PJRC forum user DD4WH made the Teensy Convolution SDR, a software defined radio for long wave, medium wave, short wave and wide band FM stereo.
Software defined radio (SDR) is a radio communication system in which the traditional hardware systems — such as mixers, amplifiers and filters — are replaced with software.
DD4WH used a Teensy 3.6, a PJRC audio board, a quadrature sampling detector (QSD), an oscillator capable of being tuned by I2C, three encoders and an antenna to make the Teensy Convolution SDR. DD4WH chose to do the main filtering and demodulation in the frequency domain using a fast convolution approach, enabling much steeper filters than the usual phasing approach.
Detailed specifications and a project guide for the Teensy Convolution SDR project have been published on DD4WH’s GitHub. The original forum post about the project is also really worth checking out, with helpful comments about sourcing components and troubleshooting the code.
Artist and “fountaineer” Alexis Richter has created a water fountain that analyses music and synchronizes its movement and light.
Richter’s hardware analyses the music being played then uses that information to control the fountain’s water pump and RGB LEDs. That gives him the ability to create colorful, kinetic displays of water synced perfectly to music.
The fountain has been on show at music festivals and public spaces all over the UK, including Glastonbury Festival and Boomtown. You can see more examples of it in motion on Instagram, and you can read more details or book it for your event on Richter’s website.
SimpleRick is a low-cost DIY 2D ultrasound imaging hardware project designed by William Meng.
SimpleRick makes innovative use of Software Defined Radio, pairing it with an ultrasound transducer to make a maker-friendly, affordable ultrasound imager. It works by sending out acoustic sound waves and then listening for audio bouncing back from objects in the path of the waves.
Meng’s project is based on an open hardware ultrasound project called un0rick. For SimpleRick, Meng replaced the more expensive specialist components in un0rick with a Teensy and Software Defined Radio.
Meng has written up the SimpleRick project and released the hardware design files and code under the TAPR Open Hardware License over on his GitHub, where you can also find an overview of the system architecture and some great experiment logs.