Page 84 - DCAP303_MULTIMEDIA_SYSTEMS

Multimedia Systems

notes with language issues, meant that in most countries monochrome-only reception did not pose a
significant problem for the authorities.

SYSTEM SECAM B,G,H SECAM D,K,K1,L
Line/Field 625/50 625/50
Horizontal Frequency 15.625 kHz 15.625 kHz
Vertical Frequency 50 Hz 50 Hz
Video Bandwidth 5.0 MHz 6.0 MHz
Sound Carrier 5.5 MHz 6.5 MHz

paL versus seCaM
The SECAM is an earlier attempt at compatible colour television which also tries to resolve the
NTSC hue problem. It does so by applying a different method to colour transmission, namely
alternate transmission of the U and V vectors and frequency modulation, while PAL attempts to
improve on the NTSC method.
The SECAM transmissions are more robust over longer distances than NTSC or PAL. However,
owing to their FM nature, the colour signal remains present, although at reduced amplitude, even
in monochrome portions of the image, thus being subject to stronger cross colour. Like PAL, a
SECAM receiver needs a delay line.

5.2.4 advanced television systems Committee (atsC)
The ATSC standards are a set of standards developed by the Advanced Television Systems
Committee for DTV transmission over terrestrial, cable and satellite networks.
The ATSC standards were developed in the early 1990s by the Grand Alliance, a consortium of
electronics and telecommunications companies that assembled to develop a specification for what
is now known as HDTV. The ATSC formats also include standard-definition formats, although
initially only HDTV services were launched in the digital format.
The high definition television standards defined by the ATSC produce wide screen 16 : 9 images
up to 1920 × 1080 pixels in size—more than six times the display resolution of the earlier standard.
However, many different image sizes are also supported. The reduced bandwidth requirements
of lower-resolution images allow up to six standard-definition “subchannels” to be broadcast on
a single 6 MHz TV channel.
The ATSC standards are marked A/x (x is the standard number) and can be downloaded freely
from the ATSC’s website at ATSC.org. The ATSC Standard A/53, which implemented the system
developed by the Grand Alliance, was published in 1995; the standard was adopted by the Federal
Communications Commission in the US in 1996. It was revised in 2009. The ATSC Standard A/72
was approved in 2008 and introduces H.264/AVC video coding to the ATSC system.
The ATSC also boasts 5.1-channel surround sound using the Dolby Digital AC-3 format. Numerous
auxiliary data casting services can also be provided.
Many aspects of ATSC are patented, including elements of the MPEG video coding, the AC-3
audio coding, and the 8VSB modulation. The cost of patent licensing, estimated at up to 50 US$
per DTV receiver, has prompted complaints by manufacturers.
As with other systems, ATSC depends on numerous interwoven standards, e.g., the EIA-708
standard for digital closed captioning, leading to variations in implementation.
5.2.5 Digital television (Dtv)

The DTV is a reality in the US and many countries around the world. Actually FCC set May, 2006
as the deadline for all terrestrial TV broadcasting to be done 100% in digital format. Some countries

78 LoveLy professionaL University