Analysis and Design of a Modern SCADA System

Table 3 .4:Transmitter’s power and receiving port's minimum sensitivity for

some standard fiber productsspecifications.

product Transmit power(dBm) Receive power range(dBm)

1000Base-LX/LH - 3 to -9.5 - 3 to - 20

1000Base-ZX +5 to 0 - 3 to - 23

3.6.3 Optical Loss Budget for 1000 Base-LH

Tocalculate the maximum cable distance of 1000 Base-LH when
the number of connections and splices are 2 and 1, respectively,and from
the product specifications of the devices in Table 3. 4 , it is shown
thatchoosing transmitting device has a -3 to -9.5dbm power output and the
receiving device has a -20dB minimum sensitivity, so we take three
possible power output values and the optical loss budget is calculated as
follows:

Maximum power budget = - 3 - (- 20 ) = - 3+20=17dB....................... ( 3 - 3)

Average power budget = - 5 - (- 20 ) =-5+20=15dB........................ ( 3 - 4)

Minimum power budget = -9.5- (- 20 ) =-9.5+20=10.5dB ................ ( 3 - 5)

Assuming that thetransmissionis over a 9μm Singlemode
@1310nm fiber transmission line and we have 2 connectors and 1 splice,
our calculation looks like this:

The total of maximum power budget = 17dB-(20.75dB) – (10.1dB) -3dB =12.4dB........ ( 3 - 6)

The total of average power budget = 15dB-(20.75dB) – (10.1dB) -3dB =10.4dB........... ( 3 - 7)

The total of minimum power budget = 150.5dB-(20.75dB) – (10.1dB) -3dB =5.9dB..... ( 3 - 8)

Then takingeach of these total and dividing it by 0.4dB/km (taken from
TIA/EIA Loss Estimates table 3.3), so

12.4dB / 0.4dB/km = 31 kilometers (the maximum total cable distance in 1000base-LH). ( 3 - 9)