ADSL runs on one wire

[Kaal]

I found this very interesting :

Our phone stopped working but I could still access the internet via ADSL ( with reduced performance).
I bought a new phone instrument, but it still didn't work.
I reported a fault to Telkom. The techie traced the line from the exchange, the "street box", and then the box on the pole, where he found that one of the wires was disconnected.
When I expressed surprise that the ADSL worked, he told me that ADSL will work on only one wire !

 

[Carlhead]

Sheesh, thought it was 2...

 

[kaspaas]

Sheesh, thought it was 2...

Now you know why ADSL is so expensive:

Telkom is using a version that requires only a single wire!

 

[bboy]

well you then have a floating ground wire.... so if it "floats" at the right voltage.. then it would work! it was probably still grounded... just badly!

 

[Kaal]

well you then have a floating ground wire.... so if it "floats" at the right voltage.. then it would work! it was probably still grounded... just badly!

I was just surprised that it works at all. The quality was not good.
Maybe it is a differential signal.

 

[caroper]

Almost wireless internet

 

[krycor]

uhm isn't the 2nd one the ground thats put there to remove the noise that will appear on both lines thereby cancelling it out ? I think thats how its down with twisted pairs. loosing the one induces more errors(since you can't use the ground to cancel anymore) hence slower adsl line?

 

[Kaal]

uhm isn't the 2nd one the ground thats put there to remove the noise that will appear on both lines thereby cancelling it out ? I think thats how its down with twisted pairs. loosing the one induces more errors(since you can't use the ground to cancel anymore) hence slower adsl line?

I think you have the answer. That's what I meant by differential signalling.
Two wires are used, but neither of them is ground. For example, if one of the wires is at 1 Volt, then the other will be at -1 Volt. The difference between the two is 2 Volts. If noise adds 0.5 Volts to both wires, the one will be at 1.5 Volts and the other at -0.5 Volts. The difference is still 2 Volts, and the noise is effectively cancelled.