I was trying to receive some Iridium signals and turned on my TV while I worked. The TV is right beside my SDR and L-band patch antenna. It's an RCA LED TV from 2014, and when the screen came on I got interference all over the spectrum window. I noticed that the lines got weaker when there was less motion, suggesting the MPEG-2 decoder was the culprit. Or maybe it was the LCD controller. Whatever it was, when the TV show's intro briefly showed the static logo, the lines went away completely.