Timing is Good, But...
"Timing" is a consideration in
component video cable quality, and while it's meaningful, it's often over-emphasized. The three cables in a
component video cable should all be of the same electrical length--which is to say, it should take a signal the same time to travel through each of them as it does to travel through the others. The speed at which a signal travels through a cable depends on two things: the physical length of the cable, and the consistency of the
dielectric material. If the manufacture of the
dielectric is highly consistent, and the cables are cut to equal length, then timing variation between cables will be insignificant. This requirement for a consistent
dielectric, as it happens, is directly tied to "
impedance tolerance," of which we spoke above. The
impedance tolerance reflects the consistency of the
dielectric, and so the tighter the tolerance, the lower the potential for timing error.
But timing, as we've suggested, is often a
bit over-sold. The broadcast-quality benchmark standard is that timing should be within 40 nanoseconds (abbreviated "ns") from one
channel (that is, one cable in the set of three in a
component video cable) to another. Using a cable having a tight
impedance tolerance of +/- 1.5 ohms, or +/- 3 ohms, it's impossible to get more than a few nanoseconds per hundred feet of timing variance from one cable to another, if those cables are cut to the same physical length. Cutting them to different lengths, of course, would do the trick--but it takes a large discrepancy in cable lengths to make up a 40 ns difference. Consider, for example, Belden 1694A. Electricity travels down the center
conductor at 82% of the speed of light (this is what's called the "velocity of propagation" of the cable), and so takes 1.24 nanoseconds to travel one
foot. To cause a 40 ns delay by cutting 1694A cables to different lengths, one would have to make one of the cables about 32 feet longer than the others--and the resulting
component video cable would still, albeit just barely, be within the broadcast quality standard.