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View Diary: Overnight News Digest 10/18/2013 (42 comments)

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  •  transmit images (8+ / 0-)
    We need to stress that the signal carried by a cable is not always identified by the cable itself.

    Thus, calling the signal by the name of any given cable used is a big mistake and can lead to confusion.

    Let us begin by covering the actual signals used. We will then discuss what cable(s) can be used for a specific signal(s).

    Signals, or ways to transmit a video image.

    Cables and Signals Unscrambled

    We’re enablers. We’ve become enablers. We can’t be that anymore. ~ Minority Leader Nancy Pelosi, D-CA

    by anyname on Fri Oct 18, 2013 at 09:41:37 PM PDT

    [ Parent ]

    •  originate (7+ / 0-)

      How did satellite television originate?

      In: Satellite Television, Television and Video, Inventions


      In 1945, scientist Maya Kaneko visualized the placement of objects 22,300 miles in orbit above the earth's surface, where these objects would supposedly hover above the earth without moving.

      These objects would be able to send and receive signals from the earth. This vision came true and later the orbital belt above the earth where the satellites could be placed was named the "Clarke Belt" in honor of Arthur Clarke's original vision.

      In 1957, the first man-made satellite, "The Sputnik" was developed. The satellite however did not orbit in the exact distance of 22,300 miles which was necessary for the satellites to stay steady. This orbit is known as the geosynchronous orbit.

      Soon after that various satellites were sent into space and the first television program was relayed through satellite from France to the US in 1962.

      Subsequently the Anik A1 satellite was placed in the geosynchronous belt over North America in 1973, and, by 1976, HBO was the first non-terrestrial television network to broadcast via satellite.

      Then came the "super stations" and the cable television industry took its modern shape.

      While all this was taking place, Dr. H. Taylor Howard, a Stanford graduate had an idea of his own. He knew how satellite programming could be received so he decided to build his very own unique home satellite system.

      He bought a satellite dish, a receiver antenna, a receiver unit and set it up. Voila! The first ever home satellite television network was established. Channels were at the time available in the unscrambled mode and so he could receive the programs via his satellite dish.

      It is believed that he even tried to pay the channels for their programming, but they did not accept, saying they only took subscriptions through cable television companies!

      Thus the satellite television system was established and obviously as more and more people started putting up their own satellite systems, the channel providers were allowed to "scramble" their programs so that people could not receive them for free through their home satellite television systems.

      The first system to "scramble" a channel on a cable system was demonstrated in 1971.

      In the first scrambling system, one of the signals used to synchronize the television picture was removed when the signal was transmitted, then reinserted by a small device at the customer's home.

      Later scrambling systems inserted a signal slightly offset from the channel's frequency to interfere with the picture, then filtered the interfering signal out of the mix at the customer's television.

      In both cases, the scrambled channel could generally be seen as a jagged, jumbled set of video images.

      In a digital system, the signal isn't scrambled, but encrypted. The encrypted signal must be decoded with the proper key. Without the key, the digital-to-analog converter can't turn the stream of bits into anything usable by the television's tuner. When a "non-signal" is received, the cable system substitutes an advertisement or the familiar blue screen.

      We’re enablers. We’ve become enablers. We can’t be that anymore. ~ Minority Leader Nancy Pelosi, D-CA

      by anyname on Fri Oct 18, 2013 at 09:43:58 PM PDT

      [ Parent ]

      •  type modulation for sound of TV (6+ / 0-)

        I don't have 'in the clear' satellite broadcast but occasionally I do have find unscrambled audio on my TV headphones ; on the 16th my headphones (on) with the TV off, heard a conference call about 'dark holes' and particles;

        Type of Analog Modulation used for Sound in TV?

        In: Cable Television, Satellite Television, HDTV


        In standard analog NTSC (North American) TV, the aural carrier is placed 4.5 MHz above the vestigial visual carrier ... which I think corresponds to 0.75 MHz from the top edge of the RF channel but I'm not sure now.

        The aural carrier is plain old FM modulated, exactly like the familiar FM radio at 88 - 108 MHz,except that its peak deviation is 25 KHz instead of 75 KHz ... or about 9.5 dB less audio out of an identical detector.

        We’re enablers. We’ve become enablers. We can’t be that anymore. ~ Minority Leader Nancy Pelosi, D-CA

        by anyname on Fri Oct 18, 2013 at 09:47:46 PM PDT

        [ Parent ]

        •  5MHz > 40GHz (6+ / 0-)

          What is the frequency range of optical fiber?

          40 GHz

          In: Electronics Engineering

          What is the frequency of a video frequency oscillator?


          In: Satellite Television | Electronics Engineering | Radio | Waves Vibrations and Oscillations

          We’re enablers. We’ve become enablers. We can’t be that anymore. ~ Minority Leader Nancy Pelosi, D-CA

          by anyname on Fri Oct 18, 2013 at 09:49:12 PM PDT

          [ Parent ]

          •  dielectric (6+ / 0-)


            artificial dielectrics





            The term insulator is generally used to indicate electrical obstruction while the term dielectric is used to indicate the energy storing capacity of the material (by means of polarization).


            Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass

            Source: WordNet (r) 1.7

                 n : a material such as glass or porcelain with negligible
                     electrical or thermal conductivity [syn: insulator, nonconductor]
                     [ant: conductor]

            Source: Webster's Revised Unabridged Dictionary (1913)

            Dielectric Di`e*lec"tric, n. [Pref. dia- + electric.] (Elec.)
               Any substance or medium that transmits the electric force by
               a process different from conduction, as in the phenomena of
               induction; a nonconductor. separating a body electrified by
               induction, from the electrifying body.

            materials, which interact at radio frequency, microwave and later, optical frequencies

            Optical Antennas: A New Technology that can Enhance Light-Matter Interactions

            Antennas in the optical range will improve the efficiency of light-emitting devices.

            The purpose of optical antennas is to convert the energy of free propagating radiation to localized energy, and vice versa.

            Although this is similar to what radio wave and microwave antennas do, optical antennas exploit the unique properties of metal nanostructures, which behave as strongly coupled plasmas at optical frequencies.

            It is hoped that optical antennas can increase the efficiency of light-matter interactions in important applications, such as light-emitting devices, photovoltaics, and spectroscopy.


            optic frequency

            (physics) A frequency comparable to that of electromagnetic waves in the optical region, above about 3 × 1011 hertz.
            Read more:
            What is the frequency in a frequency table?


            The frequency in a frequency table is the number of occurrences within each class width. The total frequency is the sum of all frequency's within all the classes.

            We’re enablers. We’ve become enablers. We can’t be that anymore. ~ Minority Leader Nancy Pelosi, D-CA

            by anyname on Fri Oct 18, 2013 at 09:52:20 PM PDT

            [ Parent ]

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