line is an internet connection technology that runs over old copper phone wires allowing for a fast broadband connection. The frequencies used by VDSL are between 25 kHz to 12 MHz, and for VDSL2 up to 30 MHz. Unfortunately the frequencies used can result in high amounts of radio interference from RFI radiating from the copper phone lines which is a major problem for HF amateurs and short wave listeners.
Recently John Rogers (M0JAV) presented a talk via the UK amateur radio organization RSGB. In the talk he explains how VDSL works, why it causes RFI and how to check for VDSL RFI using an SDR and the Lelantos software. He also shows how he drove around with a magnetic loop antenna looking for VDSL RFI sources in his neighbourhood. He then goes on to call out for more volunteers in the UK to submit RFI reports to Ofcom as they responded that they won't do anything about the interference unless there are more complaints.
The RSGB EMC Committee (EMCC) has been investigating VDSL interference since 2014. As the number of installations has risen to over 30M the interference level at amateur radio stations has also increased. The majority of radio amateurs are now impacted by this problem.
In the May 2020 RadCom we outlined how to detect and estimate the level of interference. This can be done by inspection of an SDR spectrum display or by taking a recording and then using a SW package—developed by Martin Sach of the EMCC—which identifies the VDSL signature in the recording and shows how many different VDSL lines are causing the problem and what their relative strengths are.
This talk demonstrates what to look for and how to use the tools to find out if you have a problem yourselves. We hope this will help you respond to our call for action and complain to Ofcom about the level of RFI you are subjected to.
John Rogers, M0JAV Chair EMCC
RSGB Tonight @ 8 - How to check for VDSL RFI with John Rogers, M0JAV
