I picked up an ADALM PLUTO from Analog Devices; a very powerful Software Defined Radio (SDR) for only $99. The cost is low as is the documentation. Many links on Analog site are broken, and to their credit, there are a few comments that “people found these instructions hard to follow, so we are revising them.”
That’s good, but in the meantime, here are the instructions that finally worked for me: at John’s Musings
Andrew Dawes 