Improved high gain circuit and DFE algorithm for underwater photoelectric signal recovery

Underwater long-distance optical communications, due to the influence of light scattering and absorption, it will cause severe signal attenuation, in addition, multipath propagation effects and Doppler effect of light will cause serious signal distortion. Based on the problems, an improved amplifier with Direct Current (DC) servo loop is proposed. The amplifier overcomes the shortcoming of conventional amplifiers and has high gain, wide dynamic range. Further, in order to overcome the time varying interference, an improved decision feedback equalizer (DFE) model and algorithm is given, the model can achieve faster convergence and smaller steady-state error. The new algorithms take Marr function as a basic function, and two parameters α and β used to shape the profile of functions. Experiments show that the method can greatly improve the transmission distance of underwater optical communications (UOC).