Juniper MX10004 - Calculate the Fiber-Optic Cable Power Margin for an MX10004 Router

NOTE: See the specicaons for your transmier and receiver to nd the minimum
transmier power and minimum receiver sensivity.
2. Calculate the power budget (P
B
) by subtracng (P
R
) from (P
T
):
–15 dBm – (–28 dBm) = 13 dBm
Calculate the Fiber-Opc Cable Power Margin for an MX10004 Router
Before you begin to calculate the power margin, calculate the power budget.
Calculate the link's power margin and distances when planning your ber-opc cable layout. This will
ensure that ber-opc connecons have sucient signal power to overcome system losses and sasfy
the minimum input requirements of the receiver for the required performance level. The power margin
(P
M
) is the amount of power available aer you subtract aenuaon or link loss (LL) from the power
budget (P
B
).
When you calculate the power margin, you use a worst-case analysis to provide a margin of error, even
though none of the parts of a congured system operate at worst-case levels. A power margin (P
M
)
greater than zero indicates that the power budget is sucient to operate the receiver and does not
exceed the maximum receiver input power. This means that the link will work. A power margin (P
M
) that
is zero or negave indicates insucient power to operate the receiver. See the specicaon for your
receiver to nd the maximum receiver input power.
To calculate the worst-case esmate for the power margin (P
M
) for the link:
1. Determine the maximum value for LL by adding esmated values for applicable link-loss factors. For
example, use the sample values for various factors as provided in Table 38 on page 99: the link is 2
km long and mulmode, and the (P
B
) is 13 dBm.
Table 38:
Esmated Values for Factors Causing Link Loss
Link-Loss Factor Esmated Link-Loss Value Sample Link-Loss Calculaon Values
Higher-order mode
losses
Mulmode—0.5 dBm 0.5 dBm
Single mode—None 0 dBm
99