Quick connection test results with JDSU DSLAM

A BTO person has just done a test using a JDSU configured as a DSLAM at the pole, 50m from the house, which is connected by a 4-pair cable.
ulty.

My modem saw these line attenuations ...

Line attenuation (dB) U0 U1 U2 U3 D1 D2 D3
15 Apr 2016 11:05:05 N/A 4.4 9.5 N/A 3.0 6.4 11.1

Signal attenuation (dB) U0 U1 U2 U3 D1 D2 D3
15 Apr 2016 11:05:05 N/A 4.4 9.5 N/A 3.0 6.4 11.1


The line connected at full speed for a 17a profile, but are these attenuation values proper for such a short run? I see other people report essentially 0dB values when they are close to the cabinet, hence I am a little suspicious.


added other stats for completeness below


xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 2
Max: Upstream rate = 58807 Kbps, Downstream rate = 51804 Kbps
Path: 0, Upstream rate = 50000 Kbps, Downstream rate = 105000 Kbps

Discovery Phase (Initial) Band Plan
US: (880,1195) (1984,2771)
DS: (160,859) (1216,1959) (2792,4083)
Medley Phase (Final) Band Plan
US: (880,1195) (1984,2771)
DS: (160,859) (1216,1959) (2792,4083)
VDSL Port Details Upstream Downstream
Attainable Net Data Rate: 58807 kbps 51804 kbps
Actual Aggregate Tx Power: 7.2 dBm 11.2 dBm
============================================================================
VDSL Band Status U0 U1 U2 U3 D1 D2 D3
Line Attenuation(dB): N/A 4.4 9.5 N/A 3.0 6.4 11.1
Signal Attenuation(dB): N/A 4.4 9.5 N/A 3.0 6.4 11.1
SNR Margin(dB): N/A 8.9 3.6 N/A -8.8 -8.7 -8.5
TX Power(dBm): N/A 1.7 5.8 N/A 5.7 5.5 7.8
#

Edited by godsell4 (Fri 15-Apr-16 11:45:04)

Copper or aluminium cabling?

The U0 band is missing

copper i think

Can you post QLN, Hlog & Bitloading graphs?

I am afraid not

The OP describes it as pole to house, i.e. dropwire, there has never been aluminium dropwire.

There is certainly an issue with U0 missing

In all honesty I think it isn't really a valid test at all.

We were told that using a JDSU to generate an ADSL signal was a pointless excise, and on top of that could in some cases goose end users BB CPE. I daresay it is likely to be similar for VDSL, not a 'true signal'.

You have to wonder why the engineer was running such a test in the first place, it would have proved [censored] all really.

Good point. Maybe we could compare with live stats?

Except that we are going to struggle to find a line to test which is 50m away from a real DSLAM innit.

no no no, I mean his actual stats from his modem running normally, to see what the difference is.

Ah, je comprends.

In reply to a post by Zarjaz:

You have to wonder why the engineer was running such a test in the first place, it would have proved [censored] all really.

This was the most competent SFI guy to have attended my house in the last 4 years there has been an outstanding issue which it looks like it has now been fixed.

Why the test? Because that cable has been touching a tree branch for many years, a BTO cherry picker was in the area so they cut the branch and the cable looked fine visually, so we tested it electrically too. Seems reasonable.

As a result of this test, when he went to remake the crimped connection, the cabinet side pair was found to be black and corroded, this was trimmed back to good wire.

So essentially we were just starting the process of seeing how fast the line would go at various joints/points back to the cabinet, which is +2km away. So agreed, the missing U0 is a bit strange.

But it is a result so far, DLM was reset, at 6dB I am at 5.7Mb, I expect it will settle at 9dB and maybe drop to 4.5 to 5Mb in the end with quite a large amount of interleaving. But this is a long line, so to be expected.

Current stats as follows:

xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 2
Max: Upstream rate = 1109 Kbps, Downstream rate = 6720 Kbps
Path: 0, Upstream rate = 1109 Kbps, Downstream rate = 5717 Kbps

Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3959)
Medley Phase (Final) Band Plan
US: (0,95)
DS: (32,859)
VDSL Port Details Upstream Downstream
Attainable Net Data Rate: 1109 kbps 6720 kbps
Actual Aggregate Tx Power: 10.5 dBm 8.1 dBm
============================================================================
VDSL Band Status U0 U1 U2 U3 D1 D2 D3
Line Attenuation(dB): 16.6 N/A N/A N/A 32.4 0.1 0.1
Signal Attenuation(dB): 16.6 N/A N/A N/A 32.4 N/A N/A
SNR Margin(dB): 6.6 N/A N/A N/A 6.4 N/A N/A
TX Power(dBm): 10.5 N/A N/A N/A 8.2 N/A N/A
#

Edited by godsell4 (Sat 16-Apr-16 10:37:07)

Ha! that's quite "funny", now you ONLY have U0

I think you are on a Huawei cab, so your Huawei modem is probably the best chipset match.

Edited by deleted (Sat 16-Apr-16 10:47:52)