05-10-2016, 06:59 AM
Craig correctly points out that the ultimate way of referencing AC measurements to the DC standards is thermal. It's horrible but the best we've got.
For most of us doing everyday things a decent meter plus awareness of its limitations is sufficient. As Mark says, for noise measurements you really need to be aware of exactly what you're measuring. For analogue video there's the additional problem that a given amount of noise becomes more visible the closer you get to black level. This is the main reason why video is sent using a low gamma. When you look into that more closely it's another nice can of rather wriggly worms.
For most of us doing everyday things a decent meter plus awareness of its limitations is sufficient. As Mark says, for noise measurements you really need to be aware of exactly what you're measuring. For analogue video there's the additional problem that a given amount of noise becomes more visible the closer you get to black level. This is the main reason why video is sent using a low gamma. When you look into that more closely it's another nice can of rather wriggly worms.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
