This article will serve as a kind of glossary on satellite tv. It will be a handy reference for all beginners who wish to learn more about satellite tv. The article will cover the scope, strength and the operations of satellite tv as well as differences between satellite tv and broadcast tv. You will also be introduced to the equipment needed to receive satellite tv channels. All these shall be discussed in details.
Introduction: The satellite tv first hit the market in the early 1990s. Then everything was huge, heavy and expensive. Only the rich or die hard fans can afford it. Apart from the huge capital outlay involved in buying the necessary equipment, you also have to go through the hassle of setting it up. Way back satellite tv is harder to get than cable tv or broadcast tv. Nowadays, broadcast tv is phasing out while you can see a satellite dish on the rooftops of vaitually every home.
Though satellite TV technology is still evolving, it has already become a popular choice for many TV viewers.
Definition of Satellite Tv and its distinction from broadcast and cable tv
A satellite TV is a lot like broadcast TV conceptually. It’s a wireless system for delivering television programming directly to a viewer’s house. Both broadcast television and satellite stations transmit programming via a radio signal
NOTE: Early satellite TV viewers who used C-band radio for their broadcasts were able to catch wild feeds of syndicated programs, sporting events and news. These broadcasts were free, but viewers had to hunt them down — they didn’t get previewed or listed like regular broadcast programming. These signals still exist, and Satellite Orbit magazine publishes a list of today’s wild feeds.
However, broadcast stations use a powerful antenna to transmit radio waves to the surrounding area. Viewers can pick up the signal with a much smaller internal or external antenna. The main limitation of broadcast TV is the range. The radio signals used to broadcast television shoot out from the broadcast antenna in a straight line. In order to receive these signals, you have to be in the direct line of sight of the antenna. Small obstacles like trees or small buildings aren’t a problem; but a big obstacle, such as the Earth, will reflect these radio waves. Now the earth is not flat. If the earth were to be flat, you would have been able to pick a signal of one country in another. But, the earth is curved or let me say spherical and therefore, basic obstacles interfere with the signals and this eventually breaks the signal’s line of sight This constitutes the first problem of a broadcast TV. The second problem associated with a broadcast tv is that of signal distortion. Even for those close to the source, you can still notice some waves, noise or audio failure while enjoying your channels.
HOW SATELLITE TV HAS BEEN ABLE TO SOLVE BROADCAST TV PROBLEMS
Satellite TV solves the problems of range and distortion by transmitting broadcast signals from satellites orbiting the Earth. Since satellites are high in the sky, there are a lot more customers in the line of sight. Satellite TV systems transmit and receive radio signals using specialized antennas called satellite dishes
Early satellite TV viewers used their expensive dishes to discover unique programming that wasn’t necessarily intended for mass audiences. The dish and receiving equipment gave viewers the tools to pick up foreign stations live feeds between different broadcast stations, and a lot of other stuff transmitted using satellites.
Today, most satellite TV customers get their programming through a direct broadcast satellite (DBS) provider, such as DirecTV or DISH Network. The provider selects programs and broadcasts them to subscribers as a set package(examples of these are DSTV, Canal, bein, skytv, fox and so on). Basically, the provider’s goal is to bring dozens or even hundreds of channels to your TV in a form that approximates the competition, cable TV.
Unlike earlier programming, the provider’s broadcast is completely digital, which means it has a much better picture and sound quality. Early satellite television was broadcast in C-band radio — radio in the 3.7-gigahertz (GHz) to 6.4-GHz frequency range. Digital broadcast satellite transmits programming in the Ku frequency range (11.7 GHz to 14.5 GHz ).
MAJOR COMPONENTS OF SATELLITE TV.
There are five major components involved in a direct to home (DTH) or direct broadcasting (DBS) satellite TV system: the programming source, the broadcast center, the satellite, the satellite dish and the receiver.
- Programming sources are simply the channels that provide programming for broadcast. The provider doesn’t create original programming itself; it pays other companies (HBO, for example, or ESPNr SKY) for the right to broadcast their content via satellite. In this way, the provider is kind of like a broker between you and the actual programming sources.
- The broadcast center is the central hub of the system. At the broadcast center, the TV provider receives signals from various programming sources and beams a broadcast signal to satellites in geosynchronous orbit.
- The satellites receive the signals from the broadcast station and rebroadcast them to Earth.
- The viewer’s dish picks up the signal from the satellite (or multiple satellites in the same part of the sky) and passes it on to the receiver in the viewer’s house.
- The receiver processes the signal and passes it on to a standard TV.
CABLE TV VS SATELLITE TV THE COMPARISON
- Cable advantages: Advancements in digital cable provide improved audio and picture quality with additional channels at a lower cost than satellite. You can also access cable channels from multiple rooms in your house fairly easily.
- Cable disadvantages: Cable has limited access in rural areas, and you should prepare for increased service costs as your provider updates its equipment. Your service costs are also subject to local taxes.
- Satellite advantages: Satellite offers movie-quality audio and picture display with hundreds of channels. This service is readily available in rural and urban areas and provides access to more digital and high definition programming.
- Satellite disadvantages: It is expensive to purchase all the equipment at the outset (and you can’t typically rent it). If you want to access satellite TV in multiple rooms, be prepared for extra fees. Also, satellite TV is subject to weather-related malfunctions.
SATELLITE TV SIGNALS AND THEIR COMPRESSION
There is a very long process involved before satellite tv channels appear on your TV screen in the form of your favorite TV show. Because satellite signals contain such high-quality digital data, it would be impossible to transmit them without compression. Compression simply means that unnecessary or repetitive information is removed from the signal before it is transmitted. The signal is reconstructed after transmission.
Standards of Compression
Satellite TV uses a special type of video file compression standardized by the Moving Picture Experts Group (MPEG). With MPEG compression, the provider is able to transmit significantly more channels. There are currently five of these MPEG standards, each serving a different purpose. DirecTV and DISH Network, the two major satellite TV providers once used MPEG-2, which is still used to store movies on DVDs and for digital cable television (DTV). With MPEG-2, the TV provider can reduce the 270-Mbps stream to about 5 or 10 Mbps (depending on the type of programming).
Now, DirecTV and DISH Network use MPEG-4 compression. Because MPEG-4 was originally designed for streaming video in small-screen media like computers, it can encode more efficiently and provide a greater bandwidth than MPEG-2. MPEG-2 remains the official standard for digital TV compression. MPEG-4 can produce a better picture of dynamic images through the use of spatial (space) and temporal (time) compression. This is why satellite TV using MPEG-4 compression provides a high definition of quickly-moving objects that constantly change place and direction on the screen, like in a basketball or soccer game.
HOW ARE SATELLITE TV ENCODED AND ENCRYPTED?
This is the most technical and most frustrating aspect. Hackers have though time hacking encrypted channels while we consumers wish every receivable channel is free to air. At the broadcast center, the high-quality digital stream of video goes through an MPEG encoder, which converts the programming to MPEG-4 video of the correct size and format for the satellite receiver in your house.
Encoding works in conjunction with compression to analyze each video frame and eliminate redundant or irrelevant data and extrapolate information from other frames. . Each frame can be encoded in one of three ways:
- As an intraframe, which contains the complete image data for that frame. This method provides the least compression.
- As a predicted frame, which contains just enough information to tell the satellite receiver how to display the frame based on the most recently displayed intraframe or predicted frame. A predicted frame contains only data that explains how the picture has changed from the previous frame.
- As a bidirectional frame, which displays information from the surrounding intraframe or predicted frames. Using data from the closest surrounding frames, the receiver interpolates the position and color of each pixel.
This process occasionally produces artifacts — glitches in the video image. One artifact is macroblocking, in which the fluid picture temporarily dissolves into blocks. Macroblocking is often mistakenly called pixilating, a technically incorrect term which has been accepted as slang for this annoying artifact. Graphic artists and video editors use “pixilating” more accurately to refer to the distortion of an image. There really are pixels on your TV screen, but they’re too small for your human eye to perceive them individually — they’re tiny squares of video data that make up the image you see. (
The rate of compression depends on the nature of the programming. If the encoder is converting a newscast, it can use a lot more predicted frames because most of the scene stays the same from one frame to the next. In more fast-paced programming, things change very quickly from one frame to the next, so the encoder has to create more intraframes. As a result, a newscast generally compresses to a smaller size than something like a car race.
Encryption and Transmission Process
After the video is compressed, the provider encrypts it 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 decryption algorithm and security keys.
Once the signal is compressed and encrypted, the broadcast centre beams it directly to one of its satellites. The satellite picks up the signal with an onboard dish, amplifies the signal and uses another dish to beam the signal back to Earth, where viewers can pick it up. next, we’ll see what happens when the signal reaches a viewer’s house.
HOW SATELLITE CHANNELS ARE RECEIVED BY USERS AT HOME
When the signal reaches the viewer’s house, it is captured by the satellite 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.
In some systems, the dish needs to pick up signals from two or more satellites at the same time. The satellites may be close enough together that a regular dish with a single horn can pick up signals from both. This compromises quality somewhat because the dish isn’t aimed directly at one or more of the satellites. A new dish design uses two or more horns or LNBs to pick up different satellite signals. As the beams from different satellites hit the curved dish, they reflect at different angles so that one beam hits one of the horns and another beam hits a different horn.
The central element in the feed horn is the low noise blockdown converter, or LNB. The LNB amplifies the radio signal bouncing off the dish and filters out the noise (radio signals not carrying programming). The LNB passes the amplified, filtered signal to the satellite receiver inside the viewer’s house.
AND FINALLY THE ROLE OF THE SATELLITE RECEIVER
The end component in the entire satellite TV system is the digital satellite receiver/ encoder. The receiver has four essential jobs:
- It de-scrambles the encrypted signal. In order to unlock the signal, the receiver needs the proper decoder chip for that programming package. The provider can communicate with the chip, via the satellite signal, to make necessary adjustments to its decoding programs. The provider may occasionally send signals that disrupt illegal de-scramblers as an electronic counter measure (ECM) against illegal users( Satellite receiver can also view free to air channels.
- It takes the digital MPEG-2 or MPEG-4 or HD signal and converts it into an analog format that a standard television can recognize. Some dish and receiver setups can also output an HDTV signal.
- It extracts the individual channels from the larger satellite signal. When you change the channel on the receiver, it sends just the signal for that channel to your TV. Since the receiver spits out only one channel at a time, you can’t tape one program and watch another. You also can’t watch two different programs on two TVs hooked up to the same receiver. In order to do these things, which are standard on conventional cable, you need to buy an additional receiver or get some other 3rd party components read more here.
- It keeps track of pay-per-view programs
Receivers have a number of other features as well. They pick up a programming schedule (EPG)signal from the provider and present this information in an onscreen programming guide. Many receivers have parental lock-out options, and some have built-in digital video recorders (DVRs / PVRs), which let you pause live television or record it on a hard drive.