Now that Kevtris has measured the PPU video signal at the composite output jack, we can interpret it in terms of the NTSC standard:
Taking the internal values Kevtris measured and adjusting for the range he measured at the composite output, I get 259 mV for black and 981 mV for white (relative to the sync level). Apparently the NES uses black for the blanking level. My question is, what does the decoder use as a zero reference? Bottom of sync or overall amplitude of waveform? Once I can figure out where to overlay this 981 mV range on the diagram above, I can determine where black falls.
Taking the internal values Kevtris measured and adjusting for the range he measured at the composite output, I get 259 mV for black and 981 mV for white (relative to the sync level). Apparently the NES uses black for the blanking level. My question is, what does the decoder use as a zero reference? Bottom of sync or overall amplitude of waveform? Once I can figure out where to overlay this 981 mV range on the diagram above, I can determine where black falls.