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On Sunday 22 April 2007 01:22, Andrew Spillman wrote: > On Thu, 2007-04-19 at 12:42 +0100, stinga wrote: > > It sat terms I don't think you have a 'digital' signal, the data is > > digital over an analogue signal (maybe sort of??) > > > > Isn't this the same as ADSL? > > My phone line is not digital. > > If you're interested: > > digital satellite and adsl are both digital and don't travel over > analogue signals. > > If you have adsl then your phone line IS digital, well some of it. The > adsl part is transmitted digitally and the voice part is analogue. The > two parts are separated into different frequency bands, which is why you > have to use a filter on you phone line if you have adsl as it makes sure > that these two bands are separated so that your phone doesn't interfere > with the adsl. I can pretty much guarantee that your voice call gets > digitalised if you're speaking to someone that isn't connected to the > same exchange as yourself. > > ADSL and digital satellite, like most modern digital communication > technologies are physically very similar in that they use QAM, > quadrature amplitude modulation as a carrier. My understanding was that if you want to be pedantic, then no matter what, a radio wave or a voltage in a phone line is always analogue, and that digital is just a way of saying that "if the voltage is over 2.5v, treat it as on/1, and if it's less, treat it as off/0". -- 140cf42384f90b8c349b67457b907115 Public PGP key at http://www.jameshallam.info/files/publicpgpkey.txt
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