User's Manual

Powerwave Fiber Optics
VM100 56/EN – User’s Manual Rev. P1A9-Draft 2004-11 2 - 3
Fiber Optic Transmission Versus Electrical Transmission
This section points out some differences between fiber optic transmission and electrical
transmission via copper. The most signficant differences are loss, bandwidth,
electromagnetic interference, security, signal quality, and weight.
Low loss per km
In general, optical transmission over fiber offers the lowest propagation loss but also
more complexity. It also adds conversion loss for electrical-to-optical signal conversion,
and conversion loss the other way round.
This means that there is a break-even distance due to the propagation loss, where fiber
optics starts to be more cost-effective.
For repeater usage, the following suggestion can be applicable:
For a distance shorter than 100m, use coaxial cable.
For a distance between 100m and 1000m, let the situation determine.
For a distance longer than 1000m, use fiber optics.
High bandwidth
High bandwidth is an advantage for fiber optics. It has a higher bandwidth than any other
alternative (the immense potential bandwidth of 1tHz, that is 10
12
Hz).
High bandwidth makes fiber optics become more and more common even on short
distances as the Internet and other types of data communication demand high
bandwidths. This makes fiber optic parts more and more common, which in the long run
decreases the break-even distance for fiber optics usage.
No electromagnetic (EM) interference
As fiber consists of a non-conductive material, it is unaffected by all EM radiation.
Security
For the same reason that fiber is immune to EM radiation, it does not emit any EM
radiation that can be detected.
High signal quality
Because of the immunity to EM radiation, high bandwidth, and low loss, the signal
quality can be considerably better for fiber optic transmission than for electric
transmission in copper.
Low weight
A copper cable usually has a weight of ten times that of a fiber cable.