Abstract: Repeaterless transmission of differential phase-shift keying (DPSK) at 10.7 Gb/s over at least 304 km of standard single-mode fiber is obtained through use of a coherent optical receiver including electronic dispersion compensation. High receiver sensitivity and high tolerance to nonlinearities of DPSK, allow overcoming a total link loss of 58 dB with a 3 dB system margin, through use in the receiver of heterodyne detection to preserve phase distortions resulting from chromatic dispersion, to permit electronic dispersion compensation to be used.

Abstract: Repeaterless transmission of differential phase-shift keying (DPSK) at 10.7 Gb/s over at least 304 km of standard single-mode fiber is obtained through use of a coherent optical receiver including electronic dispersion compensation. High receiver sensitivity and high tolerance to nonlinearities of DPSK, allow overcoming a total link loss of 58 dB with a 3 dB system margin, through use in the receiver of heterodyne detection to preserve phase distortions resulting from chromatic dispersion, to permit electronic dispersion compensation to be used.

Abstract: An optical coherent receiver in one embodiment has a heterodyne configuration, and in another embodiment has a homodyne configuration, in each configuration employs multiple feedback signaling and analog/digital processing to optimize response to a modulated optical input signal, the provision of both individual RF I and RF Q channel outputs.

Abstract: This application discloses a virtual ground pre-amplifier for application with magnetic phono cartridges such as moving coil, moving magnet, moving iron, or similar types. The preamplifier according to the present invention comprises a forward path (an amplifier), and a reverse path (shunt feedback). By presenting a relatively low load impedance to the phono cartridge, the preamplifier effectively damps mechanical resonances of the stylus-cartridge system, and thus serves as a "stylus stabilizer."Also disclosed are techniques for equalizing the overall response of the stylus-cartridge-preamp system so as to provide a predetermined (e.g., flat) frequency response. This predetermined frequency response can be achieved by utilizing any of several circuit arrangements which serve to compensate for the intrinsic inductance and dc resistance of the magnetic phono cartridge.