Why the 4.2km distance limit?

[Telkomhater]

Can someone explain to me, please, why ADSL only works up to a maximum of 4.2kms from the exchange. They wont install an ADSL line over that distance. Is this a phenomenon unique to Telkom or does it apply all over the world?

 

[stoke]

It's the technology self.

Checkout : http://www.pctechguide.com/28dcomms_ADSL_implementation.htm

<Q>The service was only available to subscribers who were located within 3.5km from their local ADSL-enabled exchange</Q>

There is a new/modified ADSL technology that can handle greater distances [Rate Adaptive Digital Subscriber Line] which can do like 5.5 km's, but then at a slower throughput.

The article is quite interesting and UK based - but makes me wonder how they came up with 4.2 km's.

 

[Crash]

It has to do with the Mechanics of the electrical signals used by an ADSL Network to move data around.

When you send an electrical signal down a cable there is a certain amount of signal loss per meter the signal travels.
Normally a receiving device will have amplifiers and filters to compensate for the loss of signal through it's travels.

When you exceed a finite distance however, no amount of amplification or filtering can recover the signal. In short. If you were outside the 4.2km the ADSL wouldn't work, due to signal loss, so you would be wasting money.

It's like buying a cellphone and contract, then using it outside the coverage area. Pointless

 

[morebroadband]

From what I understand using the 192kbs product Telkom can stretch this to 5.6KM. This is why they launched this product so they can get that little bit further.

 

[Daveogg]

Dont accept it until you get telkom to physically come and do impedance testing on your line.

I was told on three occasions according to their measurements i was greater then 5.5km from the exchange. Eventually, i think to finally shut me up, they sent a teckie to test the line. The end result is that i now have 512 running at full speed.