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Author Topic: Diagnostics for BT Voyager 105 USB modem.  (Read 10115 times)

Roy22

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Diagnostics for BT Voyager 105 USB modem.
« on: April 22, 2006, 12:30:17 PM »

I've been following this site's very useful info re using modem diagnostics to find out SNR and other info for my connection.  Like many people, my BT 2Mb connection  is plagued with random dropped connections, and it seems it's down to customers to solve their own problems.

I'm running the modem using the latest available drivers downloaded from BT.  Problem is, to 'save download time' BT have removed the 'diagnostics' function from the download, and of course contacting their Voyager help dept has not got me any help at all.

So, does anyone know where I can get the diagnostics-enabled driver for the Voyager 105 USB?  Without the line quality info, I won't know what to start replacing/improving in my system....
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Roy22

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Diagnostics for BT Voyager 105 USB modem.
« Reply #1 on: April 22, 2006, 04:39:56 PM »

OK, looks like I won't need the 'diagnostic tool' as despite it having been removed from the download, I have (again thanks to this site) found a hidden menu which reveals far more info than I can pretend to understand.

But, it does show my line stats (Local/Remote) which are: Attenuation=44.5/25.5, SNR Margin=18/26.

If I understand the 'interpretation' guide correctly, the SNR Margin is fine but the Attenuation is just below the lower limit for 2Mb.  Is this right?  Can you really have a good SNR margin plus bad Attenuation?  Surely SNR would suffer alongside Attenuation problems?

Most of the hints on this and other websites are about improving SNR Margins, using shielded cables/ADSL Master Socket or else using modem/routers than can better cope with poor SNR's.  But I don't see much mention re Attenuation?  Samknows.com says I'm only 1.92km from the exchange, so I would not have expected my distance to be a problem?

Can any clever person tell me whether I have any options worth trying to fix this intermittant problem (eg new modem/router?) or whether I can only ask for a downgrade to 1Mb?!
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kitz

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Diagnostics for BT Voyager 105 USB modem.
« Reply #2 on: April 23, 2006, 11:23:43 PM »

Hi roy

Glad you sucessfully found the hidden feature in the Voyager 105.

Yes you have indeed seemed to interpret your line stats correctly, and under the "old rules" it is unlikely that BTw would have given you a 2Mb connection... although sometimes it really does depend on "the mood" of the BTw database :/

An SNR margin of 18dB though is good, and from thatI would expect your line to be able to cope with 2Mb speeds.
One thing about SNR margin though is it can (and does) vary at different times of day and weather conditions.
It would be interesting to know what your SNR margin shows when you loose sync.

Attenuation should remain static at all times... its this that is related to your line length.  One thing to bear in mind that although samknows may say you are 1.92km from the exchange, this is as the crow flies.  Telecom cable does not take a direct route, and can be a heck of a lot more.


Have you tried plugging your router in to the test socket behind your master socket?  This is one of the best ways of finding out if better filters or sheilded cable is worth considering.
I know it may be a PITA plugging in at the master socket, but its certainly worth trying to see if anything can be improved.

Details how to do this here
http://www.kitz.co.uk/adsl/troubleshooting.htm

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Finally it may be worthwhile asking your ISP if they can consider putting you on maxdsl.  maxdsl uses kit in the exchange to monitor your line stats, and after a period of 10 days should hopefully be able to find your MST (maximum stable rate) which is best for your particular line.
However, before you do that, check out if theres anything on this checklist here that you can do
http://www.kitz.co.uk/adsl/lowSNR.htm
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Roy22

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Diagnostics for BT Voyager 105 USB modem.
« Reply #3 on: April 24, 2006, 08:52:40 PM »

Yes, I have connected straight to the master socket, which raises SNR margin to 23dB, but dosen't change Attenuation.  Removing a hardwired extension (which I will soon filter at the start rather than the end when I get an ADSL faceplate) greatly extends the SNR margin per bin graph, so I have hope that improving my internal wiring will help.

I agree it would be nice to know if SNR falls too low before a dropped connection, but how can I monitor it automatically?  The Log File options doesn't seem to do this?

I've had my line length checked in detail (thanks to www.samknows.co.uk) and it is indeed 1.9km, so the 45dB attentuation is much higher than it should be.

The question is, should I raise this attenuation issue with BT and if so, which part of that huge entity?  I would obviously be happy if someone found a poor connection somewhere, but will they just downgrade me to 1Mb?
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kitz

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Diagnostics for BT Voyager 105 USB modem.
« Reply #4 on: April 24, 2006, 11:06:19 PM »

Since your SNR improves when using the master socket then it does indicate that there are things that can be done to perhaps improve it such as the NTE5 faceplate.

Unfortunately there isnt any way that I know of where you can automatically monitor your line stats if you use a modem.  Some routers give you something called snmp which with the aid of mrtg allow you to do this.
Its not for the faint hearted though and needs a fair bit of experience and also an advantage if you know perl (as Ive just found out) :/

>> but dosen't change Attenuation

- as mentioned above your attenuation is normally fairly static and more depends upon the length of your line.

>> I've had my line length checked in detail (thanks to www.samknows.co.uk)

The samknows site cant check your line length in detail... it just provides an indication "as the crow flies" in a straight line distance from A to B.
As already mentioned BT cabling can and frequently does go all around the houses before it reaches a destination. :/

For example for me it says
"You are approximately x metres from the exchange (straight line distance)."

Yet I know from a BT engineers test that was performed in the past on my line that it is actually 5 times what samknows says.

If you raise it with anyone it would have to be by your ISP, who would then pass it on to BTWholesale.  BTw wont speak to the customer direct Im afraid.:/

What does the BT checker say about your line?
http://www.bt.com/broadband/

Hopefully that should give you an indication of what speeds you could be expected to receive on maxdsl.
Max dsl is more reliant on your SNR rather than attenuation.
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Roy22

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Diagnostics for BT Voyager 105 USB modem.
« Reply #5 on: April 25, 2006, 10:51:01 PM »

I emailed 'Sam' who made some unknown further checks and came back with an 'actual line length of 1966m and a capacitance of 175nF'.  I have no idea how he got this information, but you don't get capacitance from multimap.com....

I've just tried BT's broadband checker, which comes back with the following worrying paragraph:

Your exchange is ADSL enabled, and our initial test on your line indicates that your line should be able to have an ADSL broadband service that provides a line rate up to 1Mbps. However due to the length of your line the 1Mbps service may require an engineer visit who will, where possible, supply the broadband service.

Now BT seem to be implying I've a lengthy line (surely 1966m wouldn't be considered that long?) and are hesitant about connecting 1Mb.  Meanwhile, they switched me on to 2Mb just under a year ago with no engineer visits!

One final bit of confusion from BT is in the next bit:

Our test also indicates that your line should be able to support a potential ADSL Max broadband line rate of 3.5Mbps or greater.

So, if they're uncertain about my line length supporting 1Mb without an engineer visit, how can the same line be cranked upto 3.5Mb?

Kitz, do I have a 1966m line or something far longer?  I need to get to the bottom of whether I have a long line which is incapable of reliable high speed, or else a short line which is crippled by attenuation for no good reason?
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kitz

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Diagnostics for BT Voyager 105 USB modem.
« Reply #6 on: April 26, 2006, 02:15:19 AM »

Hi Roy

I have a suspicion that I may know which checker Sam used that showed the capacitance figure.  If its the LLU checker that I think it is (the mention of capacitance gave me the clue) .. then in my particular instance on my line it was more inaccurate than the crow flies one. (over 1km out).
This same particular checker when run on my parents line actually gave them a result of a line length nearer to the exchange than it could possibily physically be.

afaik only the BTw engineer line check can give you your figure, the rest are just guides. But sam does have more access to  BTw stuff than I do.  

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One of the possible things that you could do is request your ISP to send out a BT engineer to check your line.  To get them to do this mention your line stat figures to them and the fact that you appear to be frequently loosing sync.
Theres 2 sides to this - one is that you may have an genuine fault on your line which could be fixed...  or alternatively it could be the length of your line, in which case then BT may well downgrade it to 1Mb.

It is possible that you have a very varied and fluctuating SNR margin, this can and does happen - one of the guys on this forum sees the same thing.
Its good during certain times of the day, but can drop quite a bit at other times.

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The reason why you are getting 2 separate results from the BT checkers, is that the 2nd figure is using maxdsl, which uses different monitoring equipment than "traditional" adsl that has been around for the past few years and you are currently using now.
Its also able to kick in something called interleaving which can help recover errors on some lines.

I mentioned it in my post earlier, but theres more info about maxdsl here.
It may be worthwhile discussing this with your ISP as an alternative..  but I must stress that before doing so, check that you have done all you can to stablise your account from your end first.  
maxdsl isnt a magic cure..  it just gets the best it can from your line under varying circumstances.  Therefore the better your line is to start with.. the higher speeds you will receive on it
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Roy22

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Diagnostics for BT Voyager 105 USB modem.
« Reply #7 on: April 26, 2006, 10:59:23 PM »

I think you may be right re inaccuracy in Sam's checker.  If the line really was just 1.9km long, then you'd expect BT's Broadband checker to rate me as definite on 1Mb and very likely for 2Mb.  Instead, they seem to think that even 1Mb might require an engineer visit to optimise things.

I did try the engineer test phone number (17070) which has got some elaborate diagnostic info, but they've PIN restricted the service now so all that useful data is not available.  Suppose they don't want their customers using the results against BT.

I actually signed up for 1Mb just under a year ago (perhaps this was all they tested the line for?) and was confused, though obviously pleased to get 2Mb from day one.  A month or two later BT announced the 'free upgrading' of 1Mb customers to 2Mb, so I concluded that they must have put me straight onto the faster service for simplicity.

I have noticed that my 18dB SNR margin (23dB at the master socket) does indeed fluctuate, falling as low as 11.5dB sometimes.  As the software doesn't appear to keep a real time log of SNR, I haven't been able to catch the moment when the line drops, but I am hoping that it is caused by momentary low SNR within my house.  If it is, then the ADSL faceplate & Cateogory 5e cable I'm getting may well improve things.

But with my line being now described as a 1Mb one, can I take the risk of contacting engineers re a faulty 2Mb service?  Even though intermittant, I would really miss the 2Mb if they took it away, and BT's ?17.99 and download limits would suddenly seem pretty poor against the other cheaper/less restricted providers if 1Mb was all I got.

Will I regret contacting them, and would you go via BT Broadband or the phone fault reporting service?
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kitz

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Diagnostics for BT Voyager 105 USB modem.
« Reply #8 on: April 26, 2006, 11:56:14 PM »

Yep the 17070 no is the one to get your mitts on if you can..  but like you say its now been restricted due to abuse..  and I believe they keep a track of which engineer has accessed via the PIN..  so an engineer isnt likely to leak it.  

Most ISPs put their users on a 2Mb line straight away...  its no extra cost to the isp and it saves the cost of a regrade later.. so yes if the isp knew they were shortly going to be upgrading all their customers to the higher speeds it makes sense to do so from the start.

>> falling as low as 11.5dB sometimes

Drop outs can start to occur at around 10dB.
Unfortunately none of the routers or modems will keep logs of SNR margin. However, routers frequently have snmp with means that with an aid of some other software you can keep a record of your stats.

Does your modem give you a total of errored seconds CRC/HEC errors?
If you get a lot of these then this is a sign that all is not well. :/

Re the BT engineer... yes its a possibility that he may say that your line simply cannot sustain 2Mb.  Hence why Id try everything else you can do first.
I also know of people putting up with a couple of drops per day, rather than go down to the lower speeds.

If you do contact them, it will need to be by your ISP rather than via the phone (retail) side of BT.
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Roy22

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Diagnostics for BT Voyager 105 USB modem.
« Reply #9 on: April 27, 2006, 06:32:27 PM »

Yes I get quite a few errors.  For example, I've been online for less than 30mins without disconnection, and already I have 303 CRC local errors, and 237 HEC local errors (both counter 'F' that means anything).

Just how bad is this?  I notice that poor SNR margin always coincides with a shortened (and ragged-ending) frequency spectrum shown via SNR Margin per BIN.  I hope to have my ADSL filter & decent cable by the weekend.  Will SNR margin still vary much when I've improved/screened the internal wiring here?

It seems to me that much like other digital technology, the complex error correction does slightly wrong-foot the user.  It maintains data intergrity quietly in the background, despite poor conditions, giving the ordinary user no clue of problems.  When it finally collapses and loses sync, the event appears random and without cause.  Only the stats/frequency response tell the real tale, and just to finish the bad-turn, these are hidden in a secret modem menu not revealed to the owner anywhere!  Who are these guys trying to help?

I think like you say, I'll only approach BT if I get nowhere with my line improvements.  Loosing 2Mb would be a bit of a shame, most of the time it works a treat and is easily the fastest connection I know anyone else has.

So just how bad are those stats?  I've got 17.5dB SNR Margin right now despite that collection of clangers.
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mr_chris

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Diagnostics for BT Voyager 105 USB modem.
« Reply #10 on: April 27, 2006, 11:14:48 PM »

Hi Roy,

Your stats seem quite reasonable, and I'm surprised that you're getting dropouts.

18dB of SNR margin, even going down to 11.5dB, should give you no trouble at all.

However, given that the SNR increases by a large amount up to 23dB when you connect to the master socket, shows there's something up with the phone wiring in your house.

It could be that the disconnects are caused by something in your house or a closely neighbouring house, causing a burst of interference that is severe enough to make the connection drop totally.

Basically, 300-odd errors in 30 minutes isn't bad - it's not great, but certainly not a great worry... IF they gradually increase. However, if those errors were all generated within say 1 or 2 seconds, then that would be bad, it would mean something has interfered badly with the line but in a short timescale. That might be enough to knock the connection over.

It seems you're definitely on the right track to getting it sorted though - presumably when you mention that you're getting an "ADSL filter" you mean a filtered faceplate?

Good luck, and keep us informed of how it goes :)
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Chris

Roy22

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Diagnostics for BT Voyager 105 USB modem.
« Reply #11 on: April 30, 2006, 02:29:18 PM »

Chris,

As I lack any way of recording SNR Margin or Errors realtime to a file, I can't say for certain how the errors occur.  As soon as the line drops, most of the stats become meaningless.  But I am starting to fear that you may be right re bursts of interference.  Watching the graphs continuously is not practical, but I hope soon to 'catch it happening'.

What I have noticed is just how varied the SNR per BIN graph can be.  As I said before, my graph (via a poor extension, as opposed to from master socket) tends to tail off somewhere 130 to 150ish, with the odd blip beyond 150 where it tries but fails to function at higher frequency.  But it's been relatively flat for much of its range.

However, for the last couple of days, the spectrum has been dominated by 9 or more huge peaks, peaking 2 or 3 times higher than the general baseline, more like a profile of the Swiss Alps.

Is this indicative of interference?

P.S. I had hoped to be able to reveal the results of fitting a filtered ADSL master socket & 5E cable by now, but as I've been let down by the supplier, this will have to wait.
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Roy22

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Update on improvements
« Reply #12 on: May 10, 2006, 06:59:23 PM »

For those of you who may be interested or facing similar disconnection problems yourself...

My plan to fit both a filtered ADSL master socket and a new 5e shielded extension cable ran out of time this weekend, as lifting floorboards is so involved.  So I left the cabling part-done but disconnected, and reconnected the old phone line to my new ADSL filtered master socket from Clarity.  This old phone line broke all the rules incidently, often running closely parallel to a mains cable, or even touching it at times.

Well, what an improvement in line stats!  Even with the knackered old phone extension still in use, the SNR margin increased from 18db(max) to the 23dB figure I'd only previously got plugging straight into the master socket.  SNR margin does drift down sometimes, but now 20.5dB is the minimum, previously it could drop to 11.5dB which is where (I think) the disconnections were occuring.

The error stats from my Voyager 105 modem were even more improved.  Previously, several hundred each of CRC or HRC errors was the norm after an evening's use.  Now, 20 to 40 is normal.  It's too soon to talk about a cure due to the intermittant nature of the problem, but I've not had a dropped connection in three days, which is encouraging.

The SNR BIN margin graph instantly extended from a 150ish tail-off, to nearer 190.  Before it could look very patchy and uneven, but now it's fairly flat across most of the range.  It would appear that all this improvement was due to filtering-out the hardwired kitchen phone extension, not previously possible with microfilters which could fit only at the end of the line.

I will let you know what improvements the 5e cable makes once fitted, but for those with similar problems, it would appear that the vast majority of any improvement comes with a cheap & easy filtered master socket!
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kitz

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Diagnostics for BT Voyager 105 USB modem.
« Reply #13 on: May 13, 2006, 01:12:15 PM »

Thanks for letting us know how things went, and I'm pleased that you got some pretty good improvements. :)

Fitting an NTE5 filtered faceplate has proved successful for so many other users and well worth the money.
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