Do you see the oscillations in this diagram during scan time?
For there to be color in the image, you would see those during scan time, but black and white will be just flat bars at low and high brightness levels.
Look on the left and right sides of scan time, you will see that the white is high up, but flat, and the black is down low and flat. The colors all have characteristic oscillations with a phase relationship to the color burst.
If the output of your pattern generator is flat during scan time, they you're golden.
