computer networks : mik3 one more question

Discussion in 'Homework Help' started by tavati, Jan 26, 2009.

  1. tavati

    Thread Starter New Member

    Jan 26, 2009
    6
    0
    dear sir,

    i have one more question.

    when we talk about sending data in bits and talk about symbols- i want to just know the big picture here.

    suppose i have to transmit letter 'A' and suppose the binary is 11000110. so every bit is transmitted as a symbol ( i.e. a combination of bits which we decide as above ) or is a 1 transmitted as 1 only followed by another 1 followed by three zeroes etc.

    to say it other way is there a mapping of 0 and 1 with symbols as designed by engineers at the physical layer or have i mixed it up.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Bits are bits. A logical low state is a "0", and a logical high is a "1".

    Symbols, like the letter 'A', are encoded into groupings of bits. If you use ASCII, as in the U.S., the the code for A is 41h, or 0100 0001. There is another encoding standard, called Unicode, which uses twice as many bits per character/symbol, but is able to represent most of the world's languages.

    You can learn more at the link - http://ascii-table.com/.
     
  3. Skeebopstop

    Active Member

    Jan 9, 2009
    358
    3
    0 and 1 are the lowest forms of transmission.

    The only times you may represent them as 'symbols' as you say, is when modulating for carrier transmission over wireless or other mediums like telephone wires.

    If it is an enclosed system, i.e. your self contained circuit board, a 0 is sent as a 0 and a 1 generally 5V. If it is a communications channel in a nearby system you would often just use differential signalling, i.e. -12V is 0 and +12V is 1, i.e. RS 422 etc.. Ethernet uses a similar methodology but the voltages are lower.
     
  4. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    If you are using a parallel communication port then the bits will be transmitted simultaneously.

    If you are using a serial port then the bits will be transmitted one by one.
     
  5. Skeebopstop

    Active Member

    Jan 9, 2009
    358
    3
    Anyone keep up to speed with quantum computing and entanglement? Quantum computing seems clear enough, cramming more bits of information into differing quantum tunneled states, but what the heck is all this jazz about entanglement?

    I realize the really large prospect in it is the ability to transmit faster than the speed of light? I recently read a scientific american article where they were discussing how researchers are already putting it to use but the whole article flew over my head! I thought entanglement was purely theoretical and our abilities to successfully apply it were extremely limited, if at all possible!

    It makes my brain hurt. I must be getting old and not keeping up with the times anymore.
     
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