FTTC installed today, amazing attainable rates

After my FTTC installation at work, we have the following attainable rates according to the openreach modem

Downstream 132728
Upstream 41166

Cable length is about 50 metres according to the openreach engineer.

Andrew

You need to get Asbokid's instructions on how to access the modem and pull of the various details.

It should prove interesting reading for some!

Hi, which commands would like you run?

I run the following:-
# xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 40609 Kbps, Downstream rate = 132328 Kbps
Path: 0, Upstream rate = 10000 Kbps, Downstream rate = 39998 Kbps

Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3939)
Medley Phase (Final) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3939)
VDSL Port Details Upstream Downstream
Attainable Net Data Rate: 40609 kbps 132328 kbps
Actual Aggregate Tx Power: - 8.7 dBm 12.5 dBm
============================================================================
VDSL Band Status U0 U1 U2 U3 D1 D2 D3
Line Attenuation(dB): 2.3 7.9 10.3 N/A 4.3 9.3 14.1
Signal Attenuation(dB): 0.0 N/A 7.8 N/A 4.3 9.3 14.1
SNR Margin(dB): 31.0 N/A 31.0 N/A 31.2 31.2 31.8
TX Power(dBm): -23.8 -128.0 -10.0 N/A 9.8 6.7 5.5

Very nice.

Have you got the tools to plot SNR against tones?

As you have a near perfect installation it would be good to see a plot of it to use as reference. Especially as my 17a max is about 63Mbps

Managed to get the info for the graphs

http://www.andew.entadsl.com/line_stats.png

Andrew

Hi andrew,

In reply to a post by andew:

Managed to get the info for the graphs

http://www.andew.entadsl.com/line_stats.png

Andrew

I have been knocking together some Windows only batch files that auto login to a terminal program (Plink -related to, but not PuTTy), obtain the details from the 5 xdslcmd info commands:-

xdslcmd info --pbParams
xdslcmd info --linediag
xdslcmd info --bits
xdslcmd info --show
xdslcmd info --stats

& then generate these (& other) graphs.

I would be very interested in testing my batch files with data from good connections (unlike my own problematic connection - I have added a message to one of your brother's older threads from July as that is apparently a similar distance from the cabinet as mine), & would very much appreciate it if you could forward me either a PuTTy or a Plink log of the 5 commands mentioned above (for your good connection).

Please see my PM to you for my contact details.


Paul.

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 ?

And I thought mine was good with a 300 meter line.

Hi Zarjaz,

In reply to a post by Zarjaz:

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:-

Text
1 23 45	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.


Paul.


EDIT:-

It must be a really good day today:-

http://www.speedtest.net/result/1653680967.png

Edited by Bald_Eagle1 (Sat 17-Dec-11 11:36:42)