Feasibility of a Fiber-Optic Communications Link between a Submarine and a Towed Buoy.

摘要

The possibility of replacing the conventional conductive transmission line between a submarine and a towed communications buoy with a fiber-optic transmission line is explored. The general attributes of fiber-optic systems are put into proper perspective for this application. Specific emphasis is placed on the transfer to the submarine of the signals received at the buoy in the HF, VHF, and UHF bands. A system has been proposed that will permit wideband transfer of HF signals at RF and narrowband transfer of VHF/UHF signals at IFs of 70 MHz and below. The necessity of transferring VHF/UHF signals at a reduced frequency results from amplifier gain-stability considerations in the buoy electronics. The major advantages of an optical information-transfer system are wide-bandwidth transfer at HF, simultaneous transfer of HF voice, NAVSAT, SATCOM, and UHF voice, a wideband nonresonant transmission line, less frequency jitter in the coherent-frequency conversions at VHF/UHF, the potential for support of additional buoy functions, and the removal of the presently required frequency synthesizer in the buoy. Possible disadvantages are technological difficulties in producing low-noise rotating-to-stationary optical interfaces or, alternatively, in producing nontwisting cable-spooling devices, the general vulnerability of silica fibers to physical stress and attack by moisture, and less radiation hardness than conventional systems. It was determined that the best optical source was the LED because of its reliability, temperature stability, and applicability to analog modulation. Because of the high attenuation of plastic fibers, silica fibers must be used.