Technology always seems to be changing faster than we can keep up with it. One thing that hasn't changed since the fifties is the broadcast of television signal. That was when color was first introduced to the black and white signal. It didn't really catch on until Disney introduced the TV show Disney's Wonderful World of Color in September, 1961. That led to a surge in color TV set sales. Nothing has changed in over the air signal since then.
Now we have a new technology that will shake up the industry in many ways. High definition TV (HDTV for short) was introduced in the 90s and got its start in Japan where it has been the standard the longest. HDTV has as much as six times the resolution of the old analog broadcast that you are used to. Resolution is the dots on the screen that make up the picture, just like pictures you take with your digital camera. Analog TV can broadcast at no greater than 640 horizontal lines by 480 vertical lines or 480 lines for short. Almost all broadcasts in analog don't have more than 330 lines though. HDTV broadcasts have 2 common broadcast qualities, 1920 horizontal by 1080 vertical (or 1080) and 1268 X 720 (or 720).
The broadcasters also have different ways they can distribute the picture like interlaced or progressive. Interlaced is when only half of the image is shown every1/60th of a second so you get the full frame every 1/30th of a second. This is what is used on the old analog broadcasts as well. Progressive is when the show the full frame every 1/60th of a second, this is so the picture looks more fluid and natural. Interlaced is the easier of the two to be broadcast and is what is done by most networks. This way they can broadcast a higher resolution image in interlaced without taking up anymore broadcast bandwidth than a lesser resolution progressive broadcast.
Bandwidth is essentially how much space the signal takes up when it is being broadcast. There are a couple of different reasons to maintain a lower bandwidth when broadcasting. First is with the introduction of digital broadcast, the networks can actually have as many as 5 channels they can broadcast over their allotted bandwidth. Some networks are, for example, broadcasting weather on a second channel, kind of like their local version of the Weather Channel.
Are your eyes rolling into the back of your head yet? I see the deer in the headlights look in your eyes.
The second advantage for taking up less bandwidth is for the cable and satellite companies. It gives them more room to put more channels on their services. There are some differences between the networks as to what quality they broadcast at. Companies like NBC, CBS, The Discovery Channel are all broadcasting in 1080I (I for interlaced) while companies like Fox, ABC and ESPN are broadcasting in 720P (P for progressive). No stations at this point are broadcasting in 1080P, but in time that probably will change since most new TVs can handle this kind of signal.
This is an exciting time to be involved in the electronics industry with all of the improvements that are happening especially in picture quality. All of these changes are getting us steps closer to feeling like we are at that baseball game or in the movie we are watching. Next step, smellivision, I can just smell it now.
Now we have a new technology that will shake up the industry in many ways. High definition TV (HDTV for short) was introduced in the 90s and got its start in Japan where it has been the standard the longest. HDTV has as much as six times the resolution of the old analog broadcast that you are used to. Resolution is the dots on the screen that make up the picture, just like pictures you take with your digital camera. Analog TV can broadcast at no greater than 640 horizontal lines by 480 vertical lines or 480 lines for short. Almost all broadcasts in analog don't have more than 330 lines though. HDTV broadcasts have 2 common broadcast qualities, 1920 horizontal by 1080 vertical (or 1080) and 1268 X 720 (or 720).
The broadcasters also have different ways they can distribute the picture like interlaced or progressive. Interlaced is when only half of the image is shown every1/60th of a second so you get the full frame every 1/30th of a second. This is what is used on the old analog broadcasts as well. Progressive is when the show the full frame every 1/60th of a second, this is so the picture looks more fluid and natural. Interlaced is the easier of the two to be broadcast and is what is done by most networks. This way they can broadcast a higher resolution image in interlaced without taking up anymore broadcast bandwidth than a lesser resolution progressive broadcast.
Bandwidth is essentially how much space the signal takes up when it is being broadcast. There are a couple of different reasons to maintain a lower bandwidth when broadcasting. First is with the introduction of digital broadcast, the networks can actually have as many as 5 channels they can broadcast over their allotted bandwidth. Some networks are, for example, broadcasting weather on a second channel, kind of like their local version of the Weather Channel.
Are your eyes rolling into the back of your head yet? I see the deer in the headlights look in your eyes.
The second advantage for taking up less bandwidth is for the cable and satellite companies. It gives them more room to put more channels on their services. There are some differences between the networks as to what quality they broadcast at. Companies like NBC, CBS, The Discovery Channel are all broadcasting in 1080I (I for interlaced) while companies like Fox, ABC and ESPN are broadcasting in 720P (P for progressive). No stations at this point are broadcasting in 1080P, but in time that probably will change since most new TVs can handle this kind of signal.
This is an exciting time to be involved in the electronics industry with all of the improvements that are happening especially in picture quality. All of these changes are getting us steps closer to feeling like we are at that baseball game or in the movie we are watching. Next step, smellivision, I can just smell it now.
Jim Carter's Technology Blog
Posted 3/4/2008
What is HDTV