There is an excellent FlexRadio System write up on the origins of the Flex-6000 series SDR radios and SmartSDR software online :
The FLEX-6000 was born out of a government project we did that involved direct sampling. At the time in 2010 we all believed (as Elecraft has publicly stated) that it would not be possible to build a direct sampling receiver with as much dynamic range as a superhet or direct conversion radio. When we did the government project, Gerald worked a lot on the numbers and RF architecture and we discussed how to get the best dynamic range out of a direct sampling receiver. We were able to use a very early sample of an Analog Devices ADC in that project and found that we were getting better dynamic range than even Analog was reporting, largely because of how we selected key parameters. Gerald realized that we could build a better direct sampling radio than anything we’d built before.
Once we realized it was possible to build a direct sampling radio, all the “what if…” conversations started. What could we do if we did this? What would someone do with that? Would it be better if we did this or that?
….. (much more at the link)
FRS Steve N5AC on “The Chicken or the Egg” development of the FRS 6000 series article LINK: https://community.flexradio.com/flexradio/topics/chicken-or-egg
Scroll down that page for N5AC’s excellent write up.