Research On Precise Positioning Technology Based On QD

Near-terra Free Space Optics (near-terra FSO) is a kind of bidirectional broadband wireless communication technology that can directly transmit data, voice, and video et al. It uses the infrared laser as the carrier and the atmosphere as the media. Since near-terra FSO has the advantage of flexibility as RF communication, and the advantages of great capacity, good concealing and high reliability as fiber communication, as a new broadband wireless communications technology, it has become middle/short-range solutions in broadband applications. For near-terra FSO, APT is a key technology to establish and maintain the communication link.Since using a uniform spot model and the linear approximation between the spot position and its error signal, the existing positioning methods based on QD exist bigger calculation errors in fine tracking unit. To solve these problems, a jiggling method based on Gaussian spot model is proposed in this paper. Theoretical analysis and Simulations results show that the presented method can estimate the spot radius and position information precisely. In addition, by analysising the impact of the background light on the existing methods when the interference of background light is strong, an improved jiggling method is proposed to eliminate the background light interference. Numerical simulations and comparation show that the proposed method is better than the existing methods, especially on the accuracy, real-time performance and robustness.