RouterStats & Noise Margin

[#1]

Could anyone comment on the appearance of the graph below please.  I have always had a saw toothed line over 24 hrs. Suddenly in the last day or so, during daylight hours, it is as shown.  Does it mean that the BT line has improved or what?
Much appreciated.

[#2]

source of interfrence may of dissappered ie truck driven into sub station that runs near your line  or your neihgbours faulty monitor died and they now have a shiny new one or the sunny weather has done its work and dryed out a bt duct or joint some where.
theres many possabilty's all you can really do is keep an eye on what electrial stuff in your own house is upto

[#3]

Asbo Dog comments appreciated - thank you.  Maybe the sunny weather, who knows.
All seemed well until early this morning & during the day; I've added this to my still open ticket & await comment from PN.  I attach two RouterStat shots off today.  Not certain if trouble is on its way or not.  DSL dropped to 468 but back to 4768 & d'load dropped to 735, back to 3501.  Not as good as last 3 wks though.

[#4]

To be honest the last two noise margin screen shots don't look good. They are quite similar to my own i.e. multiple disconnections and intermittent bursts of noise. If your sync rate and IP profile(s) are not being affected you might just get away with it. If not, I would recommend you return it as a fault... good luck!

[#5]

For interest, today has not got off to a good start. 
PN telephones me in answer to my ticket update of yesterday; now that's the only good bit of news, a 24hr response time. 
Goes down hill after that. I'm informed on mobile left message, 'Your line is steady & fine.  Should be able d/load @ 4.0 to 4.5 meg.'
I can see the the PN ticket stats confirm that.  Looks great until one looks @ mine below. 
I have never had such fluctuating SNR results before. Utterly disappointing - nothing my end has been altered knowingly by me.  I've had good, stable speeds for 3 wks; good grief, surely between PN/BTw, they can provide a better supply than that.  What can it be this time I wonder?
Thank you Twentythree for your observations - hope you get yours sorted soon as well.

[#6]

Cannot believe it was 3 days ago when I must have asked a naive Q.  The 'system' is now getting back @me and I have the worst SNR figs I've ever had.  Dropping line, wild fluctuations shown on RouterStat graph.  Should I expect this after 3 wks. of steady, good service?  Sadly seems par for the course like many others on the forum.
Comments welcomed please; I've updated my ticket.