Yesterday, when Bush held his press conference, I noticed something interesting. We have two TV’s on the ground floor of our house, in seperate rooms, the main one is cable ready while the other one is an old B&W atenna-based TV. At the timne the speech was playing, the older TV was set to Fox Network while the other was set to Fox News(Cable). Both were carrying the speech.
What was interesting is that there was a delay in the older TV by about a second or so, creating a rather interesting repeition effect. The effect was the same no matter which room I was.
It takes the better part of a second for a television signal to travel up to a satellite and back down again. Depending on how many trips the signal must take, there are going to be differences in delays. I’m surprised the network had a longer delay than cable, usually it’s the other way around. But it all depends on where the network and cable stations were getting their feeds from.
I have digital cable set up in 2 rooms. Both boxes are DVR’s (not sure if that matters) and the one in my bedroom is about 3-5 seconds behind the one in my living room. Same service off the same cable box.
It does matter that they’re DVRs, because the buffer in the DVR box can cause you to be behind the live broadcast by a second or two even when you’re “Live”
I’ve noticed that my DVR-box TV will be a couple seconds behind one of the other regular-cable TVs. But if I change the channel on the DVR, it will be exactly in sync with the regular cable until I mess with the Pause/Rewind features. Once you get out of sync with Live TV, you can never get all the way back without purging the buffer (changing the channel).
Also, the HD simulcasts of the local network stations are usually a couple seconds behind the regular cable and analog terrestrial broadcasts. Except the NBC affiliate…which has no delays.
I’ve heard that the delay on digital TV comes about at the mpeg decoding stage, i.e. after the signal has reached your house. No idea how true this is, though.