Zenith Phonevision: Let's explore this

[old_tv_nut]

This is waaaay before my time at Zenith, and the people who originally worked on it are probably all dead. I will see if I can find anyone I know from the Cable division who knows something about it.

I do know that the long delay line was switched in and out during multiple segments of the field interval, causing the picture to be scrambled into displaced horizontal strips. The code is part of determining which segments are delayed. I don't know if the switches were wired differently on each box to prevent code sharing, but that would have required some data memory per box, which would be hard to provide at that time. I suspect the phone call simply enabled the delay line switching with some simple on-line signal.