24-03-2011, 04:48 PM
Presented By
Shashidhar.T.M
shashi- satellite.ppt (Size: 7.59 MB / Downloads: 232)
DIRECT BROADCAST SATELLITE TELEVISION
Introduction
Geostationary satellites have carried television program material almost since their inception for commercial service in the late 1960s
The first time that a GEO satellite was used extensively for video transmission was for the Tokyo Olympic games in 1968
The growth of cable TV(CATV) systems in the united states in the 1970s encouraged the use of domestic North American satellites for distribution of cable TV signals
Satellites are a very effective way to distribute wideband signals, and there was rapid growth in the use of C-band transponders for video signals, using FM and one transponder for each video signal
Fig11.1 shows the earth station complex at Virgina tech, in Blacksburg,Virgina.
Video distribution and direct broadcast (DBS-TV) have become a major source of revenue for the satellite communications industry
C-band and KU-Band Home Satellite TV
In the early 1980s, the development of low noise GaAsFET amplifiers for C-band, and improved threshold extension demodulators for video signal receivers, allowed much smaller diameter antennas to be used to receive C-band FM video signals distributed through GEO satellites.
DBS-TV originally started in Europe and the united states in the 1980s using analog FM transmission in KU band. Satellite TV was much more successful in Europe than in the united states in the 1980s.
Digital DBS TV
In the 1990s, digital video transmission became feasible, and several systems were developed in the united states in the 12.2 to 12.7GHZ band allocated to DBS-TV services.
Fig 11.2 shows the rapid growth in subscribers to DBS-TV systems and the cost of a typical home DBS-TV installation in the united states during the 1990s.
Directv, a fully digital DBS-TV system owned by Hughes Electronics Corporation, was developed by a consortium of companies led by Hughes, and began limited service in 1994 with a single GEO satellite.
The Echostar communications corporation started service with its dish network in march 1996 with a single satellite.
Table 11.1 summarizes the major parameters of two of the DBS-TV satellites serving U.S. customers in 2001.
DBS-TV satellites use digital video transmission, as do several of the European satellites.
Fig 11.3 shows EchoStar 6, a large GEO three axis stabilized DBS-TV satellite built for EchoStar by space systems Loral.
A Directv receiving antenna mounted on the wall of a house is shown in the fig 11.4a, and a dishnetwork antenna mounted on a post is shown in fig 11.4b.
Fig 11.5 shows a block diagram of a DBS-TV receiver.
Shashidhar.T.M
shashi- satellite.ppt (Size: 7.59 MB / Downloads: 232)
DIRECT BROADCAST SATELLITE TELEVISION
Introduction
Geostationary satellites have carried television program material almost since their inception for commercial service in the late 1960s
The first time that a GEO satellite was used extensively for video transmission was for the Tokyo Olympic games in 1968
The growth of cable TV(CATV) systems in the united states in the 1970s encouraged the use of domestic North American satellites for distribution of cable TV signals
Satellites are a very effective way to distribute wideband signals, and there was rapid growth in the use of C-band transponders for video signals, using FM and one transponder for each video signal
Fig11.1 shows the earth station complex at Virgina tech, in Blacksburg,Virgina.
Video distribution and direct broadcast (DBS-TV) have become a major source of revenue for the satellite communications industry
C-band and KU-Band Home Satellite TV
In the early 1980s, the development of low noise GaAsFET amplifiers for C-band, and improved threshold extension demodulators for video signal receivers, allowed much smaller diameter antennas to be used to receive C-band FM video signals distributed through GEO satellites.
DBS-TV originally started in Europe and the united states in the 1980s using analog FM transmission in KU band. Satellite TV was much more successful in Europe than in the united states in the 1980s.
Digital DBS TV
In the 1990s, digital video transmission became feasible, and several systems were developed in the united states in the 12.2 to 12.7GHZ band allocated to DBS-TV services.
Fig 11.2 shows the rapid growth in subscribers to DBS-TV systems and the cost of a typical home DBS-TV installation in the united states during the 1990s.
Directv, a fully digital DBS-TV system owned by Hughes Electronics Corporation, was developed by a consortium of companies led by Hughes, and began limited service in 1994 with a single GEO satellite.
The Echostar communications corporation started service with its dish network in march 1996 with a single satellite.
Table 11.1 summarizes the major parameters of two of the DBS-TV satellites serving U.S. customers in 2001.
DBS-TV satellites use digital video transmission, as do several of the European satellites.
Fig 11.3 shows EchoStar 6, a large GEO three axis stabilized DBS-TV satellite built for EchoStar by space systems Loral.
A Directv receiving antenna mounted on the wall of a house is shown in the fig 11.4a, and a dishnetwork antenna mounted on a post is shown in fig 11.4b.
Fig 11.5 shows a block diagram of a DBS-TV receiver.