It's hard, but it's not that hard. There are at least half a dozen companies in the space, and another half dozen with the requisite RF expertise but who just d

It's hard, but it's not that hard. There are at least half a dozen companies in the space, and another half dozen with the requisite RF expertise but who just don't need direct conversion, as you mentioned. This is more a commentary about open source hardware in general. Starting with a DirectRF receiver would be silly; the market is not that big.