"heat wave" across the networks - what is it?
 

I have noticed a clear, fluid like, vertical distortion band or seam about 1/4" wide that moves vertically across the screen during all different programs on many different networks. It looks like a heat wave as it travels across the screen. I have seen this for months if not for a few years now. At first, I thought it was something on the tape from the camera or the broadcast master. But since it is happening so often, on so many networks and during older programming, I'm thinking it's hardware related such as servers or transmisions. Any ideas as to what it may be?

I just saw that band again when a local commercial aired on cable so that tells me that it is more than likely on my local cable network.