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[Mick]

Hi All,

For the last couple of months I have been getting the attached pattern of error counts.  Some nights this may not happen, but invariably it is happening most nights.

Other than cross-talk with a neighbour who's on Economy-7 tarrif (not sure what it's called these days) what else could it be?

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[kitz]

Any weird gaps in the bit loading which may give an indication at which frequency?

[sevenlayermuddle]

Water softeners are often programmed to go through their cycle at that sort of time.  I'd expect them to follow a regular pattern however, eg same time every night, or every other night, or every three nights or whatever.  Still, it's a thought.

[Mick]

Any weird gaps in the bit loading which may give an indication at which frequency?

Not sure if they are weird, but typically these are the tones (not bins) that are zero:

211, 244, 251-256.

The next tier are these with 2:

59, 225.

I'll have a look tonight to see how much worse it gets.  Last night it seems it was particularly bad looking at the error counts.

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[orainsear]

Do you live anywhere near to a Radio 5 transmitter?  Looks like it could be radio interference.

Tone 211 ~ 909 kHz = Radio 5 live

Tone 244 ~ 1053 kHz = Talk Sport

Tone 251 - 256 ~ 1080 - 1105 kHz = Talk Sport

At night the ionosphere becomes more reflective and radio frequency signals will see improved propagation, so this is why you see a more pronounced effect at night.

Unfortunately there isn't much you can do about the ionosphere,  but what is your internal wiring setup like?  It may be possible to optimise your internal wiring to help minimise pickup.


Edited to correct frequencies.

[Mick]

Thank you all for your responses.

I looked at a map with radio 5 transmitters and the nearest one is more than 25 miles away.   Would the ionosphere phenomenon you describe be affected by cloud coverage?

My internal wiring is in good state and there is no difference if I am plugged in the test socket.

All this is a relatively recent phenomenon.  I'd say no more than 4 weeks or so.

[waltergmw]

Hi Mick,

This is a rather long shot, but it would be worth looking around for neighbours' lines to see if any have been abandoned and more particularly if any have been cut loose at the house end with the tail left dropping to the ground somewhere.

You might also check to see if any boxes have been left with the lids off and the pairs dangling, or any other damage to cabling.

These sorts of things can sometimes produce cross talk into your pair.

I doubt if cloud coverage would cause a problem but water ingress could do so.

As an irrelevant but interesting topic have a look at:-

http://en.wikipedia.org/wiki/Meteor_burst_communications

This type of system was actually used to monitor and control off-shore plant at one stage in the Southern North Sea.

Kind regards,
Walter

[general disquiet]

The timing looks horribly familiar.  How does it change over a month long cycle and what are the earliest and latest times you see it?

[Mick]

There is a broad pattern, although you wouldn't exactly set your watch on it.  See my attached weekly and monthly errors charts.  It seems that Thu, Fri it often goes quiet and most other days it goes up again.  On occasion my sync speed jumps up in the middle of the day as if the noise suddenly reduces - but never enough to increase my SNRM which is stuck at 9db during the day.

I've tried to find exposed connection boxes and disturbed wires around the neighborhood, but had no luck.  I guess I could start knocking on doors asking about cross-talk and the noise their electrical appliances generate, but they will no doubt become concerned for having me as a neighbour! 

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[jeffbb]

Hi
quote : On occasion my sync speed jumps up in the middle of the day as if the noise suddenly reduces - but never enough to increase my SNRM which is stuck at 9db during the day.

Do you mean that you notice an actual increase in synch speed without rebooting or forcing a resynch?,  An increase in synch is not going to increase SNRM  , the opposite is the norm , if you resynch at a higher speed with the same or similar SNR then the noise reducing your synch rate has stopped  .

what service are you with .??
the only time I can think that synch rate would change on the fly as you say it does is if you were on SRA  Seamless Rate Adaption


Regards Jeff

[Mick]

Sorry, I didn't explain myself.  My router (2WIRE) reports what the 'current sync' speed would be if it were to resync just now.  I assume that it runs an algorithm which calculates the sync speed it would achieve at the current SNRM level.  So if you look at the attached graph it shows a slight increase around 18:00h.  Last week this happened at around 11:00 in the morning on Friday and the jump was around 350 kb/s.  If I were to resync at that time I would get a higher effective/final sync speed (I did and that's another story) but that's what I meant by saying that the sync speed jumps.  The potential sync speed.

I am still on ADSL 1 as BT will not honour us with ADSL 2 until some time in 2011 ...  

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