Temperature data transmission by multifrequency SWFM signal using an optical fiber

This paper describes the optical transmission of multifrequency FM signals on a pair of channels. Each channel-consists of 4 bits, which correspond to multifrequencies at 210 kHz, 520 kHz, 715 kHz, and 1.02 MHz. In the sender, a pair of analog temperature data are converted into 4 bits of digital data on a pair of channels. Each bit of digital data is assigned to a frequency signal, and each multifrequency signal consisting of mixed frequency signals of 4 bits is fed to the respective FM modulator. An FM signal is mixed with another FM signal, and the mixed FM signals are fed to the VCO operating as the SWFM modulator at 20 MHz. The VCO output is fed to the electrical-to-optical (E/O) converter, and then sent to the GI optical fiber. The GI optical fiber is used to send digitized temperature data at low speed over a distance of 1 km. Data was satisfactorily transferred between the sender and the receiver.