Encoding and decoding circuits for narrow band PSK data transmission via optical fiber

Described is part of the encoding and decoding circuits for use in the narrow-angle PSK system. Data of the normal QPSK system is in the sender fed to a divide-by-four frequency counter to make the shift angle narrow. Narrow-angle PSK data is in the receiver fed to a pair of frequency doubler to make the shift angle wide so that normal QPSK data can be obtained. Narrow-angle PSK data is transmitted from the sender to the receiver through the optical fiber. Data was at 1.432 MHz during the transmission on the optical fiber and the maximum phase angle was 90 degrees. By the use of the frequency counter and doublers, the synchronizing in the receiver was drastically improved and stabilized. >