DTH (Direct to Home)

8/7/2019 DTH (Direct to Home)

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DTH (Direct to Home)



Presented by:



What Is DTH

�The Direct-To-Home (DTH) service is a digital satellite service that provides televisionservices direct to subscribers anywhere in the

country.�Since it makes use of wireless technology,progr ams are sent to the subscriber'stelevision direct from the satellite, eliminatingthe need for cables and any cableinfr astructure.

�This is particular ly valuable in remote anddifficult to reach areas where cable and inmany cases, terrestrial television services arepoor or non existent.



Problems with Broadcast TV or

Need for DTH� Conceptually, DTH(satellite TV) is a lot like

broadcast TV

� The main limitation of broadcast TV is r ange.

The r adio signals used to broadcast televisionshoot out from the broadcast antenna in a str aight line. In order to receive these signals,you have to be in the direct line of sight of theantenn

a.� The other problem with broadcast TV is that the

signal is often distorted, even in the viewingarea.



The DTH Solution

� DTH solves the problems of r ange anddistortion by tr ansmitting broadcast signalsfrom satellites orbiting the Earth.

� Since satellites are high in the sky, thereare a lot more customers in the line of

sigh

t. DTH systems tr a

nsmita

nd receiver adio signals using specialized antennascalled satellite dishes.



Satellites are higher in the sky than TV antennas,

so they have a much larger line of sight r ange.



Satellites Used by DTH providers

� The TV satellites are all in geosynchronous orbit,

meaning that they stay in one place in the sky

relative to the Earth.

� The satellite keeps pace with our moving planet

exactly. This way, you only have to direct the

dish at the s

atellite once,

and from t

hen on itpicks up the signal without adjustment,



Direct broadcast satellite (DBS)

provider [DishTV,T

ataSky]� The provider selects progr ams and broadcasts

them to subscribers as a set package. Basically,the provider's goal is to bring dozens or evenhundreds of channels to your TV.

� Unlike ear lier progr amming, the provider'sbroadcast is completely digital, which means ithas much better picture and sound quality .Ear ly satellite television was broadcast in C-

band r

adio(3.7-gig

ahertz (GHz) to 6.4-GHzfrequency r ange). Digital broadcast satellite

tr ansmits progr amming in the Ku frequencyr ange (11.7 GHz to 14.5 GHz ).



The Components of DTH

� There are five ma jor components involved in a direct to home (DTH) or direct broadcasting (DBS) satellite system: the progr amming source, thebroadcast center, the satellite, the satellite dish and the receiver.

1. Progr amming sources are simply the channels that provide progr amming for broadcast. The provider doesn't create original progr amming itself; it paysother companies (HBO, for example, or ESPN) for the right to broadcasttheir content via satellite. In this way, the provider is kind of like a broker between you and the actual progr amming sources. (Cable TV companieswor k on the same principle.)

2. The broadcast center is the centr al hub of the system. At the broadcastcenter, the TV provider receives signals from various progr amming sources

and beams a broadcast signal to satellites in geosynchronous orbit.



The Components of DTH(contd.)

3. The satellites receive the signals from the broadcaststation and rebroadcast them to Earth.

4. The viewer's dish picks up the signal from the satellite(or multiple satellites in the same part of the sky) andpasses it on to the receiver in the viewer's house.

5. The receiver processes the signal and passes it on to a standard TV.



Satellite TV Progr amming

� Satellite TV providers get progr amming from two ma jor sources: national turnaround channels (such as HBO,ESPN and CNN) and various local channels (the ABC,CBS, Fox, NBC and PBS affiliates in a particular area).

Most of the turnaround channels also provideprogr amming for cable TV, and the local channelstypically broadcast their progr amming over the airwaves.

� Turnaround channels usually have a distribution center that beams their progr amming to a geosynchronoussatellite. The broadcast center uses large satellite dishesto pick up these analog and digital signals from sever al sources.



Satellite Progr amming(contd.)

� The broadcast center converts all of this progr amming

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 tr ansmit the signal from there, the broadcast

center has to compress it. Otherwise, it would be too big

for the satellite to handle. In the next section, we'll find

out how the signal is compressed.



Satellite TV Signal

� Satellite signals have a pretty long path to follow before they appear

on your TV screen in the form of your f avorite TV show. Because

satellite signals contain such high-quality digital data, it would be

impossible to tr ansmit them without compression. Compression

simply means that unnecessary or repetitive information is removedfrom the signal before it is tr ansmitted. The signal is reconstructed

after tr ansmission.

� 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 tr ansmit significantly

more channels. There are currently five of these MPEG standards,

each serving a different purpose.



Compression used

� First MPEG-2, which is still used to store movies onDVDs and for digital cable television (DTV). With MPEG-2, the TV provider can reduce the 270-Mbps stream toabout 5 or 10 Mbps (depending on the type of progr amming).

� MPEG-4 can encode more efficiently and provide a greater bandwidth than MPEG-2. MPEG-2 remains theofficial standard for digital TV compression, but it isbetter equipped to analyze static images, like those yousee on a talk show or newscast, than moving, dynamic

images.



Satellite TV Encoding and

Encryption� At the broadcast center, the high-quality digital stream of video goes through

an MPEG encoder, which converts the progr amming to MPEG-4 video of thecorrect size and format for the satellite receiver in your house.

� Encoding wor ks in conjunction with compression to analyze each videofr ame and eliminate redundant or irrelevant data and extr apolate informationfrom other fr ames. This process reduces the over all size of the file. Each fr ame can be encoded in one of three ways:

As an intr afr ame, which contains the complete image data for that fr ame.This method provides the least compression.

As a predicted fr ame, which contains just enough information to tell thesatellite receiver how to display the fr ame based on the most recentlydisplayed intr afr ame or predicted fr ame. A predicted fr ame contains onlydata that explains how the picture has changed from the previous fr ame.

As a bidirectional fr ame, which displays information from the surroundingintr afr ame or predicted fr ames. Using data from the closest surroundingfr ames, the receiver interpolates the position and color of each pixel.



Encryption and Tr ansmission

� After the video is compressed, the provider encrypts it tokeep people from accessing it for free. Encryptionscr ambles the digital data in such a way that it can onlybe decrypted (converted back into usable data) if the

receiver has the correct decryption algorithm andsecurity keys.

� Once the signal is compressed and encrypted, thebroadcast center 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 thesignal back to Earth, where viewers can pick it up.



Satellite Dish

� When the signal reaches theviewer's house, it is capturedby the satellite dish. A satellitedish is just a special kind of antenna designed to focus on

a specific broadcast source.The standard dish consists of a par abolic (bowl-shaped)surf ace and a centr al feedhorn. To tr ansmit a signal, a controller sends it through the

horn, and the dish focuses thesignal into a relatively narrowbeam.



� The end component in the entire satellite TV system isthe receiver. The receiver has four essential jobs:

� * It de-scr ambles the encrypted signal. In order to

unlock the signal, the receiver needs the proper decoder chip for that progr amming package. The provider cancommunicate with the chip, via the satellite signal, tomake necessary adjustments to its decoding progr ams.The provider may occasionally send signals that disruptillegal de-scr amblers as an electronic counter measure

(ECM) against illegal users.� * It takes the digital MPEG-2 or MPEG-4 signal and

converts it into an analog format that a standardtelevision can recognize.



Satellite Receiver

� The end component in the entire satellite TV system is the receiver.The receiver has four essential jobs:

� It de-scr ambles the encrypted signal. In order to unlock the signal,the receiver needs the proper decoder chip for that progr amming

package. The provider can communicate with the chip, via thesatellite signal, to make necessary adjustments to its decodingprogr ams. The provider may occasionally send signals that disruptillegal de-scr amblers as an electronic counter measure (ECM)against illegal users.

� It takes the digital MPEG-2 or MPEG-4 signal and converts it into ananalog format that a standard television can recognize. In the UnitedStates, receivers convert the digital signal to the analog National Television Systems Committee (NTSC) format. Some dish andreceiver setups can also output an HDTV signal.



Satellite Receiver (contd.)

� It extr acts the individual channels from the larger satellite signal.When you change the channel on the receiver, it sends just thesignal for that channel to your TV. Since the receiver spits out onlyone channel at a time, you can't tape one progr am and watch another. You also can't watch two different progr ams on two TVshooked up to the same receiver. In order to do these things, which are standard on conventional cable, you need to buy an additional receiver.

� It keeps tr ack of pay-per-view progr ams and periodically phones a computer at the provider's headquarters to communicate billinginformation.

� Receivers have a number of other features as well. They pick up a

progr amming schedule signal from the provider and present thisinformation in an onscreen progr amming guide. Many receivershave parental lock-out options, and some have built-in digital videorecorders (DVRs), which let you pause live television or record it ona hard drive.



Cable: Satellite's Biggest

Contender � With emerging technologies in each service, the hardest decision in TV

viewing is no longer just what channel to watch -- it's what service tochoose.

� Cable advantages: Advancements in digital cable provide improved audioand picture quality with additional channels at a lower cost than satellite.

You can also access cable channels from multiple rooms in your housef air ly easily.

� Cable disadvantages: Cable has limited access in rur al areas, and youshould prepare for increased service costs as your provider updates itsequipment. Your service costs are also subject to local taxes.

� Satellite advantages: Satellite offers movie-quality audio and picture displaywith hundreds of channels. This service is readily available in rur al and

urban areas and provides access to more digital and high definitionprogr amming.

� Satellite disadvantages: It is expensive to purchase all the equipment at theoutset (and you can't typically rent it). If you want to access satellite TV inmultiple rooms, be prepared for extr a fees. Also, satellite TV is subject toweather-related malfunctions.



Thank You

DTH (Direct to Home)

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