Originally Posted by viamadeu
Is it possible that a simultaneous HD broadcast increases the quality of the picture that we get in the regular channel?
Seems logical that a downconversion (to 480i) from a 1080i or 720p scanned broadcast would have better fidelity than original 480i camera scanning. (As outlined here
, such downconversions, even with home converters, make images appear sharper, at the same resolution, by widening the MTF [modulation transfer function] curve.) See Matt Cowan's "Black Paper,"
page 26 of 36. Upconverted programs on H/DTV channels, like true HD, can use up to ~19 Mbps compared to the same program on an SD digital cable channel with only ~40/8-12 Mbps. And the same program on an analog channel would have 6 MHz of bandwidth, but must undergo NTSC's heavy filtering and of course lacks digital compression, (although overly compressed digital 480i often appears similar to analog 480i here). Some details on what various networks are doing would be useful. -- John