I found the following on the Edexcel Website: GCSE Specimen Paper Paper 4H Physics A  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?