Digital TV is taking the world by storm as more and more people everyday purchase set top digital boxes or in built digital televisions. Digital TV’s have a far superior picture quality over normal (or analogue) televisions, which is why it is a popular choice for millions of people. This post will quickly explain how analogue TV works to answer the question: how does digital TV work?
The Basics of Analogue TV
Understanding how does digital TV work is a lot easier if you understand how analogue TV works first. Firstly, a video camera takes a recording of something at a rate of about 30 frames per second (in other words, it takes 30 pictures per second). The camera then turns each and every picture it takes into rows of ‘dots’ called pixels. Each of these pixels carries information about the color and brightness of the picture. The analogue TV knows exactly how to arrange these pixels by ‘synchronization signals’ sent by the television statement. Sound is sent separately to the picture.
The Basics of Digital TV
Now we can look to answer the question, how does digital TV work. Firstly, a digital video camera takes recordings of something at about 60 frames per second (although this varies for each individual digital video camera). As with analogue TV, the digital video camera turns each of the pictures and turns them into pixels. The difference with digital TV is that it has sharper detail as it coverts the pictures to considerably more pixels. The different formats that a television program may be sent in (480i, 480p, 720p, 1080i and 1080p) is a measure of how many pixels the digital camera converts the picture to. With digital TV, each pixel stores its information about placement on the TV, color and brightness in a series of digital code. This code is similar to computer code as it is stored in 0’s and 1’s. The digital television then knows where to place the pixel, what color it is and how brightly the color should be shown.
That’s a LOT of Pixels
With 60 or more pictures taken by the digital video camera each second it is sending a lot of pixels to your digital TV. Many television stations (especially cable TV) compress the number of pixels that each television program sends to reduce this amazing amount of information that has to be sent. This is how the compression is done: As each frame is very much the same (as it covers a fraction of a second), pixels in each frame can be compared. The unchanged pixels send a ‘do the same’ command to the digital TV for each frame they remain unchanged. The data can be cut by up to 80% without any reduction in picture quality. This allows many cable networks to expand their channel capacity without affecting picture quality.
So what is HD?
High Definition refers to the amount of pixels that your source material is presented in and that your television can display.
480i and 480p are Standard Definition.
720p,1080i and 1080p are High Definition.
So now you know the answer to one of life’s biggest questions- how does digital TV work. Next time someone asks you ‘how does digital TV work’ you can surprise them with a great answer!