An adaptive weak signal extraction algorithm based on four-element infrared detecting system

摘要

The four-element infrared detecting system is a common used detecting system to detect a target from sky background. However, one of the main application limits of this system is the short detecting distance. Consequently, this paper presents an adaptive weak signal extraction algorithm, with which the weak distant target signal can be extracted, thus the detecting distance can be obviously lengthened. The algorithm is designed as follows: Firstly, estimates the target signal when the signal is extremely weak. To a given detecting system, the target signal can be estimated by the geometry relationship among the physical references. Secondly, gets the initial normalized coefficients h(i) of the BPFIR filter by sampling the first harmonic of the estimated target signal and then normalized coefficients Sigma0Nh(i) = 1 Thirdly, gets the amplification value k of the algorithm using the radiation equation L = radic(Irho/EnKc) and the response property curve of the sensors. Finally, updates the coefficients of the BPFIR filter H(i) using the output y(i) of the detecting system and changes the amplification value k using PID method, The newer output of the BPFIR filter will be used to obtain newer updated coefficients of the BPFIR filter, and hence the adaptive weak signal extraction algorithm is realized. With the application of this algorithm on a four-element detecting system, the distant weak target signal can be extracted properly. Experiments shows that the detecting distance is lengthened more than 20 percents.