24-08-2012, 03:58 PM
DIRECT-TO-HOME TV: TRANSMISSION AND RECEPTION
[attachment=32653]
In direct-to-home (DTH) telecast, TV
channels/programmes are directly distributed
via satellite to the subscribers’
homes without the intervention of a
cable operator. The signals are transmitted
in Ku band (10.7 GHz to 18 GHz) and
are received by the subscribers through a
small dish antenna (about 45cm in dia.)
and a set-top box (or an integrated receiver
decoder).
The DTH system can also provide
many value-added services such as the
Internet, e-mail, data casting, e-commerce,
and interactive multimedia. It has the provision
for a subscriber management system
similar to the one for conditional access
system (CAS). The current means of
broadcasting in India don’t provide quality
reception in shadow areas, particularly
in the north-eastern region. The DTH can
fill this void easily. All in all, DTH offers
immense opportunities to both the broadcasters
and the viewers.
The DVB core system
Generally, a digital video broadcasting
(DVB) system valid for all media carries a
flexible combination of MPEG-2 video, audio,
and data using the common MPEG-2
transport stream multiplex. The common
service information system gives details
of the programmes. Modulation and additional
channel coding system, if any, are
chosen to meet the requirements of different
transmission media. A common scrambling
system and a common conditional
access interface are available.
DVB-S is the DVB standard for satellite
delivery. It is an extension of MPEG-2
standard with specific instructions for
implementing the satellite links. This standard
is widely adopted.
DVB-S transmission
Many of the formats and transmission aspects
of satellite DVB services are
standardised by international bodies such
as the International Organisation for
Standardisation (ISO) and the International
Telecommunications Union (ITU).
The standard developed by the European
Telecommunication Standard
Organisation (part of ITU) applies to Kuband
satellites operating at 11/12 GHz. It
is designed to provide quasi error-free
(QEF) service at bit error rates (BERs) of
10-10 to 10-11. By using a fairly robust
error-prevention scheme.
DVB-S reception
Reception system architecture. In general,
reception systems are of two types, namely,
individual reception systems and collective
reception systems. Individual reception
systems are simply referred to as DTH
systems, while collective reception systems
are often referred to as satellite master
antenna television (SMATV) systems. The
installed reception systems should have
the maximum configuration flexibility, regardless
of their architecture.
[attachment=32653]
In direct-to-home (DTH) telecast, TV
channels/programmes are directly distributed
via satellite to the subscribers’
homes without the intervention of a
cable operator. The signals are transmitted
in Ku band (10.7 GHz to 18 GHz) and
are received by the subscribers through a
small dish antenna (about 45cm in dia.)
and a set-top box (or an integrated receiver
decoder).
The DTH system can also provide
many value-added services such as the
Internet, e-mail, data casting, e-commerce,
and interactive multimedia. It has the provision
for a subscriber management system
similar to the one for conditional access
system (CAS). The current means of
broadcasting in India don’t provide quality
reception in shadow areas, particularly
in the north-eastern region. The DTH can
fill this void easily. All in all, DTH offers
immense opportunities to both the broadcasters
and the viewers.
The DVB core system
Generally, a digital video broadcasting
(DVB) system valid for all media carries a
flexible combination of MPEG-2 video, audio,
and data using the common MPEG-2
transport stream multiplex. The common
service information system gives details
of the programmes. Modulation and additional
channel coding system, if any, are
chosen to meet the requirements of different
transmission media. A common scrambling
system and a common conditional
access interface are available.
DVB-S is the DVB standard for satellite
delivery. It is an extension of MPEG-2
standard with specific instructions for
implementing the satellite links. This standard
is widely adopted.
DVB-S transmission
Many of the formats and transmission aspects
of satellite DVB services are
standardised by international bodies such
as the International Organisation for
Standardisation (ISO) and the International
Telecommunications Union (ITU).
The standard developed by the European
Telecommunication Standard
Organisation (part of ITU) applies to Kuband
satellites operating at 11/12 GHz. It
is designed to provide quasi error-free
(QEF) service at bit error rates (BERs) of
10-10 to 10-11. By using a fairly robust
error-prevention scheme.
DVB-S reception
Reception system architecture. In general,
reception systems are of two types, namely,
individual reception systems and collective
reception systems. Individual reception
systems are simply referred to as DTH
systems, while collective reception systems
are often referred to as satellite master
antenna television (SMATV) systems. The
installed reception systems should have
the maximum configuration flexibility, regardless
of their architecture.