Optical-fiber data-word transmission system for use with microcomputer controller

Experiments were carried out on a new type of data word transmission system employing a GI glass fiber. A frequency division multiplexed scheme was employed because of simple circuit configuration and low cost. Parallel data consisting of multiple frequency signals occupy separate frequencies in a specified frequency domain. The frequency domain used for the parallel data transmission system is described. A square wave frequency modulation (SWFM) scheme was used. Since the SWFM scheme enables the transmission system to be constructed very simply, a data word is easily recovered from the received SWFM signal by using a 4-b parallel data detector. For applying the new system to the industrial field, a Z80 data processor was built into the receiver to process the data words and to output the instructions to the associated external devices. This optical fiber transmission system has high reliability against electromagnetic interference.<>