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Author Topic: large swings in snr (eci), resyncs etc - advice sought please  (Read 10563 times)

skyeci

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Hi,

Any ideas what leads to large drops in snr... I have had 3 recent resyncs within the last 24 hours. At one point the DS snr dropped to 0.8. I have asked my ISP (sky) to do some tests and not surprisingly they said all was normal...

Thoughts about what can cause the large snr drop appreciated.

thanks

broadstairs

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Re: large swings in snr (eci), resyncs etc - advice sought please
« Reply #1 on: April 27, 2017, 04:24:00 PM »

This is rather like what I was experiencing for some 4 months last summer with TT and an ECI cabinet, you can see some wild swings on MDWS between May and September 2016. TT always said they cold find nothing wrong when they tested. It was never fixed - it just disappeared despite 3 BTOR visits.

Stuart
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skyeci

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Re: large swings in snr (eci), resyncs etc - advice sought please
« Reply #2 on: April 27, 2017, 06:27:30 PM »

Thanks - I recall all the trouble you had. I have have had a lengthy open case with sky which eventually resulted in rein engineers visting . They have advised there is rein present but unable to resolve even though its affecting their network. The reason for my question was even though the line is affected by rein supposedly  it normally doesnt suffer with all these resyncs which seems to be a new thing now..

Chrysalis

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Re: large swings in snr (eci), resyncs etc - advice sought please
« Reply #3 on: April 29, 2017, 03:44:49 PM »

is mdws down right now? I get a blank white page.

Since I cannot load it can you confirm your US margin is going down to close to 2db snrm?
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ejs

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Re: large swings in snr (eci), resyncs etc - advice sought please
« Reply #4 on: April 29, 2017, 04:33:22 PM »

From the posted graph, I assumed the vertical axis was 0, 4, 8, 12, 16, but the "1" digit had been cropped off.
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skyeci

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Re: large swings in snr (eci), resyncs etc - advice sought please
« Reply #5 on: April 29, 2017, 04:56:25 PM »

sorry - this might be a bit better. Couple of snapshots around the resyncs, Since the 4 resyncs with overall loss of 4mb on the ds sync but attainable still below sync with snr under the target I am not seeing any further resyncs but I am seeing regular SES. At the time of the resyncs the 24 hour period was 535 ses or something along that lines.

It just seems to be getting worse but OR seem unable to help any further. Sky never seem to detect any faults either. They have said they won't pursue things until the sync goes below 60.5 - currently around 67 sync with attainable lower than sync which has always been the problem.

Thanks

Chrysalis

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Re: large swings in snr (eci), resyncs etc - advice sought please
« Reply #6 on: April 29, 2017, 05:32:50 PM »

looks a mess, sadly tho the way this service is supported is very simplistic, they dont really care about snrm that fluctuates, it is why there is a snr margin so fluctuations can occur.

All they really care about is 2 factors, line stability and line performance.  By stability I mean outages or packet loss not a flat lined SNRM.

So unless your line drops out excessively or the sync speed falls below the figure given to you by sky there is not much you can do.
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skyeci

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Re: large swings in snr (eci), resyncs etc - advice sought please
« Reply #7 on: April 29, 2017, 05:42:37 PM »

here's hoping it will just give up eventually then something might be done perhaps...

thanks for taking a look

ses 550

burakkucat

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Re: large swings in snr (eci), resyncs etc - advice sought please
« Reply #8 on: April 29, 2017, 05:58:25 PM »

I am wondering if there is a developing high resistance joint in the circuit.

Have you recently tried a Quiet Line Test and a Faultsman's Ring-Back, via 17070, whilst watching what DSLstats reports?
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skyeci

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Re: large swings in snr (eci), resyncs etc - advice sought please
« Reply #9 on: April 29, 2017, 06:11:51 PM »

Hi bc

Quiet line test says it can hear echo but not noise. I notice the ds snr falls a few points (e.g 5.8 to 5.5)when making a call out- is this normal?

I told the rein engineer about the echo  on the test but was not concerned with the result.

qln around the worst of it and hlog around that time of the 3 resyncs I think possibly after, not sure tbh

thanks
« Last Edit: April 29, 2017, 06:14:05 PM by skyeci »
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burakkucat

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Re: large swings in snr (eci), resyncs etc - advice sought please
« Reply #10 on: April 29, 2017, 06:27:23 PM »

I notice the ds snr falls a few points (e.g 5.8 to 5.5)when making a call out- is this normal?

There will be extra loading applied to the circuit when a telephone has "looped the line" to originate or answer a call, so I would not be too concerned with an observed drop in SNRM of, say, 0.2 - 0.3 dB.

Quote
qln around the worst of it and hlog around that time of the 3 resyncs I think possibly after, not sure tbh

Both the QLN and the Hlog plots that you have shown do not give me any cause for concern (although you have only shown a section of each). A G.993.2 (VDSL2), Profile 17a, circuit has 4096 sub-carriers available (numbered from 0 to 4095).

If the circuit was being troubled by a HR (or semiconducting) joint, it would most likely become visible in the SNRM plot -- coinciding with usage of the telephone.
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skyeci

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Re: large swings in snr (eci), resyncs etc - advice sought please
« Reply #11 on: April 29, 2017, 06:30:06 PM »

Ok cheers.

Will see how things progress in time..

skyeci

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Re: large swings in snr (eci), resyncs etc - advice sought please
« Reply #12 on: May 14, 2017, 09:07:20 PM »

I am wondering if there is a developing high resistance joint in the circuit.

Have you recently tried a Quiet Line Test and a Faultsman's Ring-Back, via 17070, whilst watching what DSLstats reports?

More trouble this evening.. DS SNR just hit 0.0! - bands look a mess. 140+ SES..

wish  I could get this sorted.. - any further thoughts?

cheers



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burakkucat

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Re: large swings in snr (eci), resyncs etc - advice sought please
« Reply #13 on: May 14, 2017, 09:27:09 PM »

More trouble this evening.. DS SNR just hit 0.0! - bands look a mess. 140+ SES..

wish  I could get this sorted.. - any further thoughts?

There is definitely a fault in the metallic pathway but as to the nature of the fault, I am not too sure. Initially I thought there might be a HR or semi-conducting joint. However the plots you have shown do not "fit the pattern".

I wonder if WWWombat has noticed anything?  :-\
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skyeci

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Re: large swings in snr (eci), resyncs etc - advice sought please
« Reply #14 on: May 14, 2017, 09:29:40 PM »

resync at -2.0 on the DS... so gradual loss from 73mb sync only a few months ago.

seems to have a mind of its own..

all over the place now sync wise..
« Last Edit: May 14, 2017, 09:48:06 PM by skyeci »
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