Satellite TV Service

Dish Network and Directv provides Satellite TV service throughout USA.Compared to cable TV services Satellite TV service providers offering more number of channes at low price.

Cable and Satellite TV Comparison

Number of Channels

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Satellite TV can offer more number of channels than cable.Normally the full bandwidth digital signal could barely carry 40 or 50 channels only.But the Satellite TV system uses MPEG compression technology and can provide more than 500 channels.A typical Cable network provides approximately 75OMHz of bandwidth, and each channel requires 6MHz. Therefore, because the television channels start at about 5OMHz, you would find channel 2 in the SOMHz-56MHz range, channel 3 at 57MHz-63MHz, and so on up the frequency spectrum. At this rate, an HFC network can support maximum 110 channels only.

Type of Signal(Analog or Digital)

Digital signal offers high quality picture and sound than analog signal.The digital TV or HDTV requires digital signal input only. Cable still is facing problems delivering HDTV.Satellite TV service provides 100% digital signals.Cable offers both digital and analog signals,but digital signal offered by cable companies are much costlier than Satellite TV system.

Prices

Satellite TV monthly cost is less than cable cost.

Drawbacks of Satellite TV

A clear line of sight from a dish antenna to the southern sky is necessary to receive a direct signal from the satellite.Heavy rain,snow,trees and tall buildings could also causes to lose signal strength due to the dish antenna not being able to see the satellite. Cable systems are not affected by these factors.

Satellite TV service broadcasting works quite differently from terrestrial television broadcasting. Satellite are very expensive to launch, and the broadcast coverage may be as large as an entire hemisphere, but satellites more typically broadcast to a smaller area (footprint), such as a country or group of countries. Most satellites are located in a geostationary orbit, 22,225 miles above the equator. Orbiting the earth 24 hours, they appear to remain stationary in the sky, so the receiving antenna, the now familiar dish, points at a fixed spot in the sky. For coverage in high latitudes, a few satellites operate on inclined or polar orbits; the receiving dishes must track such satellites as they move. More elaborate dish receivers can be moved to point at different satellites.

TV transmission satellites operate on internationally agreed-upon frequencies in two-bands the C band, 3.4 to 6.425 GHz, and the Ku band, 10.95 to 14.5 GHz. Taken together, that’s 6.575 GHz, or 16 times the combined spectrum bandwidths of AM< FM, and VHF/UHF television, which add up only 408MHz.(Other frequencies in the C and Ku bands are used by point-to-point satellites that handle general telecommunications.) With such massive bandwidth capabilities and wide coverage, it’s easy to see the attraction of satellite broadcasting, especially once you also factor ion the digital transmission capabilities of the satellites.

Satellites must operate in specific location around the equator. For a given frequency, satellites must be separated by 2 degrees. However, satellites operating on different frequencies or aimed at widely different areas can occupy locations closer to one another. For obvious reasons, the positions over landmasses are much more desirable than positions over oceans. The satellites slots for North American coverage are completely full. Each satellite carries from 10 to 48 transponders operating in the C or Ku band or both. Each transponder acts independently, receiving a signal from an earth station (uplink) at one frequency and sending that signal back to earth(downlink) on a different frequency.

SATELLITE DISH SIZE

The size of the receiving dish depends on several factors. The power of the transponder is one important variable. The more powerful the transponder, the smaller the dish can be. In addition, the smaller the coverage area, the greater the effective power in that coverage area, allowing for a smaller dish. C band dishes are large, typically 6-10 feet in diameter, while Ku band dishes are only 1.5-4 feet in diameter. Many transponders in the Ku band transmit with much more power than C band transponders, enabling the most popular receiving dishes to be more 18 inches in diameter. Modern Satellite TV service providers are using very small dish and very easy to install anywhere.

Dish size also controls the quality of the reception, for a number of reasons. The larger the dish, the better the signal to noise ratio for the received signal. Also, dishes located of the edges of coverage such as in the northern concerns of the continental United States-often must be larger to maintain signal quality. Finally Ku band reception is susceptible top interference from heavy rainstorms; a larger antenna can usually overcome such disruptions.

C band television signals were originally intended only for relaying programs-both television and radio-to feed network afflicted stations or cable systems across the country. The television industry never expected anyone else to install the 8 foot diameter dishes necessary to eavesdrop on the signals from satellite transmitting in the C band. But many people did, in large part because all the satellite channels were originally available without subscription fees.

Today most of the programs sent via satellite are scrambled, with subscription fees similar to or even less than cable TV. Nevertheless people living in areas not served by either broadcast or cable TV or wanting more programming choices continue to use satellite dishes. In fact, some surveys show that satellite television systems are drawing as many as a million people a year away from cable. The main reasons are that satellite TV service can offer highly quality audio and video, plus significantly broader programming choices.

SATELLITE TV BANDWIDTH: ANALOG

A transponder abroad a satellite can broadcast TV either analog or digital form. The analog TV is sent in FM modulation rather than the AM modulation of terrestrial TV. FM modulation eliminates interference with adjacent ant satellites (remember that FM receives lock onto the transmitted signal), but does use more bandwidth than an AM TV signal. An analog transponder in the C band typically has a spectrum bandwidth of 36 MHz, with the entire bandwidth being given to the TV signal. Some C band transponders send a half-bandwidth (18MHz), lower quality TV signal. In the Ku band, transponders use mainly 42-MHz bandwidths for TV broadcasting. A Ku transponder may also have 27-,54-,72-, and 108- MHz bandwidths; these typically handle data, but they can also be used for digital television signals.Satellite TV service providers are using ku band instead of C band.

SATELLITE TV BANDWIDTH: DIGITAL

In digital mode, a 42-MHz bandwidth Ku band transponder can send a 23-Mbps data stream 9after forward error correction), enough to support either four to six NTSC quality television programs or one high-definition television program. The most popular Ku band services such as the DSS broadcasts, Send fully digital TV signals, the first consumer application of true digital television.

The attraction of switching from an analog to a digital signal for satellite television should be obvious; a single transponder generally supports a single channel of analog television, although some transponders can send two channels. But using digital enables either four to six channels for NTSC-quality television or one high definition channel.

And that’s even before you factor in the flexibility of being able to use the digital signal for other types of information. For instance, Hughes offers the DirecPC Internet Service, which provides up to 400 JKbps of incoming bandwidths, received by 21 inch dish that can also receive satellite television. Of course, because consumers have no way of transmitting back to the satellite, a standard telephone line and modern provide the outgoing bandwidth.