The ka9q-radio SDR package (Invited Tutorial)

KA9Q-radio is a general purpose open source software defined radio (SDR) that uses fast convolution and IP multicast to digitally downconvert, demodulate and distribute hundreds of simultaneous channels from hardware front ends such as the RX888, Airspy R2/HF+ and RTL-SDR using only modest hardware such as the Raspberry Pi and X86-64. No special hardware is needed such as an FPGA or GPU. Example applications include FM repeater monitoring and the HamSCI wsprdaemon project.