GarrettCom 4K-Series manual Fiber Port Module

Magnum 4K8 Switches Installation and User Guide (10/04)

4.8Power Budget Calculations for 4K-Series FPM’s with 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 (Agilent’s and Siemens’) web sites and catalogs to provide guidance to network designers and installers.

Fiber

Port

Module

FPM10-

FST

FPM10-

SST

FPM-

MST, MSC

FPM-SSC

FPM-SSCL

Long reach

FPM-

MTRJ

Speed,		Std.	Wave	Cable	X’mitr	R’cvr	Worst	Worst*	typical	typical*
Std.	Mode	km	-	Size	Output	Sens.	OPB,	distance	OPB,	distance
		fdx	length	∝m	PT , dB	PR ,dB	dB	Km, fdx	dB	Km, fdx
		(hdx)	nm
10 Mb	Multi-	2		62.5/125	-15.0	-31	14	5	17	6
			850	100/140	-9.5	-31	19.5	5.9	23.5	7
FL	mode	(2)
				50/125	-19.5	-31	9.5	3.4	13.5	4.8
10 Mb	Single-	10	1300	9/125	-30	-39	7	14	13	26
FL	mode	(5)
100Mb	Multi-	2	1300	62.5/125	-20	-31	9.0	2.5	14	5
FX	mode	(0.4)		50/125	-23.5	-31	5.5	2.0	12	4
100Mb	Single-	18+	1300	9/125	-15	-31	14	28	17.5	35
FX	mode	(0.4)
100MB	single-	40	1300	9/125	-5	-34	27	54	32.5	65
FX	mode	(0.4)
100Mb	Multi-	2	1300	62.5/125	-20	-31	9.0	3.0	15.8	5.5
FX	mode	(0.4)		50/125	-23.5	-31	5.5	2.0	12.2	4.0

*Note: The use of either multi-mode or single-mode fiber to operate at 100Mbps speed over long distances (i.e., in excess of 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, i.e. the full-duplex (factory default) setting for 100Mbps fiber ports must be used, 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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