Fixed the zero issue. Fixed that direct sampling wasn't enabled
   (quickly and shoddily).
   It's not behaving how I expect, indicating I'm missing some knowledge.
   Direct sampling quickly picks up the 3V source if and only if there is
   no resistor between it and the antenna port, even if the resistor is
   very small, giving the same voltage on a voltmeter.
   Given this isn't the primary goal atm and takes some learning, I might
   think about it a bit, maybe try harder to flash my oscilloscope
   firmware.
   Or I could switch over to oscilloscope stuff.
   I found a bug in pysoapysdr I could contribute, maybe.