24-03-2018, 02:50 PM
Alan Pemberton gives the following figures:
Line blanking period 18.5µs
Front porch 1.7µs
Line sync pulse width 9 ±1µs
Time reference point to line blanking end 16.8 ±0.5µs
All measured between the 50% points. I think we can take these as being the parameters in use up until the end of 405-line transmissions but he does add the following footnote:
The c.1950 diagrams give the line blanking period of the 405-line standard as 16.5 ±0.5µs, rather than 18.5µs. Blumlein defines it as 1/200 + 1/10 + 1/20 of a line period = 0.494 + 9.88 + 4.94 = 15.314µs.
It might be interesting to compare the actual timings of the various generators and converters to see how they compare with these figures.
Line blanking period 18.5µs
Front porch 1.7µs
Line sync pulse width 9 ±1µs
Time reference point to line blanking end 16.8 ±0.5µs
All measured between the 50% points. I think we can take these as being the parameters in use up until the end of 405-line transmissions but he does add the following footnote:
The c.1950 diagrams give the line blanking period of the 405-line standard as 16.5 ±0.5µs, rather than 18.5µs. Blumlein defines it as 1/200 + 1/10 + 1/20 of a line period = 0.494 + 9.88 + 4.94 = 15.314µs.
It might be interesting to compare the actual timings of the various generators and converters to see how they compare with these figures.
