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Physical limits of DSL/Cable?

  • 15-04-2005 8:36am
    #1
    pickarooney
    Moderators, Arts Moderators Posts: 35,478 Mod ✭✭✭✭


    With the broadband wars hotting up here (Holland) we're seeing some dramatic improvements in the maximum ul/dl speeds of ADSL and cable speeds.
    Over the last while, the speeds of standard packages have moved from 512kbps to 1Mbps to 2Mbps to 4Mbps, with the deluxe packages topping out at 8Mbps. I thought 8 would be about the maximum possible on a phone line or cable, but that seems to be far from the case. Recently, fibre-optic pilot schemes have been launched promising speeds of 10Mbps rising to 30Mbps both ways. I received an e-mail yesterday promoting my ISPs new 'extreme' cable/ADSL service at an almighty 40 (forty) Mbps both ways, with no physical alterations to the connection necessary. The ad featured the attractive, if somewhat dodgy claim of being able to download full DVDs in a half hour or somesuch.
    I don't know how much they intend to charge, nor do I see any real use in having such speeds when the majority of what anyone would want to download will be upload-throttled at about 1/40th of that (multiple streams I suppose is an option, but what kind of hard-drive space would that entail?).

    Anyway, I'm just curious as to what the physical capabilities of a standard phone line are.


Comments

  • #2
    crawler
    Registered Users, Registered Users 2 Posts: 1,660 ✭✭✭crawler


    pickarooney wrote:
    With the broadband wars hotting up here (Holland) we're seeing some dramatic improvements in the maximum ul/dl speeds of ADSL and cable speeds.
    Over the last while, the speeds of standard packages have moved from 512kbps to 1Mbps to 2Mbps to 4Mbps, with the deluxe packages topping out at 8Mbps. I thought 8 would be about the maximum possible on a phone line or cable, but that seems to be far from the case. Recently, fibre-optic pilot schemes have been launched promising speeds of 10Mbps rising to 30Mbps both ways. I received an e-mail yesterday promoting my ISPs new 'extreme' cable/ADSL service at an almighty 40 (forty) Mbps both ways, with no physical alterations to the connection necessary. The ad featured the attractive, if somewhat dodgy claim of being able to download full DVDs in a half hour or somesuch.
    I don't know how much they intend to charge, nor do I see any real use in having such speeds when the majority of what anyone would want to download will be upload-throttled at about 1/40th of that (multiple streams I suppose is an option, but what kind of hard-drive space would that entail?).

    Anyway, I'm just curious as to what the physical capabilities of a standard phone line are.

    Maybe a better question would be "With today's technologies, what are the limits of a standard phone line / coax"

    Cable can do up to 200Mbps on a single chanel ( Google DOCSIS 3.0 ) or any multiple using bonding of frequencies. http://www.cedmagazine.com/ced/2004/0704/07d.htm

    xDSL - have a google for ADSL(2+),VDSL, SDSL etc but there are limits with distance.http://www.cid.alcatel.com/doctypes/techpaper/dsl/dsl_types.jhtml

    On a fibre pair you can run a huge number of DWDM channels, with each channel capable of up to 10Gbps.


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