Raymond, thanks for that interesting article. Some flags go off, though. One idea that occurs to me is that Powell may be predisposed, for whatever reason, to DMT, maybe from a religious standpoint. I don't know that for a fact, but it occurs to me.
Secondly, if the following statement is true, then the pre-existing T1 line may have been unhealthy all along, and "needed" to be changed out with one that was in better health.
>For now, the ILECs just attribute slow performance to a bad circuit and change it.<
A T1 could be limping along, albeit error free, hanging on the threshold of error-causing conditions, on a pair of wires that is slightly unbalanced, in the longitudinal sense.
[Unbalance, in this case, means that each wire conductor, with respect to each other, and with respect to earth ground, has a different capacitance, and/or an overall resistance that differs from one conductor to the other, or there may be inductive inequalities between the two, etc. When these conditions exist, the pair is said to be "unbalanced."]
If this be the case, then the unbalanced pair will be more susceptable to interference, and at the same time it will be more error prone.
It shouldn't surprise anyone that the Bellcore imprimatur was placed on the DMT approach, and most of the faithful among ILECs still view this as the way to go (although some ILECs are deploying CAP).
And then again, maybe the transmission specifications with respect to EMI/RFI and pair balance in unscreened cable sheath bundles needs to be revisited.
[WTC? What do you think?]
Those are a few of the things that occur to me. Frank_C. |
