May '13 cat only has CCA and picture of the untwisted pair flat stuff...
As I suspected the modem did resync over night, twice, first time down to 6800 then again to 6200 (ish). Daytime SN is 7 or 8 dB.
Also did some maths on the resistance, that 10 yards of CCS would have a resistance of about 7 ohms per leg, same length of copper about an ohm per leg. That to me is a significant difference...
En el artículo , Dave Liquorice escribió:
Not sure the resistance matters much, after all you've got miles of BT wet string between you and the exchange. I'd be looking at the capacitance per m, and the number of twists per m, of the CCS vs. copper.
True enough but at 97.8 ohms/km assuming 0.5 mm copper, which might be a bad assumption, longer local ends tend to be laid with heavier cable. 0.5 mm CCS is 700 ohms/km...
Won't that be governed by conductor size and spacing, which are essentially the same? The higher resistance will upset the characteristic impedance of the transmisson line and introduce an impedance discontinuity at the transition from copper to steel.
The sample I have is fairly tightly twisted, the orange pair about 80 twists/m, green about 50 and blue maybe a bit less than green. A lot higher than I've seen in several samples of copper.
I am surprised it was not so from the start... changing the front (or in this cases adding under the front panel) of an NTE5 for the new style filter can't be any harder than for the old ADSL only style...
Unless there is some other magic the BT bod does on his visit?
Which explains their extra depth...
I should imagine putting a tone tracer on the end of the line so he can find the right pair in the rats nest cabinet to jumper across to the fibre cab and back. B-) It's not quite the same as ADSL from the exchange, they know which "port" the line is connected to in the exchange so can find that relatively easily.
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