NTSC Composite Video Signals, and the RS - 170A Standards

Part 7 - Maestro, the Alignment Please.
First, set up your test equipment ( vectorscope and waveform monitor ) and switcher / router so you see color bars ( or black ) on the scopes. I tend to prefer bars. We will call this our first video source. Make sure that you have both pieces of test equipment set to EXTERNAL SYNC mode.

If after setting everything up to external sync, you see the waveform monitor drifting or the vectorscope spinning, something is probably drastically wrong with your house wiring. ( This usually indicates a missing reference or sync cable either on the source signal, or on the scopes. )Go back and compare with the diagram on page 2 of this course.

If the first video signal remains steady then comes the next step. Setting up the waveform monitor for fine viewing. Push the magnify button ( or whatever enlarges your view on your particular scope ) so you see a picture like this. Align the center of the leading edge of the horizontal sync pulse with a tick mark on the waveform monitor, so that you can closely monitor any movement of the signal.

Now on your switcher, router, etc., change to another video source ( VTR 1 for instance ).



    If you see no change in the position of the horizontal sync pulse, then the second source is in sync horizontally with the first source.

    If you do see any change, left & right, up & down, of the position of the horizontal sync, then you need to adjust the horizontal of the second source ( the VTR ) to match up with the first ( the color bars ). This is usually accomplished by either a knob ( as in a beta deck ), or a software setting ( as in a DVC Pro deck ), adjusting until the two signals match. Keep switching back and forth between the two sources as you are adjusting, until the second matches up perfectly with the first.

    If the second video source, when switched, doesn't lock up at all, and moves continually, then the second source is not genlocked, or at least is using a different sync source than the first video source. Check again the cabling as per page 2.

Now let's examine the vectorscope. If after switching to the second video source, we see that the reference line has moved, then the chroma phasing for this source is off from it's horizontal sync, as compared to the original source. We must align the chroma phase for this device. This typically has 2 adjustments. The first adjustment is a COURSE phase adjustment, which normally " clicks " 90 degrees at a time. Then it has a secondary FINE phase adustment, which smoothly rotates it the rest of the way, until you are back at the zero line.


Once you've done one adjustment, the rest are easy. Simply continue doing these simple adjustments for the rest of the video sources on your switcher or router. Then all the glitches and funky switches will be smooth as silk. Note that satellite or other non-syncronous sources ( things you can't run a sync cable to ) can not be syncronized by this method. They must go through a frame sync or proc amp in order to syncronyze them. Sometimes a VTR in E-E mode can be used for this purpose in a pinch.

Finally, once in a while, you will find a piece of equpment that, even though it is locked up on the scope, and the horizontal and chroma is in sync & phase, still has blue people. Look on the device for a " Hue" control, and either adjust using chroma bars, or use the " people color " for a reference.

That's it.

Hope this was of help to you.

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