10-08-2020, 07:01 PM
Many thanks for the welcome. I have met Paul and given him a few obscure bits and pieces over the recent years. I hope he is looking after that editor - I know of only one other in the UK! Very rare.
I'm familiar with some Courtyard kit, in particular the VT Clock in SDI days. Very reliable as I recall. For SPG's we used Acron and subsequently Trilogy Mentor. We would sort of routinely check the Sc/H phase on the outputs of the production studios to ensure they were within spec. We took the easy route and used the a TEK Vectorscope unit that gave the circular loop and 'dot' position to indicate the precise Sc/H phase setting. I think stability was perhaps more important than accuracy.
You may know, but in the very early days of PAL although it was appreciated that line syncs and subcarrier both had to be within their respective +/- specifications, it was not realised that they had to be actually locked to one another. It was discovered, when playing back colour tapes, that due to the electro/mechanical nature of a VT machine that the VT's mono timebase corrector could be gently correcting in one 'time direction' and the colour timebase corrector could be gently correcting in the opposite 'time direction'. Usually the colour time base corrector feeds back into the mono timebase corrector which then feeds back into the head servo to keep it all Hunky Dory. In the example I give above, the CTBC would eventually run out of range and dump uncorrected video into the MTBC which would also run out of range and dump uncorrected video into the head servo causing the picture to twitch sideways! I think this was appreciated in the very early days and from then on line signals were derived from subcarrier so it was all locked. I think you will know much more about that than me.
A final thought, I can't remember if it was an agreed industry standard or not but the Acron SPG's could be User Linked to give a full single line of white video (On a particular line in the vertical interval) to indicate Field 1. Looking at a signal on a monitor you's see the white line flicking at 8 times a second (Obviously). All well and good, but we never used that facility. Until one day ..
.. someone decided to change the Acron SPG on a telecine machine about to play out a live children's cartoon and set that User Link to output this signal for some unknown reason. All was well until the machine was cut live to air in presentation. Then all hell broke loose and after 30 seconds or so it had to be whipped off air. What was not realised was that the Grass Valley Presentation desk used that self same line to perform a vertical clamp on the video, it did so, and caused the resultant video desk output to be jabbering away to nonsense on a regular heartbeat 8 field pattern! Happy days, and then the computers took over.
I'm familiar with some Courtyard kit, in particular the VT Clock in SDI days. Very reliable as I recall. For SPG's we used Acron and subsequently Trilogy Mentor. We would sort of routinely check the Sc/H phase on the outputs of the production studios to ensure they were within spec. We took the easy route and used the a TEK Vectorscope unit that gave the circular loop and 'dot' position to indicate the precise Sc/H phase setting. I think stability was perhaps more important than accuracy.
You may know, but in the very early days of PAL although it was appreciated that line syncs and subcarrier both had to be within their respective +/- specifications, it was not realised that they had to be actually locked to one another. It was discovered, when playing back colour tapes, that due to the electro/mechanical nature of a VT machine that the VT's mono timebase corrector could be gently correcting in one 'time direction' and the colour timebase corrector could be gently correcting in the opposite 'time direction'. Usually the colour time base corrector feeds back into the mono timebase corrector which then feeds back into the head servo to keep it all Hunky Dory. In the example I give above, the CTBC would eventually run out of range and dump uncorrected video into the MTBC which would also run out of range and dump uncorrected video into the head servo causing the picture to twitch sideways! I think this was appreciated in the very early days and from then on line signals were derived from subcarrier so it was all locked. I think you will know much more about that than me.
A final thought, I can't remember if it was an agreed industry standard or not but the Acron SPG's could be User Linked to give a full single line of white video (On a particular line in the vertical interval) to indicate Field 1. Looking at a signal on a monitor you's see the white line flicking at 8 times a second (Obviously). All well and good, but we never used that facility. Until one day ..
.. someone decided to change the Acron SPG on a telecine machine about to play out a live children's cartoon and set that User Link to output this signal for some unknown reason. All was well until the machine was cut live to air in presentation. Then all hell broke loose and after 30 seconds or so it had to be whipped off air. What was not realised was that the Grass Valley Presentation desk used that self same line to perform a vertical clamp on the video, it did so, and caused the resultant video desk output to be jabbering away to nonsense on a regular heartbeat 8 field pattern! Happy days, and then the computers took over.
