Still picture transmission through optical fiber utilizing multifrequency sinewave signals

This paper describes an optical fiber multifrequency data transmission system which is used to transmit NTSC still picture codes utilizing video RAMs which temporarily store still picture codes. In addition to the basic multifrequency data transmission system, the RAM installed in the sender (TX-RAM) and associated read/write circuits are used so that the data rate of the NTSC picture codes at 14.3 MHz is converted to 20 kHz which is suitable for multifrequency data transmission. On the other hand, the RAM installed in the receiver (RX-RAM) and associated read/write circuits are used so that the data rate of the picture codes transmitted in accordance with the multifrequency data transmission scheme is converted to the original high speed data rate at 14.3 MHz. When the write strobe specifying the start of storing data in the TX-RAM is generated, the picture frame recognized as a still picture can be sent from the sender to the receiver through optical fibers. Picture codes were satisfactorily transmitted without any trouble, and the quality of the transmitted still picture was good enough to monitor the status of the plant apparatus.