Owen DeLong <o...@delong.com> wrote: > Nope The power going into each fiber out of the splitter is 1/16th > that of what went into the splitter.
... which is 12 dB loss. > Yes, your total in-line loss is still 10km, but you are forgetting > about the fact that you lost 15/16th of the power effectively going > to the fiber when you went through the splitter (in addition to the > splitter loss itself). > > So: CO Based splitter: > > Each customer gets (IN - 16dB - (10km x .26db))/32 Each customer gets IN - ~0dB - 12 dB - 2.6 dB = IN - 14.6 dB. > Splitter at 9km: > > Each customer gets (IN - (9km x .26dB) -16db)/32-(1km x .26db) Each customer gets IN - 2.34 dB - 12 dB - 0.26 dB = IN - 14.6 dB. > If we use 5dBm as our input, this works out: > > CO: (5db - 16db - (10km x .26db) / 32 > /32 is effectively -15 db (-3db = ½ power, 32 = 2^5) > Substituting: (5db - 16db - 2.6db) -15db = -28.6db to each customer. > > Spitter at 9km: (5db - (9km x .26db) -16db)/32-(1km x .26db) > Substituting: (5db - 2.34db -16db)-15db-.26db = -28.08db to each customer > > So there is a difference, but it seems rather negligible now that I've > run the numbers. > > However, it's entirely possible that I got this wrong somewhere, > so I invite those more expert than I to review the calculations > and tell me what I got wrong. You are multiplying logarithmic values. > Owen --Johnny