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Standard User Bald_Eagle1
(committed) Sun 01-Apr-12 07:54:04
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Zarjaz] [link to this post]
 
Cheers Zarjaz,


In reply to a post by Zarjaz:
I'm guessing 61 was the AC balance. A 'mythical' overall test result, you can only raise an REIN fault if the AC balance is over 50.

So ask again, for a TDR test.


Oh No! I hope it hasn't been a REIN fault all along.

I've heard they are even harder to track down than internmittent line faults.

RRTC is the data helc on BTw's remote monitoring system, see's stability and the like, and gives results per day in a green yellow or red format.

Scripted tests on a JDSU, not worth a [censored] IMHO. Running a live manual test is the way to go.


O.K.

Hope this makes sense, more than a little tipsy.... will check again in the a.m.


I seems to make sense & thanks again.

The connection got a bit messy in the early hours of this morning & re-synced again at 23389 k.

Strangely, DLM has decided to turn Interleaving off again.

FWIW, these are my ongoing stats from the last 4 days:-

4 Day Stats

Cheers,

Paul.
Standard User Bald_Eagle1
(committed) Mon 09-Apr-12 09:48:57
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Zarjaz] [link to this post]
 
Well,

The engineer visited on Saturday morning.

He firstly ran a TDR test from the cabinet which on arrival at my home said was all clear.

He did say he had cleanedu up slightly corroded connections in the cabinet that may have made a slight difference.

He also replaced the filtered part of the faceplate & when carrying out various other tests from his Exfo, noticed that the last 5mm or so of the incoming drop wire snapped off one of the legs (insulation test failed).

He stripped back the insulation & all the other tests were then O.K.

The Leg Balance Test came back with a result of around 12 for each leg, which is apparently perfect.

A final TDR test on completion of his work was apparently O.K. too.

I don't have a photo of the trace, but it looked roughly like this:-

TDR Trace

The cabinet is shown by the large peak & the "hump" that I queried is apparently typical & nothing to be concerned about.

The engineer also said that it looks like the line is all copper, otherwise he would have seen other small peaks/troughs in the trace.

On requesting a sync recalc/DLM reset, the guy at the fibre centre (I think the engineer called it OMC or some similar abbreviation) mentioned they are aware of a long history of instability & frequent re-syncs & low(ish) speeds for my connection.

He & the engineer both agreed that I should really have a stable & slightly higher speed connection over the 834m line length as reported by the Exfo.

The OMC guy believes there is still some other "underlying" issue regarding my connection.
I wonder if the "hump" in the TDR trace is anything of a pointer.

I would say the "hump" is roughly one third of the distance from my house, going toward the cabinet.

Do you have any thoughts on this?


As the engineer first sorted the slight corrosion before running his first TDR test, we don't have "before & after" TDR traces, but the work carried out on Saturday appears to have cured the dropping SNRM when the phone is in use issue.
Now, SNRM only drops by around 0.1dB & 0.2dB when the phone is in use.

SNRM, fluctuating output power levels, attainable rates, error counts etc. all now appear quite stable.

However, from my modem stats, attenuation for each band is still slightly higher than it was for a few months previously.

from the Exfo:-

Text
1
23
45
67
8
US      DS
Actual Line Rate        6       24Max Rate                6       33
Capacity                100%    75%Noise Margin            6       9
Output                  6.3     11.2Loop Attenuation        7.9     31.6
Signal Attenuation      11      31.4


DS attenuation looks surprisingly high & US attenuation looks surprisingly low when compared against previous JDSU stats.

Is that a known phenomenon with the 2 different testers?


My sync speed is currently 32209 k, whereas a fairly recent DLM reset (a couple of weeks prior to the SNRM issue) achieved a sync speed of 35322 k.
Standard User Zarjaz
(knowledge is power) Mon 09-Apr-12 11:07:08
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Bald_Eagle1] [link to this post]
 
Sounds like the engineer was fairly thorough.

Loving your picture of the TDR trace, Looks to me like a side on view of Mr + Mrs.Zarjaz's bed first thing in the morning ! smile

Yes, seeing the DSLAM cab appearing as a hike/spike/peak on a TDR is normal.

I don't agree about a TDR showing whether the pair is all copper. Network records, or local knowledge is the usual route.

The 'hump' ain't right, but then you'd really have to be looking at the result for yourself to judge.

I can't say if that's a known issue with an Exfo, I don't use one. The hopeful thing is that the D/S shows only at 75%, so if it does now stay stable, and.....

appears to have cured the dropping SNRM when the phone is in use issue.
Now, SNRM only drops by around 0.1dB & 0.2dB when the phone is in use."


.. looks promising, then more speed could be achievable.

Stability is the thing now.

Good luck.


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Standard User Bald_Eagle1
(committed) Mon 09-Apr-12 11:29:45
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Zarjaz] [link to this post]
 
Cheers Zarjaz,

We did have a look at Network Records - no evidence of ally there either.

What they did confirm for me though, was that an additional 60m is added to my connection that I wasn't aware of as the cable goes underground past my house by 30m to a footpath joint chamber & then doubles back again to the pole directly across the road from my house.

The 75% was no doubt showing as my connection was still stuck at 24999 k at that point (before the DLM re-set).

Reading up on TDR stuff (like I do wink), a 'hump' can apparently be the result of "an impedance mismatch that is caused by an inductance discontinuity in the transmission line."

In other words, an open circuit, or in my language, "a dodgy joint".

Your'e right though, a stable connection is the most important thing now.

Edited by Bald_Eagle1 (Mon 09-Apr-12 11:31:16)

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