reply to joewho
Re: Any 5100b technician page DMT/SNR data experts?
said by joewho  :I'm not an expert, but until someone arrives with a better answer..... I can tell you that the first read out shows 0.0 snr, which means that there is no signal to noise margin. I gotta admit that I edited that. The 5100b modem reports erroneous SNRM when the signal to noise ratio goes off the scale. Notice the 126.0 and 127.0 samples in the SNRM Carrier Frequency data. It actually recorded an insanely large value for the SNRM (2147483646.0) that I replaced with 0.0 since it was unable to correctly calculate the SNRM. I figured 0.0 made more sense than an insanely large value due to the modem miscalculating the SNRM.
said by joewho :The second graph shows a snr of 13 which is perfectly acceptable. This means that there is noise on the line. Something that could possibly be corrected by you. No guarantee, but in order for sbc to zero in on the problem, they will probably ask you to check your set up from the nid to the inside wiring. To do this, the first thing you'll want to do is find a way to plug the modem in directly to the nid (gray box mounted outside, usually near the electric meter). Been there, done that.
I have a "Home Run". It's a known-good 8 foot CAT 5 cable going directly from the NID into a microfilter, split directly into the modem and 1 telephone.
I have tried 4 different modems. They all saw the loss of DSL sync problem. The last DSL sync time is on the graph. For the first failure case, the line dropped syn 26 minutes earlier. After 30 minutes of signals that looked poor and jagged like the first chart, the problem disappeared as the second chart showed.
I also literally turned off every electronic component in my house and disconnected the POTS telephone. The problem still occurred.
said by joewho :Just run a line fromt the modem to the nid. Unplug the phone wire, and plug in the modem. Check the stats and post them here. That's a "Home Run". That is exactly what I've been doing for the last 16 days.
said by joewho :This is a good start, I'm sure someone else with more expertise will reply soon. Good luck. PS: Also, if you have a router, eliminate it from the setup temorarily. When you run the modem to the nid, also run it to the computer directly. This isn't a Internet routing problem. The DSL modem loses sync during the problem period. The modem records a loss of sync.
For the first problem shown, the modem logged this:
2005/06/02 07:45:00
32 Time Since Last Sync 000 days 00:26:35
+001 days 22:44:12 E |DSL |Link Down
+001 days 22:44:12 E |DSL |State: WAITING
+001 days 22:44:20 E |DSL |State: INITIALIZING
+001 days 22:44:27 E |DSL |HYBRID 1
+001 days 22:44:27 E |DSL |Link up 17 US 512 DS 2464 (FAST:G.dmt)
Right before the problem occurred, I recored this:
2005/06/02 07:15:00
32 Time Since Last Sync 000 days 10:55:59
140 Current Rate 2496 512
141 Previous Rate 2432000 672000
142 DSL Max Rate - -
143 DSL Min Rate - -
144 Current ATTN DR 2496 -
145 Current SNRM 14.0 -
146 Current LATN - -
147 Current SATN 53.0 -
148 Current TP - 0.0
Right afterwards:
32 Time Since Last Sync 000 days 00:01:40
140 Current Rate 2464 512
141 Previous Rate 2496000 672000
142 DSL Max Rate - -
143 DSL Min Rate - -
144 Current ATTN DR 2464 -
145 Current SNRM 0.0 -
146 Current LATN - -
147 Current SATN 55.0 -
148 Current TP - 0.0
Does anyone know how to calculate Maximum Attainable Rate from the SNRM/DMT bit bin data? Are there any other interesting values I can calculate from these two hunks of data?
--justbits | 
·
