GarrettCom manual Power Budget Calculations for P62-Series Fiber Media, Typical

Magnum P62-Series Hardened Switches Installation and User Guide (08/03)

longer distances, about 20Km with the single-mode SC.

The same procedures as for multi-mode fiber apply to single-mode fiber connectors. Follow the steps listed in Section 3.2.2 above.

3.2.5Power Budget Calculations for P62-Series Fiber Media

Receiver Sensitivity and Transmitter Power are the parameters necessary to compute the power budget. To calculate the power budget of different fiber media installations using Magnum products, the following equations should be used:

OPB (Optical Power Budget) = PT(min) - PR(min)

where PT = Transmitter Output Power, and PR = Receiver Sensitivity

Worst case OPB = OPB - 1dB(for LED aging) - 1dB(for insertion loss) Worst case distance = {Worst case OPB, in dB} / [Cable Loss, in dB/Km]

where the “Cable Loss” for 62.5/125 and 50/125∝m (m.m.) is 2.8 dB/km, and the “Cable Loss” for 100/140 (Multi-mode) is 3.3 dB/km, and the “Cable Loss” for 9/125 (Single-mode) is 0.5 dB/km

The following data has been collected from component manufacturer’s (HP’s and Siemens’) web sites and catalogs to provide guidance to network designers and installers.

Fiber	Speed,		Std. km	Wave-	Cable	X’mitr	R’cvr	Worst	Worst*	typical	typical*
Port	Std.	Mode		length	Size	Output	Sens.		distance	OPB,	distance
Module			fdx	nm	∝m	PT , dB	PR ,dB	OPB,	Km, fdx	dB	Km, fdx
			(hdx)					dB
P62-	100Mb	Multi-	2	1300	62.5/125	-20	-31	9.0	2.5	14	5
xMSC	FX	mode	(0.4)		50/125	-23.5	-31	5.5	2.0	12	4
P62-	100Mb	Single-	20	1300	9/125	-15	-31	14	28	17.5	35
xSSC	FX	mode	(0.4)
“Long	100Mb	Single-	40	1300	9/125	-5	-34	27	54	32.5	65
	FX	mode
Reach”			(0.4)

*Note: The use of either multi-mode or single-mode fiber to operate at 100Mbps speed over long distances (i.e., over approx. 400 meters) can be achieved only if the following factors are both applied:

•The 100Mb fiber segment must operate in full-duplex (FDX) mode, and

•The worst-case OPB of the fiber link must be greater than the fiber cable’s passive

Attenuation.

(Attenuation = Cable loss + LED aging loss + Insertion loss + safety factor)

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