Multifrequency parallel signal transmission for use in new optical GPIB

Describes a new type of optical fiber general purpose interface bus (GPIB) in which the parallel data transmission is actualized by multifrequency parallel signals. The multifrequency signals used as parallel data are generated by a set of sine-wave generators and are detected by a set of bandpass filters. By using the frequency multiplex technique, the multifrequency parallel signals are combined, modulated by square-wave frequency modulation (SWFM) scheme, and then transmitted through the optical fibers. This kind of multifrequency parallel signals have been used as the handshake and management signals on the GPIB bus, which can be transmitted over a distance of 1 km. Eight data lines have also been constructed by using 8 optical fibers