Distinct from regular digital video recorders, the PVR uses the built-in electronic program guide that enables its subscribers which programs to be recorded.
However, because of the limited frequency spectrum allowed for modulated digital video signal, the digital video signal must become a continuous-time digital video signal.
Brightness and contrast controls shouldn't be there because, for digital video, the black level is fixed at level 16, reference white at 235 and peak white at 255.
The decryption cards will probably license for $10 to $20, much less than the $50 for a simple decoder or $500 for a full featured digital video recorder.
