OpenAstroTracker is a recently published open hardware 3D printed tracking mount designed to move DSLR cameras for astrophotography. The mount supports heavy long lenses, so we think that this mount could also have the ability to move long directional antennas for satellite tracking. It could also be interesting to modify it for automatic aircraft photography, similar to what we've seen in this previous post where a Raspberry Pi camera on a pan-tilt mount was used with ADS-B data from an RTL-SDR to track aircraft in the sky with the camera.
The 3D printer files are available on Thingiverse, and the mechanical and electronics build guide, and Arduino code is available on GitHub. The build seems to be quite a bit easier compared to a SatNOGS rotator which is another 3D printed open hardware rotator, but it is yet to be seen what sort of antenna sizes it could rotate.
At the Hackaday Supercon Michael Ossmann & Kate Temkin presented a talk called "Software-Defined Everything" where they demonstrated some applications of the "GreatFET One" interface board. Michael Ossmann is best known for creating the HackRF software defined radio which is a highly versatile and low cost open hardware/software SDR transceiver. His company Great Scott Gadgets also employs Kate Temkin who is the lead software developer who worked on their latest product called the GreatFET One.
The GreatFET One is a multi-purpose digital interface board that plugs into a PC via USB. It contains multiple digital IO pins, supports SPI, I2C, UART and JTAG serial protocols, can do logic analysis, and also has a built in ADC and DAC.
In the talk Michael and Kate show how a simple light sensor can be plugged into the GreatFET's ADC, allowing the sensor's data to be digitized and processed in GNU Radio. This results in a software defined light sensor. By analyzing the light data in the frequency domain via an FFT graph they're able to determine the refresh rate of the ceiling lights.
Later they also show how GreatFET can be combined with i2C sensors and GNU Radio to do creative things like use an accelerometer as a microphone for a guitar pickup, with audio effects like guitar clipping controlled by GNU Radio blocks.
Michael Ossmann & Kate Temkin - Software-Defined Everything
The Flex 6500 is a now discontinued (only refurb units available for US$2,600) transceiver SDR made for amateur radio use. Together with the optional Maestro control panel, it forms a fully standalone SDR based transceiver, with built in SDR software available on the Maestro's LCD screen. The system runs embedded Windows and is locked down to prevent the user from getting outside the Flex radio software.
Fortunately the students were able to hack the Windows filesystem via a backdoor found in the built in software, allowing them full access to the Windows desktop. The hack is fairly simple, consisting of gaining access to Notepad and thus the filesystem and command prompt via a "view source" right click menu on the web login interface. Once hacked, the students were able to install custom software like the N1MM+ contest logger, and WSJT-X for WSPR decoding. They were also able to connect a Bluetooth keyboard and mouse which was not supported by default.
Thank you to Happysat who has shared with us a useful tutorial that explains how we can run Linux only SDR programs on a Windows 10 system using the Windows Subsystem For Linux (WSL) feature. WSL is a feature available on Windows 10 which is a Linux compatibility layer designed for running Linux binaries natively on Windows 10. This means that no Virtual Machine with shared resources is required, instead the full resources of your system are available.
Many people using Windows 10 now since Windows 7 is EOL, and WSL is part of the system kinda "free" so why not use it :)
Together with a X-Server and and Desktop like XFCE4, it can be great for running SDR applications in Linux thru rtl_tcp.
Very fast startup in seconds and not much packet loss thru tcp, quite alot linux sdr applications are working very good.
No allocating resources like a VM.
Sometimes better then Ubuntu on a VM.
Software tested: AX-25 Packet Radio, Dab Radio, DSD, Es-Hail Beacon Tracker, Sat Tracking with Gpredict and Gqrx, NOAA Reception WxToImg, Radiosonde Decoding, Shortwave Reception and some more tips and tricks about WSl and SDR.
The steps appear to be fairly simple. Just enable WSL in the Windows 10 Features panel, download a Linux distro built for WSL and run the .exe file. Then you'll have access to a Linux terminal where you can install a GUI desktop environment, the RTL-SDR drivers, and other Linux SDR programs. Happysats tutorial shows how to install and use various Linux programs via WSL.
It seems that the RTL-SDR cannot be directly accessed via the USB in WSL, however, by the workaround is to simply run rtl_tcp in your Windows environment, and connect to the local IP in the Linux environment. This means that only programs that accept rtl_tcp as an input, or demodulated audio from a program like GQRX can be used.
Over on YouTube, Elektor have uploaded an overview of their Elektor SDR Hands-on kit. The €49.46 kit is an Arduino shield, that turns an Arduino microcontroller board into a 150 kHz to 30 MHz capable SDR receiver. 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.
To compliment the SDR is a book that 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 transmissions. Overall this looks like a good kit for learning about the technical basics of SDRs.
The Spin Semiconductor FV-1 is a digital reverb chip designed for creating custom audio effects in products. As it is a digital chip it makes use of an ADC and DAC, with the audio effects DSP placed in the middle of the chain. However, by using custom code Ray was able to convert the ADC into an SDR by creating custom AM/FM and LSB demodulators on the programmable DSP instead of the audio effects.
His post contains the full schematics, code and PCB files required to recreate his work if desired.
Thank you to Tysonpower (aka Manuel DO5TY) for submitting information about how he's managed to convert a cheap €14.33 USB audio control dial into a VFO tuning knob for use in SDR programs like SDR-Console V3. He writes:
I sometimes miss a VFO Knob while using my SDRs, especially with SSB Signals or CW where you need to adjust the Frequency very fine.
Because of that I got myself an Audio Dial with USB, reverse engineered it somewhat and wrote a new Firmware for the STM32 used in the USB Dial.
It all worked out and it now simulates a mouse wheel with three different scroll speeds. There is also a Mute Function when you long press the Button.
I had a lot of fun during this project, even when it was a lot of time just for a VFO Knob :)
Software defined radios can have many more applications other than just radio. For example, it's possible to connect an ultrasonic sensor which outputs a waveform at some frequency above DC directly to the input of an SDR. We can then simply treat the sensor output as an RF signal, and view it in any SDR compatible software that shows us a spectrum. Normally you'd use a microcontroller with ADC to process the output of these sensors, but using an SDR makes visualizing and experimenting with these sensors much easier.
Over on YouTube W1VLF has uploaded a video showing his experiments with an ultrasonic sensor connected to his Airspy HF+. In his experiment he places the Airspy HF+ with directly connected ultrasonic sensor in one room, and sets up an ultrasonic emitter in another room. He then uses SDR# to view the 24 kHz ultrasonic sensor signal output on the computer. As he moves the sensor around it's possible to clearly see the doppler shift of the ultrasonic sound waves on the waterfall.
In the past we've also posted about Jan de Jong who experimented with using a piezo speaker connected to an SDRplay RSP1A to detect the ultrasonic navigation sounds from bats.