VBI "noise" caused by broadcasters

Several boxes such as the CM7000 and DTVpal and Zinwell ZAT show "garbage" at the top of the image. These lines are mostly digital data such as closed captions being sent "above" the actual image on old NTSC analog signals. They are part of the signal's vertical blanking interval (VBI) and normally are hidden by the plastic edge of your set.

While watching NBC's Today show, they displayed a 4:3 videotape surrounded by a graphic on the left & right side of the image. The pillars on the left and right looked flawless, but the center part of the image had a visible VBI.

This indicates to me that it's not the box that is the problem (otherwise the VBI would be imposed across the entire width of the image). It is the *broadcaster* incorrectly framing the image, making visible part of the 4:3 analog videotape that was supposed to be invisible.

In the example I cited, the VBI was only on the 4:3 part of the screen, not on the NBC "pillars" on the sides. NBC had improperly converted their 4:3 analog tape.
The Zenith chops-off the top 5 lines of the picture, while the other boxes display everything. The VBI is there, but the Zenith crops-it out. Unfortunately that also means it crops-out part of the actual picture.

The easy fix is for stations to stop capture exactly one NTSC scanline per DTV scanline. NTSC's visible frame is 486 lines, and DTV is 480, so if the analog-to-digital converter is properly centered, you won't see any closed captioning data. Unfortunately the broadcasters don't properly center their devices.