| 摘要 |
PURPOSE: To obtain a system which uses continuous phase frequency shift key modulation of laser in an optical transmission system. CONSTITUTION: A transmitter 100 is provided with a reference oscillator means 18 and a modulator 12 which give transmitter optical power and low frequency modulation to the frequency deviation. A receiver 200 is provided with a means 28 which extracts duplicate of the low frequency modulation from a receiver AGC control signal, a multiplier stage 32 which demodulates modulated frequency deviation of a received optical signal in synchronism with an extracted low frequency signal, an integration and frequency controller 34 which obtains an error signal from a demodulated signal and a control system that responds to the error signal to control the frequency of a receiver local oscillator 22. |
