Quote:
Originally Posted by inaxeon
Quote:
Originally Posted by rambo1152
As to where these weightings would be applied, I am not sure, as I was only a humble TV repair person, and not a broadcast engineer, but I would suspect it was done inside your PM5680.
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Well that is an interesting thing to point out. I actually just managed to get a copy of the manual for the previous generation PM5580 which looks to have quite similar functionality. I can't see anything about adjustment of weightings in there but I'll probably have to read through it a few more times to be sure. |
These weighting factors to the R-Y and B-Y signals were applied at source.
A typical bit of broadcast tv kit would produce RGB outputs but obviously we needed PAL (eventually) so the RGB signals were applied to a PAL coder which transformed these signals to Y, R-Y and B-Y, the R-Y and B-Y signals were then weighted (by the factors already given) and modulated onto a colour subcarrier to give the U and V signals. these were then 'multiplexed' together to give us the familiar PAL signal. This process of weighting the R-Y and B-Y signals was universal inside PAL coders and as such was not something to concern transmitter engineers. Broadcast kit that worked entirely in the PAL domain, such as a VTR machine for example, would obviously be working with PAL signals throughout so these considerations were of no concern.
The process of weighting the R-Y and B-Y signals to derive the U and V signals inside a PAL coder was a 'run of the mill' consideration and as such not something to concern your average broadcast engineer because it was 'built in' and not really anything you thought about because it was so fundamental to the whole signal chain at source.
They would be nothing to stop someone running transmitter site putting in additional signal limiting if they chose to, but I am not aware that they did. But who knows ..