After the DTV transition date (June 12, 2009) many people, myself included, had to retune their TV's and even HTPC's. If you haven't then you're probably getting programming from CableTV or Satellite service. But even now you may wonder why that was even necessary. This is because some stations changed the frequency they broadcast on. To see what changed if you live in Los Angeles area, read on.
The following chart shows the major TV networks (CBS, NBC, ABC, FOX) and their resolution, digital channel assignments, physical channel number, and broadcasting frequency. Highlighted areas are where changes have occurred.
Because of the changes in frequency for off-the-air "OTA" channels, namely for ABC (KABC Los Angeles), the signal strength on my TV has dropped to 76% versus 98% for CBS. As a result the video and audio seem a bit more jumpy at times or may drop in and out. For a useful tool, I like to use TVfool.com to visualize where the broadcasting towers are in my area, as the picture below somewhat illustrates.