3.6 Transmission Media Selection
After the network topology is detected, a proper transmission
media is selected.This thesis presents an evolutionary approach to the
design of loaded networks considering cost and performance to select a
suitable cable type which fits the system design. Optical gigabit Ethernet
solutions have become a necessity with the accelerating growth of LAN
traffic and are applied in new SCADA systems, which necessitatetheir
usein the present study.
3.6.1 Maximum Cable Distance for Ethernet
To calculate the maximum possible distance of the network links
needed, the IEEE's table of recommended distances for networking
Ethernet is used; see Table 3.2.This table assumes a continuous cable
length without any devices, splices, connector mating or other loss factors
that affect signal transmission [ 43 ].
Table 3. 2 :Table of recommended distances for networking Ethernet
Ethernet Standards (IEEE) Data Rate Cable Fiber Type Maximum Distance (IEEE)
Gigabit Ethernet
(1000Base-LX/LH) 1000 Mbps^
9μm Singlemode
@1310nm 5km^
Gigabit Ethernet
(1000Base-ZX) 1000 Mbps^
9μm Singlemode
@1550nm 70km^From the previous table the (1000 base-LH and 1000 base-ZX)
standardsare chosen which are single mode cables that transmit light at
9μm core diameter Single mode @ (1310nm and 1550nm wave length),
which have 5km and 70km, respectively as a maximum length.
After determining the type of Ethernet standard it is possible to
calculate or estimate the amount of loss that occurs in different fiber optic
cable types (62.5/125μm, 50/125μm or 9/125μm core/clad diameter) at