Getting zeros out of my code even when the antenna is driven with
   100mV. Also when the voltage is toggled. And when I ramp the gain from
   0 up to the max of around 50dB.
   So next step is to get any signal at all.
   The missing data could be an undrained buffer issue, since it starts
   with zeros.
   Or the radio could be broken, as many of my old rtlsdrs are.