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Digital vs Analogue Comms

  1. Jul 28, 2005 #1
    I found the following on the Edexcel Website:

    GCSE Specimen Paper
    Paper 4H
    Physics A [1540]
    URL http://www.edexcel.org.uk/VirtualContent/18085.pdf

    Question 1(b)(ii) “Digital signals have an advantage over analogue signals since more information can be sent over the cable. Explain this.”

    Answer “An explanation to include: very short time interval between pulses; lots can be placed close together.”

    Is this right?
    I've re-read Nyquist, Shannon, Hartley and Turing and I can't find anything like this. Surely the cable IS an analogue communication channel.

    If I send two identical signals down two identical channels.
    Both look like digital data. I view one as analogue and the other as digital. Apparently, I get more information out of the identical digital one!

    I rushed to my Physics textbook:
    Physics for AQA
    Separate Award Edition.
    Published by Heinemann
    ISBN 0 435 584 219

    only to find on page 52,

    “Second, a particular cable, optical fibre or carrier wave is able to carry more information if it is transmitted as a digital signal than if it is transmitted as an analogue signal.”

    This surely is rubbish too.

    I thought there was simple catch-all rule in Physics: "You get nothing for nothing." Apparently in GCSE Physics you can.

    Comments? Am I cracking up?
  2. jcsd
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