Very nice. It's not a "crystal radio", though. It's a direct sampling receiver. That is, the processing takes place at the RF frequency directly. Most receivers use heterodyne conversion to down-convert a desired chunk of spectrum to a convenient working frequency. This doesn't. It just runs the raw RF through an A/D.
As A/D devices and processing have improved, the frequency upper limit for direct conversion receivers has moved up. There are low-cost direct conversion receivers going up to 50MHz, but they have to use an FPGA rather than doing all the work in software.
Very nice. It's not a "crystal radio", though. It's a direct sampling receiver. That is, the processing takes place at the RF frequency directly. Most receivers use heterodyne conversion to down-convert a desired chunk of spectrum to a convenient working frequency. This doesn't. It just runs the raw RF through an A/D.
As A/D devices and processing have improved, the frequency upper limit for direct conversion receivers has moved up. There are low-cost direct conversion receivers going up to 50MHz, but they have to use an FPGA rather than doing all the work in software.