Technical details on why DSL modem does not stay synched

Question

[ Please no rantings about Verizon for this thread ]
I would greatly appreciate if a technically knowledgeable individual would explain why DSL modems lose synch with the central office. Sometimes the modem can stay connected all day without one interruption. And sometimes the modem will lose synch several times in one hour. Why does this happen? Is this just due to noise on the line or are there more technical explanations for this situation?
In my case, I have a Westell 6100G modem. My DSL service is 1 Mbps. These are my typical statistics
Transceiver Revision  3.3.2.2.0.1
Vendor ID Code            4D54
Line Mode                      ADSL_2plus
Data Path                       FAST
Transceiver              Down     Up
DSL speed               1184     447
Margin (dB)                 31.5   29.9
Line attentuation       32.5   13.6
Transmit power           6.0    12.0
Thank you.
    David

Answer 1

David_3 wrote:
Sometimes the modem can stay connected all day without one interruption. And sometimes the modem will lose synch several times in one hour. Why does this happen? 
    David
Basically the modem has a sliding scale as to the Variance in it's Signal to Noise Ratio.    These are measured in Decibals.
The variance comes from line conditions, so typically this is affected by a lot of things, moisture in the air at night or in the morning, condensation on the telephone lines, heat and cold expanding and contracting the copper wiring, so depending on conditions in the field that are environemental in nature, the line will fluctuate it's signal.  This particular problem is between the CO And your house only so there isn't a issue with other users affecting your service at all, but the quality of the line outside.  There are several break points that a technician can look at to find the problem, and there are SEVERAL things that they could change in order to fix the problem, HOWEVER if they change it to interleave provisioning, it is designed to do auto correction on the line, and if the line is not severely affected, it will compensate and correct all those problems.  There are instances where interleave provisioning can not fix those issues, and that means that your trouble could be more severe than you though, and then a VZ technician would have to go out and start isolating where the problem is.  They will test in the Central office, in the outside plant and then ultimately back at your house.   
8/10 times interleave provisioning will fix a problem like that for 1.5 mb customers and lower speed tiers.   higher speed tiers are a little tricker.