A robust fibre optic active star coupler for the SAE linear token-passing multiplex data bus

The Society of Automative Engineers (SAE) linear token-passing multiplex data bus draft standard, AS4074.1-version 2.0, includes slash sheets for two sets of fibre-optic medium characteristics which support a generous power low budget of about 30 dB. Details are presented of a simple, low power, high reliability active star-coupler design meeting the overall requirements of the SAE high-speed data bus (HSDB) standard without changes to the fibre optic implementation characteristics. The basic active star network is introduced and important quantities defined. Technical issues which influence the active star design are discussed. Component options are introduced and a completed design offered. Its performance in a HSDB environment is characterized. Modifications to the standard for best active-star performance are suggested.<>