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!