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[Black Sheep]

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[Black Sheep]

Apologies for the pics being distributed haphazardly.

[kitz]

Well done BS.    What's the 15db nm about though?

[waltergmw]

Hi BS,

Thanks for those JDSU pictures.
I expect you are very pleased with your connection's sync speed compared to ADSL's bump and grind !
It would be interesting to see what figures a BT speed test now produces.

I'm often trying to improve VDSL services but your drop of nearly 26 Mbps from the max figure on a line length of 600 m does seem rather large ?
Note though that I don't have a clue as to whether the JDSU figures are the same as those obtained directly from a Huawei modem ?
(I have observed much poorer figures on an ADSL2 line from a JDSU when compared to those in a 2700 HGV modem.)

Anyway the very best of good luck with your new-found emancipation !

Kind regards,
Walter

[burakkucat]

I understand that a JDSU HST-3000 presents a lower impedance to the line being tested when compared with that of a Huawei HG6xx device. Hence the heavier loading results in lower values being recorded. 

[Bald_Eagle1]

Note though that I don't have a clue as to whether the JDSU figures are the same as those obtained directly from a Huawei modem ?

I'm sure that BS couldn't possibly personally condone such a suggestion, but it might be rather interesting at some stage to be able to compare the equivalent stats as obtained via both a JDSU & an unlocked HG612 on the same connection 

These would be particularly interesting, along with Bitloading, SNR, QLN & Hlog across all the DS & US tones:-

Code: [Select]

xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 2
Max: Upstream rate = 4833 Kbps, Downstream rate = 21216 Kbps
Path: 0, Upstream rate = 4859 Kbps, Downstream rate = 20764 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) (868,1207)
DS: (32,859) (1216,1963)
       VDSL Port Details       Upstream        Downstream
Attainable Net Data Rate:       4833 kbps         21216 kbps
Actual Aggregate Tx Power:        6.2 dBm          12.1 dBm
============================================================================
  VDSL Band Status        U0      U1      U2      U3      D1      D2      D3
  Line Attenuation(dB): 8.1 54.0   N/A   N/A 21.9 64.1 0.1
Signal Attenuation(dB): 8.1 53.3   N/A   N/A 21.9 64.1   N/A
        SNR Margin(dB): 6.1 6.1   N/A   N/A 6.3 6.4   N/A
         TX Power(dBm): -4.6 5.9   N/A   N/A 11.3 4.4   N/A



xdslcmd info --stats

xdslcmd: ADSL driver and PHY status

Status: Showtime

Retrain Reason: 2

Max: Upstream rate = 4833 Kbps, Downstream rate = 21216 Kbps

Path: 0, Upstream rate = 4859 Kbps, Downstream rate = 20764 Kbps



Link Power State: L0

Mode: VDSL2 Annex B

VDSL2 Profile: Profile 17a

TPS-TC: PTM Mode

Trellis: U:ON /D:ON

Line Status: No Defect

Training Status: Showtime

Down Up

SNR (dB): 6.3 6.1

Attn(dB): 0.0 0.0

Pwr(dBm): 12.1 6.2

VDSL2 framing

Path 0

B: 239 143

M: 1 1

T: 59 37

R: 0 12

S: 0.3676 0.9391

L: 5223 1329

D: 1 1

I: 240 78

N: 240 156

Counters

Path 0

OHF: 22657180 678610

OHFErr: 9496 30

RS: 0 1290471

RSCorr: 0 70

RSUnCorr: 0 0



Path 0

HEC: 13633 0

OCD: 0 0

LCD: 0 0

Total Cells: 622081142 0

Data Cells: 22109187 0

Drop Cells: 0

Bit Errors: 0 0



ES: 2665 55

SES: 63 0

UAS: 135 135

AS: 123335



Path 0

INP: 0.00 0.00

PER: 5.42 8.68

delay: 0.00 0.00

OR: 47.21 29.47



Bitswap: 23820 2480



Total time = 1 days 22 hours 16 min 20 sec

FEC: 0 0

CRC: 18390 0

ES: 2665 55

SES: 63 0

UAS: 135 135

LOS: 5 0

LOF: 5 0

Latest 15 minutes time = 1 min 20 sec

FEC: 0 0

CRC: 3 0

ES: 3 0

SES: 0 0

UAS: 0 0

LOS: 0 0

LOF: 0 0

Previous 15 minutes time = 15 min 0 sec

FEC: 0 0

CRC: 213 0

ES: 22 0

SES: 0 0

UAS: 0 0

LOS: 0 0

LOF: 0 0

Latest 1 day time = 22 hours 16 min 20 sec

FEC: 0 0

CRC: 7034 0

ES: 885 12

SES: 24 0

UAS: 0 0

LOS: 0 0

LOF: 0 0

Previous 1 day time = 24 hours 0 sec

FEC: 0 0

CRC: 6235 0

ES: 965 24

SES: 25 0

UAS: 21 21

LOS: 0 0

LOF: 0 0

Since Link time = 1 days 10 hours 15 min 33 sec

FEC: 0 70

CRC: 9496 30

ES: 1383 26

SES: 33 0

UAS: 0 0

LOS: 0 0

LOF: 0 0


We know it can be very easily done via a Windows PC, but as a Mac user, are you able to confirm that all that lot (including the Bitloading, SNR, QLN & Hlog data) can be very easily obtained via Telnet (or whatever program Macs may use) & stored as a plain text file for subsequent examination/graphing via my programs?

[Black Sheep]

Well done BS.    What's the 15db nm about though?

Ha ha, cheers Kitz. The increased dB is due to a 'Bridged Tap', where the hell that 'tap' is, is anybody's guess as I assumed it was due to my previous dongle-filtered installation. Further tests show this is not the case ?? I'll be visiting my PCP sometime soon !!!

[Black Sheep]

Hi BS,

Thanks for those JDSU pictures.
I expect you are very pleased with your connection's sync speed compared to ADSL's bump and grind !
It would be interesting to see what figures a BT speed test now produces.

I'm often trying to improve VDSL services but your drop of nearly 26 Mbps from the max figure on a line length of 600 m does seem rather large ?
Note though that I don't have a clue as to whether the JDSU figures are the same as those obtained directly from a Huawei modem ?
(I have observed much poorer figures on an ADSL2 line from a JDSU when compared to those in a 2700 HGV modem.)

Anyway the very best of good luck with your new-found emancipation !

Kind regards,
Walter

Thank you Walter, appreciate your comments. You are, of course, quite right about the large speed drop (see post to Kitz above). Investigations to commence sometime this week, time permitting. 

[Black Sheep]

I understand that a JDSU HST-3000 presents a lower impedance to the line being tested when compared with that of a Huawei HG6xx device. Hence the heavier loading results in lower values being recorded. 

Hmm ?? Interesting thoughts there B*Cat. My experience with the 'Jeddy' has shown me that it appears to have a larger impedance factor than most modems/routers out there. The one and only router I've come across that has the reverse effect, is SKY's grey-coloured one (not the newer white square one).
I have to admit to being baffled as to why this is ??

[waltergmw]

@ BS,

Far be it for an amateur to pervert the course of the highly experienced practioners, but I wonder if an examination with a tone generator of your DP and perhaps the next one up the line might detect the cause of the bridge tap.

The esteemed BKK has affirmed that bridge tap causes are more usually associated with the EU's near end connections.

Kind regards,
Walter

[Black Sheep]

Hi Walt

I live on a new estate with new cabling all the way back to the PCP, and the wiring from the BT66 and beyond doesn't contain any 'Taps'. This really only leaves a potential 'Tap' at the PCP on the Krone strips, as its easily done where the engineer can't see the presence of additional wires on the lower connections.

That said, I attended a multiple-repeat fault on VDSL once, along with another engineer. The GEA result (like mine) kept showing a Bridged Tap. The PQT tests passed with flying colours, and it was only by changing it onto another D-side pair that we got a 'Pass' on the GEA test. Our only conclusion was either a 'Split Pair' or a slight contact fault with a dead pair ?? It was the fact that all the parameters passed perfectly, that you wouldn't normally associate with 'Splits' or 'Dead contacts' ...... ie: AC Balance and 'Capacitance'.

This electrickery is a dark art !! 

   

[kitz]

Well done BS.    What's the 15db nm about though?

Ha ha, cheers Kitz. The increased dB is due to a 'Bridged Tap', where the hell that 'tap' is, is anybody's guess as I assumed it was due to my previous dongle-filtered installation. Further tests show this is not the case ?? I'll be visiting my PCP sometime soon !!!

So the DLM has kicked in and put you on 15dB SNRM? ...  which will of course be stripping you of quite a bit of sync speed.

[Black Sheep]

Yup ........... bus-mans holiday time !! 

[burakkucat]

Just for the record . . .

Was the installation performed by an Openreach employee or a contractor? Assuming a "Yea, nay" response to that split question, the next split question queries whether the installer was a minimalist-trained new recruit (perhaps ex-MOD) or a significantly time-served technician (of the Ezzer / Black Sheep standard)?

Of course we must not assume that the tie-pair connections within the FTTC are perfect.    I guess that you could isolate both sets of tie-pairs within the PCP and then test down each pair to the FTTC, in turn.

It will be interesting to know the exact location when you find the line defect . . .

[Black Sheep]

For info ......... I was attending to other personal matters the day of the install, so I just plugged the Huawei Modem in (and the link to the Hub), and awaited a mate of mine (26yrs as a BT engineer and more than capable) to perform the Cab work. It was he that informed me it was testing as 'Bridged Tap'.
Sure as eggs are eggs, when I finally had the time available to me, I utilised WHOOSH and the results do show as a 'B Tap'.

Tonight, I've proved that it isn't the wiring at my premises, and have got a damned good 'Spare pair' ready for swopping over to, again, when time allows ?? It's got an AC Balance of 82dB and both legs are showing as -56dB on the crosstalk 'Noise' function (-60dB being perfection). 'Impulse Noise' function didn't even register one single 'Count' after a couple of minutes. Again, indicating a really good pair of wires.

It's slow going but I'll hopefully get there in the end, and will certainly report back my findings.