The field of the disclosure relates generally to data communications and more specifically, to an optical fiber serial interface module that interfaces between a terminal controller and a data bus.
At least some known applications include an ARINC 629 data bus that uses metal twisted pair electrical bus cables, stub cables, bus terminators and current mode couplers (CMC) mounted on heavy metallic panels. However, because of such components, the data bus is bulky, heavy and expensive. Optical communications solutions, such as those that utilize optical fiber as a communications media, are desirable due to the reduced weight, which may be advantageous in an aircraft.
One existing solution for implementing an optical fiber data bus incorporates glass optical fibers (GOFs). This system utilizes 850 nm wavelength transmitters and receivers that are packaged individually in a pair, called a Fiber Optic Serial Interface Module (FOSIM). The FOSIM transmitter and receiver have interface electronics to the terminal controller which transmit and receive electrical signal to and from the FOSIM in Manchester bi-phase format. In the typical aircraft application, these FOSIMs are located inside the various avionics subsystems of the aircraft that utilize the data bus for communications. Often, such avionic subsystems are referred to as Line Replaceable Units (LRUs). Inside the LRU, the FOSIMs are mounted along with the terminal controller on a multilayer 6U (full size) VME circuit card.
However, GOFs may be relatively fragile and break relatively easily during installation on a vehicle, such as an airplane. Further, GOFs have a relatively small diameter, which may make optical alignment difficult. Therefore, components associated with GOFs, such as connectors and optoelectronic devices, may be relatively expensive. There is a strong desire in the aircraft production community to develop an optical data bus that uses more robust optical fiber, such as a plastic optical fiber data bus, to replace the current electrical ARINC 629 data bus for future upgrades of such aircraft, although implementations would not be limited to aircraft applications.