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ADSL2+ and min SNR

itsme
Grafter
Posts: 5,924
Thanks: 1
Registered: ‎07-04-2007

Re: ADSL2+ and min SNR

I have now been on the trial for 35 days. Originally I was on fixed 2mb connection as I stopped the line being put on dslMAX as the line is long and goes through the centre of a major town so do experience noise at night.
I also decided to allow the system to run without me raising any tickets to PN or forcing any reboots or tampering with the SNR margin. After going live on the trial I was syncing in the high 4 thousands with a SNRM of 6. PN profile stayed at 2000 for the first 11/12days even though BT profile was higher. I put this down to the fact that until BT informed PN the order had completed PN was not tracking the BT profile. When I saw the update to the tickets showing the completion of the order I saw the PN profile and been increased and a PPP disconnect/connect had taken place.
I was having loads of resyncing staying a 6dB SNRM but with other parameters changing, one being the interleave depth. At day 6 the SNRM was increased to 9 and I started to sync in the low 4 thousands giving me a profile of 3500. Still seeing loads of resyncs and on the 11 the profile was reduced to 3000 which also coincided with PN system folling the BT profile.
So the first higher speed profile I experienced was 3000. Over the next 15 days the number of resyncs decreased and the profile did have momemts at 3500. In each occasion it took 3 days at the higher speed for the DLM to increase the profile. Saw the higher profile for a few days before dropping back to 3000.
Then in the early hours of Wednesday morning, 1:00, had a resync and the SNRM was increased to 12dB with the profile being reduced to 2500. As I said early I have made a decision not to reboot the modem but to leave the system to do it stuff. At 10:00 on the Friday the modem resync'ed at 3655 which would give me a profile of 3000 in 3 days time. But the line must have been hit by a burst of noise at 13:00 as the SNR margin was increased to 18dB and the profile was reduced to 2000. So a month on the trial I was back to the to where I started.
This must have been a short burst of noise as I could see the SNRM increasing, but still did not reboot the modem. Eventually the modem resyn'ed at 10:30 on Sunday at 3668 which is a 3000 profile but the BT system obversely was still giving me 2000. But the SNRM had been reduced down to 12dB.
Then at 9:00 this morning another resync with a SNRM reduced to 9dB and the speed at 4398. This will give a profile of 3500 but BT speedtest was still giving a profile of 2000 at 12:00. I then did another  BT speedtest at 17:00 and the profile had been increased to 3500. So it only took approximately 30 hours for BT system to change the profile from 2000 to 3500 and also the SNRM was reduced from 18dB to 9dB in 2 days.
Now have to wait for PN sysytem to catch up.

Edit  at 17:55 PN system has caught up.
fredor
Grafter
Posts: 83
Registered: ‎05-04-2007

Re: ADSL2+ and min SNR

With interleaving on Min SNR has now reduced to 6dB.
Stats are:-
Quote
adsl: ADSL driver and PHY status
Status: ShowtimeRetrain Reason: 8000
Channel: FAST, Upstream rate = 888 Kbps, Downstream rate = 8569 Kbps
Link Power State: L0                                               
Mode:                  ADSL2+                                     
Channel:                Fast                                       
Trellis:                U:ON /D:ON                                 
Line Status:            No Defect                                 
Training Status:        Showtime                                   
                Down            Up                                 
SNR (dB):      5.6            11.9                               
Attn(dB):      43.5            21.5                               
Pwr(dBm):      0.0            12.4                               
Max(Kbps):      9864            888                               
Rate (Kbps):    8569            888                               
                        G.dmt framing                             
K:              134(0)          14                                 
R:              10              16                                 
S:              1              8                                 
D:              64              8

Recorded errored seconds are also quite low.
G.dmt D has gone up from 32 8 to 64 8 whatever this means!