aouedujouserfilesfilefile_type_pptBlock3_Par by tyndale


									T175 Networked Living

   Block3 Part2: Information
   Study session 1: Bringing the news on the back of a horse
   Study session 2: From newsreels to real news
   Study session 3: Newsgathering now
   Study session 4: Anatomy of a digital camcorder
   Study session 5: Signal transmission
   Study session 6: Trust
Study session 1: Bringing the news on the
back of a horse
    At any time before the Industrial Revolution;

        The fastest means of transport on land would
         have been a horse, so news used to travel at up
         to a few tens of kilometres an hour.
        The factor that determined how much information
         you could get about an event was how good the
         messenger‟s memory is, or they might have some
         written text to supplement their memory, either
         way, a messenger can bring quite a lot of

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Bringing the news on the back of a horse
        The number of people that could find out about an event
         depends on the spreading way;
             “word of mouth” news spreading, where one person tells two
              or three others who each tell another two or three people and
              so on. The total number of people who know the news rises
              rapidly in this way.
             “written text” news spreading, once printing has been
              invented, large numbers of copies can be produced and many
              people can read it at the same time.

        How far news can travel?
             In principle there is no limit to how far news can travel.
             In practice, only the most important news items are likely to
              get very far.

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Study session 2: From newsreels to real
    “From newsreels to real
     news” is a paper written by
     „E. V. Taylor 1995‟

    Taylor‟s paper highlights a
     number of important dates
     in the development of the
     technologies used for news-
     gathering and broadcasting.

    Taylor‟s paper describes
     these development.

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“From newsreels to real news” paper

    Main topics in Taylor‟s paper;

        Newspapers
        Radio and newsreels
        Early television
        Communications satellites
        From film to videotapes
        Into the digital era

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    Early ICTs that had an impact upon newspapers;

        The telegraph by William Cooke in 1837
        The telephone by Alexander Graham Bell in 1876.
        Lines Infrastructures, which refers to the network
         of wires connecting different places together („line‟
         as in „telephone line‟ or „transmission line‟).
        Wire picture, a method of coding an image in a
         way that allows it to be transmitted over „a wire‟.

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Radio and newsreels

    Taylor compare radio, newsreels and newspaper, as
     sources of news;

        Newsreels; cinematic way of broadcasting news which
         were a compilation of the week‟s best visual stories shot
         and made on high quality 35 mm film, but they were not
        Radio; broadcasting news as audible live reports, with no
        Newspapers; broadcasting detailed news, in which the
         reader can choose when or what to read, but they don‟t
         include sound or moving images and there is a delay „not

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Early television

    The BBC started a TV service in 1936, the quality of
     the picture was like the cinema newsreels shot on
     35mm film.
    In 1955 came the Commercial Television and the
     creation of Independent Television News (ITN).
    ITN took a controversial decision to adopt 16mm
        The wider a film, The bigger the picture and the higher the
         quality of the projected image.
        The 16mm camera was very light, more manageable and
         much more affordable to purchase and operate.
    By the end of the 1960s, colour TV was introduced.
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Communications satellites

    Communications satellites Orbit the Earth and allow
     communications by microwave links between terrestrial
     locations that are a long way apart.
    Geostationary satellite;
        It‟s orbit is a ring directly above the equator,
        It‟s about 36000 km above the ground,
        It‟s orbit time is 24 hours.
    The development of the communications satellite took place
     in the later half of 1960s, which had an impact on the
     immediacy of TV news.
    Example, Telstar I was the first communications satellite that
     allowed television signals to be sent across the Atlantic.

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From film to videotapes

    Disadvantages of film:
        There were processing delays,
        the telecine equipment needed to convert from film to
         electronic video for broadcasting was expensive and bulky,
        It could not be used for live coverage.
    In 1976, the first camcorder was introduced by the
     Radio Corporation of America (RCA) which called it
    In 1980, ITN became the first UK broadcaster to
     introduce large scale Electronic newsgathering
     (ENG) operations.

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From film to videotapes (cont.)
    Areas which did not have a wideband cable infrastructure or
     possess large expensive satellite ground stations were called
     communication dead spots.
    To satisfy the need of users in such areas, ITN formed an
     alliance with the Independent Broadcasting Authority (IBA) and
     McMichael Electronics to develop the world‟s first Satellite
     Newsgathering (SNG) the Newshawk which was first used in
    This alliance became the ITC (Independent Television
     Commission) in 1990, which in turn ceased to exist in December
     2003 when its function was taken over by the Office of
     Communications (OFCOM)

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Into the digital era

    The potential for digital computer based solutions to
     deliver high quality news programmes.

    The digital newsgathering promise:
        More efficient newsgathering.
        More options for getting the story back.
        Greater editorial freedom.
        Easier automation.
        Improved technical quality.
        Lower operating costs.

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Study session 3: Newsgathering now

3.1 Introduction to SNG and ENG Microwave

3.2 ICT processes in newsgathering

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3.1 Introduction to SNG and ENG
    This section is about an extract titles
     "Introduction to SNG and ENG Microwave"
     from a book (Higgins, 2004).
    This extract introduce an overview of the role
     of ENG/SNG.
    It explains the principal elements used by a
     TV station to get a report for broadcast.

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Basic Overview of the Role of ENG/SNG

    Television newsgathering is the process by which
     materials, i.e. pictures and sound, that help tell a
     story about a particular event are acquired and sent
     back to the studio. On arrival, they may be either
     relayed directly live to the viewer, or edited
     (packaged) for later transmission.

    The process of newsgathering involves:
        a cameraman
        a reporter
        A means of delivering the story back to the studio.
        For live coverage, voice communication from the studio
         back to the reporter at the scene of the story.

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Principal Elements in Covering an Event

1)       Cameraman for shooting and a reporter for gathering
         information and interviews.
2)       Editing the pictures and sound to form a story.
3)       Getting the story back to the studio, it can be:
           taken back in person by the reporter and/or the cameraman
           Sent back via motorbike despatch rider
           Transmitted from an ENG microwave or SNG microwave truck
4)       Going live, the reporter may actually have to do a „live‟ report
         back to the studio during the news bulletin, and this is
         accomplished by connecting the camera to the microwave link
5)       Transmission chain between the location and the studio.

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3.2 ICT processes in newsgathering

        Transmitter
             Receives from User 1 by the camera and microphone, which convert the
              image and sound to electrical signals.
             Manipulates. Editing on site is an example of manipulation.
             Send. The transmitter on the truck sends the signals via microwave.
             Stores/retrieves. the material being recorded to tape, and then retrieved to
              send back to the studio.
        Network
             Conveying the story back to the studio.
        Receiver (Equipment at the TV studio, including video servers and the
         computers used by the editors)
             Receives from network. the microwave signal (or the tapes) is received
             Manipulates. Signals manipulated if any further editing is required.
             Stores/retrieves. If the item is not being broadcast live then it will be stored
              and subsequently retrieved at the time of broadcast.

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Study session 4: Anatomy of a digital

    „Camcorder’ is a contraction of „(video) camera
     and recorder‟.
    Camcorder‟s main inputs are; light, sound and
     user‟s instructions.
    Camcorder contain embedded computer for
    Camcorder stores information on tapes or DVDs
     or memory cards.
    Camcorder uses batteries as a power source.

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4.1 Sound and light input

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Microphone & microphone input
    Transducer is a device that converts energy
     or information from one medium to another,
     ex of transducers are microphone and
    Microphone converts time-varying pressure
     “sound” to time-varying voltage or current.
    Microphone input subsystem converts
     analogue audio signal to a digital signal.
    Speakers reverses conversion.
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Lens system & CCD light sensor

    Lens system project an image onto the CCD
     light sensor.
    To ensure that the image is sharp and bright;
        a good quality glass lens
        and accurate focusing is needed.
    CCD light sensor is a transducer that
     convert light to an electrical signal.
    CCD stands for charge coupled device.

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CCD light sensor

    CCD light sensor is an integrated circuit with a transparent
    Under the cover is a rectangular array of light-sensitive
     electronic components called photosites.
    Each photosite contribute one pixel to the detected image
     by providing an analogue electrical output after measuring
     how bright the light is on that site.
    The number of pixels in the image a CCD can produce
     depends on:
        The size of the light-sensitive area.
        The number of photosites.

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CCD light sensor (cont.)
    To get colour information, coloured filters are placed in front of
     the CCD so that separate photosites measure the brightness in
     each of the three primary colours of light: red, blue and green.
    CCD input system converts analogue electrical signal to a
     digital signal.

    Complementary metal oxide semiconductor (CMOS) sensors
     could be used instead of CCDs.
    CMOS sensors and CCDs perform the same function but,
      CCDs sensors provide better image quality.

      Cameras using CMOS sensors are smaller.

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    Focusing is done by adjusting the size of the gap
     between the lens and the light sensor.
    To focus on distant object the gab has to be smaller
     than when focusing on close object.
    Focusing could be done manually „by a user‟ with an
     electric motor.

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    Focusing could be done automatically (auto-
    Auto-focusing is either passive or active.
    Passive auto-focusing;
        The camera‟s embedded computer does it.
        The embedded computer determine whether an image is in
         focus by seeing how „sharp‟ it is.
        A sharp image contain sharp edges „sudden changes in
         colour or brightness.
        The computer will instruct the motor to move the lens in
         and out to find the best focus.

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Active auto-focusing

    Active auto-focusing works by the camera
     measuring the distance to the object viewed, and
     using that to calculate the gap needed between lens
     and light sensor.
    It measures the distance by sending out pulses of
     infrared light towards the object being filmed, and
     measuring how long it takes the reflected light to get
     back to the camera.
    Half the time between sending and receiving the
     pulse is called the transit time.
    Transit time is being used to calculate the distance.

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Active auto-focusing (cont.)

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Active auto-focusing (cont.)

        The infrared transmitter/receiver:
             Receives a digital signal from the rest of the camcorder which
              instructs it to generate and transmit a pulse of infrared light.
             Detects the reflected pulse of infrared light which it reports
              back to the rest of the camcorder in the form of a digital signal.
        The motor output subsystem:
             Receives a digital signal from the rest of the camcorder which
              it converts to the appropriate analogue electrical signal that
              drives the focusing motor.
        The focusing motor:
             Changes the position of the lenses so that light is focused in
              the light sensor.
             It is controlled by the electrical signal it receives from the
              motor output subsystem

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Active auto-focusing (cont.)

    Distance to the object (m) = transit time (s) * speed of light (m/s)
                   d (m)        = t (s)           * c (m/s)
                                                        c= 3 * 108 m/s
    Activity 16  d (m)         = t (ns)          * c (m/ns)
                                                        c= 0.3 m/ns
                 d = 0.3 t (t in ns)
    Activity 17   d = 0.3 * 14 = 4.2 m

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4.2 Recorder

    Camcorder stores information on tapes or
     DVDs or memory cards.

    Tape is a magnetic storage medium;
        Data on tape can only be accessed sequentially, It
         is not possible to jump to somewhere in the
         middle of the tape.
        Tape is less robust than DVDs and memory
         cards, “can be easily damaged and wears out
         after repeated use”.

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DVD based camcorders

    DVD is an optical storage medium;
        Data on DVD can be accessed randomly, it is
         possible to jump straight to anywhere on the disk.
        No significant degradation to the disk by the
         number of times it is being used, „more robust
         than tapes‟.
    If the blue disk DVD technology is being used
     with 27 GB capacity, it will provide about 2
     and half hours of recording at 25 Mbps.

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Memory cards based camcorders
    Memory cards are electrical storage medium.
    Some types of memory cards are randomly accessed, but others
     require sequential access.
    Writing to and reading from memory cards is faster than with a
    There are no mechanical movements involved in using a memory
     card this is called solid state.
    Solid state components tend to be more reliable and last longer.
    „P2 CAM‟ is a camcorder that uses four memory card embedded
     in a standard package called the P2 card.
    If a single memory card stores 16 GB is used in P2 CAM, then a
     P2 card can store 64 GB, which is nearly five hours.

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4.3 Batteries (electric circuit)

    Main elements of electric circuit:

        Active elements; are the elements that generate
         the power, example, batteries.
        Passive elements; are the elements that
         consumes or stores electric energy, example of
         consuming element is resistance.

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4.3 Batteries (ohm’s law)

    Voltage is a measure of the force with which
     electricity is „pushed‟.
    Resistance is the ability of a material to
     resists the flow of electricity.
    Current is the rate of electricity flow.
    Ohm‟s law  I = V/R
        Current in amps = Voltage in volts
                          Resistance in ohms

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4.3 Batteries (size)

        Battery cells have different sizes,
         example of sizes;
             AA size which is used in portable
              radios and CD players.
             C size which is used for torches and
              portable stereos.
        C size battery has more capacity than
         AA size.
        Batteries could be connected in series
         to provide more voltage.
        Batteries could be rechargeable or

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4.3 Batteries (chemicals)
        Batteries produce electricity by a chemical reaction.
        Referring to the chemicals used in batteries, two main technologies:
             Nickel--cadmium (NiCd) batteries.
             Nickel--metal hydride (NiMH) batteries.
        The chemistry of NiCd and NiMH is similar, so they produce the same
         voltage as each other. (voltage of each cell is around 1.2 volts).
        The NiMH batteries are more expensive but have a greater capacity.
        In rechargeable batteries; NiMH batteries can be recharged more
         times than NiCd batteries.
        Cadmium is highly toxic (poisonous) and so NiCd batteries should be
         handled carefully and should not be disposed of with other waste, but
         should be recycled so that the cadmium is extracted safely.
        For all these reasons, NiCd batteries are falling out of favour.
        „Lithium Ion‟ (Li-ion) batteries are commonly used in laptop computers
         and other portable ICT equipment.
        Voltage delivered by a Li-ion cell is around 3.6 volts

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4.3 Batteries (capacity)

    Capacity (amps.hours) = current (amps) * Running time (hours)
    C = I * t , I = C/t , t = C/I

    Activity 24 ( pp.116)
    Activity 25
    Activity 27

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Study session 5: Signal transmission

5.1 Transmission of electrical signals on wires

5.2 Other transmission media (Microwaves and
  Optical fibre)

5.3 Signal speeds, propagation times and
  distance: the formula triangle

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5.1 Transmission of electrical signals on
    For transmitting an electrical signal on wires an
     electrical circuit has to be closed.
    The electrical circuit can be closed and opened
     using an electrical switch.

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     Voltmeter is a device used to measure the voltage
      between the wires.
             It has two wires and a display.
             When you touch the ends of the wires to the terminals of a
              power source like a battery,
             the display on the voltmeter tells you what the voltage is
              between the terminals.

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Voltmeter (cont.)

    Activities 28, 29, 30

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Attenuation & Distortion

    Attenuation is caused because;
        some energy from the electricity is absorbed by heating the wires.
        some energy is radiated into the air as the wires act as aerial.
    Amplifiers are used to recover the attenuated signal.
    Distortion is caused by noise, noise is the unavoidable effect
     of meaningless signals.
    Regenerator is used to recover the distorted signal and it can
     be used for amplification.

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5.2 Other transmission media

    Optical fibre;
        Is a piece of glass or plastic, not much thicker than a
         human hair, which guides light from one end to the other.
        Is being used as a transmission medium for high data rates
         over long distances.
        Light in fibre travels at about 2/3 of the speed of light in the
         air (light travels more slowly in glass than in the air)

    Microwave;
        The term „microwave‟ identifies a particular range of
         frequencies used for radio communications which is from
         about 200 MHz to 50 GHz.
        Radio waves travel at the speed of light (3*108m/s)

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5.3 Signal speeds, propagation times and
distance, the formula triangle

                                         Activities 33, 34

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Study session 6: Trust

    Information is worthless if you have no trust in it.

    Two main elements will build your trust in
        The authority of the information source, example,
         BBC is a trustful information source.
        Authentication of the message.

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6.1 Authority and the variety of
information sources

    Information sources varies, ex, printed books,
     magazines, newspapers, digital TV and radio
     broadcasting, and the internet.
    Their has to be some degree of editorial control
     over the content, to maintain standards of honesty
     appropriate to their publication or channel.
    Example, in the UK, newspapers and magazines are
     regulated by the Press Complaints Commission

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6.2 Authentication of information

    Authentication of information can be done by
     adding a signature.
    A signature can help in identifying if the
     source of the information is the right one.
    A digital signature is a special piece of data
     which is added to a message.
    Example, Authentication of emails is possible
     by the use of digital signatures.

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6.3 Pictures

    It was said that „The camera never lies‟.

    But images can be altered and modified
     easily especially if it is digital.

    So The idea that the camera never lies has
     always been a myth.

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