METHOD FOR OPTICAL COMMUNICATIONS

There is provide a method for optical telecommunications with which an optic al signal modulated for the plane of polarization can be received for certain w ithout lowering the threshold level and being affected by noises so that any optica l telecommunications can be identified without fail. With the method, an optic al signal is modulated by continuous pulses a at the transmitting side before transmis sion and a predetermined number (n) of pulses a are extracted within a given period o f time in synchronism at the receiving side so that the presence of a modulated optica l signal is acknowledged only when the number of pulses a received within the given p eriod of time is smaller than the predetermined number (n) but greater than anothe r predetermined number (m) (n m). This method may be so modified that the ab sence of a modulated optical signal is acknowledged even when the above defined nu mberof pulses are received if k or more than k (k 1) n oise signals b are found between any successive two of the received pulses. There is provide a method for optical telecommunications with which an optical signal modulated for the plane of polarization can be received for certain without lowering the threshold level and being affected by noises so that any optical telecommunications can be identified without fail. With the method, an optical signal is modulated by continuous pulses a at the transmitting side before transmission and a predetermined number (n) of pulses a are extracted within a given period of time in synchronism at the receiving side so that the presence of a modulated optical signal is acknowledged only when the number of pulses a received within the given period of time is smaller than the predetermined number (n) but greater than another predetermined number (m) (n absence of a modulated optical signal is acknowledged even when the above defined numberof pulses are received if k or more than k (k found between any successive two of the received pulses.