tailieunhanh - Do the Standards go far enough?

Do the Standards go far enough? Current position and focus of Standards versus what we now know regarding component matching. For some time now we have had ratified standards throughout the world relating to generic, or structured cabling. We have seen progress from the initial Category 3 cable and connectors, to Category 4 albeit very briefly, to Category 5 where we are today. We have also seen a shift of emphasis from component specifications to link and channel specifications which is somewhat more meaningful to the end user. In more recent times we have seen many drafts of Cat. 5, or Cat. | B KRONE TRUE I TH WHITE PAPER 1 of 4 pages Do the Standards go far enough Current position and focus of Standards versus what we now know regarding component matching. For some time now we have had ratified standards throughout the world relating to generic or structured cabling. We have seen progress from the initial Category 3 cable and connectors to Category 4 albeit very briefly to Category 5 where we are today. We have also seen a shift of emphasis from component specifications to link and channel specifications which is somewhat more meaningful to the end user. In more recent times we have seen many drafts of Cat. 5 or Cat 5e Category 6 and 7. All of these specifications focus heavily on bandwidth with progression from 16 MHz for Cat 3 to 20 MHz for Cat 4 and for or Cat. 5e still focuses on 100MHz of bandwidth with some parameters tightened and some new parameters added. Category 6 doubles this bandwidth to 250 MHz so it is a quantum leap over Cat 5 Cat 5E. Category 7 if it ever comes to fruition takes a further giant leap to 600MHz however it will be a heavily screened solution with possibly non-RJ45 connecting hardware. As previously mentioned we have seen many drafts of both Cat 5e and Cat 6 but the actual ratified published versions seem to be forever coming but never arriving. In fact as this paper is being written we are up to draft 11 of So why the delay Well a couple reasons come to mind. Firstly and most importantly there is an ongoing problem with a relatively new parameter called return loss. Return loss is a signal echo resulting from inconsistencies in the channel structure mainly due to poor component impedance matching. The other reason is that it is no easy feat to produce a Category 6 jack that performs adequately at 250MHz and that remains backwards compatible with Cat 5e patch cords. BKRONE TBUE WHITE PAPER 2 of 4 pages Return Loss RL Let me come back to the issue of Return Loss RL . For some time now the standards bodies have .