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Sync drops when phone rings (subject was "Is this a record?)

Townman
Superuser
Superuser
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Registered: ‎22-08-2007

Re: Sync drops when phone rings (subject was "Is this a record?)

Hi,
A long and interesting story, which looks like it might be drawing to a conclusion, even if not ideal.  After weeks of trial and tribulation, it sounds like it boils down to BTw having configured a service on equipment known to be not capable of delivering that service without issue.
TBH it is unbelievable that equipment with such a fundamental failure (will drop DSL synch in the presence of ring current) is actually in use and thought to be acceptable. One wonders how many other users are similarly configured.  This is one for the lessons learnt list... If the user complains of loss of synch on in bound call then check these things.....
I recall a few years back that I could loose synch and not re-establish it until receiving an inbound call.
The more insight I gain to BTw/BTOR the more I despair for the future of the UK's digital network.  As noted in this thread, the delivery of FTTC should be prioritised for those areas presently receiving sub 8M before anyone else already getting this on DSL sees fibre.
Kevin

Superusers are not staff, but they do have a direct line of communication into the business in order to raise issues, concerns and feedback from the community.

jelv
Seasoned Hero
Posts: 26,785
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Registered: ‎10-04-2007

Re: Sync drops when phone rings (subject was "Is this a record?)

I see you've put me back on to fastpath as well.
I've tried an incoming call with iPlayer desktop reporting downloading at 6.3Mbps and let it run for the full time until 1571 kicked in: downstream CRC:2, HEC:5, upstream CRC:4. That's a dramatic drop from the hundreds of errors I was seeing previously.
I'll now have to see if the lower upload speed and lower priority on the BT network affects anything I do too adversely.
For getting to where I am now I really have to thank Andrews & Arnold who I contacted on 26th April about their money back guarantee:
[quote=http://aaisp.net.uk/broadband-trial.html]Like most broadband lines we make use of links from BT to connect your broadband line to our network. This is a sensible way of providing a broadband service to the whole country, but does mean we have to deal with BT - particularly if and when things break.
We pride ourselves in having a very capable team of people that deal with faults. We have a close working relationship with BT, and our team are well known within all parts of BT for not tolerating being fobbed off.
We have detailed monitoring of lines that allow us to quickly identify faults and take action to resolve them (whether BT, or changes at your end).
In fact, we are so confident we know what we are doing, we'll even take on problems other ISPs leave behind, and that is why we make this offer.
Give us a month and we'll sort your problem broadband line or your money back.
If you are migrating your service to us, even though you know you have a problem with your broadband line, we'll take on the fault. We'll tackle the problem and get it fixed within one month. If we don't then you can migrate away and owe us nothing for your migration to us and your service charges for that month.

We'll even give you visibility of the dialogue we have with BT on the fault tickets we raise (via our control pages) so you can see what is going on.
Within 15 minutes of contacting them via an enquiry on their website I'd been told it was a known problem on Marconi 20CN DSLAMs that only affected Max Premium users. They also said that in such a case they'd firstly request a tie pair change on to a different manufacturer. (Plusnet had been unaware of this issue affecting Marconi 20CN exchanges until they were told about it in one of the engineer reports)
I gave Plusnet support the opportunity to prove their worth. On Saturday I told them what I'd known for over a fortnight that it was only Max Premium that was affected. It was my request that if the latest lift and shift didn't help (totally expected as by then Plusnet had established that the exchange was Marconi only) we try dropping back to standard Max.
Interestingly, during the course of this I came across another ex-Plusnet user who had the same issue - he fixed it by moving to LLU!
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
Broadband: Andrews & Arnold Home::1 (FTTC 80/20)
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jelv
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Re: Sync drops when phone rings (subject was "Is this a record?)

I now have a very, very stable connection. Here's the stats for over 3 days 14 hours up time:
Downstream:
Noise Margin:  6.0    dB
Bandwidth:    7616  kbps
Attenuation:  21.0  dB
Power:        19.9  dBm
Errors:
  FEC:  0
  CRC:  16
  HEC:  25
Failures since last reset:
  LOF:  0
  LOS:  0
  LPR:  0
  ES :  16

Upstream:
Noise Margin:  24.0   dB
Bandwidth:    448    kbps
Attenuation:  14.0  dB
Power:        12.1  dBm
Errors:
  FEC:  0
  CRC:  15
  HEC:  N/A

The one mystery is why with my attenuation am I not getting a faster sync? I suspect the clue may be some tones not being used (see attached). If anyone is on 20CN with a full speed sync and a similar attenuation to mine I'd like to see their Bits/Tone graph to compare.
I'm thinking of digging out my old Netgear router to see what I get with that.
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
Broadband: Andrews & Arnold Home::1 (FTTC 80/20)
Line rental: Pulse 8 Home Line Rental (£14.40/month)
Mobile: iD mobile (£4/month)
Oldjim
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Registered: ‎15-06-2007

Re: Sync drops when phone rings (subject was "Is this a record?)

The 7616 limit is there when the line is interleaved http://www.kitz.co.uk/adsl/interleaving.htm although some routers are thought to bypass it
jelv
Seasoned Hero
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Re: Sync drops when phone rings (subject was "Is this a record?)

Interleaving is off! (sorry I should have also said that)
Edit: Zero FEC errors over 31/2 days if interleaving was on? That would be going some!
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
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Oldjim
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Re: Sync drops when phone rings (subject was "Is this a record?)

I should have said - I see interleaving is off (no FEC) but the relevant BT system may still think it is on
jelv
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Re: Sync drops when phone rings (subject was "Is this a record?)

Hmmm... That's possible - but I'm wondering if this is another 'feature' of these dratted Marconi 20CN exchanges.
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
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Anotherone
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Re: Sync drops when phone rings (subject was "Is this a record?)

I suspect the speed issue is a "feature" of these damned Marconi DSLAMs. As far as the tones go, 64 is the pilot never filled on 20CN, and 157 is currently the one only loaded with 2 bits. This seems to be another "feature" of 20CN not just Marconi cards. The tone only loaded with 2 bits can be anywhere lower down or a bit higher than 157. Your current SNRM plot (daytime) should be virtually flat. If you happened to resync where there wasn't a tone only loaded with 2 bits your SNRM would look something like the plot you started this thread with.
Edit: BTW is your 582n one without a USB port or one with?
jelv
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Re: Sync drops when phone rings (subject was "Is this a record?)

It's the lack of any bit's on tones 32 to 36 that I find significant. Also I'd be interested to compare the drop off on the other low end downstream tones with someone on a non-Marconi exchange.
Without a USB port.
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
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Anotherone
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Re: Sync drops when phone rings (subject was "Is this a record?)

32 is a guard tone, I'd thought we'd established that 33-36 were a feature of this damned Marconi DSLAM.
But, yes, sorry, so used to the shape of the fall off didn't take account of the missing tones and the fall off just above.
That fall-off is poor - here are some typical bit allocations with a 20CN TSTC Card & 582n combination
33 - 7bits; 34/35 - 8bits; 36/37/38 - 9bits; 40/41 - 11 bits; 42/43 - 12 bits; 44 - 11 bits, 45 - 12 bits; 46to63 - 13 bits;
What was the line card on your previous exchange by the way, when you had the 8.4.4.J firmware you had to change?
It would be interesting to see what you get from your Netgear and if you want to experiment a bit further, try 8.4.4.J with this Marconi card.
Edit: Have you removed your bell wires yet?
Anonymous
Not applicable

Re: Sync drops when phone rings (subject was "Is this a record?)

Quote from: Anotherone
Have you removed your bell wires yet?

Is that the Master socket or the bell end ?  Wink

Quote from: jelv
I'd be interested to compare the drop off on the other low end downstream tones with someone on a non-Marconi exchange.

How about this -
jelv
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Re: Sync drops when phone rings (subject was "Is this a record?)

What's your attenuation?
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
Broadband: Andrews & Arnold Home::1 (FTTC 80/20)
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Anonymous
Not applicable

Re: Sync drops when phone rings (subject was "Is this a record?)

10.0dB
Oldjim
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Re: Sync drops when phone rings (subject was "Is this a record?)

This may be of interest
This was the difference when I moved from 20CN to 21CN - 50dB attenuation
jelv
Seasoned Hero
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Re: Sync drops when phone rings (subject was "Is this a record?)

That's got the same gap between up and down. Were you on Max or Max Premium?
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
Broadband: Andrews & Arnold Home::1 (FTTC 80/20)
Line rental: Pulse 8 Home Line Rental (£14.40/month)
Mobile: iD mobile (£4/month)