Airborne free space optical communication apparatus and method with subcarrier multiplexing
First Claim
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1. Apparatus for communicating data in free space comprising:
- first and second communication terminals, each of said communication terminals further comprising;
an RF transmission module for receiving multiple data channels from a data source and processing said data channels to combine said data channels into an aggregate radio frequency subcarrier signal;
an optical transmission module for receiving said aggregate radio frequency subcarrier signal, impressing said subcarrier signal onto a laser optical carrier signal, and transmitting said laser carrier signal in free space;
an optical reception module for receiving a laser carrier signal from free space and extracting an aggregate radio frequency subcarrier signal therefrom;
an RF reception module for receiving said aggregate radio frequency subcarrier signal and separating said data channels therefrom; and
wherein said optical transmission and reception modules have means to acquire and track a remote communication terminal.
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Abstract
A free space laser communication system uses subcarrier multiplexing to prepare multiple data communication channels for impressing onto a laser carrier. Sending and receiving terminals mutually track to insure acquisition of the transmitted data signals.
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Citations
26 Claims
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1. Apparatus for communicating data in free space comprising:
first and second communication terminals, each of said communication terminals further comprising;
an RF transmission module for receiving multiple data channels from a data source and processing said data channels to combine said data channels into an aggregate radio frequency subcarrier signal;
an optical transmission module for receiving said aggregate radio frequency subcarrier signal, impressing said subcarrier signal onto a laser optical carrier signal, and transmitting said laser carrier signal in free space;
an optical reception module for receiving a laser carrier signal from free space and extracting an aggregate radio frequency subcarrier signal therefrom;
an RF reception module for receiving said aggregate radio frequency subcarrier signal and separating said data channels therefrom; and
wherein said optical transmission and reception modules have means to acquire and track a remote communication terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. In a communication system of a local communication terminal and a remote communication terminal, a method for communicating data in free space comprising the steps of:
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receiving multiple individual channels of data from a data source at said local communication terminal;
digitally processing said individual data channels for RF transmission;
modulating said individual data channels on an intermediate frequency subcarrier signal;
combining said individual data channels into an aggregate RF subcarrier signal;
generating a communication laser carrier signal;
impressing said aggregate RF subcarrier signal on said laser carrier signal;
acquiring and tracking a remote communication terminal from said local communication terminal;
transmitting said laser carrier signal in free space from said local communication terminal to said remote communication terminal;
acquiring and tracking said local communication terminal from said remote communication terminal;
receiving said laser carrier signal from free space from said local communication terminal;
extracting said aggregate RF subcarrier signal from said laser carrier signal;
decombining said aggregate RF subcarrier signal into a subcarrier signal containing said individual data signals;
demodulating said intermediate subcarrier signal to obtain said individual data channels; and
digitally processing said individual data channels for storage and use. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification