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Rick, when I proposed to maintain a list of pros and cons for the two discovery methods, I stated that the area that would be most controversial would be asssigning a value to the importance of each of the factors. That determination I left for each of us to decide, so that we would not be in an endless battle on those fine points. I think that your note provides us with good input, which we need to consider. In an attempt to separate the listing of benefits from weighting the benefits, I would like to propose a melding of your input and Don's as follows:
Don has recommended:
(I-2) Minimizes cross-talk interference potential to Gigabit Ethernet and
unidentified future services,
which you would like to see rewritten as:
(I-2) Does not interfere with Gigabit Ethernet
I would propose resolving this disagreement as follows:
Include the following distinctions:
(I-2a) Does not interfere with Gigabit Ethernet
(I-2b) Further minimizes cross-talk interference potential to Gigabit Ethernet
(I-2c) Minimizes cross-talk interference potential to unidentified future services
When listed in this way, each of us can make the independent assessment on how much weight to give the benefits of not interfering with Gigabit Ethernet, with further minimizing cross-talk interference potential to Gigabit Ethernet, and with minimizing cross-talk interferfence potential to unidentified future services. I-2b and I-2c may be categories that Don gives a stronger weighting to than you do.
With this proliferation of catgegories, I would advise the members of the task force to give each of the super categories a percentage weighting (i.e. assign % values to categories I, R, D, C, and S so that the toal equals 100%) As a next step, assign relative weightings within each category. Using COSTS as an example, assume you have assigned to COSTS a 25% overall weighting: Take the 8 sub-bullets under COSTS and assign them them relative percentage values that total 100%, and then multiply each of those values by the 25% CATEGORY value to detemine the final overall weighting of the sub-categories. This still leaves you the task of determining how well each Discovery method meets each of these criteria. When carrying out the analysis in this manner, disecting a single benefit into many sub-benefits does not end up giving it more weighting in the final quantified evaluation of the trade-offs.
Rick, you questioned proposed benefit (I-3). Certainly, "(I-3) minimizes EMI" is a benefit that many of us would give at least some weighting to. The fact that one of the benefits of a dc scheme is to minimize EMI should not prejudice us to remove or modify this potential benefit. I strongly recommend we do not remove or change this category.
For R-1 and R-2 you make the comment We need to define "noisy" environment. I agree with your comment and hope that we have e-mail input proposing how to define those environments. Ultimately, we each must give a weighting to this benefit and relative scores to each of the discovery methods. Tests presented will be a substantial help for all of us in making both assessments. I welcome adding "proposed tests" to the notes on this benefit which may provide useful criteria for making the assessments.
For (R-3) you state: We need further definition on this one. I agree. Good definitions are appropriately placed in the notes and will aid in determining the assigned weights.
Per your suggestion we can add:
"R-5) Avoids failure to detect a valid powerable device".
"(R-6) Automatic recovery from a cable discharge or ESD event".
Rick, for (D-1) Low risk of equipment damage IF power is ever inappropriately provided
you say How is this an issue of the discovery method, that is not covered above under robustness?
I looked closely at the 4 Robustness items Don proposed, and your 2 additional ones, and fail to see where (D-1) is covered at all by any of them. Further, D-1, does not appear to be a Robustness Issue. If anything it is in a different super category of SAFETY. If we have other safety issues that surface, we could certainly place D-1 there. In the meantime, I would strongly favor just leaving it where it is. Again, each of us must decide what the appropriate relative weighting is for this benefit.
For (C-1) you state: Doesn't this assume a fact that is not yet in evidence?
Are you saying that discovery and load current measurement must use the same method?
I urge all with strong opinions in these areas to present their arguements for and against via e-mail. These argurements will assist us in determining the weightings to give both to the category, and to how well each Discovery method satisfies this criteria.
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