Bunched pairs

I was just reading through some of the posts about the problems of ADSL on long lines. It bought back distant memories about a solution to similar issues (normally faint transmission) that was sometimes used on long lines back in the "good old days".

You would occasionally see "bunched pairs" - simply using two (or more?) pairs in parallel for the connection between the exchange and the customer.

Anyone know if this would work for ADSL, or might this do something unspeakable to the crosstalk and make the ADSL unusable. Has it ever been tried?

Ian

Easynet were using two pairs for faster LLU SDSL delivery (4M), don't know if it was a 4 wire modem or just two pairs in parallel.

I don't think you could do this without a special sort of router to handle it. Unless the pairs were exactly the same length, the ADSL signals could arrive out of phase and cancel each other out.

I think BT looked into this in the early days and found it caused lots of problems , I think due to the slight difference between the pairs and propogation delays.
Note, bunched is not the same as pair bonding.

In reply to:

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Easynet were using two pairs for faster LLU SDSL delivery (4M), don't know if it was a 4 wire modem or just two pairs in parallel.

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Well since SDSL only goes up to 2Mbps, woud that not have to be bonded SDSL, i.e. 2 lines?

Cheers

Andrew.

You can get 4 wire SDSL modems, though the ones I have still only give you a 2 meg connection just able to work much further.

In short, no. ADSL and bunched pairs are not happy bed fellows.