Patent ID: 6782212
Filing Date: 2004-08-24
Classification: H04B

Abstract:
A coherent optical communication receiver of a satellite optical communication system, comprising:a telescope, receiving a light signal emitted from a satellite; an automatic frequency control circuit, using a fiber connected to the telescope to receive the light signal received and transmitted by the telescope and convert the light signal into a mixing signal to be output; and a frequency shift keying demodulator, electrically connecting the automatic frequency control circuit to receive the mixing signal and to output a data, wherein the frequency shift keying demodulator further comprises: a heterodyne receiver, electrically connected to the automatic frequency control circuit to receive the electrical signal output from the automatic frequency control circuit, and to output a plurality of demodulated signals; an adder, to sum up the demodulated signals output by the heterodyne receiver to obtain a total demodulated signal; a first low pass frequency filter, to receive the total demodulated signal and to output a low frequency signal; and a decision threshold, electrically connected to the low frequency signal to receive the low frequency signal and to output a data; wherein the light signal emitted by the satellite including a modulated signal laser frequency and a microwave reference frequency, the automatic frequency control circuit converting the modulated signal laser frequency and the microwave reference frequency into a mixing signal, the mixing signal including a microwave reference and a modulated signal, the automatic frequency control circuit using the microwave reference signal to control the demodulated signal, and the frequency shift keying demodulator correctly demodulate the demodulated signal to output the data.