Transmission Media

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  • Transmission Media
    • Bandwidth
      • - a measure of the capacity of a communication channel.
        • - the range of frequencies that a channel can handle.
        • - may be given as a frequency, such as 3 kHz, or as a transmission rate in bits per second.
        • - transmission rate is often referred to as line speed, for example, channels might be described as having line speeds.
    • Broadband
      • - a method of connecting to the internet usually achieved by a technique known as digital subscriber line (DSL).
      • - uses physical connections of the telephone system, but transmits data in a way that does not interfere with the voice frequencies.
      • consequence of this are that data can be transmitted much faster than over a dial up connection, that ordinary voice calls are possible at the same time, and that there are no seperate call chargers for computer connection.
    • Metal Cables
      • Coaxial cable
        • - made to a variety of specifications, same kind used for connection aerial to tv.
        • - two conductors, one wire down the center which may be a single trans (insulated from the second), which is made up of many strands braided around the insulation for the inner wire.
      • Twisted Pair
        • - commonly used for data transmission
        • - a pair of insulated copper wires twisted together surroned bya copper braid and external insulation
        • - some cables are made up of a number of twisted pairs surronded by an overall earthed braid screen
      • Unshielded Twisted Pair
        • - similar to twisted pair, has no earthed shield
        • - suitable circumstance allow for use in data transmission
    • Fibre Optic
      • - consists of very fine glass strands that allow rapid transmission of data, using modulated light beams
      • - provides interference-free, secure data transmission and is not subject to corrosion.
      • - it is usual to put many strands together in a single cable, each 1 capable of carrying 1 or more data signals.
    • Wireless
      • - wireless covers a range of possible methods of data transmission which can be used for linking computers within networks or for links within computer systems.
      • - wifi is a way of connecting computers to a network ia radio waves.
        • - each computer has a Wi-Fi wireless interface that connects to a wireless access point attached to the network.
      • - bluetooth is a short range wireless communications standard that uses low-power radio waves.
        • -  allows bluetooth equipped devices to communicate with other bluetooth devices in a peer-to-peer relationship.

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