Calculating Power Margin for Fiber-Optic Cable for the SRX5600 Services
Gateway
After calculating a link's power budget, you can calculate the power margin (P
M
), which represents the
amount of power available after subtracting attenuation or link loss (LL) from the power budget (P
B
). A
worst-case estimate of P
M
assumes maximum LL:
P
M
= P
B
– LL
A P
M
greater than zero indicates that the power budget is sufficient to operate the receiver.
Factors that can cause link loss include higher-order mode losses, modal and chromatic dispersion,
connectors, splices, and fiber attenuation.
lists an estimated amount of loss for the
factors used in the following sample calculations. For information about the actual amount of signal loss
caused by equipment and other factors, see your vendor documentation.
Table 50: Estimated Values for Factors That Cause Link Loss
Estimated Link-Loss Value
Link-Loss Factor
Single-mode—None
Multimode—0.5 dB
Higher-order mode losses
Single-mode—None
Multimode—None, if product of bandwidth and distance is less
than 500 MHz–km
Modal and chromatic dispersion
0.5 dB
Connector
0.5 dB
Splice
Single-mode—0.5 dB/km
Multimode—1 dB/km
Fiber attenuation
The following example uses the estimated values in
to calculate link loss (LL) for a
2 km-long multimode link with a power budget (P
B
) of 13 dB:
•
Fiber attenuation for 2 km @ 1.0 dB/km= 2 dB
•
Loss for five connectors @ 0.5 dB per connector = 5(0.5 dB) = 2.5 dB
•
Loss for two splices @ 0.5 dB per splice =2(0.5 dB) = 1 dB
181
Summary of Contents for SRX5600
Page 1: ...SRX5600 Services Gateway Hardware Guide Published 2020 02 14 ...
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Page 193: ...Figure 84 Installing the Front Mounting Hardware for a Four Post Rack or Cabinet 196 ...
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Page 285: ...c Upload the configuration to RE2 from the USB device 288 ...
Page 372: ...5 CHAPTER Troubleshooting Hardware Troubleshooting the SRX5600 377 ...
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Page 460: ...DC Power Wiring Sequence Warning 463 ...
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