Hey Ray! How Broadcasting A TV Signal Works
PITTSBURGH (KDKA) -- For most of us, television has been around for most of our lives. A click of a remote, and information and entertainment appears before our eyes. A lot goes into making that seemingly easy thing happen, though.
To find out how it works, we chatted with KDKA-TV's Director of Broadcast Operations & Engineering, Todd Harbaugh.
Ray Petelin: How does TV work?
Todd Harbaugh: So, when we bring KDKA-TV to our viewers, it starts in the Studio. Let's say at the weather wall with Ray at the green screen.
Ray is standing in front of a blank, green screen that we use the video switcher behind me to electronically insert the image of the weather computer behind.
The camera picks up that image, the switcher electronically adds the weather graphic behind him.
We then send all that video up to what is called the encoder.
That video encoder signal is then sent over a fiber optic strand to the transmitter 5 miles away from downtown Pittsburgh.
That fiber optic strand is about 1/11 the thickness of a human hair.
From there, the signal enters what are called exciters at the transmitter.
The exciters take that video signal that we send to them, and make an RF modulated signal out of it.
That RF modulated signal then travels to the top of our tower that you may have seen on TV in the past week, about 650 feet in the air, then broadcasts that RF signal to all the viewers at home, over the open air waves.
Elizabeth Petelin: How long does all that take to happen?
Harbaugh: All in all, it takes about three to four seconds.
When KDKA-TV News at 6 starts, it's actually starting at 5:59:56, for example, because it does take about 4 seconds to get to everybody at home.
Now, cable and satellite are a little different.
They're more about 15 seconds because those systems do a little additional processing on their end.
Elizabeth: Wow! That is fast.
Ray: It sure is! We heard about the new transmitter. What are some of the things that will become possible with broadcast TV in the future?
Harbaugh: In the future, what I think we're going to start to see from television is next gen-TV, or ATSC 3.0.
It is a new form of television that will actually allow you to receive KDKA as an over the air broadcast directly on your cell phone.
Currently ATSC 3.0 is in the development stage, and there are very few cell phones of the market capable of accepting or displaying it, but that is what will happen in the future.
ATSC 3.0 is also capable of 4K transmission. For anyone familiar with 4K transmission, that's just a much higher resolution than the current 1920 x 1080 HD that we use.
I think it may be a while before we see broadcasters pushing that because there is a lot of bandwidth complexities with 4K.
