Unresolved support ticket open for more than six months - is this a record?

[#1]

Thanks Mike - I knew most of that as I worked for Nokia , who installed a lot of the BT Cellnet infrastructure, and all of  the early Orange network 

[#2]

Quote from: WWWombat

the SNRM graphs are showing regular bursts of clear, interspersed with longer periods of noise, rather than vice-versa?

Indeed, my interpretation is that it looks like a slowly rotating source of interference that drops sharply to a minimum every 6.5 minutes (if my arithmetic is right).
The slope is steep in and out of the minima (SNRM peaks on your graph) with a dome shape in between. And it's symmetrical.
But what device (static or rotating) behaves like that? 

[#3]

Radar - civilian 

[#4]

What sort, weather radar?
Anything else would need to be much faster.

[#5]

http://weather.unisys.com/radar/nids.html but it's a bit far away

[#6]

http://www.metoffice.gov.uk/weather/uk/radar/ is closer - but I don't know where the SE England one is

[#7]

http://www.metoffice.gov.uk/corporate/library/factsheets/factsheet15.pdf
Nowhere near.

[#8]

Quote from: HPsauce

it looks like a slowly rotating source of interference that drops sharply to a minimum every 6.5 minutes (if my arithmetic is right). The slope is steep in and out of the minima (SNRM peaks on your graph) with a dome shape in between. And it's symmetrical. But what device (static or rotating) behaves like that?

I tried measuring the peaks again - the early ones are roughly 7.75 mins apart, while the later ones are more like 6.5 mins.
But whatever it is doing the sweep, its the fact that it's a short peak of clear that makes it weird.
I wonder if the interference has a different pattern really, and we're just seeing an artifact of the way the modem calculates it's headline SNRM to show us.
How does a modem calculate one figure to use when there are 256 frequency bins, with independent SNR values?
Mike

[#9]

Sorry if you answered this before, but do you get any interference with your TV.
If you do, you can report it to Ofcom - and they will come along and make tests
This website seems down at the moment - but is where you can find out more when it's back
or it may be some other illegal activity - not necessarily pirate broadcast radio......
http://www.ofcom.org.uk/complain/inter/tv/terrestrial/?itemid=300133
It may be worth phoning Ofcomm.
It's a long time ago when I used them, ( well there predecessors ) they were very helpful, and very very good. They have a network of reciving / monitoring radio sites over the country and can monitor it all in great detail.

[#10]

Quote from: jelv

http://www.metoffice.gov.uk/corporate/library/factsheets/factsheet15.pdf Nowhere near.

Yep, Thurnham is the nearest and that's 30-40 miles away - interesting document, though!

Quote from: mal0z

So could could monitor your ADSL with routerstats etc, leave the cellphone by the router and then call the cellphone from your landline to see if that effects the noise level on the landline.

I put the mobile on the router and dialled from the landline several times, but this didn't seem to change the noise graph at all - I did this about 19:15 and took a DMT snapshot at the same time; I also took another snapshot just now to see if there's much difference.
I've also attached another Telnet Rx noise graph - this shows an interesting change around 18:45. I don't think I can adjust the Routerstats monitoring period to be more frequent - 20 seconds seems to be the minimum, and that's what it's set at now.
I'll check some of the other comments later.

[#11]

Quote from: Catweazle

I put the mobile on the router and dialled from the landline several times, but this didn't seem to change the noise graph at all - I did this about 19:15 and took a DMT snapshot at the same time; I also took another snapshot just now to see if there's much difference.

As I suspected -
out of interest - do you know where your local base station is:
http://www.sitefinder.ofcom.org.uk/
or what "signal strength does the mobile show" - if you are very close to the base station - the cellphone reduces it's transmitter output to enough to be recieved ok by the base station. The further you are away then the power has to increase to compensate.
Obviously the more power output - the more likely it is cause interferences to other electronic equipment nearby.
And incidentally this is one reason why when the base station is nearby, the cellphone battery charge lasts longer.

[#12]

The nearest base station is about 900m away (Orange) and the next closest is 1250m away (Vodafone - which is the network I use for my company mobile). I tend not to use my mobile at home, though. The signal strength meter is showing three bars at present (the phone's a Nokia 3109).
You also asked earlier about TV interference in an earlier post - I just receive terrestrial stations (BBC 1, 2, ITV 1, C4, Five) and all are very clear with no problems that I can detect.

[#13]

Quote from: Anotherone

I also wondered did that most recent "engineer that came use any thing like - http://www.trendtest.com/trendweb/resource.nsf/vlFileURLLookup/MC2/$FILE/al.mc2plus.html

No, not seen one of these before - apart from the laptop, I think he said he used a reflectometer (big, chunky meter about the size of two or three house bricks) to test the line quality (none of the previous engineers had used this on previous visits).

[#14]

TBH, I'm not sure it is interference - it just doesn't seem to add up.  The interference pattern is almost certainly not a typical interference situation.
It looks like some sort of capacitance charge/discharge pattern, but with a ~7 minute cycle, would mean that the capacitor would need to be around 0.7F at a nominal 300 Ohm circult, (which is apparently standard on BT telephone lines).  That's a VERY big capacitor!
However, (and this is where it gets interesting) if there is a high resistance fault on your line, the requred capacitance of the theoretical capacitor would decrease dramatically.
My gut reaction right now is an issue with the line card at the exchange.  I think that PN should insist on a lift and shift on your behalf, to be able to rule out the line card completely.  I think that there is possibly another problem in addition, but it needs to be systematically tracked down.  Getting hold of a REIN engineer to visit you and spend some time assessing your line would be a win - I wonder how difficult it is to find a proper REIN engineer nowadays?
B.

[#15]

Quote from: Catweazle

I've also attached another Telnet Rx noise graph - this shows an interesting change around 18:45.

You need to have the sync speed graph alongside the Noise graph; they only make sense together.
(a change in noise may be due to a resync at a different speed)