ET2530 Research Paper Wil Hardeman Satellite TV

The role of satellite networks in global communications is growing at an unprecedented pace. From direct broadcast satellite (DBS) television, to satellite phones, to credit card transactions, to the Internet, corporations and consumers are embracing these new services and placing demands on bandwidth. With this demand have come expectations in terms of basic service costs, hardware costs, and ease-of-use. These expectations have forced the industry to examine its traditional ways of operating in order to make satellite services as accessible and convenient as its terrestrial competitors.
Recent current events, such as the World Trade Center tragedy and its aftermath, have demonstrated our need for and how reliant we have become on communication medium. As the World Trade Center lay in ruins, also destroyed were a vast array of communication equipment from transmission antennae for radio and TV stations to switching equipment for phone service. Though throughout all this people were still able to communicate, TV and radio stations were still transmitting their signal. Much of this was a result of wireless and satellite technology.
Satellite television is a system of supplying television programming using broadcast signals relayed from communication satellites. The signals are received via an outdoor parabolic reflector antenna usually referred to as a satellite dish and a low-noise block downconverter (LNB). A satellite receiver then decodes the desired television program for viewing on a television set. Receivers can be external set-top boxes, or a built-in television tuner. Satellite television provides a wide range of channels and services, especially to geographic areas without terrestrial television or cable television.
The direct-broadcast satellite television signal can be either older analogue signals, or newer digital signals, both of which require a compatible receiver. Digital signals may include high-definition television (HDTV). Some transmissions and channels are free-to-air or free-to-view, while many other channels are pay television requiring a subscription.
Satellites used for television signals are generally in either naturally highly elliptical (with inclination of +/-63.4 degrees and orbital period of about twelve hours, also known as Molniya orbit) or geostationary orbit 37,000 km (23,000 mi) above the earth's equator.
Satellite television, like other communications relayed by satellite, starts with a transmitting antenna located at an uplink facility. Uplink satellite dishes are very large, as much as 9 to 12 meters (30 to 40 feet) in diameter. The increased diameter results in more accurate aiming and increased signal strength at the satellite. The uplink dish is pointed toward a specific satellite and the uplinked signals are transmitted within a specific frequency range, so as to be received by one of the transponders tuned to that frequency range aboard that satellite. The transponder retransmits the signals back to Earth but at a different frequency band (a process known as translation, used to avoid interference with the uplink signal), typically in the C-band (4–8 GHz) or K-band (12–18 GHz) or both. The leg of the signal path from the satellite to the receiving Earth station is called the downlink. http://www.whitefence.com/information/history-of-satellite-television. In telecommunications, modulation is the process of conveying a message signal, for example a digital bit stream or an analog audio signal, inside another signal that can be physically transmitted. Modulation of a sine waveform transforms a baseband message signal into a passband signal. A modulator is a device that performs modulation. A demodulator (sometimes detector or demod) is a device that performs demodulation, the inverse of modulation. A modem (from modulator-demodulator) can perform both operations.
Transmission and reception of data is performed in four steps. 1. The data is coded as binary numbers at the sender end 2. A carrier signal is modulated as specified by the binary representation of the data 3. At the receiving end, the incoming signal is demodulated into the respective binary numbers 4. Decoding of the binary numbers is performed
One of the most common physical medias used in networking is copper wire. Copper wire to carry signals to long distances using relatively low amounts of power. The unshielded twisted pair (UTP) is eight strands of copper wire, organized into four pairs. Another example of a physical medium is optical fiber, which has emerged as the most commonly used transmission medium for long-distance communications. Optical fiber is a thin strand of glass that guides light along its length. Four major factors favor optical fiber over copper- data rates, distance, installation, and costs. Optical fiber can carry huge amounts of data compared to copper. It can be run for hundreds of miles without the need for signal repeaters, in turn, reducing maintenance costs and improving the reliability of the communication system because repeaters are a common source of network failures. Glass is lighter than copper allowing for less need for specialized heavy-lifting equipment when installing long-distance optical fiber. Optical fiber for indoor applications cost approximately a dollar a foot, the same as copper.
A typical satellite has up to 32 transponders for Ku-band and up to 24 for a C-band only satellite, or more for hybrid satellites. Typical transponders each have a bandwidth between 27 and 50 MHz. Each geostationary C-band satellite needs to be spaced 2° from the next satellite to avoid interference; for Ku the spacing can be 1°. This means that there is an upper limit of 360/2 = 180 geostationary C-band satellites or 360/1 = 360 geostationary Ku-band satellites C-band transmission is susceptible to terrestrial interference while Ku-band transmission is affected by rain (as water is an excellent absorber of microwaves at this particular frequency). The latter is even more adversely affected by ice crystals in thunder clouds.
The history of satellite TV communications spans back to the creation of Sputnik, which was launched by the Russians in 1957; however, the first communications satellite didn't come until 1963. This satellite, the Syncom II, was launched by a consortium of business and government entities. Telephone providers began using satellites as land lines became overloaded and cable providers soon followed that trend. Satellite television was first broadcast over satellite on March 1, 1978, when the Public Broadcasting System (PBS) launched the Public Television Satellite System. As more broadcast networks adopted satellite communication for distribution, it became evident that everyone could receive satellite signals. http://www.whitefence.com/information/history-of-satellite-television.
Satellite TV at Home
In the early 1980s, Direct to Home (DTH) satellite receivers were developed. These receivers allowed people to receive television programming in rural communities where cable television was previously unavailable. After learning the hard way that people could illegally receive satellite signals through the Television Receive Only (TVRO) system, satellite providers began to scramble their signals so that subscribers would then have to buy a decoder in order to unscramble the signal.
In 1980, the Direct Broadcast Satellite (DBS) system was established by the Federal Communications Commission (FCC), which sets the stage for today's satellite television market. Japan and Hong Kong were the first to be successful at launching satellites for the consumer market, but the U.S. was not far behind. In the 1990s, the first successful satellite provider was Prime star, followed soon after by DIRECTV and DISH Network. Now, it is common to find people in your neighborhood with satellite TV, and there are a number of options for people that prefer it over cable.