GarrettCom DS50 - Manual (Page 25)

Magnum DS50 / DS60s Dual Speed Hubs Installation and User Guide (06/02)
5. The LINK LED for the fiber connector will illuminate when a proper connection has
been established at both ends (and when power is ON in the unit). If LINK is not lit
after cable connection, the normal cause is improper cable polarity. Swap the fiber
cables at the fiber connector to remedy this situation.
3.2.3 Connecting Single-Mode Fiber Optic
When using single-mode fiber cable, be sure to use single-mode fiber port
connectors. Single-mode fiber cable has a smaller diameter than multi-mode fiber cable (9/125
microns for single-mode, 50/125 or 62.5/125 microns for multi-mode where xx/xx are the
diameters of the core and the core plus the cladding respectively). Single-mode fiber allows full
bandwidth at 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.
3.2.4 Power Budget Calculations for DS60F 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) = P
T
(min) - P
R
(min)
where P
T
= Transmitter Output Power, and P
R
= 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
µm (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
Port
Module
Speed,
Std.
Mode
Std. km
fdx
(hdx)
Wave-
length
nm
Cable
Size
µm
X’mitr
Output
P
T ,
dB
R’cvr
Sens.
P
R ,
dB
Worst
OPB,
dB
Worst*
distance
Km, fdx
typical
OPB,
dB
typical*
distance
Km, fdx
DS60F-
xMSC
100Mb
FX
Multi-
mode
2
(0.4)
1300
62.5/125
50/125
-20
-23.5
-31
-31
9.0
5.5
2.5
2.0
14
12
5
4
DS60F-
xSSC
100Mb
FX
Single-
mode
20
(0.4)
1300 9/125 -15 -31 14 28 17.5 35
“Long
Reach”
100Mb
FX
Single-
mode
40
(0.4)
1300
9/125 -5 -34 27 54 32.5 65
* 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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