| 摘要 |
A fiber optic multiplexer and demultiplexer system uses programmable controllers to coordinate the acquisition of switch and sensor state information, to control fiber optic sources, to control fiber optic detectors, to format output, and to perform all timing functions and error correction. The system includes a multiplexer which has an input interface that presents groups of one-bit state information to a plurality of storage latches. A programmable controller selects each latch, reads the state information and drives an optical source to send the information in a multiplexed format. The system also includes a demultiplexer which has a programmable controller that monitors an optical detector for an incoming optical signal. The controller decodes the signal, checks the data for errors, and sends the data to the proper output storage latch. The system also includes a multiple channel fiber optic driver having a source, an associated detector for each channel, processing circuitry, and a power source common to all channels. The system also includes a master controller which has a precise time base to sequentially access each channel. Power requirements are reduced since only one source is on at a time. The master controller measures the background noise level and subtracts it from the received signal. If the background noise level is too high, or the received signal too low, the master controller provides a warning. The controller also considers the signal history as an aid in locking onto signals and providing cleaner switching.
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