by Staff Writer
High-definition televisions, commonly known as HDTVs, are quickly taking over the home entertainment world. They offer improved digital picture, sound and features over older technologies, and few manufacturers continue to produce old CRT (cathode ray tube) TVs. But high-definition TV technology comes with a lot of new terms, like "1080p" and "aspect ratio," that may be confusing. If you're looking for information to help you upgrade your television, here are some answers to frequently asked questions about high-definition television technology.
What does high definition mean?The term "high definition" refers to the quality of image or sound for a TV or radio. An HD signal can contain around five times more picture data than a standard-definition TV signal does. High-definition TV transmissions use from 700 to 1000 lines of colored pixels to form the picture on your TV screen, whereas SDTV transmissions use only about 500 to 600 horizontal lines of pixels.
What is a pixel?All TV signals, whether analog or digital, transmit images made up of millions of dots that are known as pixels (short for picture elements). So, the higher number of pixels used, the more detailed the image that is displayed on your TV.
What do analog and digital mean?Analog is the process of taking an audio or video signal and translating it into electronic pulses. Analog signals have data size limitations. Digital TV means that the HDTV signal is coded into a binary format where the audio or video information is represented by a series of ones and zeros, identical to how computers store and transmit information. Digital signals transfer high-definition information through broadcast signals to another device, like a cell phone or an HDTV. The device then decodes all the numbers and reassembles them into a picture, sound or other information. A digital signal provides the ability for high-definition signals, which are higher quality than analog signals.
What's the difference between 1080p and 1080i?The number 1080 is related to the screen resolution of the HDTV. The higher the screen resolution, the more pixels your HDTV can display. An HDTV labeled 1080 uses a screen that is 1080 pixels tall. Another standard incremental size is 720 pixels, though 1080 is becoming more standard. The letters "p" and "i" stand for progressive and interlaced, respectively, and refer to how your HDTV scans image information and displays it on the screen. The scanning modes are two different ways of capturing, transporting and displaying high-definition video on an HDTV.
Interlaced scanning uses an image (or frame) made up of two separate scans. First, the HDTV displays every other line of the image and then fills the gaps left after the first scan. This works best with SD signals and programming.
Progressive scanning doesn't split the video frame into two separate fields as the interlacing scan does. The image is drawn sequentially from top to the bottom in a single scan. After the switch to digital broadcast signals, progressive scan became the new standard. A 1080p HDTV will have a high-definition progressive-scan picture.
Do I need additional equipment with an HDTV?You will need to change the cables that connect your HDTV to your cable or satellite system to receive proper HDTV signals. HDMI (high-definition module interface) cables, DVI (digital visual interface) cables and component video or VGA (video graphics array) cables all support a high-definition signal. If you use other types of cables, you won't get the high-definition picture, but a standard-definition picture can still look nice on an HDTV. You may also need to subscribe to an HD programming package from your satellite or cable TV provider in order to receive HD programming, and they will provide you with a high-definition reciever.
What does aspect ratio mean? Aspect ratio is the ratio of width to height of a TV monitor or program. A 4:3 ratio has a square appearance and is four units wide by three units high. The 16:9 aspect ratio has a rectangular or "wide screen" appearance and is 16 units wide by 9 units high. HDTVs have a 16:9 aspect ratio.