17-01-2012, 03:44 PM
Digital Television
[attachment=16184]
Introduction
If you have looked at television sets at any of the big electronics retailers lately, you know that digital TV or DTV, is a BIG deal right now .
In this talk ,we will explore the world of digital television so that everybody can understand what is going on in this medium.
But before we start knowing digital TV, it is helpful to understand analog TV so that we can see the differences.
Basics Of Analog TV
A video camera takes a picture of a scene. It does this at a frame rate of 30 frames per second.
The camera RESTERIZES the scene i.e. the camera turns the picture into rows of individual dots called pixels. Each pixel is assigned a color and intensity.
The rows of pixels are combined with synchronization signals, called horizontal sync and vertical sync signals, so that the electronics inside a TV displays the rows of pixels .
Uses Of Composite Video Signals
They are broadcasted as radio waves.
They can be recorded with a VCR.
We can transmit them through a cable TV system along with hundreds of other composite signals.
Demerits Of Analog TV
Resolution:
Resolution in ATV is less due to less number of pixels.
Interlacing:
An ATV set can display 525 horizontal lines of resolution every 30th of a sec.The ATV displays half of the lines in a 60th of sec & then displays the other half in next 60th.So whole frame is updated in every 30th of a second.This is called INTERLACING.
Even the worst digital TV monitors can display about 10 times more pixels than the Analog TV,which makes the picture more detailed and stable.
[attachment=16184]
Introduction
If you have looked at television sets at any of the big electronics retailers lately, you know that digital TV or DTV, is a BIG deal right now .
In this talk ,we will explore the world of digital television so that everybody can understand what is going on in this medium.
But before we start knowing digital TV, it is helpful to understand analog TV so that we can see the differences.
Basics Of Analog TV
A video camera takes a picture of a scene. It does this at a frame rate of 30 frames per second.
The camera RESTERIZES the scene i.e. the camera turns the picture into rows of individual dots called pixels. Each pixel is assigned a color and intensity.
The rows of pixels are combined with synchronization signals, called horizontal sync and vertical sync signals, so that the electronics inside a TV displays the rows of pixels .
Uses Of Composite Video Signals
They are broadcasted as radio waves.
They can be recorded with a VCR.
We can transmit them through a cable TV system along with hundreds of other composite signals.
Demerits Of Analog TV
Resolution:
Resolution in ATV is less due to less number of pixels.
Interlacing:
An ATV set can display 525 horizontal lines of resolution every 30th of a sec.The ATV displays half of the lines in a 60th of sec & then displays the other half in next 60th.So whole frame is updated in every 30th of a second.This is called INTERLACING.
Even the worst digital TV monitors can display about 10 times more pixels than the Analog TV,which makes the picture more detailed and stable.