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Standard User Bald_Eagle1
(committed) Wed 28-Mar-12 08:44:27
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HG612 Modem - Ongoing stats - Power Levels


[link to this post]
 
Hi All,

I am still attempting (after many months) to get to the bottom of why my 800m or so connection is quite unstable & can only sync at around 28Mb to 30Mb.

I have recently had a few days worth of an issue where downstream SNRM levels dropped dramatically when the phone (in the test socket via a dangly filter) was in use.

Even when the phone was not in use, DS SNRM levels dropped dramatically to 2dB or less.

As using the phone caused a further drop in DS SNRM levels, one occasion actually caused the connection to re-sync 4 times within a 10 minute phone conversation.

DS SNRM levels now appear normal & steady again, even when using the phone.

My question is, do any of you who monitor "Ongoing" stats via the Windows graphing scripts see fluctuations in DS power levels.

The available scripts do not currently graph power levels, but I am working on an update that will do so.

In the meantime, this is what my power levels look likethis :-

BE 6 Day Power Levels


In comparison, any other users' connections I have seen look like this:-

Other User 6 Day Power Levels


Arrrgggghhhh!!!!!!

While typing this message, my connection re-synced at only 21172 k - The phone was not in use at the time.

DS SNRM has shot up from 6.1dB to 9.9dB accordingly.

If anyone wants to send me their modem_stats.log for me to graph power levels, please send me a PM including an email address, or post the whole modem_stats.log somewhere that I can download it.


EDIT:

Within a few minutes, DS SNRM had dropped to 2.5dB & just picking up the telephone handset caused it to jump back up to 10dB.

Does this suggest a particular D-side or even a cabinet DSLAM issue to any of our erstwhile engineers?

Edited by Bald_Eagle1 (Wed 28-Mar-12 09:23:13)

Standard User yarwell
(sensei) Wed 28-Mar-12 09:51:29
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Bald_Eagle1] [link to this post]
 
total power will be the sum of the individual frequency bands / tones in use, so if the sync speed is changing as some frequency bands become unusable the power will go up and down.

Full sync speed ADSL on short lines always has more output power than slower speeds on long lines.

Phil

MaxDSL - goes as fast as it can and doesn't read the line checker first.

MaxDSL diagnostics
Anonymous
(Unregistered)Wed 28-Mar-12 10:30:15
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: yarwell] [link to this post]
 
Fibre uses VDSL


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Standard User RobertoS
(sensei) Wed 28-Mar-12 11:29:07
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Anonymous] [link to this post]
 
In reply to a post by Anonymous:
Fibre uses VDSL
No it doesn't.

Irrelevant to what yarwell said anyway. He was merely drawing a parallel with the known way the way power and frequency loadings work on ADSL.

____________________________________________________________________________
My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - Plusnet Value Fibre.

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
Anonymous
(Unregistered)Wed 28-Mar-12 12:20:40
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: RobertoS] [link to this post]
 
In reply to a post by RobertoS:
In reply to a post by Anonymous:
Fibre uses VDSL
No it doesn't.
Yes it does
Fibre to the cabinet (FTTC)

Fibre-to-the-Cabinet (FTTC) involves running fibre optic cables from the telephone exchange or distribution point to the street cabinets which then connect to a standard phone line to provide broadband.

This is combined with a copper cable from the cabinet to the home or business which uses VDSL
Administrator MrSaffron
(staff) Wed 28-Mar-12 12:23:25
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Anonymous] [link to this post]
 
The fibre element is NOT VDSL. The copper element from the cabinet to the property is the VDSL2 segment

Andrew Ferguson, [email protected]
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Anonymous
(Unregistered)Wed 28-Mar-12 12:32:08
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: MrSaffron] [link to this post]
 
That's just splitting hairs.
Standard User RobertoS
(sensei) Wed 28-Mar-12 12:35:04
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: MrSaffron] [link to this post]
 
Might be an idea to edit the page the Anon poster linked to Andrew? Completing his selective (frown ) quote - "This is combined with a copper cable from the cabinet to the home or business which uses VDSL or similar technology" it might be better to say "VDSL2 or similar technology"?

____________________________________________________________________________
My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - Plusnet Value Fibre.

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
Standard User yarwell
(sensei) Wed 28-Mar-12 12:36:48
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Anonymous] [link to this post]
 
That's just splitting hairs.


said the poster who wanted to differentiate one flavour of xDSL from another when the principle under discussion is common to both. LOL.

Phil

MaxDSL - goes as fast as it can and doesn't read the line checker first.

MaxDSL diagnostics
Standard User smurf46
(member) Wed 28-Mar-12 13:01:52
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: MrSaffron] [link to this post]
 
Haven't we got a bit sidetracked here folks? The interesting bit for (not just) me is "what can you reasonably report as an FTTC fault?". When you are talking about superfast, as you do in the news . . . endlessly - and BT for instance on my line quote a speed range as acceptable between 12Mbps and 38Mbps that's a wide range and a materially different level of service, especially problematic when the Quiet Line voice test is OK.

I know the lazy answer is "we don't know" - well it would be nice if someone made an effort to find out, or at least offer some intelligent pointers please! I can surmise that many resyncs (more than one a day?), a fluctuating profile of more than a couple of Meg, or widely varying noise margin of more than a couple of db (if obtainable from the modem) show something is not right, and should your tones also be fairly consistent, but with the OR faceplate your own phone set up is out of the equation? - but that's all a guess. Whilst my own line is not brilliant, but consistent and stable - so I've no complaint - I sympathise with the frustration of those whose lines aren't.

We see things not as they are, but as we are .
- Anais Nin

Edited by smurf46 (Wed 28-Mar-12 13:29:17)

Administrator MrSaffron
(staff) Wed 28-Mar-12 13:55:34
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: smurf46] [link to this post]
 
One problem is that VDSL is still new, so how it performs is a big unknown to lots of ISP support.

Also a lot of the time slow throughput is nothing to do with the VDSL component but more to do with the way the WBC backhaul some providers use (the majority of FTTC, until TalkTalk and Sky get their numbers up).

I would say that expecting a wider speed swing at peak times is to be expected on FTTC and FTTP. Logic and evidence from other countries suggests this is the norm.

In terms of drop outs/resyncs, should be no worse than ADSL, my guide is one or two a day (no matter how annoying with their timing) is OK, 10 to 20 a day and you are in fault investigation area.

The phone rining/picking up causing drops is sign of dodgy install, perhaps an engineer missed a star wire config so the abliet filtered phone) is causing problems. or a pre-existing HR fault is more evident at the VDSL2 frequencies.

FTTP would remove the resync/noise issues, but would do nothing for throughput, as backhaul issues would remain, and possibly be worse.

Andrew Ferguson, [email protected]
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User Bald_Eagle1
(committed) Wed 28-Mar-12 17:18:27
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: MrSaffron] [link to this post]
 
For my connection, the drop wire comes from the DP at the top of the pole across the road from my house to another pole on my side of the road & then straight into the master socket.

When FTTC was first installed the drop wire came in upstairs at the front of the house.

The installing engineer re-used my existing high speed braided data extension cable to reposition the master socket downstairs, near my P.C.

He then used a spare pair in the braided cable to back-wire to what was the original master socket upstairs, making it an extension.

A number of other phone extensions run from that socket, some plugged in & one hard wired in a daisy chain sort of configuration.

It all worked perfectly for around a month, giving me 33 Mb steady throughput download speeds (which must have meant a sync speed of around 35Mb on the original 8c profile - I didn't have access to any modem stats back then, June 2011).

Come near the end of July, my telephone & FTTC services were completely cut off for 4 days. I believe it was some sort of earth fault somewhere external to my house, but I have no idea exactly where.
My wife who was at home at the time the engineers visited told me it took at least 3 of them them a few hours to restore services.

Ever since then, my connection has been rather unstable (almost unuseable at times) with sync speeds as low as 7Mb or 8Mb.

Back in November, the drop wire was replaced from the DP at the top of the 2nd pole & rerouted to make the downstairs socket at the rear of the house a true master socket (the whole socket was also replaced), again re-using my braided cable to make upstairs the first extension socket.

I have tried a few 2 week periods of running the connection with everything else disconnected by removing the faceplate, both from when the drop wire came in upstairs at the front & more recently since it came directly in directly to the downstairs master socket.

I could cope with occasional slow throughput at congested periods.
However, I don't really see any congestion on my connection, usually achieving throughput of around 97% of IP Profile (regardless of the time of day), IP Profile usually being 96.79% of sync speed.

I suspect that an intermittent D-side HR fault was introduced at the time my 4 day loss of service was restored.

An engineer once used a 'Hawk' to run a TDR test on my connection from the end of the drop wire (when it came in upstairs at the front of the house), stating that he had found "something" near the cabinet.

On his return from his trip to the cabinet, he said he had found that someone had "absolutely stupidly" double-jumpered my connection, actually inside the cabinet, which must have been the cause of my connection's problems.

This engineer would not run another TDR test to confirm he had located & fixed the one & only fault as he said "it wasn't necessary".

Unfortunately, the removal of the double-jumpering appeared to have no lasting effect whatsoever on the performance & stability of my connection.
That was back in August 2011.

Despite being requested (by me), not one of the other visiting engineers have been prepared/willing to run a TDR test on my connection

I have tried to purchase a 'Mole' 301C tester on Ebay a few times, just so that I could run a TDR test myself, but was outbid in the closing seconds each time.

I have never achieved much in the way of bit-loading in the D2 frequency band & have never achieved anything at all from the higher D3 frequency band.

However, today I see that my Line & Signal attenuation have increase a little & I am achieving nothing at all from the D2 band:-

Text
1
23
45
67
89
1011
1213
1415
1617
1819
2021
22
# xdslcmd info --pbParams 
xdslcmd: ADSL driver and PHY statusStatus: Showtime
Retrain Reason: 2Max:    Upstream rate = 6015 Kbps, Downstream rate = 29240 Kbps
Path:   0, Upstream rate = 6004 Kbps, Downstream rate = 21172 Kbps 
Discovery Phase (Initial) Band PlanUS: (0,95) (868,1207) (1972,2783) 
DS: (32,859) (1216,1963) (2792,3939) Medley Phase (Final) Band Plan
US: (0,95) (868,1207) DS: (32,859) 
       VDSL Port Details       Upstream        DownstreamAttainable Net Data Rate:       6015 kbps         29240 kbps
Actual Aggregate Tx Power:        6.3 dBm          10.9 dBm============================================================================
  VDSL Band Status        U0      U1      U2      U3      D1      D2      D3  Line Attenuation(dB):  8.4     54.0    64.0     N/A    22.1    64.1    0.1    
Signal Attenuation(dB):  10.7    53.3     N/A     N/A    22.1     N/A     N/A           SNR Margin(dB):  6.0     6.1      N/A     N/A    10.3     N/A     N/A   
         TX Power(dBm): -4.1     5.8      N/A     N/A    10.9     N/A     N/A



Along with US attenuation looking rather high in comparison with other users' stats, fluctuating SNRM levels when the phone is used, fluctuating power levels most of the time (unlike other users' "straight line" power levels, regular re-syncs & low speeds, what else can I do to provide evidence that there is a physical fault - probably intermittent - somewhere between my home & the cabinet (or even inside the cabinet itself) to get this fixed once & for all?

My connection is probably only 800m or so in length.
Standard User Zarjaz
(knowledge is power) Wed 28-Mar-12 18:22:33
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Bald_Eagle1] [link to this post]
 
I'd be creating merry hell with your ISP. That does sound a bit HR-ish to me.

Standard User Bald_Eagle1
(committed) Fri 30-Mar-12 11:07:43
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Zarjaz] [link to this post]
 
Hi Zarjaz,

In reply to a post by Zarjaz:
I'd be creating merry hell with your ISP. That does sound a bit HR-ish to me.



It's taken from Sunday until this morning of constant stats updates to my ISP, but it appears they are planning to arrange an engineer's visit.

Apparently most ISPs don't see all the FTTC re-syncs as they are simply too quick (16 seconds or so) to be detected by the ISP & thus a new PPP session that an ISP would see is not initiated.

BT's reported IP Profile from their tester doesn't update until a new PPP session is initiated either.

I wonder how many users & ISPs have been confused by a high BT IP Profile, simply not being aware that the modem may well have re-synced very quickly at a much lower speed?

I have mentioned PQT/Eclipse tests tending to return a LTOK result & have also mentioned TDR tests.

I know it's almost impossible to diagnose unless actually on site, but do you have any suggestions as to what I should say, or ask of the engineer?

This does appear to be an "intermittent" fault where major symptoms, such as disconnections & large SNRM drops when the phone is being used, only last for a few days at a time.

Indeed, from around 8:30 this morning I can now use the phone with only a 0.1dB drop in SNRM.
I suppose that is normal?

Following more disconnections yesterday, the connection had re-synced yet again at only 24999 k in the early hours of this morning.
That looks suspiciously like a capped DLM sync speed profile that now needs to be reset to me.

Any thoughts?

The weather is much cooler & slightly damp today (quite misty), unlike it being very warm & dry over the last few days.

The last time I had this exact same issue, the weather had been very cold & very wet for quite a few days.

Is that probably just a red herring that could mis-lead everyone?


Cheers,


Paul.


EDIT:

I could now almost write a book about my various connection issues.

Oh, it looks like I already have done (32 forum pages so far anyway) smile :-


Topic: FTTC - Distance from the Cabinet - Realistic speed estimate (Read 16110 times)

Edited by Bald_Eagle1 (Fri 30-Mar-12 11:23:10)

Standard User Zarjaz
(knowledge is power) Sat 31-Mar-12 18:02:49
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Bald_Eagle1] [link to this post]
 
I'd be explaining to the engineer that you have an intermittent issue, mention the drop outs when the phone is used, mention the SNR dips in association with phone use.

Politely ask the the engineer if you can see the test results from the mandatory pair quality test, examine the difference in leg resistance figures. I would be looking for a difference of no more than 5 between A to earth and B to earth, the tester will often show a pass right up to 15 difference, but that can mask an HR. Ask what the TDR function shows, 'auto ID' may help if using a JDSU. You should be able to clearly see the DSLAM cab 'spiking' up on the TDR, that will give you the distance to cab.

Ask the engineer if the Boost of FTTC helpdesk (depends what type of fault has been raised) can see any issues on the RRTC data for your circuit.

On a manual (non scripted) test, check for ANY errors, also does the error count increment more when the phone is used at the same time....

If it is a JDSU, then you can ask to see the band statistics, that way you can compare them with yours !

When finished, and the engineer is telling you it's all fixed, ask if they can get a sync recalc done.

Happy hunting.

Standard User Bald_Eagle1
(committed) Sat 31-Mar-12 22:30:15
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Zarjaz] [link to this post]
 
In reply to a post by Zarjaz:
I'd be explaining to the engineer that you have an intermittent issue, mention the drop outs when the phone is used, mention the SNR dips in association with phone use.

Politely ask the the engineer if you can see the test results from the mandatory pair quality test, examine the difference in leg resistance figures. I would be looking for a difference of no more than 5 between A to earth and B to earth, the tester will often show a pass right up to 15 difference, but that can mask an HR.


Hmmm.
When an engineer requested a DLM reset (I take it that's the same thing as a sync recalc?) 9th March, he told me the result from the PQT was 61 whick looked O.K.
Could he have actually said 6 to 1 (meaning a ratio)?

He also mentioned AC balance, but I have to admit I wasn't sure what he meant by that.


Ask what the TDR function shows, 'auto ID' may help if using a JDSU. You should be able to clearly see the DSLAM cab 'spiking' up on the TDR, that will give you the distance to cab.


I seem to be having great difficulty in getting a TDR test carried out.
I have asked each visiting engineer to conduct one, explaining a suspected HR issue, but they always politely decline (apart from one who used a 'Hawk' from my master socket's incoming feed directly from the drop wire (no external junction boxes) & then identified & removed a double-jumpered connection at the cabinet).

He didn't retest the line though as he was convinced the double-jumpering must have been the cause.
Unfortunately it made very little (if any) difference.
Perhaps a retest MIGHT have detected another issue, possibly the real/main issue that has been causing the problems?

Are the wrong types of engineer being sent for the task (maybe PSTN engineers rather than broadband/fibre engineers?), or are they restricted to time, or given insufficient information via my ISP's notes I wonder?



Ask the engineer if the Boost of FTTC helpdesk (depends what type of fault has been raised) can see any issues on the RRTC data for your circuit.


Just so I "appear" to know what I'm on about, could you please confirm what RRTC stands for?



On a manual (non scripted) test, check for ANY errors, also does the error count increment more when the phone is used at the same time....


When SNRM drops to zero while using the phone (sometimes minus values) & the connection re-syncs, I see massive error counts in my graphs, but not when SNRM doesn't drop quite enough to cause a re-sync.

I'm not quite sure what you mean by a manual (non scripted) test???

If it is a JDSU, then you can ask to see the band statistics, that way you can compare them with yours !

When finished, and the engineer is telling you it's all fixed, ask if they can get a sync recalc done.

Happy hunting.



Thanks for the advice.

Frustratingly my ISP hasn't confirmed the visit date yet.

I hope the issue is still present when the engineer arrives.
It had disappeared for the last 2 days, until I used the phone this evening which caused a re-sync, now at only 18199 k.

On re-syncing at such a low speed, SNRM ended up at over 13dB.
When my connection is "behaving", SNRM is usually around 6dB

Subsequent dialing out & dialing in caused SNRM to drop by 7dB.
This continued for about 1/2 hour, with the drops in SNRM getting less each time.

Now, I can use the phone with only 0.2dB drop in SNRM, which I suppose is normal?

I have tried different handsets in the test socket (with & without dangly filters while the FTTC is still plugged into its dedicated socket) throughout these issues with the same results.

Mrs. eagle is now playing merry hell with me as all the other internal wiring has been disconnected for a week & she has to get up & walk at least 15 feet to use the phone.

It must be a real P.I.T.A. to track down intermittent faults, probably a case of needing to be in the right place at the right time.

Hopefully, I'll be updating things next week to say I am achieving at least 40Mb, with a completely stable connection.
Standard User RobertoS
(sensei) Sun 01-Apr-12 00:03:51
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Bald_Eagle1] [link to this post]
 
Mrs. eagle is now playing merry hell with me as all the other internal wiring has been disconnected for a week & she has to get up & walk at least 15 feet to use the phone.
...
Hopefully, I'll be updating things next week to say I am achieving at least 40Mb, with a completely stable connection.
Or else arranging a kennel connection as that's where you will be.

____________________________________________________________________________
My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - Plusnet Value Fibre.

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
Standard User Zarjaz
(knowledge is power) Sun 01-Apr-12 00:08:51
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Bald_Eagle1] [link to this post]
 
When an engineer requested a DLM reset (I take it that's the same thing as a sync recalc?) 9th March, he told me the result from the PQT was 61 whick looked O.K.
Could he have actually said 6 to 1 (meaning a ratio)?

He also mentioned AC balance, but I have to admit I wasn't sure what he meant by that.

Yes that's a sync recalc.
I'm guessing 61 was the AC balance. A 'mythical' overall test result, you can only raise an REIN fault if the AC balance is over 50.

So ask again, for a TDR test.
Are the wrong types of engineer being sent for the task (maybe PSTN engineers rather than broadband/fibre engineers?), or are they restricted to time, or given insufficient information via my ISP's notes I wonder?

No they will be FTTC trained, but there are 'engineers' and 'engineers' if you get my drift.

RRTC is the data helc on BTw's remote monitoring system, see's stability and the like, and gives results per day in a green yellow or red format.

Scripted tests on a JDSU, not worth a [censored] IMHO. Running a live manual test is the way to go.

Hope this makes sense, more than a little tipsy.... will check again in the a.m.

Standard User RobertoS
(sensei) Sun 01-Apr-12 00:14:31
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Zarjaz] [link to this post]
 
In reply to a post by Zarjaz:
.... will check again in the a.m.
It is "the a.m." tongue.

____________________________________________________________________________
My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - Plusnet Value Fibre.

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
Standard User Bald_Eagle1
(committed) Sun 01-Apr-12 07:33:56
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: RobertoS] [link to this post]
 
In reply to a post by RobertoS:
Or else arranging a kennel connection as that's where you will be.


smile smile smile
Standard User Bald_Eagle1
(committed) Sun 01-Apr-12 07:54:04
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Zarjaz] [link to this post]
 
Cheers Zarjaz,


In reply to a post by Zarjaz:
I'm guessing 61 was the AC balance. A 'mythical' overall test result, you can only raise an REIN fault if the AC balance is over 50.

So ask again, for a TDR test.


Oh No! I hope it hasn't been a REIN fault all along.

I've heard they are even harder to track down than internmittent line faults.

RRTC is the data helc on BTw's remote monitoring system, see's stability and the like, and gives results per day in a green yellow or red format.

Scripted tests on a JDSU, not worth a [censored] IMHO. Running a live manual test is the way to go.


O.K.

Hope this makes sense, more than a little tipsy.... will check again in the a.m.


I seems to make sense & thanks again.

The connection got a bit messy in the early hours of this morning & re-synced again at 23389 k.

Strangely, DLM has decided to turn Interleaving off again.

FWIW, these are my ongoing stats from the last 4 days:-

4 Day Stats

Cheers,

Paul.
Standard User Bald_Eagle1
(committed) Mon 09-Apr-12 09:48:57
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Zarjaz] [link to this post]
 
Well,

The engineer visited on Saturday morning.

He firstly ran a TDR test from the cabinet which on arrival at my home said was all clear.

He did say he had cleanedu up slightly corroded connections in the cabinet that may have made a slight difference.

He also replaced the filtered part of the faceplate & when carrying out various other tests from his Exfo, noticed that the last 5mm or so of the incoming drop wire snapped off one of the legs (insulation test failed).

He stripped back the insulation & all the other tests were then O.K.

The Leg Balance Test came back with a result of around 12 for each leg, which is apparently perfect.

A final TDR test on completion of his work was apparently O.K. too.

I don't have a photo of the trace, but it looked roughly like this:-

TDR Trace

The cabinet is shown by the large peak & the "hump" that I queried is apparently typical & nothing to be concerned about.

The engineer also said that it looks like the line is all copper, otherwise he would have seen other small peaks/troughs in the trace.

On requesting a sync recalc/DLM reset, the guy at the fibre centre (I think the engineer called it OMC or some similar abbreviation) mentioned they are aware of a long history of instability & frequent re-syncs & low(ish) speeds for my connection.

He & the engineer both agreed that I should really have a stable & slightly higher speed connection over the 834m line length as reported by the Exfo.

The OMC guy believes there is still some other "underlying" issue regarding my connection.
I wonder if the "hump" in the TDR trace is anything of a pointer.

I would say the "hump" is roughly one third of the distance from my house, going toward the cabinet.

Do you have any thoughts on this?


As the engineer first sorted the slight corrosion before running his first TDR test, we don't have "before & after" TDR traces, but the work carried out on Saturday appears to have cured the dropping SNRM when the phone is in use issue.
Now, SNRM only drops by around 0.1dB & 0.2dB when the phone is in use.

SNRM, fluctuating output power levels, attainable rates, error counts etc. all now appear quite stable.

However, from my modem stats, attenuation for each band is still slightly higher than it was for a few months previously.

from the Exfo:-

Text
1
23
45
67
8
US      DS
Actual Line Rate        6       24Max Rate                6       33
Capacity                100%    75%Noise Margin            6       9
Output                  6.3     11.2Loop Attenuation        7.9     31.6
Signal Attenuation      11      31.4


DS attenuation looks surprisingly high & US attenuation looks surprisingly low when compared against previous JDSU stats.

Is that a known phenomenon with the 2 different testers?


My sync speed is currently 32209 k, whereas a fairly recent DLM reset (a couple of weeks prior to the SNRM issue) achieved a sync speed of 35322 k.
Standard User Zarjaz
(knowledge is power) Mon 09-Apr-12 11:07:08
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Bald_Eagle1] [link to this post]
 
Sounds like the engineer was fairly thorough.

Loving your picture of the TDR trace, Looks to me like a side on view of Mr + Mrs.Zarjaz's bed first thing in the morning ! smile

Yes, seeing the DSLAM cab appearing as a hike/spike/peak on a TDR is normal.

I don't agree about a TDR showing whether the pair is all copper. Network records, or local knowledge is the usual route.

The 'hump' ain't right, but then you'd really have to be looking at the result for yourself to judge.

I can't say if that's a known issue with an Exfo, I don't use one. The hopeful thing is that the D/S shows only at 75%, so if it does now stay stable, and.....

appears to have cured the dropping SNRM when the phone is in use issue.
Now, SNRM only drops by around 0.1dB & 0.2dB when the phone is in use."


.. looks promising, then more speed could be achievable.

Stability is the thing now.

Good luck.

Standard User Bald_Eagle1
(committed) Mon 09-Apr-12 11:29:45
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Re: HG612 Modem - Ongoing stats - Power Levels


[re: Zarjaz] [link to this post]
 
Cheers Zarjaz,

We did have a look at Network Records - no evidence of ally there either.

What they did confirm for me though, was that an additional 60m is added to my connection that I wasn't aware of as the cable goes underground past my house by 30m to a footpath joint chamber & then doubles back again to the pole directly across the road from my house.

The 75% was no doubt showing as my connection was still stuck at 24999 k at that point (before the DLM re-set).

Reading up on TDR stuff (like I do wink), a 'hump' can apparently be the result of "an impedance mismatch that is caused by an inductance discontinuity in the transmission line."

In other words, an open circuit, or in my language, "a dodgy joint".

Your'e right though, a stable connection is the most important thing now.

Edited by Bald_Eagle1 (Mon 09-Apr-12 11:31:16)

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