Kitz Forum
Broadband Related => FTTC and FTTP Issues => Topic started by: ColinS on June 02, 2013, 10:40:09 AM
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Please see the attached snapshot below.
IMO, it appears to be, more or less, 2:1 (thanks Eric!) square-wave periodic, and has been like this since it 'suddenly' appeared at about 3pm on 08/05/2013. Not causing me any problems, but it is strange, to say the least. Can't think what it could possibly be trying to achieve if it's deliberate. :-\ There is no corresponding pattern in output power levels in case you were wondering.
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What does it look like if you reduce the number of hours per page to 2 (say)?
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Like below Eric. For possible reassurance, a copy of BE's equivalent graph is also attached. :)
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I have a slightly similar issue in my thread to this, not sure as to the cause though. A couple of months back mine was virtually flat all day long.
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It seems to go up and down on a roughly 10-minute cycle, with about 3 minutes at the higher level and 7 minutes at the lower. I can't think of anything obvious which has that sort of cycle.
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It seems to go up and down on a roughly 10-minute cycle, with about 3 minutes at the higher level and 7 minutes at the lower. I can't think of anything obvious which has that sort of cycle.
Yeah, and it's hard to decide if the excursions are positive or negative. Presumably downward :-\
Like you, I can't think of anything (certainly not around here!) with that sort of cycle, and the squared-off flip-flop nature of it is very unusual.
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I have a slightly similar issue in my thread to this, not sure as to the cause though. A couple of months back mine was virtually flat all day long.
Yes, I was tempted to answer your question with +/- 0.5dB :lol: But I thought it was best not to confuse matters. I've had ONE night since this started when it suddenly went flat again, but then reverted to the flip-flop business again in the morning. The cynic in me believes it's something in the cabinet, but then I would say that wouldn't I. ::)
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I've seen that on a DG834GT before - was the wall-wart PSU.
Got another you could try?
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I had this 7 days ago when I had a re-sync (manual restart), exact same but more frequently. After 4/5 hours just went flat, wasn't there before I restarted the modem appeared after the re-sync so was kinda weird for me.
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I've seen that on a DG834GT before - was the wall-wart PSU.
Got another you could try?
Well, if you're referring to the one that powers the modem, in a way I already have: during this time I have swapped out the HG612 for the HG622 and back again, and this ripple continued unabashed.
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I had this 7 days ago when I had a re-sync (manual restart), exact same but more frequently. After 4/5 hours just went flat, wasn't there before I restarted the modem appeared after the re-sync so was kinda weird for me.
:hmm: It's only gone flat for me once during the last month - once overnight - without other intervention (e.g. resync). Are you on the HG612 too, I can't remember if you said somewhere?
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Yea, I'm using the HG612.
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Thought it might be informative to show the impact that this SNRm 'ripple' has on bitloadings. :graduate:
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Have you checked it's not the VDSL2 faceplate filter?
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Have you checked it's not the VDSL2 faceplate filter?
Actually, I don't use a SSFP. I'm on distributed filtering. :) However, I have changed these, yes.
There has been a change today that makes me more certain that it is the DSLAM. After a resync at ~5:30 this morning, it continued with the same ~7 min 2:1 square wave for another 3 hours before settling into something more like the normal line variation for 7hrs before a ripple re-emerges, though now at half the amplitude and twice the rate!
Go figure, but my guess is it's the DSLAM itself. Perhaps a faulty line card or PSU in the cabinet. :-\ Still can't think of any useful reason for such behaviour. :no:
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Have you reported the issue yet?
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@ Colin,
We do know that all DSLAMs provide a beacon signal for TDR trace applications.
I wonder if that might be affecting your observations ?
Kind regards,
Walter
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Have you reported the issue yet?
Well Ryan, it's a bit like when the hospital xrays your chest - they may see things that aren't actually causing you any harm, but everybody thinks "Mmmm. That doesn't look right does it? Let's open him up and have a look." :no: :lol:
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We do know that all DSLAMs provide a beacon signal for TDR trace applications.
I wonder if that might be affecting your observations ?
:hmm: Interesting suggestion Walter. Wouldn't everyone see it then, or could it be that it's just attenuated out of sight on longer D-sides?
Very helpful thought though, thank you.
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I understand fully what you are saying Colin and you would get that... if you contact the wrong department.
Just contact BT Care or the ELC team and they will actually be able to deal and attempt to diagnose the problem.