13-07-2012, 12:44 PM
direct broadcast satellite (DBS)
[attachment=27540]
INTRODUCTION
Today, most satellite TV customers in developed television markets get their programming through a direct broadcast satellite (DBS) provider, such as DISH TV or DTH platform. The provider selects programs and broadcasts them to subscribers as a set package. Basically, the provider’s goal is to bring dozens or even hundreds of channels to the customers television in a form that approximates the competition from Cable TV. Unlike earlier programming, the provider’s broadcast is completely digital, which means it has high picture and stereo sound quality. Early satellite television was broadcast in C-band - radio in the 3.4-gigahertz (GHz) to 7-GHz frequency range. Digital broadcast satellite transmits programming in the Ku frequency range (10 GHz to 14 GHz ). There are five major components involved in a direct to home (DTH) satellite system: the programming source, the broadcast center, the satellite, the satellite dish and the receiver.
DTH services also provide the finest of picture and sound quality which is considered to be second to none worldwide. Now surround sound, home theaters, live concerts and daily television programming are al delivered to your home with the same quality as any modern movie theater.
Programming sources are simply the channels that provide programming for broadcast. The provider (the DTH platform) doesn’t create original programming itself; it pays other companies (HBO, for example, or ESPN or STAR TV or Sahara etc.) for the right to broadcast their content via satellite. In this way, the provider is kind of like a broker between the viewer and the actual programming sources. (Cable television networks also work on the same principle.) The broadcast center is the central hub of the system. At the broadcast center or the Playout & Uplink location, the television provider receives signals from various programming sources, compreses I using digital compression, if necessary scrambles it and beams a broadcast signal to the satellite being used by it. The satellites receive the signals from the broadcast station and rebroadcast them to the ground. The viewer’s dish picks up the signal from the satellite (or multiple satellites in the same part of the sky) receiver in the viewer’s house. The receiver processes the signal and passes it on to a standard television.
HISTORY OF DTH
1) DTH was first proposed in INDIA in 1996. But it was not approved consent over National security.
2) Finally, in 2000 DTH was allowed and it was Doordarshan which make it possible to provide its facilities to consumers from 1st April 2000.
3) The detailed guidelines for starting the DTH service in India were issued by the government on March 15, 2001, followed by guidelines in March 2003 for uplinking of foreign-owned news channels.
4) The DTH service was started to provide cable transmission digitally with high quality and system can also provide many value-added services such as the Internet, e-mail, data casting, e-commerce, and interactive multimedia.
5) IN earlier days only three companies have applied for starting the DTH broadcasting service. These are Space TV, A.S.C. Enterprises, and Essel Shyam Communications.
6) Broadcasters like STAR and ZEE are pushing hard for DTH services in INDIA.
7) The operators were required to setup earth stations in INDIA within 12 month for getting license of broadcasting whose cost was $2.14 million and will be valid for 10 years.
Broadcasting center
The DTH network consists of components:
Programming
Broadcast centre
Uplink antenna
Satellite (encryption & transmission)
The Dish (downlink antenna)
The Reciever
Set top box
DTH NETWORK
THE PROGRAMMING:
Satellite TV providers get programming from two major sources: International turnaround channels (such as HBO, ESPN and CNN, STAR TV, SET, B4U etc) and various local channels (SaBe TV, Sahara TV, Doordarshan, etc). Most of the turnaround channels also provide programming for cable television, so sometimes some of the DTH platforms will ad in some special channels exclusive to itself to attract more subscriptions.
Turnaround channels usually have a distribution center that beams their programming to a geostationary satellite. The broadcast center uses large satellite dishes to pick up these analog and digital signals from several sources.
BROADCAST CENTRE:
The broadcast center converts all of this programming into a high-quality, uncompressed digital stream. At this point, the stream contains a vast quantity of data — about 270 megabits per second (Mbps) for each channel. In order to transmit the signal from there, the broadcast center has to compress it. Otherwise, it would be too big for the satellite to handle. The providers use the MPEG-2 compressed video format — the same format used to store movies on DVDs. With MPEG-2 compression, the provider can reduce the 270-Mbps stream to about 3 or 10 Mbps (depending on the type of programming). This is the crucial step that has made DTH service a success. With digital compression, a typical satellite can transmit about 200 channels. Without digital compression, it can transmit about 30 channels. At the broadcast center, the high-quality digital stream of video goes through an MPEG-2 encoder, which converts the programming to MPEG-2 video of the correct size and format for the satellite receiver in your house.
UPLINK ANTENNA:
The signals from the broadcast centre are given to the uplink antenna these signals are encoded signals and they are transmitted to the satellites. Uplink satellite Dishes are large in size which provides accurate aiming and signal strength. They are pointed towards specific satellite and uses specific frequency so the satellite transponder can receive the signal. Uplink signals are transmitted in ku band frequencies. It ranges from 10 GHz to 18 GHz.
SATELLITE:
After the video is compressed, the provider needs to encrypt it in order to keep people from accessing it for free. Encryption scrambles the digital data in such a way that it can only be decrypted (converted back into usable data) if the receiver has the correct decoding satellite receiver with decryption algorithm and security keys. Once the signal is compressed and encrypted, the broadcast center beams it directly to one of its satellites.The satellite picks up the signal, amplifies it and beams it back to Earth, where viewers can pick it up.
THE DISH
A satellite dish is just a special kind of antenna designed to focus on a specific broadcast source. The standard dish consists of a parabolic (bowl-shaped) surface and a central feed horn. To transmit a signal, a controller sends it through the horn, and the dish focuses the signal into a relatively narrow beam. The dish on the receiving end can’t transmit information; it can only receive it. The receiving dish works in the exact opposite way of the transmitter. When a beam hits the curved dish, the parabola shape reflects the radio signal inward onto a particular point, just like a concave mirror focuses light onto a particular point.
[attachment=27540]
INTRODUCTION
Today, most satellite TV customers in developed television markets get their programming through a direct broadcast satellite (DBS) provider, such as DISH TV or DTH platform. The provider selects programs and broadcasts them to subscribers as a set package. Basically, the provider’s goal is to bring dozens or even hundreds of channels to the customers television in a form that approximates the competition from Cable TV. Unlike earlier programming, the provider’s broadcast is completely digital, which means it has high picture and stereo sound quality. Early satellite television was broadcast in C-band - radio in the 3.4-gigahertz (GHz) to 7-GHz frequency range. Digital broadcast satellite transmits programming in the Ku frequency range (10 GHz to 14 GHz ). There are five major components involved in a direct to home (DTH) satellite system: the programming source, the broadcast center, the satellite, the satellite dish and the receiver.
DTH services also provide the finest of picture and sound quality which is considered to be second to none worldwide. Now surround sound, home theaters, live concerts and daily television programming are al delivered to your home with the same quality as any modern movie theater.
Programming sources are simply the channels that provide programming for broadcast. The provider (the DTH platform) doesn’t create original programming itself; it pays other companies (HBO, for example, or ESPN or STAR TV or Sahara etc.) for the right to broadcast their content via satellite. In this way, the provider is kind of like a broker between the viewer and the actual programming sources. (Cable television networks also work on the same principle.) The broadcast center is the central hub of the system. At the broadcast center or the Playout & Uplink location, the television provider receives signals from various programming sources, compreses I using digital compression, if necessary scrambles it and beams a broadcast signal to the satellite being used by it. The satellites receive the signals from the broadcast station and rebroadcast them to the ground. The viewer’s dish picks up the signal from the satellite (or multiple satellites in the same part of the sky) receiver in the viewer’s house. The receiver processes the signal and passes it on to a standard television.
HISTORY OF DTH
1) DTH was first proposed in INDIA in 1996. But it was not approved consent over National security.
2) Finally, in 2000 DTH was allowed and it was Doordarshan which make it possible to provide its facilities to consumers from 1st April 2000.
3) The detailed guidelines for starting the DTH service in India were issued by the government on March 15, 2001, followed by guidelines in March 2003 for uplinking of foreign-owned news channels.
4) The DTH service was started to provide cable transmission digitally with high quality and system can also provide many value-added services such as the Internet, e-mail, data casting, e-commerce, and interactive multimedia.
5) IN earlier days only three companies have applied for starting the DTH broadcasting service. These are Space TV, A.S.C. Enterprises, and Essel Shyam Communications.
6) Broadcasters like STAR and ZEE are pushing hard for DTH services in INDIA.
7) The operators were required to setup earth stations in INDIA within 12 month for getting license of broadcasting whose cost was $2.14 million and will be valid for 10 years.
Broadcasting center
The DTH network consists of components:
Programming
Broadcast centre
Uplink antenna
Satellite (encryption & transmission)
The Dish (downlink antenna)
The Reciever
Set top box
DTH NETWORK
THE PROGRAMMING:
Satellite TV providers get programming from two major sources: International turnaround channels (such as HBO, ESPN and CNN, STAR TV, SET, B4U etc) and various local channels (SaBe TV, Sahara TV, Doordarshan, etc). Most of the turnaround channels also provide programming for cable television, so sometimes some of the DTH platforms will ad in some special channels exclusive to itself to attract more subscriptions.
Turnaround channels usually have a distribution center that beams their programming to a geostationary satellite. The broadcast center uses large satellite dishes to pick up these analog and digital signals from several sources.
BROADCAST CENTRE:
The broadcast center converts all of this programming into a high-quality, uncompressed digital stream. At this point, the stream contains a vast quantity of data — about 270 megabits per second (Mbps) for each channel. In order to transmit the signal from there, the broadcast center has to compress it. Otherwise, it would be too big for the satellite to handle. The providers use the MPEG-2 compressed video format — the same format used to store movies on DVDs. With MPEG-2 compression, the provider can reduce the 270-Mbps stream to about 3 or 10 Mbps (depending on the type of programming). This is the crucial step that has made DTH service a success. With digital compression, a typical satellite can transmit about 200 channels. Without digital compression, it can transmit about 30 channels. At the broadcast center, the high-quality digital stream of video goes through an MPEG-2 encoder, which converts the programming to MPEG-2 video of the correct size and format for the satellite receiver in your house.
UPLINK ANTENNA:
The signals from the broadcast centre are given to the uplink antenna these signals are encoded signals and they are transmitted to the satellites. Uplink satellite Dishes are large in size which provides accurate aiming and signal strength. They are pointed towards specific satellite and uses specific frequency so the satellite transponder can receive the signal. Uplink signals are transmitted in ku band frequencies. It ranges from 10 GHz to 18 GHz.
SATELLITE:
After the video is compressed, the provider needs to encrypt it in order to keep people from accessing it for free. Encryption scrambles the digital data in such a way that it can only be decrypted (converted back into usable data) if the receiver has the correct decoding satellite receiver with decryption algorithm and security keys. Once the signal is compressed and encrypted, the broadcast center beams it directly to one of its satellites.The satellite picks up the signal, amplifies it and beams it back to Earth, where viewers can pick it up.
THE DISH
A satellite dish is just a special kind of antenna designed to focus on a specific broadcast source. The standard dish consists of a parabolic (bowl-shaped) surface and a central feed horn. To transmit a signal, a controller sends it through the horn, and the dish focuses the signal into a relatively narrow beam. The dish on the receiving end can’t transmit information; it can only receive it. The receiving dish works in the exact opposite way of the transmitter. When a beam hits the curved dish, the parabola shape reflects the radio signal inward onto a particular point, just like a concave mirror focuses light onto a particular point.