Fiber Optic Bus Networks: Notes

The ever-increasing level of features available in today's automobiles require a corresponding increase in vehicle electronic systems. The transmission of data, voice and images require an efficient method to move data.

Copper wire bus networks offer many advantages. However high data transmission rates in copper wires can cause electro-magnetic interference with other vehicle systems. Compared with copper wires, fiber optic lines require less space and are lighter in weight for the same transmission band width. In contrast with copper wires, which carry digital or analog voltage signals as the means of transmitting data, fiber optic busses transmit light pulses.

Fiber Optic technology has been in use in the telecommunications industry for many years. However, this type of fiber-optic cable is not practical for automotive use. These cable utilize glass based fibers which are not practical for automotive use. They are subject to fracture from vibration and do not hold up to "tight radius" installations.

POF (polymer optical fibers) were developed for the automotive industry. These fibers were developed and manufactured by Dow-Corning.

Fig 1: Construction Of Fiber Optic Cable

Courtesy of BMW OF NORTH AMERICA, INC.

There are significant advantage to using POF fiber optic cables:

• There is a low sensitivity to dust. Small amounts of contamination do not adversely affect communication.
• They are easy to work with. These fibers can be bent to a radius of approximately 50 mm. This allows for practical installation within the vehicle.
• Processing is practical, these fibers can be cut and modified which makes the production of wiring looms easy. Service repairs are also made simple.
• These fibers are inexpensive to manufacture and do not require expensive connections or housings.