| 摘要 |
The invention pertains to a short range communication system using laser beams and direct sequence spread spectrum encoding technique for aircraft flying in formation. The exploitation of this invention as an aircraft communication system is not a limiting factor and can be extended to other free space optical communication systems for tactical applications. The invention is composed by one transmitter (t) and one receiver (r). In the transmitter the audio signal is converted to electrical signal through the micro (1.1t) and the audio amplifier (1.2t), further the analogue signal is digitized by the Delta modulator (1.3t). The direct sequence spread spectrum encoder (1.4t) encodes the binary message. Further this is to the optoelectronic transmission unit (1.5t, 1.6t, 1.9t) by which it is transmitted as a laser beam. In the receiver the optical signal is received by the optoelectronic unit (1.9r, 1.7r and 1.5r) where it is converted to electrical signal. Further this is decoded using a locally generated and synchronized code sequence. The decoded binary signal is converted to analogue by the Delta demodulator (1.3r) in order to be inserted into the audio unit (1.2r and 1.1r). The synchronization is achieved by the Delay Lock Tracking Loop - DLL technique. |
