10-08-2020, 08:14 PM
All the SPGs I have designed have had a user selectable F1L7 flag. It's not quite a standard but it's commonplace. It's not a 100% guarantee that SCH phase is correct. I like the story about the GVG desk using the active part of L7 as a black level reference. Naughty GVG.
If the F1L7 flag isn't present on a signal you can't, in isolation, determine the 8 field sequence. 180 degree SCH error is simply saying that F1 is actually F5 etc. If two sources are genlocked then you can determine whether they are 0 or 4 fields apart.
The VT clock has an interesting history. From 1980 to 1984 I worked for Michael Cox Electronics as a design engineer. Thames TV had designed a largely analogue VT clock which Cox made under licence as model 350. It was a bit of an abortion - I looked at some its problems once. The guys who started Courtyard were colleagues at Cox. One of them designed the digital Cox 650 VTR clock. I wasn't involved with either the Cox 650 or the CY200 clocks but I think the designs had certain similarities
The only VT clock related job I did for Courtyard was a little add-on PCB to convert the output to SDI. A bit of a kludge but it worked well enough.
I didn't know the Amtec/Colortec story. Herr Bruch certainly decreed that SC and H were to be locked to each other in PAL and I thought all broadcast grade kit ensured this was so. Though the concept of SCH phase came later. Outside broadcast grade kit "wild" subcarrier was commonplace.
If the F1L7 flag isn't present on a signal you can't, in isolation, determine the 8 field sequence. 180 degree SCH error is simply saying that F1 is actually F5 etc. If two sources are genlocked then you can determine whether they are 0 or 4 fields apart.
The VT clock has an interesting history. From 1980 to 1984 I worked for Michael Cox Electronics as a design engineer. Thames TV had designed a largely analogue VT clock which Cox made under licence as model 350. It was a bit of an abortion - I looked at some its problems once. The guys who started Courtyard were colleagues at Cox. One of them designed the digital Cox 650 VTR clock. I wasn't involved with either the Cox 650 or the CY200 clocks but I think the designs had certain similarities
The only VT clock related job I did for Courtyard was a little add-on PCB to convert the output to SDI. A bit of a kludge but it worked well enough.I didn't know the Amtec/Colortec story. Herr Bruch certainly decreed that SC and H were to be locked to each other in PAL and I thought all broadcast grade kit ensured this was so. Though the concept of SCH phase came later. Outside broadcast grade kit "wild" subcarrier was commonplace.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
