> The ADI9801 and the Xilinx RF-SOC are multi-gigasample per second converters and so you can (in theory) just grab all the spectrum and then pull out any signals you want with DSP. Works great on paper but wow is it difficult to design hardware and pipelines for that stuff.

What is the dynamic range on these converters? I suspect that if you want to pull out a signal that is 120dB below the strongest signal in the spectrum, you're going to have a bad time.