Optical telecommunications systems

摘要

A telecommunications systems employs signals transmitted along optical fibres. A broad transmission band is provided and enables both video and a number of speech channels to be provided. The system uses PFM signals which have no baseband component, the baseband component being regenerated in the receiver. The receiver includes a wide-band PIN FET (20), and a demodulator using a pulse counting technique. The received pulses are converted to fixed width by an ECL monostable (25) and the baseband signal obtained by a low-pass filter (26).