CH-5 COLOUR TV

HDTV High Definition Television Used Digital techniques Improvement in both vertical and horizontal resolution of the reproduced picture. Improve colour reproduction. Higher aspect ratio Stereophonic sound. Good picture, sound quality

NHK MUSE System MUSE – Multiple Sub-Nyquist Sampling Encoding It is HDTV bandwidth compression scheme developed by NHK

NHK Broadcast Japan’s NHK launched HDTV in 1990 by satellite. Required bandwidth reduces from 50MHz to 10MHz. Receiver screen diameter over 48’’ i.e 100cm with good viewing.

It uses concept of spatial – temporal interpolation to reduce transmission bandwidth down to near 10MHz.

Temporal Interpolation In MUSE, luminance & colour information are sent by Time multiplexed components(TMC). The colour information sent sequentially. TMC signal is reduces bandwidth over four field sequences. Stationary area of picture are reconstructed by Temporal Interpolation from four field sequences

Spatial Interpolation Moving portion of the picture is reconstructed by spatial interpolation. Require one-quarter spatial resolution. The spatial frequency response of both stationary and moving areas of the picture.

LCD TV Liquid crystal display technology to produce image. Liquid crystals are specialized molecule that flow like liquids but polarize light like solid, crystalline structure Components of LCD TV Liquid crystals Cold cathode fluorescent lamps(CCFLs) Polarizer plates Thin film transistor(TFT),Indium tin oxide, In-plane switching(IPS)

Advantages Thinner & lighter than CRTs Disadvantages Poor contrast ratio More expensive Colour can distort

LED TV LED TV use LCD panel with LED backlighting. LED TV illuminates panel with Light emitted diodes LEDs glow during exposure of electric current. LEDs have several advantage over fluorescent lamp require less energy, able to produces brighter screen colour.

Two types of technology 1] Full array LED backlighting – Array or bank of LEDs that cover the entire back surface of LEDs TV screens. Provide superior contrast ratio & picture quality. 2]Edge lit LED backlighting – LEDs only around the edges of LEDs TV screens.