Analysis And Processing Of The Noise In Photoelectric Detection Circuit

With the development of modern technology, optical-electricity technology has been applied widely. And people pay more and more attention to the noise of the detecting circuit. But sometimes, compared to the noise, signal is so weak that difficult to detect. In order to solve the noise problem when detects the weak signal using the photoelectric detection circuit, this paper analyzes the inside and outside noise sources. And for analyzing the causes of noise, this paper researches the photoelectric detector and preamplifier in detail. Then this paper designs the pre-amplifier circuit with low noise based on the semiconductor photodiode and proposes noise model of it, deduces output SNR(Signal to Noise Rate), and explain the factors which influence output SNR of photoelectric detection circuit in detail.When studied the noise characteristics of photoelectric detection circuit which are mentioned above, this paper uses LMS adaptive filtering algorithm to reduce noise. Based on analysis of LMS adaptive filtering algorithm and its performances, this paper designs a LMS adaptive filter to solve the noise jamming. Simulated result using Matlab software. In the simulation, it posits two noise generator. One is white Gaussian noise to act as the random noise, and the other is a signal mixed with two different frequencies to act as the outside interference. The simulation results show that the LMS Adaptive Filtering achieves good results in solving the noise jamming. Based on the simulation, this paper designs a 8th-order LMS adaptive filter using the powerful data processing function, explains the design method in detail, and programs by Verilog HDL, expected results are gotten after testing.Finally, a summary is made to generalize the work in this paper and the study for future development was suggested.