CompuServe Messages

In order to get the I and Q vectors on SMPTE bars you would need to generate a negative RGB value. Since it is difficult (if not impossible) for most PC-type systems to do this, you won't find these generated on most computer systems. My understanding is that the pluge also requires a negative RGB value for the blacker-than-black portion. (If you want the true functions as you find them in test signal generators). The probable reason for the differing values is that there is a variance in the encoder/decoder circuits of the devices. Since they use different resostors, caps, etc., they need to massage the test images they ship with the unit to give ideal results. This is not uncommon, I know of many companies that do this in the PC world. What you need to look at is the end result. If it is RS-170A/SMPTE 170M and fits your WFM/VS as it should, you are OK. James Bell Jr. — Multimedia Contributor – CompuServe