How long is your D-side ? I see 75 - 77 prospective with my line, isn't it making very hard work of this all unless the attenuation is known ?
Do you have any ideas as to how an engineer's JDSU calculates an overall attenuation value?
Those who have access to an unlocked modem can see attenuation values, but they are split across the various 17a profile band plans:-
VDSL Band Status U0 U1 U2 U3 D1 D2 D3
Line Attenuation(dB): 8.3 52.8 64.1 N/A 21.6 63.0 0.1 Signal Attenuation(dB): 14.8 52.0 N/A N/A 21.6 63.0 N/A
SNR Margin(dB): 6.1 6.3 N/A N/A 3.8 3.7 N/A TX Power(dBm): -4.2 5.8 N/A N/A 10.9 6.6 N/A
It would be really useful to know how the JDSU & modem reported values relate to each other.
Ideally, someone with access to both an unlocked modem AND a JDSU at the same time could post some comparative values, either here or via a PM?
A visiting BT engineer quite recently told me that my DS attenuation was around 22 dB, but that would appear to only match the downstream D1 band as shown above.
He also told me my D-side was 1000m from the cabinet to the DP before he replaced some overhead cabling, & 900m afterward (again from his JDSU).
Those attenuation values & reported D-side lengths could explain my current relatively low speeds (DS of 32084 K Attainable & 27131 K Sync speeds).
I THINK I may still have a potential HR issue somewhere in my D-side as I DID achieve actual download speeds of 32 Mb - 33 Mb for the first month (solid & stable connection).
Now it only averages around 22 - 23 Mb (on a good day, outside peak periods).
Unfortunately the engineer refused to carry out a TDR test to confirm that one way or the other, as he stated that the Pair Quality Test showed as LTOK.
I am unable to confirm what my reported attenuation & D-side lengths were at the time I was achieving the more reasonable speeds, but the original installing engineer did say that my connection's sync speed was around 35 Mb.
A previously visiting BT engineer told my that my D-side was around 820m in length, but that figure came from his laptop, not his JDSU.
It must be a really good day today:-
Edited by Bald_Eagle1 (Sat 17-Dec-11 11:36:42)