Method of carrier frequency arrangement for suppressing the adjacent channel interference caused by camera nonlinearity during LED-multispectral imaging

Abstract

Using a camera and frequency-division modulation to obtain LED-multispectral images has the advantages of fast speed and low cost. However, when the carrier frequency is not arranged properly, the nonlinearity of the camera causes harmonic interference, which affects the signal quality of adjacent channels. This paper proposes a scheme for carrier frequency arrangement according to the high frequency, which is four times as high as the adjacent low frequency; that is fn+1=4fn,(n=1,2,3,…). The experimental result shows that the scheme can suppress the interference among carrier channels. In addition, the high-speed, phase-locked algorithm is used to demodulate the images, saving about 97.73% of the time compared to the traditional demodulation algorithm. The method not only realizes the fast acquisition of LED-multispectral images, but also improves the demodulation quality and speed of the images. It also provides a reference for a camera to obtain high-quality, LED-multispectral images.