| CPC H04B 10/11 (2013.01) [H04B 10/5161 (2013.01); H04B 10/615 (2013.01); H01S 3/06716 (2013.01)] | 19 Claims |
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1. A free space optical communication system for optically transmitting data through a variably refractive medium, the free space optical communication system comprising:
a transmitting element configured to receive a first signal, wherein the transmitting element includes:
a processor configured to:
separate the first signal into an in-phase component and a quadrature component;
based on the in-phase component and the quadrature component, generate at least two signals;
quadrature-modulate the at least two signals to generate at least two outputs; and
combine the at least two outputs in a time-division manner to generate a first time-division combined signal;
an optical source configured to generate a beam of light;
a modulator configured to receive the first time-division combined signal and the beam of light, and modulate the beam of light based on the first time-division combined signal to form a modulated beam of light;
a first amplifier configured to receive the modulated beam of light from the modulator and amplify the modulated beam of light to produce an amplified beam of light; and
a telescope configured to transmit the amplified beam of light through the variably refractive medium;
a receiving element comprising:
a photoreceiver configured to receive the amplified beam of light and extract a second time-division combined signal from the amplified beam of light after the amplified beam of light was transmitted through the variably refractive medium;
a correction unit configured to correct distortion in the second time-division combined signal created during transmission of the amplified beam of light through the variably refractive medium, thereby producing a corrected signal;
a mixer configured to receive the corrected signal, and multiply the corrected signal by a signal having a predetermined frequency to produce a multiplied signal;
a second amplifier configured to amplify the multiplied signal to produce an amplified multiplied signal;
a band-pass filter configured to generate a radio signal by removing a frequency component contained in a predetermined frequency band from the amplified multiplied signal; and
an antenna configured to emit the radio signal,
wherein the correction unit uses threshold detection to correct the distortion in the second time-division combined signal created during the transmission of the amplified beam of light through the variably refractive medium.
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