SNR Drops Under Load??

When I'm downloading my downstream SNR goes from 6.3db down to as low as 5.6db...

Is this normal??

When I'm downloading my downstream SNR goes from 6.3db down to as low as 5.6db...

Is this normal??

Does it actually affect any of the connections functionality ????

If that's a no, (and I'll wager it is) then stop fretting, go out, enjoy the sun.

Well it seems to make the connection less stable than it used to be...

BQM also seems to be a lot more jittery that it used to be when downloading... actually I remember the BQM staying pretty smooth when downloading at high speed, it was only uploading that upset the BQM...

and I'm not sure but would say DLM won't look kindly on my SNR going from 6.4 - 5.6 and hopping up and down during the time the connections under load.

I think your reply is harsh, he didnt ask if he should stop worrying about it.

To the OP its definitely not normal, it would suggest maybe when the router/modem is more busy its increased power draw is interfering with the signal. Or possibly the device downloading to its higher processing is the source of interference.

I would make sure power cables are not tangled up with any other cables, if you have separate router/modem close to each other maybe move them further apart. IF these options are not available then do some diagnosis with swapping out equipment.

DLM wont care about your snr margin, it will only be bothered if your ES rates get too high or if you have too many lost sync events.

Also using BQM for diagnosis for this is not a good idea, downloading creates utilisation and yes can cause jitter, especially without bandwidth policies.

Why have you chose to not make your VDSL TBB BQM public?

Edited by Chrysalis (Tue 29-Mar-16 06:20:47)

My SNR has plummeted to 2db on downstream while up seems barely affected meaning next time my modem resync's I'm going to be losing 15+Mb/s....

How does this happen in a matter of hours.... Now extremely dissapointed... and not looking forward to the arguing with BT I'm gonna need to do to get this sorted ''

I think this might be something to fret about now

Yesterday's Stats:

lcmd info --pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 24114 Kbps, Downstream rate = 78100 Kbps
Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 78564 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Discovery Phase (Initial) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3959)
Medley Phase (Final) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3959)
VDSL Port Details Upstream Downstream
Attainable Net Data Rate: 24114 kbps 78100 kbps
Actual Aggregate Tx Power: 7.1 dBm 13.4 dBm
====================================================================================
VDSL Band Status U0 U1 U2 U3 U4 D1 D2 D3
Line Attenuation(dB): 4.6 22.1 33.1 N/A N/A 11.7 28.6 43.7
Signal Attenuation(dB): 4.6 21.1 32.3 N/A N/A 13.2 28.4 43.7
SNR Margin(dB): 16.1 15.7 15.5 N/A N/A 6.3 6.2 6.3
TX Power(dBm): -2.5 -21.5 6.6 N/A N/A 10.2 7.9 7.0

Today's Stats:

xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 22253 Kbps, Downstream rate = 63720 Kbps
Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 78564 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Discovery Phase (Initial) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3959)
Medley Phase (Final) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3959)
VDSL Port Details Upstream Downstream
Attainable Net Data Rate: 22253 kbps 63720 kbps
Actual Aggregate Tx Power: 7.1 dBm 13.4 dBm
====================================================================================
VDSL Band Status U0 U1 U2 U3 U4 D1 D2 D3
Line Attenuation(dB): 4.6 22.1 33.1 N/A N/A 11.7 28.6 43.7
Signal Attenuation(dB): 4.6 21.2 32.1 N/A N/A 13.2 28.4 43.7
SNR Margin(dB): 13.3 12.5 12.5 N/A N/A 2.4 2.4 2.4
TX Power(dBm): -2.5 -21.5 6.6 N/A N/A 10.2 7.9 7.0
#

What the hell has gone wrong???

I see now you on g.inp, has this helped at all?

Been on G.INP for months now, since it was still showing 100+attainable....

I had to resync the modem this morning, There was errors occuring and streams kept dropping, I think G.INP as now been enabled on upstream as a result.

This is my speed now compared to 72/18 on Thursday

Edited by mlmclaren (Sat 02-Apr-16 12:34:50)

What are your speed estmations on the DSL checker?

Looks like you may need an engineer visit.

80 - 64

PS. I need to check a neighbours connection but he's on Sky... and I think 40/10

Edited by mlmclaren (Sat 02-Apr-16 11:58:34)

In reply to a post by lee111s:

Looks like you may need an engineer visit.

Well after 'finally' getting through to someone 'representing' BT, they first said no faults...blah blah blah... usual 'is this over wireless' blah blah blah...

Anyway he then runs more tests and says, there's a network fault, he said that someone will monitor my connection and then call back in 4 days 'on the 3/4/2016'

I still get a gut feeling this is going to be escalated as a complaint so I can talk to someone in the UK.... this is where BT sucks!

Their online troubleshooting is funny too... its based on a traffic light affect... "does you hub show, Blue, Yellow, Red.."

What a load of pish!

In reply to a post by lee111s:

Looks like you may need an engineer visit.

Well BT's customer service is definitely a new level of non-existence!

They've done nothing, not even spoke to anybody from BT since this time last week and then I was promised a call back...

The DSL line continues to be unstable, one day its reporting loads of errors of downstream (scary considering I have G.INP enabled) and then its errors on upstream, then the SNR's rising and sinking....

It been a bit more stable the last 24 hours but no where near what it used to be...

Folks over at Kitz think it may be a split pair, I've done endless amounts of troubleshooting, even powered down everything but the modem to check noise noise coming off anything in the apartment and even tested other DSL equipment, cables, even tested from the entry point of the line to rule out dodgy run of cable.

I've now logged a complaint with both BT and Ofcom regarding the last 4 months of poor customer care, lies and also what might be a breach of contractual agreement.

In reply to a post by mlmclaren:

BTInfinity - 66000/21000kbps

I see your new sig claims a speed above the upstream cap of 20000. Or are you using your max attainable?

max attainable

At Last :

Finally got someone from BT that understands DSL!

At first they said that my line was performing inside the estimates, however I then asked if they knew what SNR was....

I explained that my sync was 78000kbps with stable 6.3db SNR but then its dropped to 2.4db and was dipping to 0.2db over night until I was forced to resync due to rising errors, then explained how there continued to be errors even after resyncing at the -15mbps lesser rate and that the SNR still continuing to jump around.... I went to go on but he stopped me and said he would book an engineer in that case.

So engineer booked for Wednesday morning, hopefully can get this sorted, anyone got any recommendations of what to ask when they arrive?

I'll mention the split pair possibility, maybe ask them for a pair swap and DLM reset?

Well my connections now worse off.... Engineer didn't know abotu Error correction... all we know is theres a REIN issue outisde the the apartment block, a pair change hasn't improved anything.

Also learn't that there a 200 pair cable running down the street from PCP that feeds our 50 pairand that 200 pair is aluminium....

Also learnt that the little white tube next to the 50 pair rising in the DP cupboard contains a fibre (inactive) don't know who's but from when it was office building.

End result, still got loads of erros on line, been interleaved and still getting errors....

Nothing REIN wise will be done unless other customers complaine and even then "good luck"

So once again Openreach have proved themselves useless, wasted my time and ruined my connection a little bit more.

Just thought too, whats going to happen when another 183 apartments become availble next door....

I might just cancel this rubbish BT service and get an ADSL connection....

EDIT: Until I move!

Edited by mlmclaren (Wed 13-Apr-16 12:55:35)

What do you propose Openreach do regarding the REIN issue? Their network is not the problem.

No one has lawful powers to force whatever is causing the REIN issue to be resolved.

At least try and find it!

Exactly! Openreach can see there is a problem, they may even be able to trace it, however, as you say, they cannot force those responsible to change/modify/repair/remove the cause or equipment.

Openreach have, in this case, done all they can.

Well the Openreach guy I had couldn't be certain it was a noise ingress issue and wasn't going to recommend a REIN engineer come check it out, actually he seemed to wanna put the blame on internal cabling from DP to Flat despite the issues still existing from the DP itself.

Once again BT just dismissing problems as not theirs!

If the line conforms to SIN349 then that's all Openreach have to prove.

Isn't that voice based?

Yes, which is all Openreach are legally obliged to provide.

Well done to our government for investing all that money into a company that will keep the nuisance calls ringing I suppose.....

[censored] useless bunch of [censored]...

In reply to a post by mlmclaren:

Well done to our government for investing all that money into a company that will keep the nuisance calls ringing I suppose.....

[censored] useless bunch of [censored]...

What money into what company?

HMG certainly do not have any investment in BT or any of their subsidiaries.

Giving Openreach funding to roll out "superfast" broadband...

Yes investing was the incorrect word to use.

The government bought a service from BT. They didn't "give" them funding they paid to get works done and additional services added. There are contracts around it and the local authorities share in the profits above contracted thresholds. Would you say when you buy a toaster from a company that you are "giving them funding"?

Sorry but why pick at this, you all know exactly what I mean.... whether they brought it, funded it, invested in it....

The message I'm trying to get across is that money has exchanged hands/accounts for a next gen network to be built and that isn't what folks have got....

It's become more of a temporary gap fix that is now starting to fail, due to the lack of money, maintenance and the correct regulations and guidelines behind the idea.

I disagree

That's fine....

I'm past caring now to be honest, nearly didn't bother posting that last reply.

Only responded because a lot of people think BT have been given a handout as if it was a charitable donation rather then them being paid to provide a service. Many people seem to be of the opinion that BT were given something for nothing to bolster their profits.

That's not what I'm saying.... what I'm saying is that work has been done to fill a gap when more gaps are going to appear, 'I' think they should of just done it properly the first time, but as usual just a big competition for who's got the biggest .....

If you pick up the phone, does the SNR change at all vs. normal SNR fluctuations?

I remember having an issue a few years ago that looked like REIN but turned out to be a dodgy Tee connection which annoyingly was a direct-burial. The SNR would fluctuate and cause our ADSL connection to go down and there didn't seem to be any particular pattern to the behavior apart from sometimes picking up the phone would cause it to go haywire.

No-one knew what they were talking about until we got an engineer around when the issue was happening and he found it to be a problem located under the pavement so over the next month they had to dig a new box and new lead-in cable up to the box on the house.

Also if you pick up the phone (hard wired), is it completely silent or is there some crackling? If it's crackling then you need to get that sorted as that's a fault immediately and could be the cause of your SNR woes.

Edited by chris6273 (Thu 14-Apr-16 13:53:45)

BT have just notified me that the Broadband Boost engineer they booked was cancelled by BT Wholesale and that one of their engineers was sent instead, which might explain him not understanding what he was looking at half the time when it came to DSL.

As far as a QLT goes its fine, however I have no phone connected or filter for that matter, just direct from NTE to HG612 Modem.

I am going to run a test in a moment though, see if ringing the line upset the modem...

Well 2nd engineer came this morning, a real Broadband engineer this time...

He determined the issue is bad aluminium length which is struggling with crosstalk and also a REIN issue...

Aluminium cable issues is common around the area aparently and Openreach aren't interested in replacing any cables.... specially on BDUK funded cabs too aparently...

The REIN issue could be located if an engineer was sent out but thats a different fight and all he could do is make a note...

We also determined that BT's DSL testing kit is not G.INP capable which is fine, just shows that my speeds are well below BT's expectations...

I get the feeling that if it wasn;t for G.INP, alot of connections would now be performing underneath there expectations.... but for that matter it impressive how much improvement G.INP provides on a line too.

Shame it don't seem to be on upstream anymore....

As it stands connections still got a lot of errors on upstream, downstream has a few Errored Seconds and a mighty whole load of FEC's (which is fine because of G.INP ut theres a lot more th there should be), and currently still seeing chunks at 3-4mb a go dissapearing off my sync and SNR dipping (crosstalk...new lines..)

So the guy appologised, expressed dismay about Openreach and there inabiltiy to do whats required of them... yadda yadda yadda... oh and wished me look when the 180+ apartments next door come on... he said "that's when it will get interesting, both capacity and cable quality wise"

Think its time for some more investigations into the UK's telecoms infrastructure, it don't seem to be going in the direction it should be... however that my oppinion and I'm sure some will stick up for Openreach as usual. :L