Satellite television is a service that delivers television programming to viewers by delivering it from a communications satellite orbiting directly to the viewer's location. The signal is received through an external parabolic antenna commonly referred to as a parabola and a low noise block downconverter.
The satellite receiver then translates the desired television program to be viewed on television. The receiver can be either an external set-top box, or a built-in television tuner. Satellite television provides a variety of channels and services. Usually only television is available in many distant geographical areas without terrestrial television or cable television services.
The modern system signals are transmitted from the communication satellites at the frequency band K u (12-18Ã, GHz) which requires only a small dish with a diameter of less than one meter. The first satellite TV system was an outdated type that is now known as a television that only accepts. This system receives weak analog signals transmitted in C-band (4-8Ã, GHz) of FSS type satellites, requiring the use of large 2-3-meter disks. As a result, the system is dubbed a "big plate" system, and is more expensive and less popular.
Initial systems use analog signals, but modern ones use digital signals that allow the transmission of high definition television of modern television, as the spectral efficiency of digital increases significantly. In 2018, Star One C2 from Brazil is the only remaining satellite broadcast in analog signals, as well as one channel (C-SPAN) at AMC-11 from the United States.
Different recipients are required for two types. Some transmissions and channels are unencrypted and therefore free-to-air or free-to-view, while many other channels are transmitted with encryption (pay-TV), which requires viewers to subscribe and pay monthly fees to receive programming.
Video Satellite television
Technology
The satellite used for television broadcasting is usually in geostationary orbit 37,000 km (23,000 mi) above the equator of the earth. The advantage of this orbit is that the satellite's orbital period is equal to the Earth's rotational level, so that the satellite appears in a fixed position in the sky. Thus the satellite dish receiver that receives the signal can be routed permanently to the satellite location, and does not have to track the moving satellite. Some systems in turn use a very elliptical orbit with a slope of/- 63.4 degrees and a twelve hour orbital period, known as the Molniya orbit.
Satellite television, like other communications broadcast by satellite, begins with a transmitting antenna located in an uplink facility. Uplink satellite dishes are very large, with a diameter of 9 to 12 meters (30 to 40 feet). Increased diameters result in more accurate targeting and increased signal strength on satellites. The uplink plate is directed to a particular satellite and the uplink signal is transmitted within a certain frequency range, so it is received by one of the transponders tuned to the frequency range above the satellite. The transponder retransmits signals back to Earth at different frequencies (a process known as translation, used to avoid interference with uplink signals), usually in C-bands (4-8Ã, GHz), K u - band (12-18Ã, GHz), or both. The foot of the signal path from the satellite to the receiving Earth station is called downlink.
Typical satellites have up to 32 K u -band or 24 C-band transponders, or more for hybrid satellites K u /C. Typical transponders each have bandwidths between 27 and 50 MHz. Each geostationary C-band satellite must be spaced 2 Â ° longitude from the next satellite to avoid interference; for K u the distance can be 1 Â °. This means that there is an upper limit of 360/2 = 180 geostationary satellite C-band or 360/1 = 360 geostationary K u -band satellite. C-band transmission is susceptible to terrestrial interference while transmission of K u -band is influenced by rain (because water is an excellent microwave absorber at a certain frequency). The latter is even more influenced by ice crystals in the thunder clouds.
Sometimes, a blackout will occur when the sun's line is just behind the geostationary satellite that is targeted by the receiving antenna. Downlink satellite signals, quite weak after traveling a great distance (see inverse-square law), are collected with a parabolic receiver dish, which reflects a weak signal to the focal point of the dish. Mounted on the brackets at the focal point of the dish is a device called a feedhorn or collector. Feedhorn is part of a waveguide with a blazing front-end that collects signals at or near the focal point and directs them to a probe or pickup connected to a low-noise block downconverter (LNB). The LNB amplifies the signal and lowers it to the lower-frequency block (IF), usually in L-band.
The original C-band satellite television system used low-noise (LNA) amplifiers connected to the feedhorn at the focal point of the dish. The amplified signal, still at higher microwave frequencies, must be channeled through a very cheap low impedance 50-ohm impedance cable filled with a hardline coaxial cable with a relatively complex N connector to an indoor receiver or, in another design, downconverter (a mixer and a voltage-tuned oscillator with multiple filter circuits) for downconversion to intermediate frequency. Channel selection is controlled specifically by the oscillator tuned voltage with the tuning voltage inserted through a separate cable to the headend, but this design evolves.
The design for microstrip-based converters for amateur radio frequencies is adjusted for C-band 4 GHz. The core of this design is the concept of block downconversion from various frequencies to the lower IF and more easily handled.
The advantage of using an LNB is that the cheaper cable can be used to connect the indoor receiver to the satellite dish and the LNB, and that the technology to handle signals in L-band and UHF is much cheaper than to handle signals in C-band Frequency. The shift to cheaper technology from the N-hardline and N-connectors of the early C-band systems to the cheaper and simpler 75-ohm and F cables enabled early satellite television receivers to be used, what actually, modified UHF TV tuners that chose satellite television channels for conversion down to a lower center frequency centered at 70 MHz, where it was demodulated. This shift allows the DTH satellite television industry to change from being largely a hobbyist where only a small number of systems cost thousands of US dollars are built, into a much more commercial mass production.
In the United States, service providers use the frequency range between 950-2150 MHz to carry signals from LNBF on the dish to the receiver. This allows for the transmission of UHF signals along the same coaxial wire range at the same time. In some applications (DirecTV AU9-S and AT-9), ranges from lower B-band and 2250-3000 MHz, are used. The new LNBF used by DirecTV, called SWM (Single Wire Multiswitch), is used to implement a single cable distribution and uses a wider 2-2150 MHz frequency range.
The satellite receiver or set-top box demodulates and converts the signal to the desired shape (output for television, audio, data, etc.). Often, the recipient includes the ability to selectively decipher or decrypt received signals to provide premium services for multiple customers; The receiver is then called an integrated receiver/decoder or IRD. Low loss cable (eg RG-6, RG-11, etc.) Used to connect receiver to LNBF or LNB. RG-59 is not recommended for this application because it is not technically designed to carry frequencies above 950 MHz, but can work in some circumstances, depending on the quality of the coaxial cable, signal level, cable length, etc.
A practical problem with regards to home satellite reception is that an LNB can basically handle only one recipient. This is because the LNB translates two different circular polarizations (right and left) and, in the case of K-band, two different frequency bands (lower and higher) to the same frequency range on the cable. Depending on the frequency and polarization used by the transponder, the satellite receiver must convert the LNB into one of four different modes to receive a certain "channel". This is handled by the receiver using DiSEqC protocol to control LNB mode. If multiple satellite receivers have to be attached to a single disk, a multiswitch should be used in conjunction with a special LNB type. There are also available LNBs with integrated multiswitches. This problem becomes more complicated when some receivers use multiple dishes (or multiple LNBs mounted on one disc) pointing to different satellites.
A common solution for consumers who want to access multiple satellites is to use a single disc with a single LNB and rotate the dish using an electric motor. The rotation axis should be set in the north-south direction and, depending on the geographical location of the disc, has a certain vertical slope. Properly adjusting the motorized antenna when deflected will sweep all positions possible for the satellites along the geostationary orbit just above the equator. The disk will then be able to receive geostationary satellites that are visible in certain locations, ie above the horizon. The DiSEqC protocol has been expanded to include commands for the rotor of the steering plates.
There are five major components in a satellite system: programming sources, broadcast centers, satellites, satellite dishes, and receivers. Satellite "live broadcast" used for transmitting satellite television signals is generally located in geostationary orbit 37,000 km (23,000 mi) above the equator of the earth. The reason for using this orbit is that the satellites circle the Earth at the same rate as the Earth rotates, so the satellites appear at fixed points in the sky. So satellite dishes can be permanently directed at that point, and there is no need for a tracking system to follow a moving satellite. Some satellite TV systems use satellites in Molniya orbit, highly elliptical orbits with a slope of/- 63.4 degrees and orbital periods of about twelve hours.
Satellite television, like other communications broadcast by satellite, begins with a transmitting antenna located in an uplink facility. The Uplink facility sends signals to the satellite through a narrow microwave beam, usually in the C-band frequency range as its resistance to rain fades. Uplink satellite dishes are very large, often 9 to 12 meters (30 to 40 feet) to achieve accurate targets and increase signal strength in satellites, to improve reliability. The uplink plate is directed to a particular satellite and the uplink signal is transmitted within a certain frequency range, so it is received by one of the transponders tuned to the frequency range above the satellite. The transponder then converts the signal to K u band, a process known as "translation," and sends it back to earth to be received by the home satellite station.
Downlink satellite signals, weaker after long distances (see inverse square law), are collected by using parabolic dish receivers on the roof ("parabola"), which reflects weak signals to the focal point of the disc. Mounted in parentheses at the focal point of the disk is a feedhorn that passes a signal through a wave guide to a device called a low noise block converter (LNB) or low-noise converter (LNC) attached to the horn. LNBs amplify weak signals, filter out the frequency blocks in which satellite television signals are transmitted, and convert frequency blocks to lower frequency ranges within the L-band range. The signal then passes the coaxial cable to the residence to the satellite television receiver, the set-top box next to the television.
The reason for using an LNB to do the frequency translation on the disk is so that the signal can be taken to the residence using cheap coaxial cable. To transmit signals into the home at the original microwave wave K u will require expensive waveguides, metal pipes to carry radio waves. The cable connecting the receiver to the LNB is a low loss type RG-6, quad shield RG-6, or RG-11. RG-59 is not recommended for this application as it is not technically designed to carry frequencies above 950 MHz, but will work in many circumstances, depending on the quality of the coaxial cable. The shift to a more affordable technology from 50 ohm-impedance and N-cable connectors from the initial C-band system to the less expensive 75 ohms and F-connectors allowed early satellite television receivers to use, what is actually, a modified UHF television tuner that chooses a satellite television channel for conversion down to a lower middle frequency centered at 70 MHz where it is demodulated.
The LNB can handle only one recipient. This is due to the fact that the LNB maps two different circular polarizations - right hand and left hand - and in the case of K u -band two different acceptance bands - lower and higher - for one and ribbon the same frequency on the cable, and is a practical problem for home satellite reception. Depending on the frequency of transponders transmitting on and on what polarization is used, the satellite receiver must redirect the LNB to one of four different modes to receive certain desired programs on a particular transponder. The receiver uses the DiSEqC protocol to control the LNB mode, which handles this. If multiple satellite receivers must be attached to a single disk, then multiswitches should be used in conjunction with special type LNBs. There are also available LNBs with integrated multiswitches. This problem becomes more complicated when some receivers use multiple dishes or multiple LNBs mounted on one disc intended for different satellites.
The set-top box selects the channel the user wants by filtering channels from multiple channels received from satellites, changing the signal to lower intermediate frequencies, decrypting the encrypted signal, demodulating the radio signal and sending the resulting video signal to the television via cable. To decrypt the signal, the receiver must be "enabled" by the satellite company. If a customer fails to pay his monthly bill, the box is "disabled" by a signal from the company, and the system will not work until the company re-enables it. Some receivers are able to decrypt the received signal itself. This receiver is called integrated receiver/decoder or IRD.
Analog television distributed via satellite is usually sent scrambled or not scrambled in standard NTSC, PAL, or SECAM television broadcasts. An analog signal is a frequency modulated and converted from an FM signal to a so-called baseband. This baseband consists of video signal and audio subcarrier (s). Subcarrier audio is further demodulated to provide a raw audio signal.
The signal then is a digital television signal or multiplex signal, usually QPSK. In general, digital television, including transmitted via satellite, is based on open standards such as MPEG and DVB-S/DVB-S2 or ISDB-S.
Conditional access encryption/scrambling methods include NDS, BISS, Conax, Digicipher, Irdeto, Cryptoworks, DG Crypt, Digital Beta, SECA Mediaguard, Logiways, Nagravision, PowerVu, Viaccess, Videocipher, and VideoGuard. Many conditional access systems have been compromised.
Sun outage
An event called solar outage occurs when the sun line is directly behind the satellite in the receiving antenna satellite view. This happens for about 10 minutes every day around midday, twice every year for a two-week period in spring and falls around the equinox. During this period, the sun is within the main lobe of the dish receiving pattern, so that the powerful microwaves emitted by the sun at the same frequency used by satellite transponders drown out reception.
Maps Satellite television
Usage
Live broadcast via satellite
Direct-To-Home (DTHTV) may refer to the communication satellite itself that provides actual television services or services. Most satellite television subscribers in the advanced television market get their program through direct broadcast satellite providers. The signal is transmitted using K u band and is fully digital which means it has high image and stereo sound quality.
Programming for satellite television channels comes from a variety of sources and may include live studio feeds. The broadcast center assembles and bundles the program into a channel for transmission and, if necessary, encrypts the channel. The signal is then sent to the uplink where it is transmitted to the satellite. With multiple broadcast centers, studios, administration and up-links are part of the same campus. The satellite then translates and broadcasts the channel.
Most systems use DVB-S standards for transmission. With pay-TV services, the datastream is encrypted and requires proprietary receipts. While the underlying receiving technology is similar, pay-TV technology is proprietary, often consisting of conditional access and smart card modules. This measure assures the only authorized satellite television provider, paid subscribers have access to pay for television content but at the same time can allow free channels to be viewed even by people with standard equipment available in the market.
Some countries operate satellite television services that are acceptable for free, without paying a subscription fee. This is called free-to-air satellite television. Germany is likely a leader in free-to-air with about 250 digital channels (including 83 HDTV channels and various regional channels) broadcasted from the 19.2-degree Astra satellite constellation. It is not marketed as a DBS service, but is accepted in around 18 million homes , as well as in every home using the Sky Deutschland commercial DBS system. All German analog satellite broadcasts stop on April 30, 2012.
The United Kingdom has about 160 digital channels (including variations of regional BBC channels, channel ITV, Channel 4 and Channel 5) that are broadcast unencrypted from the constellation of Astra 28.2 Â ° E satellite, and can be received on any DVB-S receiver (DVB receiver -S2 is required for certain high definition television services). Most of these channels are included in EPG Sky, and more and more in Freesat EPG.
Indian national broadcaster Doordarshan promoted the free-to-air DBS package as "Dish Free DD", which is provided as fill-in for state terrestrial transmission networks. It is broadcast from GSAT-15 at 93.5 Â ° E and contains about 80 FTA channels.
Although originally launched as a backhaul for their terrestrial digital television service, a large number of free-on-air French channels on satellites are at 5 ° C, and recently announced as official charging for the DTT network.
In North America (USA, Canada and Mexico) there are over 80 digital FTA channels available at Galaxy 19 (with ethnic or religious majority in nature). Other FTA satellites include AMC-4, AMC-6, Galaxy 18, and Satmex 5. A company called GloryStar promotes FTA religious broadcasters on Galaxy 19.
Receive only television
The term Television receiving only, or TVRO, appeared in the early days of satellite television reception to distinguish it from uplink and downlink commercial satellite television (sending and receiving) operations. This was the main method of satellite television transmission before the satellite television industry shifted, with the launch of high powered DBS satellites in the early 1990s that transmitted their signals at the frequency band K u . The satellite television channel at that time was intended for use by cable television networks rather than accepted by home viewers. The early satellite television receiver systems were mostly built by fans and engineers. This early TVRO system operated mainly on C-band frequencies and large required disks; usually more than 3 meters (10Ã, ft) in diameter. As a result, TVRO is often referred to as "big dish" or "Big Ugly Dish" (BUD) satellite television.
The TVRO system is designed to receive analog and digital satellite feeds from both television or audio from both C-band transponders and K u -band on FSS type satellites. The higher frequency of K u -band systems tend to resemble DBS systems and can use smaller dish antennas due to higher power transmission and greater antenna gain. TVRO systems tend to use larger satellite dish antennas than smaller dish antennas, as it is more likely that the owner of the TVRO system will have a C-band setup instead of the only-band setup. Additional receiver boxes allow different types of digital satellite signal reception, such as DVB/MPEG-2 and 4DTV.
The narrow beam width of a normal parabolic satellite antenna means it can only receive signals from one satellite at a time. Simulsat or Vertex-RSI TORUS, is a quasi-parabolic Earth satellite antenna capable of receiving satellite transmissions from 35 or more C- and K sub-sat-bands simultaneously.
History
Initial history
In 1945 the English science fiction writer Arthur C. Clarke proposed a worldwide communication system that would function in the way of three satellites that were equally placed separately in Earth's orbit. It was published in the October issue of Wireless World magazine and won the Stuart Ballantine Medal at the Franklin Institute in 1963.
The first public satellite television signal from Europe to North America was transmitted via Telstar satellite over the Atlantic Ocean on July 23, 1962, although test broadcasts had been conducted almost two weeks earlier on July 11. Signals are received and broadcast in North American and European countries and watched over 100 million. Launched in 1962, the Relay 1 satellite was the first satellite to transmit television signals from the US to Japan. The first geosynchronous communications satellite, Syncom 2, was launched on July 26, 1963.
The world's first commercial communications satellite, called Intelsat I and dubbed "Early Bird", was launched into geosynchronous orbit on April 6, 1965. The first satellite satellite network, called Orbita, was created by the Soviet Union in October 1967, and based on the principle of using the Molniya which is highly elliptical for re-broadcasting and transmitting television signals to ground downlink stations. The first North American commercial satellite carrying a television transmission was the Canadian geostationary Anik 1, which was launched on November 9, 1972. ATS-6, the world's first experimental broadcasting broadcast and broadcast, was launched on May 30, 1974. at 860 MHz using wideband FM modulation and has two voice channels. Transmission is focused on the Indian subcontinent but researchers are able to receive signals in Western Europe using exciting home-made equipment on already used UHF television design techniques.
The first in a series of Soviet geostationary satellites to bring live television to home, Ekran 1, was launched on October 26, 1976. It uses a 714 MHz UHF downlink frequency so transmission can be received with existing UHF television technology rather than microwave technology.
Initial Satellite TV industry, 1976-1980
The satellite television industry was first developed in the United States from the cable television industry because communications satellites are used to distribute television programs to long-distance cable television titles. The Home Box Office (HBO), the Turner Broadcasting System (TBS), and the Christian Broadcasting Network (CBN, then The Family Channel) include the first to use satellite television to deliver programming. Taylor Howard from San Andreas, California became the first person to receive a C-band satellite signal with his own homemade system in 1976.
In the US, PBS, a non-profit public broadcasting service, began distributing its satellite television program in 1978.
In 1979, Soviet engineers developed the Moskva (or Moscow) broadcasting system and sent TV signals via satellite. They launched the Gorizont communication satellite later in the same year. These satellites use geostationary orbit. They are equipped with powerful on-board transponders, so the size of the parabolic antenna from the downlink station is reduced to 4 and 2.5 meters. On October 18, 1979, the Federal Communications Commission (FCC) began allowing people to own earth satellite earth stations without a federal government license. The front cover of Christmas catalog of Neiman-Marcus 1979 featured the first home satellite TV station that sold for $ 36,500. The plate was nearly 20 feet (6.1 m) in diameter and remotely controlled. Prices dropped half soon after, but there are only eight more channels. Society for Private Earth and Commercial Stations (SPACE), an organization representing consumers and owners of satellite TV systems, was founded in 1980.
Early satellite television systems were not very popular due to the cost and size of their large disks. The satellite television dishes from the system in the late 1970s and early 1980s were 10 to 16 feet (3.0 to 4.9 m) in diameter, made of fiberglass or solid aluminum or steel, and in the United States it cost more than $ 5,000, sometimes as much as $ 10,000. Programming sent from earth stations is forwarded from eighteen satellites in geostationary orbit located 22.300 miles (35,900 km) above Earth.
TVRO/C-band satellite era, 1980 -1986
In 1980, satellite television was well established in the United States and Europe. On April 26, 1982, the first satellite channel in the UK, Satellite Television Ltd. (later Sky1), launched. The signal is sent from the ESA Orbital Test Satellite. Between 1981 and 1985, TVRO system sales rates increased as prices fell. Advances in recipient technology and the use of gallium arsenide FET technology allow the use of smaller plates. Five hundred thousand systems, some costing as little as $ 2000, were sold in the US in 1984. Plates leading to one satellite were cheaper. People in areas that do not have a local broadcast station or cable television service can obtain good quality acceptance without monthly fees. The big dishes are a subject of concern, as many people consider them a bad sight, and in the US most condominiums, neighborhoods and other homeowners associations limit their use strictly, except in areas where such restrictions are illegal. This restriction was changed in 1986 when the Federal Communications Commission decided everything was illegal. A municipality may require the property owner to move the plate if it violates other zoning restrictions, such as regression requirements, but can not prohibit its use. The need for this restriction will decrease slowly as the dish is smaller.
Initially, all channels are broadcasted clearly (ITC) because the equipment needed to receive programming is too expensive for consumers. With the increasing number of TVRO systems, program providers and broadcasters have to scramble their signals and develop subscription systems.
In October 1984, the US Congress passed the Cable Communications Policy Act of 1984, which gave them the TVRO system the right to receive signals for free unless they were randomized, and required those who scrambled to make their signal available for a reasonable fee. Because cable channels can prevent reception by large disks, other companies have an incentive to offer competition. In January 1986, HBO started using the now obsolete VideoCipher II system to encrypt their channel. Other channels use a less secure encryption system. The seizure of HBO is filled with much protest from the owner of the big-dish system, most of whom have no choice when receiving the channel, claiming that a clear signal from the cable channel would be difficult to accept. Finally HBO allows the owner of the dish to subscribe directly to their service for $ 12.95 per month, the price is equal to or higher than what the paying subscriber subscribes, and requires the descrambler to be purchased for $ 395. This led to attacks on the Galaxy 1 HBO transponder by John R. MacDougall in April 1986. One by one, all commercial channels follow the footsteps of HBO and start randomizing their channels. The Association of Broadcasting and Satellite Communications (SBCA) was established on December 2, 1986 as a result of a merger between SPACE and the Direct Broadcast Satellite Association (DBSA).
Videocipher II uses analogue randomization of video signals and Encryption Standard-based encryption data on audio signals. VideoCipher II was defeated, and there was a black market for descrambler devices that were originally sold as "test" devices.
The need for better satellite television programs than TVRO emerged in the 1980s. The satellite television service, first in Europe, began transmitting signal band K u in the late 1980s. On December 11, 1988, Luxembourg launched Astra 1A, the first satellite to provide medium power satellite coverage to Western Europe. This is one of the first satellites to be empowered, transmitting signals in the K u band and enabling reception with a small disc (90 cm) for the first time. The launch of Astra overcame the direct state satellite direct broadcast winner, British Satellite Broadcasting, into the marketplace, and accelerated its destruction.
1990s to present
In 1987, nine channels were randomized, but 99 other channels were available free-for-air. While HBO initially imposed a $ 19.95 monthly fee, it soon became possible to outline all channels for $ 200 per year. The sale of the dish dropped from 600,000 in 1985 to 350,000 in 1986, but the pay television service saw the dish as something positive because some people would never have cable services, and the industry began to recover as a result. Randomizing also causes the development of pay-per-view events. On November 1, 1988, NBC began randomizing C-band signals but leaving K u signals unencrypted so that affiliates did not lose viewers who could not see their ads. Most of the two million satellite satellite users in the United States are still using C-band. ABC and CBS are considering randomization, although CBS is reluctant because of the number of people who can not accept local network affiliates. Piracy on satellite television networks in the US led to the introduction of the Consumer Protection and Cable Television Competition Act of 1992. The law allows anyone caught involved in the theft of the signal to be fined up to $ 50,000 and sentenced to a maximum of two years in prison. Repeat offenders can be fined up to $ 100,000 and incarcerated for up to five years.
Satellite television has also been developed in Europe but initially used low power communication satellites and required antenna size over 1.7 meters. On December 11, 1988, Luxembourg launched Astra 1A, the first satellite to provide medium power satellite coverage to Western Europe. This is one of the first empowered satellites, transmitting signals in the ribbon K u and enabling reception with a small disc (90 cm). The launch of Astra defeated the winner of Direct Broadcast Satellite Direct British license, British Satellite Broadcasting, to market.
In the US in the early 1990s, four major cable companies launched PrimeStar, a direct broadcasting company that uses medium power satellites. The relatively strong transmission allows the use of smaller (90 cm) plates. Its popularity declined with the 1994 launch of Hughes DirecTV and Dish Network satellite television systems.
On March 4, 1996, EchoStar introduced the Digital Sky Highway (Dish Network) using the EchoStar 1 satellite. EchoStar launched its second satellite in September 1996 to increase the number of channels available on Dish Network to 170. The system provides better stereo images and sound on 150-200 video and audio channels, and allowing small dishes to be used. This greatly reduces the popularity of TVRO systems. In the mid-1990s, channels began to move their broadcasts to digital television transmissions using DigiCipher's conditional access system.
In addition to encryption, widespread availability, in the US, DBS services such as PrimeStar and DirecTV have reduced the popularity of TVRO systems since the early 1990s. Signals from DBS satellites (operating in the newer K u bands) are higher both in frequency and power (due to improvements in solar panels and modern satellite energy efficiency) and therefore require more disks than C -band, and the now used digital modulation method requires less signal strength in the receiver than the analog modulation method. Each satellite can also carry up to 32 transponders in the K u band, but only 24 in band C, and multiple digital subchannels can be multiplexed (MCPC) or taken separately (SCPC) on a single transponder.. Advances in noise reduction due to improved microwave technology and semiconductor materials also have an effect. However, one consequence of the higher frequencies used for DBS services is the faded showers where viewers lose their signal during heavy rain. C-band satellite television signals are less susceptible to fading rain.
To return to the older (but proven) satellite communications technology, the current US-based provider of DBS satellites in the US (Dish Network and DirecTV) is now using additional capacity on the existing FSS class F-class satellite transponders , in addition to the capacity on their own DBS satellite fleet that is in orbit. This is done to provide more channel capacity for their systems, as demanded by the increasing number of local High-Definition broadcast channels and simulcast. Channel reception made on satellite transponders K u -band FSS has been achieved by DirecTV & amp; Dish Network unleashes their customers' plates two times larger in diameter (36 ") than the previous 18" (& amp; 20 "for Dish Network" Dish500 ") presents the service used initially, equipped with 2 circularly polarized LNBF (for acceptance of 2 the original DBS satellite of the provider, 1 per LNBF), and 1 linearly polarized LNB for channel reception from the FSS type satellites.This new DBS/FSS-hybrid dish, marketed by DirecTV and Dish Network as the "SlimLine Model" and "SuperDish" respectively, are now the current standard for both providers, with their now obsolete single or dual 18 "/20" LNBF dish, or used only for program packages, separate channels, or services only broadcast via DBS provider satellite.
On 29 November 1999, US President Bill Clinton signed the Act on Increasing the Satellite Home Watch (SHVIA). The action allows Americans to receive local broadcast signals via a live broadcast satellite system for the first time.
Satellite Television for the Asian Region (STAR), a service based in Mumbai and Hong Kong that now provides satellite TV coverage to Asia and Australia, introduced satellite TV to the Asian region in the early 1990s. It started broadcasting signals using the AsiaSat 1 satellite on January 1, 1991.
See also
- Freesat
- TV Dishes
- Places Home
- List of satellite broadcast providers directly
- Only receive television
- Satellite television by region
- Commercialization of space
- Free-to-air
- Microwave antenna
- Molniya orbit
- Satellite plates
- Subcarrier audio satellites
- Smart TV: provides television via internet connection
- SMATV
- Television antenna
References
Media related to satellite television on Wikimedia Commons
Source of the article : Wikipedia
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