GarettCom 5843HRT User Manual
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Contents
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Models 5843, 5844, 5843S and 5844SRS-232 or TTL3-2Single-mode:19 dB of optical budget is typically available and is essentially consistent forfiber diameters.3.2.1.2 FittingsAdding additional splices, feed throughs, or patches to the FOC will add lossesto the available optical budget. When using multi-mode Fiber Optic Cableterminated and supplied by DYMEC, optical connector losses can be ignoredbecause the cable is tested after the terminations are added. If you are usingfittings not supplied by DYMEC, you can get the optical budget loss informationfrom their manufacturer(s).3.2.1.3 AgingAs FOC ages, tiny cracks will form in the glass core of the fiber. These willcause the attenuation of the cable to increase. The optical emitters age overtime causing a reduction in their optical launch power.DYMEC suggests that a buffer be applied to the optical budget to assure properoperation of the unit over a 20-year life. A 2.5 dB to 3 dB loss factor issuggested to compensate for system aging over 20 years.EXAMPLE:FOC is 62.5/125 μm multi-mode (DYMEC supplied)100 kpsi rated 3 dB/km and 3 dB for agingNo other attenuating items in the circuitinitial: 19.5 dB Optical Budgetless: 3 dB agingless: 0 dB for other circuit attenuation fittingsequals: 16.5 dBdivided by: 3 dB/kmequals: 5.5 km maximum distance of FOC betweentransmitter and receiverNOTEFOC extends communication beyond normal RS-232 or TTL Standards limits. The distanceallowable between Link/Repeaters must be calculated using the factors listed above.3.2.2 Extending the DistanceShould the distance between two devices exceed that calculated above, it is possible toinsert a Model 5843HRT or Model 5844HRT Link/Repeater to function as a stand alonerepeater, not connected to an IED. Two Link/Repeaters would be necessary, one for eachfiber path. When installed as a repeater only, the 9 Pin D-connector of either Model5843HRT or Model 5844HRT should be installed with a terminator that covers the pins andconnects the transmit pin (2 or 3 - depending on the DTE/DCE switch position) to the signalcommon pin 5 and also connects the signal common pin 5 to the chassis ground pin 1. |
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