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[Wildy]

Hi all, I'm hoping someone can help me sort out what's going on with my connection. Router stats show as:

Connection Speed   1088 kbps   416 kbps
Line Attenuation   50 db               29 db
Noise Margin               10 db               22 db

According to the max speed calc on this site that puts line length at about 3.6km  (confirmed by a friendly BT engineer with a copy of Google Earth) and a potential max speed of 4-5 meg, but we've never been able to connect faster than 1meg. In fact, until we changed isp about a year ago we could only get 500k.

Our friendly engineer also fitted a filtered faceplate when we first moved in and had these problems, but it didn't make any difference.

Any suggestions for anything else I can try please?

Cheers
Wildy

[roseway]

Hi and welcome,

The filtered faceplate should eliminate your internal extension wiring from causing the problem, so it's down to external interference, or (less probable) a faulty router. If you can beg borrow or steal a different router to try, that would eliminate that possibility.

Assuming that you're on a BT-based ADSL service (i.e. ADSL Max) then the upstream connection speed is a bit lower than it should be although it currently has a very large noise margin. This suggests that you may have some sort of intermittent interference. The easiest way to diagnose this is to install Routerstats or Routerstats-Lite if it's compatible with your router, and monitor the noise margin over time.

Also, a quick and easy thing to check is to dial 17070 and select option 2 for the quiet line test. If you hear any crackling or loud hissing then you may have a line fault.

[Wildy]

Thanks for that Roseway.  We're with Sky bb so looks like it's not trivial to try a different router (may have a go later in the week). Quiet line test only gave a slight background hiss that I assume is normal.

Routerstats graph should be attached, unless I've screwed that up too   

[attachment deleted by admin]

[roseway]

The Routerstats graph is fine (no screw-up ). You do seem to have a bit of an interference problem. Those irregular downward dips in the noise margin could be caused by a line fault, but if the quiet line test is almost quiet, then it looks as though it's electrical impulse noise (REIN). This can be the very devil to diagnose, but there's a lot of information about it here.

I suggest that you keep Routerstats running to see if the same pattern continues or something changes.

[Wildy]

Sorry, more cluelessness inc.

As a first step I moved the router as far away as possible from the morass of power cables behind the pc.  This seems to have bumped up the noise margin noticeably from what it was.  Don't have a graph to link as I forgot to capture it   . Noise margin was still varying, but much less often than before.  I'll keep an eye on this, see if I can spot if it gets worse in time with the street lights coming on or something.  

One thing that I may have misunderstood though, I was connected OK for maybe 20 minutes with a noise margin of 13db and no dips, shouldn't my router have tried a faster connection speed in that case?

Thanks again for the help
Wildy

[roseway]

No, the router won't re-sync by itself unless something like a very low noise margin causes it to do so.

[jeffbb]

Hi
quote from Roseway  like a very low noise margin causes it to do so.

and generally connects at a lower synch rate 

Regards Jeff

[Wildy]

It can't get much lower 

Seems like the street lights may be having an effect, will link before and after shots below.  What I still don't understand (sorry if I'm being a bit dim here) is if it can manage a 1meg connection with the noise margin all over the shop as in 2nd graph, why can't it do better when the noise margin is apparently higher and more stable?





[attachment deleted by admin]

[orainsear]

Does the drop wire from outside pass through any other boxes prior to your master socket?  Perhaps a small white box, matchbox sized?

[jeffbb]

Hi
quote What I still don't understand (sorry if I'm being a bit dim here) is if it can manage a 1meg connection with the noise margin all over the shop as in 2nd graph, why can't it do better when the noise margin is apparently higher and more stable?

Your connection speed(SYNCH RATE ) is negotiated when you first establish your connection to the exchange . During any particular session the SNR margin may go up ,that happens if the noise on the line is reduced . The SNR margin may  go down , that is caused by more noise coming on the line. This can be gradual decrease , or a step change caused by something switching on.The SNR margin can become very noisy showing many spikes ,if however the SNR margin is not too low then the synch rate will be maintained . The synch speed Will NOT change as long as the connection is maintained . If the Margin gets too low or the error rates get too high then  down it goes as mentioned by  Roseway.

At that point everything is renegotiated 

Regards Jeff

[Wildy]

Does the drop wire from outside pass through any other boxes prior to your master socket?  Perhaps a small white box, matchbox sized?

Not sure about this, the wire comes up out of the ground and into the wall a couple of feet up, but the whole thing is concealed by a plastic cover screwed to the wall. If it might be important I can try taking the cover off and having a look.

I still can't shake the feeling that there's a switch somewhere at the exchange that needs flipping from "crap braodband" to "decent broadband" and all would be good.