Nope… no ‘heterodyne’, and no local oscillator for RF conversions or demodulation. The incoming RF is directly bit-sliced and converted into a digital bit stream, and the digital processing of the waveform (formerly RF) is where the modulation is removed, the noise processed out, etc. ALL of the internal functions are digital bitstream processing at speeds that can exceed 1 GHz (or Gigabits), so it can handle a 50 MHz incoming waveform easily.
I know it’s hard to wrap your head around if you are not familiar with current digital technology. A decade ago I had the most intense learning curve of my TV broadcast career when we went to digital TV and learned how this was all done for Hi-Def video. It defies the laws of physics and modulation that we learned as kids. HDTV nowadays is packing 40 lbs of ‘stuff’ into a 6 lb channel bandwidth that was thought impossible before the turn of the century.