Kitz Forum
Broadband Related => ADSL Issues => Topic started by: Loading on March 09, 2014, 10:31:06 AM
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Does anyone have any idea about the spikes that appear in the QLN which relates then to not being able to use any of the tones after tone 123 as there is such large spikes?
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Also although it would have been said impossible for the connection to be better in the test socket, it appears not, if i try to sync at 2016 Kbps at 3.0db snr in the spare room, this would be stable throught the night, dropping down to 1.2db at worst, but in the test socket at the same 2016kbps it would sync, with a snr of 1.4db, fluctuating around 1.0db down to 0.6db. The speed was changed, by snr tweaking. This has me well and truly puzzled, that a longer line length throught the extensions would prove with a higher snr and to be more stable? ??? :o :no:
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Yeah seen that before here:
On top of hill
Master socket in hall at front
Study at back of house.
Sync direct from master socket is ALWAYS lower than sync when used on the study extension.
Cat 5e cable used between the two.
My explanation:
More RFI in the front of the house - less RFI at the rear.
Front of house points towards city and also a radio mast just visible on the horizon from top of house at night by the lights on the thing.
Additionally as I recall QLN was worse on the master socket than on the study extension as final confirmation.
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Yeah the QLN is slightly worse, half way up a hill, but seems on that before engineer worked on the line, the sync was faster in test socket, and more stable? The test socket points higher up towards the hill, but even a few weeks ago a higher speed could be obtained from the test socket? Also how come it is worse after the engineer fiddled and manage to add attenuation? Also neighbours have crackly lines, mines more hissy as hr fault. But it's the erratic QLN graphs as soon as its dark!
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I have read, that i could be the AC balance is too low, allowing the frequencies to interfere with the adsl? But how would the hr allow these signals on the line?
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The xDSL loop operates in differential mode. If the is any imbalance in the loop -- a HR or semi-conducting joint, for example -- then the common mode rejection that normally "takes care" of extraneous signals will be perturbed. ;)
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Is there an easy way for an engineer to look for a hr fault? What is differential mode
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Is there an easy way for an engineer to look for a hr fault?
Time domain reflectometry, frequency domain reflectometry, AC balance, basic resistive measurements, etc.
What is differential mode
Please take a look at these Wikipedia pages --
Differential Amplifier (http://en.wikipedia.org/wiki/Differential_amplifier)
Common-mode Rejection Ratio (http://en.wikipedia.org/wiki/Common-mode_rejection_ratio)
Common-mode Interference (http://en.wikipedia.org/wiki/Common-mode_interference)
Common-mode Signal (http://en.wikipedia.org/wiki/Common-mode_signal)
-- 'cause b*cat is very hungry and needs to go foraging for food! :yum:
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Can one see a possible HR (High Resistance) fault in the DLSstats/HG612 graphs, as I am starting to wonder if my High RFI in the evenings is coming in from an HR fault.
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Can one see a possible HR (High Resistance) fault in the DLSstats/HG612 graphs,
Only when it has developed into an extremely bad fault . . . then you may see big swings in the SNRM graph (in both positive and negative directions), coupled with a significant and sudden drop in SNRM when the pair is looped (by using the telephone). See Kitz' thread from the time when she was migrating from Be to Plusnet, for a good example.
as I am starting to wonder if my High RFI in the evenings is coming in from an HR fault.
b*cat begins to think that he has provided too much technical information and kittehs are "clutching at straws". ::) Yes, if your pair is not operating 100% perfectly in differential mode (and, to date, I have not seen a perfect pair) then there is the potential for common mode ingress of a disturbing signal. If you also have a non-linear element somewhere in the pair that will enhance common mode acceptance . . . of Radio China International, for example. :P
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Only when it has developed into an extremely bad fault . . . then you may see big swings in the SNRM graph (in both positive and negative directions), coupled with a significant and sudden drop in SNRM when the pair is looped (by using the telephone).
Burakkucat that rules me out then with HF fault cheers, and TBH your as close as you can get to OpenReach, your knowledge is fanstasic and helps all kittehs and we are in your debt hopefully some day we can repay you :)
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Happy to help . . . if I can. ;)
And I am still learning, 50+ years after first taking an interest in telecommunications. :swoon:
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Why are the errors much higher in the dry weather?
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Why are the errors much higher in the dry weather?
Sorry, I have no idea. :no:
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When my connection suffered from frequent, but intermittent disconnections, it performed far more reliably in wet, cold weather than it it did in warm, dry weather.
The fault was eventually traced to a poor connection between the underground cable & the pole mounted DP.
The theory was that the dampness actually 'filled' the space where the connection wasn't quite perfect & it opened up, causing disconnections when it dried out.
Dialling in from another phone would often improve SNRM & stability for a while (sometimes hours & sometimes for a day or so) as the additional dialling voltage temporarily 'welded' the connection at the DP.
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That seems to be very very close to whats happening with me but, don't suffer from the disconnections?
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. . . as the additional dialling voltage . . .
I suspect you intended to type as the "ringing" voltage . . . ? :-\
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Yeah ;D
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. . . as the additional dialling voltage . . .
I suspect you intended to type as the "ringing" voltage . . . ? :-\
Hmm.
I seem to be doing this a lot just lately :o.
I'll put it all down to the stress of work ???
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Also when the weather is hot, the sync speed is about 300kbps lower, also just seen another bt engineer leaving next door neighbor, so must be affecting more than just me!