A REPORT ON “BROADCASTING” Submitted in Partial fulfillment for the Award of the Degree of Bachelor of technology in INFORMATION TECHNOLOGY Session : 2012-2013Submitted To: Submitted by:Mr.Nitin Gupta Komal ChoudharyLecturer IT Department VII Semester,IT DEPARTMENT OF INFORMATION TECHNOLOGY JECRC UDML COLLEGE OF ENGINEERING VIA- Nangal Susamata, Dhab Ka Nala, Chimanpura,kukas JAIPUR-DELHI Road, JAIPUR – 302028
WHAT DOES IT MEAN ?????Broadcasting is the distribution of audio and video content to adispersed audience via any audio or visual mass communicationmedium, but usually one using electromagnetic radiation (radiowaves). The receiving parties may include the general public ora relatively large subset thereof. Broadcasting has been used forpurposes of private recreation, non-commercial exchange ofmessages, experimentation, self-training, and emergencycommunication such as amateur (ham) radio and amateurtelevision (ATV) in addition to commercial purposes likepopular radio or TV stations with advertisements.Or simply defining:To simultaneously send the same message to multiple recipients.Broadcasting is a useful feature in e-mail systems. It isalso supported by some fax systems.In networking, a distinction is made between broadcasting andmulticasting. Broadcasting sends a message to everyone on thenetwork whereas multicasting sends a message to a select list ofrecipients.
HISTORY OF BROADCASTINGThe ancient Greeks were the first to experiment with alternative(i.e. other than sending a messenger) methods of transmittinginformation over long distances. These early transmissionsinvolved the tops of hills, and fire by night, plus columns ofsmoke or large mirrors by day. This principle did not evolvevery far until the 19th century, when experiments began totransmit messages via a series of electrical clicks on wires. Thusthe telegraph system was born, laying the foundations for thebroadcast of the human voice and other noises.The first documented radio transmission occurred in 1895 andwas sent by a 21 year old Italian, Guglielmo Marconi, whoconducted simple experiments using a radio transmitter andreceiver, the transmitter placed at his house, and the receiverplaced three miles away. He got his servant to fire a gun whenthe transmission had been received - the three dots ··· of theletter S in Morse Code. The Italian government were not at allinterested in Marconis invention, so he continued hisexperiments in Britain where he had the full support of theMinister of Post. Marconi (who had never been to university andhad taught himself physics and electronics!) took out severalpatents and started to build radio stations across the south coastof Britain. In late 1901 he crossed the Atlantic to St JohnsTerranova, and there, on 12 December, received the first weaktransatlantic radio signal, another ···.
TYPES OF BROADCASTINGHistorically, there have been several different types of electronicmedia broadcasting: Telephone broadcasting (1881–1932): the earliest form of electronic broadcasting (not counting data services offered by stock telegraph companies from 1867, if ticker-tapes are excluded from the definition). Telephone broadcasting began with the advent of Théâtrophone ("Theatre Phone") systems, which were telephone-based distribution systems allowing subscribers to listen to live opera and theatre performances over telephone lines, created by French inventor Clément Ader in 1881. Telephone broadcasting also grew to include telephone newspaper services for news and entertainment programming which were introduced in the 1890s, primarily located in large European cities. These telephone-based subscription services were the first examples of electrical/electronic broadcasting and offered a wide variety of programming. Radio broadcasting (experimentally from 1906, commercially from 1920): radio broadcasting is an audio (sound) broadcasting service, broadcast through the air as radio waves from a transmitter to a radio antenna and, thus, to a receiver. Stations can be linked in radio networks to broadcast common radio programs, either in broadcast syndication, simulcast or subchannels. History of television broadcasting (telecast), experimentally from 1925, commercial television from the 1930s: this television programming medium was long-awaited by the
general public and rapidly rose to compete with its older radio-broadcasting sibling. Cable radio (also called "cable FM", from 1928) and cable television (from 1932): both via coaxial cable, serving principally as transmission mediums for programming produced at either radio or television stations, with limited production of cable-dedicated programming. Direct-broadcast satellite (DBS) (from circa 1974) and satellite radio (from circa 1990): meant for direct-to- home broadcast programming (as opposed to studio network uplinks and downlinks), provides a mix of traditional radio or television broadcast programming, or both, with dedicated satellite radio programming. (See also: Satellite television) Webcasting of video/television (from circa 1993) and audio/radio (from circa 1994) streams: offers a mix of traditional radio and television station broadcast programming with dedicated internet radio-webcast programming.
SATELLITE .As the satellites orbit the earth, programs are beamed to them from broadcast stations.The satellites then transmit the signal to special antennas on homes, cars and portableradios. Terrestrial repeaters throughout the country also receive the signal and helpensure that its transmitted to receivers, especially in areas with tall buildings that mightblock the signal
ROLE OF A SATELLITE. A satellite broadcast is the distribution of video content over asatellite network. The audio and video signals are acquired at theorigination point and transmitted through anuplink truck to ageo-synchronous satellite. The orbiting satellite re-transmits thesignal to a predetermined geographical area over an "open" orsecure channel. Small, inexpensive "downlinks" receive thesignal and display the content on television monitorsLIVE BROADCAST:Satellites play important role in live broadcasting these days oneof them is DBS.Direct broadcast satellite (DBS) is a term usedto refer to satellite television broadcasts intended for homereception.A designation broader than DBS would be direct-to-home signals, or DTH. This has initially distinguished thetransmissions directly intended for home viewers from cabletelevision distribution services that sometimes carried on thesame satellite. The term DTH predates DBS and is often used inreference to services carried by lower power satellites whichrequired larger dishes (1.7m diameter or greater) for reception.
LIVE BROADCASTINGA live broadcast generally refers to various types of mediabroadcast without a significant delay.It could refer to: Live radio Live television Internet television Internet radio Live blogging Streaming media
LIVE RADIO:Live radio is radio broadcast without delay. Before the daysof television, audiences listened to live dramas, comedies, quizshows, and concerts on the radio much the same way that theynow do on TV. Most talk radio is live radio where people canspeak (anonymously) about their opinions/livesLIVE TELEVISION:Live television refers to a television production broadcast inreal-time, as events happen, in the present. From the early daysof television until about 1958, live television was used heavily,except for filmed shows such as I LoveLucy and Gunsmoke. Videotape did not exist until1957. Television networks provide most live television mostlyfor morning shows with television programs suchas: Today, Good Morning America & CBS This Morning inthe US (albeit...only airing live in the Eastern Time Zone),and Daybreak, BBC Breakfast, This Morning, etc. in the UK.
INTERNET TELEVISION:Internet television (otherwise known as InternetTV, or Online TV) is the digitaldistribution of television content via the Internet. Itshould not be confused with Web television - shortprograms or videos created by a wide variety ofcompanies and individuals, or Internet protocoltelevision (IPTV) - an emerging internet technologystandard for use by television broadcasters. SomeInternet television is known as catch-up TV. InternetTelevision is a general term that covers the delivery oftelevision shows and other video content over theinternet by video streaming technology, typically bymajor traditional television broadcasters. It does notdescribe a technology used to deliver content(see Internet protocol television).Internet televisionallows the users to choose the content or the televisionshow they want to watch from an archive of contentor from a channel directory. The two forms ofviewing Internet television are streaming the contentdirectly to a media player or simply downloading themedia to the users computer. With the "TV onDemand" market growing, these on-demand websitesor applications are essential for major televisionbroadcasters.
INTERNET RADIO:Internet radio (also web radio, net radio, streaming radio, e-radio webcasting) is an audio service transmitted viathe Internet. Music streaming on the Internet is usually referredto as webcasting since it is not transmitted broadly throughwireless means.Internet radio involves streaming media, presenting listenerswith a continuous stream of audio that cannot be paused orreplayed, much like traditional broadcast media; in this respect,it is distinct from on-demand file serving. Internet radio is alsodistinct from podcasting, which involves downloadingratherthan streaming. Many Internet radio services are associated witha corresponding traditional (terrestrial) radio station or radionetwork. Internet-only radio stations are independent of suchassociations.Internet radio services are usually accessible from anywhere inthe world—for example, one could listen to an Australian stationfrom Europe or America. Some major networks like CBSRadio and Citadel Broadcasting (except for news/talk and sportsstations) in the US, and Chrysalis in the UK restrict listening toin-country because of music licensing and advertisingconcerns. Internet radio remains popular among expatriates andlisteners with interests that are often not adequately served bylocal radio stations (such as eurodance, progressiverock, ambient music, folk music,classical music, and stand-upcomedy). Internet radio services offer news, sports, talk, andvarious genres of music—every format that is available ontraditional radio stations.
LIVE BLOGGING:A liveblog is a blog post which is intended to providea rolling textual coverage of an ongoing event, similarto Live television or live radio. Liveblogging hasincreased in usage by news organizations andblogging establishments since the mid-2000s, whenthey were initially used to broadcast updates oftechnology conferences in the absence of or alongsidestreaming video captures, and like microblogs, havegained currency as an online publication format whichperforms the same function as that of live televisionnews coverage.A live blog is a single post which iscontinuously updated with timestamped micro-updates which are placed above previous micro-updates. During liveblogs, a wide number of media,including video, audio, images and text, can beincorporated in order to explain what is going on at aspecific location. Such content may be posted fromexternal sources, such as other press agencies andnon-employees.
STREAMING MEDIA:Streaming media is multimedia that is constantly received byand presented to an end-user while being delivered by aprovider. Its verb form, "to stream", refers to the process ofdelivering media in this manner; the term refers to the deliverymethod of the medium rather than the medium itself.A client media player can begin playing the data (such as amovie) before the entire file has been transmitted.Distinguishing delivery method from the media distributedapplies specifically to telecommunications networks, as mostother delivery systems are either inherently streaming(e.g., radio, television) or inherently non-streaming(e.g., books, video cassettes, audio CDs). For example, in the1930s, muzak was among the earliest popularly availablestreaming media; nowadays Internet television is a commonform of streamed media. The term "streaming media" can applyto media other than video and audio such as live closedcaptioning, stock ticker, and real-time text, which are allconsidered "streaming text".Live streaming, delivering live over the Internet, involves acamera for the media, an encoder to digitize the content, a mediapublisher, and a content delivery network to distribute anddeliver the content.
DIGITAL AUDIO BROADCASTINGDAB had been under development since 80’s and Eureka 147(European standard) was established for developing DABstandard.Conventional sound broadcasting employs analoguetransmission technology using the Very HighFrequency/Frequency Modulation (VHF/FM) and MediumFrequency/Amplitude Modulation (MF/AM). While this modeof transmission has been used to provide terrestrial soundbroadcasting services for decades and will continue to be used infuture, it has inherent technical limitations, such as the relativelyinefficient use of radio spectrum and susceptibility tointerference.Digital audio broadcasting is a new way of transmitting soundand data addressing the limitations of analogue broadcasting.Sound and information including text and images are processedelectronically and converted into digital format.
WORKING OF DAB TRANSMITTERTransmission of a DAB Signal:Each signal is coded individually at source level, error protectedand time interleaved in the source encoder. The signals are thendigitized and compressed using MUSICAM compressionformat. Multiplexing will then begin in the Main ServiceChannel (MSC). It uses time division multiplexing to operate atthe rates of 2048 B/Sec consisting of 24, 48 or 96mstransmission frames (DAB Modes I, II, III and IV). For yourinformation, our present transmission in Singapore is in DABmode I. The output is combined with Multiplex Control andService information, which travel in the fast InformationChannel (FIC), to form the transmission frames in themultiplexer. Orthogonal Frequency Division Multiplexing(OFDM) is applied to shape the DAB signal. FFT is performedand the resultant coded data is sent to the DAC which creates themodulated analog IF signal. The signal is then upconverted,amplified and transmitted.
WORKING OF DAB RECEIVER:Reception of a DAB signalThe DAB ensemble is selected in the analogue tuner, the outputis fed to the demodulator and channel decoder to eliminatetransmission errors. The information contained in the FIC ispassed to the user interface for selection and is used to set up thereceiver appropriately. Resulting in the desired output (whateverthat may be).BENEFITS OF DAB:Improved features for usersDAB radios automatically tune to all the available stations,offering a list for the user to select from.DAB can carry "radiotext" (in DAB terminology, DynamicLabel Segment, or DLS) from the station giving real-timeinformation such as song titles, music type and news or trafficupdates. Advance programme guides can also be transmitted. Asimilar feature also exists on FM in the form of the RDS.(However, not all FM receivers allow radio stations to be storedby name.)DAB receivers can display time of day as encoded intotransmissions, so is automatically corrected when travellingbetween time zones and when changing to or from DaylightSaving. This is not implemented on all receivers, and somedisplay time only when in "Standby" mode.Some radios offer a pause facility on live broadcasts, cachingthe broadcast stream on local flash memory, although thisfunction is limited.
More stationsDAB is not more bandwidth efficient than analogue measured inprogrammes per MHz of a specific transmitter (the so called linkspectral efficiency). However, it is less susceptible to co-channelinterference (cross talk), which makes it possible to reducethe reuse distance, i.e. use the same radio frequency channelmore densely. The system spectral efficiency (the averagenumber of radio programmes per MHz and transmitter) is afactor three more efficient than analog FM for local radiostations, as can be seen in the above numerical example. Fornational and regional radio networks, the efficiency is improvedby more than an order of magnitude due to the use of SFNs. Inthat case, adjacent transmitters use the same frequency.In certain areas — particularly rural areas — the introduction ofDAB gives radio listeners a greater choice of radio stations. Forinstance, in South Norway, radio listeners experienced anincrease in available stations from 6 to 21 when DAB wasintroduced in November 2006.Reception qualityThe DAB standard integrates features to reduce the negativeconsequences of multipath fading and signal noise, which afflictexisting analogue systems.Also, as DAB transmits digital audio, there is no hiss with aweak signal, which can happen on FM. However, radios in thefringe of a DAB signal, can experience a "bubbling mud" soundinterrupting the audio and/or the audio cutting out altogether.Due to sensitivity to doppler shift in combination with multipathpropagation, DAB reception range (but not audio quality) is
reduced when traveling speeds of more than 120 to 200 km/h,depending on carrier frequency.Less pirate interferenceThe specialised nature and cost of DAB broadcasting equipmentprovide barriers to pirate radio stations broadcasting on DAB. Incities such as London with large numbers of pirate radio stationsbroadcasting on FM, this means that some stations can bereliably received via DAB in areas where they are regularlydifficult or impossible to receive on FM due to pirate radiointerference.Variable bandwidthMono talk radio, news and weather channels and other non-music programs need significantly less bandwidth than a typicalmusic radio station, which allows DAB to carry theseprogrammes at lower bit rates, leaving more bandwidth to beused for other programs.However, this had led to the situation where some stations arebeing broadcast in mono, see music radio stations broadcastingin mono for more details.Transmission costsIt is common belief that DAB is more expensive to transmit thanFM. It is true that DAB uses higher frequencies than FM andtherefore there is a need to compensate with more transmitters,higher radiated powers, or a combination, to achieve the samecoverage. A DAB network is also more expensive than an FMnetwork. However, the last couple of years has seen significantimprovement in power efficiency for DAB-transmitters.This efficiency originates from the ability a DAB network has inbroadcasting more channels per network. One network can
broadcast 6-10 channels (with MPEG audio codec) or 10-16channels (with HE AAC codec). Hence, it is thought that thereplacement of FM-radios and FM-transmitters with new DAB-radios and DAB-transmitters will not cost any more as opposedto newer FM facilities.Cheaper transmission costs is backed by independent networkstudies from Teracom (Sweden) and SSR/SRG(Switzerland). Among other things they show that DAB is up to6 times less expensive than FM.DISADVANTAGES OF DAB:Reception qualityThe reception quality on DAB can be poor even for people thatlive well within the coverage area. The reason for this is that theold version of DAB uses weak error correction coding, so thatwhen there are a lot of errors with the received data not enoughof the errors can be corrected and a "bubbling mud" soundoccurs. In some cases a complete loss of signal can happen. Thissituation will be improved upon in the new DAB standard(DAB+, discussed below) that uses stronger error correctioncoding and as additional transmitters are built.Audio QualityBroadcasters have been criticized for ‘squeezing in’ morestations per ensemble than recommended by: Minimizing the bit-rate, to the lowest level of sound-quality that listeners are willing to tolerate, such as 128 kbit/s for stereo and even 64 kbit/s for mono speech radio.
Having few digital channels broadcasting in stereo.Signal delayThe nature of a SFN is such that the transmitters in a networkmust broadcast the same signal at the same time. To achievesynchronization, the broadcaster must counter any differences inpropagation time incurred by the different methods anddistances involved in carrying the signal from the multiplexer tothe different transmitters. This is done by applying a delay to theincoming signal at the transmitter based on a timestampgenerated at the multiplexer, created taking into account themaximum likely propagation time, with a generous addedmargin for safety. Delays in the receiver due to digitalprocessing (e.g. de-interleaving) add to the overall delayperceived by the listener. The signal is delayed by 2–4 secondsdepending on the decoding circuitry used. This hasdisadvantages: DAB radios are out of step with live events, so the experience of listening to live commentaries on events being watched is impaired; Listeners using a combination of analog (AM or FM) and DAB radios (e.g. in different rooms of a house) will hear a confusing mixture when both receivers are within earshot.Time signals, on the contrary, are not a problem in a well-defined network with a fixed delay. The DAB multiplexer addsthe proper offset to the distributed time information. The timeinformation is also independent from the (possibly varying)audio decoding delay in receivers since the time is notembedded inside the audio frames. This means that built inclocks in receivers will be spot on.
CoverageAs DAB is at a relatively early stage of deployment, DABcoverage is poor in nearly all countries in comparison to thehigh population coverage provided by FM.CompatibilityIn 2006 tests began using the much improved HE-AAC codecfor DAB+. Virtually none of the receivers made before 2008support the new codec, however, thus making them partiallyobsolete once DAB+ broadcasts begin and completely obsoleteonce the old MPEG-1 Layer 2 stations are switched off. Newreceivers are both DAB and DAB+ compatible; however, theissue is exacerbated by some manufacturers disabling the DAB+features on otherwise compatible radios to save on licensing feeswhen sold in countries without current DAB+ broadcasts.Power requirementsAs DAB requires digital signal processing techniques to convertfrom the received digitally encoded signal to the analogue audiocontent, the complexity of the electronic circuitry required to dothis is high. This translates into needing more power to effectthis conversion than compared to an analogue FM to audioconversion, meaning that portable receiving equipment will tendto have a shorter battery life, or require higher power (and hencemore bulk). This means that they use more energy than analogueBand II VHF receivers.As an indicator of this increased power consumption, some radiomanaufacturers quote the length of time their receivers can playon a single charge. For a commonly used FM/DAB-receiverfrom manufacturer PURE, this is stated as: DAB 10 hours, FM22 hours.
Use of Licensed CodeThe use of MPEG previously and later AAC has promptedcriticism of the fact that a (large) public system is financiallysupporting a private company. In general, an open system willpermit equipment to be bought from various sources incompetition with each other but by selecting a single vendor ofcodec, with which all equipment must be compatible, this is notpossible.
DIGITAL VIDEO BROADCASTINGDigital Video Broadcasting (DVB) is a set of standards thatdefine digital broadcasting using existing satellite, cable, andterrestrial infrastructures. DVB-compliant digitalbroadcasting and equipment is widely available and isdistinguished by the DVB logo. Numerous DVB broadcastservices are available in Europe, North and South America,Africa, Asia, and Australia. The term digital television issometimes used as a synonym for DVB.The Digital Video Broadcasting Project (DVB) is anindustry-led consortium of over 270 broadcasters,manufacturers, network operators, software developers,regulatory bodies and others in over 35 countries committedto designing open technical standards for the global deliveryof digital television and data services. Services using DVBstandards are available on every continent with more than220 million DVB receivers deployed.As a transmission scheme, Digital Video Broadcasting(DVB) is based on the MPEG-2 video compression /transmission scheme and utilizing the standard MPEG-2Transmission scheme. It is however much more than a simplereplacement for existing analogue television transmission. Inthe first case, DVB provides superior picture quality with theopportunity to view pictures in standard format or widescreen (16:9) format, along with mono, stereo or surroundsound. It also allows a range of new features and servicesincluding subtitling, multiple audio tracks, interactivecontent, multimedia content – where, for instance,programmers may be linked to world wide web material.
DVB FOR HIGH SPEED INTERNET ACCESS:Digital Video Broadcasting (DVB) provides the opportunity forhigh-speed Internet delivery direct to users homes and offices.Most applications require full duplex communication, and thereturn path from the user to the Internet will be provided usinglower speed terrestrial connections. Two challenges arepresented when using DVB for high-speed Internet access: thepoor performance of TCP over network paths with a highbandwidth delay product (LFN) and the impact of asymmetricnetwork paths. The second effect is most significant and resultsin a problem, which we have termed "ACK congestion". Theperformance of TCP using a DVB satellite link is analysedthrough simulation and a set of techniques is proposed whichprovide significant improvement. 1 Introduction The growinguse of multimedia-capable personnel computers to access theInternet and in particular, the use of world wide web, hasresulted in a growing demand for Internet bandwidth.