What happended here?

Extract from RouterStats log last night:

Fri 25 Mar 2011 20:12:16, Noise Margin= 6.0, Sync Speed= 6720
Fri 25 Mar 2011 20:12:21, Noise Margin= , Sync Speed=
Fri 25 Mar 2011 20:12:26, Noise Margin= , Sync Speed=
Fri 25 Mar 2011 20:19:12, Noise Margin= 6.0, Sync Speed= 6880

I had been synced at 6720 for almost a week then suddenly I lost sync for no apparent reason @ 20:12. I waited a while for the router (ST585 v6) to reconnect but it didn't in the usual time frame so I initiated a soft restart after 7 minutes to sync at 6880, much higher than I ever achieve during darkness. I am approx 2.4km from my exchange and AFAIK nothing has changed on my line other than the fact it hasn't rained for over a week! Downstream attenuation has not changed for years!!

Stats this morning:

Uptime:0 days, 13:00:20
Modulation:G.992.1 annex A
Bandwidth (Up/Down) [kbps/kbps]:448 / 6,880
Data Transferred (Sent/Received) [MB/MB]:3.72 / 33.41
Output Power (Up/Down) [dBm]:11.5 / 19.5
Line Attenuation (Up/Down) [dB]:25.0 / 40.0
SN Margin (Up/Down) [dB]:23.0 / 6.5

Edited by Andrew_W (Sat 26-Mar-11 09:29:19)

What was your noise margin immediately after the previous re-sync? (Whatever the reason for that was or whatever time).

In reply to a post by RobertoS:

What was your noise margin immediately after the previous re-sync? (Whatever the reason for that was or whatever time).

Last resync:

Mon 21 Mar 2011 19:23:13, Noise Margin= 6.5, Sync Speed= 6720

Not an SNRM drop then.

I pass. A nice 500kbps profile rise on its way in time .

Knowing my luck, it wont last

Not much happened. Seems your connection dropped and reconnected a tad higher.

In reply to a post by orly:

Not much happened. Seems your connection dropped and reconnected a tad higher.

Well, actually, I have just been looking back through RouterStats log and way back in early December 2010, my d/s margin was ~12dB for weeks. Since that time it has steadily improved, first hovering around 9dB during January and early February and now 6.

The point is, whenever I have had a resync during darkness, it has never reconnected at 6dB, always higher. It's still 6 as I type this so something has improved, down the line as it were

Also, last night I had to soft reset the router in order to reconnect, normally it happens automatically within a minute or two.

Not bad for a Saturday afternoon on my line

That's what I was looking for. A target margin drop from 9dB to 6dB.

The time of day you re-sync has no effect on the sync-time margin. That's the whole point of it. But you gave me a log report showing it as 6dB from a sync earlier than this odd one.

OK Bob, thanks!

In reply to a post by Andrew_W:

Not bad for a Saturday afternoon on my line

And when my profile rises........who knows what might happen?

Wonders will never cease


Mon 28 Mar 2011 10:02:28, Noise Margin= 6.5, Sync Speed= 6880
Mon 28 Mar 2011 10:02:33, Noise Margin= , Sync Speed=
Mon 28 Mar 2011 10:02:38, Noise Margin= , Sync Speed=
Mon 28 Mar 2011 10:02:43, Noise Margin= 7.0, Sync Speed= 7616

Bandwidth (Up/Down) [kbps/kbps]: 448 / 7,616
Output Power (Up/Down) [dBm]: 11.5 / 19.5
Line Attenuation (Up/Down) [dB]: 25.0 / 41.0
SN Margin (Up/Down) [dB]: 21.0 / 7.0

Did you cause the re-sync, or did it just happen?

It just happened!

So we seem to have a very short burst of noise, as it disappeared before the serious re-sync speed negotiation started.

Near to an hour-point.

Any clue there? Central heating timer or switch?

Central heating not on but upon reflection, mi esposa did remark that there was a short period of noise when she was on the 'phone around that time. She's well trained in reporting such matters That noise ceased within seconds.

Anyway, the honeymoon appears to be over as my higher sync has reverted back overnight to a more usual 6784/6.5dB. Better than it used to be and quite acceptable for my purposes

BTW Bob, thanks for your input on the matter!

Edited by Andrew_W (Tue 29-Mar-11 08:35:56)