the Ettus USRP SDRs predate RTL-SDR by almost (not quite) a decade.
I was always into the soundcard HF SDRs, they were so simple and elegant. An oscillator, a ring counter, a 4052 MUX and one really fast dual opamp.
alt Hacker News
I was always into the soundcard HF SDRs, they were so simple and elegant. An oscillator, a ring counter, a 4052 MUX and one really fast dual opamp.