Abstarct: The calculation of apparent resistivity, baxsed on the model of a homogeneous half-space, is commonly the first step in order to evaluate helicopter electromagnetic (HEM) data. Several algorithms for deriving enhanced resistivity–depth profiles, which are more sensitive to resistivity variations with respect to depth, are presented. These algorithms have been devised in two domains, time and frequency. Some simple methods for this purpose are Sengpiel's algorithm (1988), Siemon's algorithm (2000), Huang & Fraser algorithm (1997) and reformed Siemon's method (2000). So, in this thesis we try to explain some airborne electromagnetic algorithms and describe them, to know which one is the best. We try to say some benefits and blemishes whichever. We also, devise two free softwares, forward and inversion, for solve these algorithms, because no free software was available. We plan them with Visual C# 2005 and SQL-SERVER 2005, all codes are free and you can change them every time you want. All result have been attained with these softwares. At last we understand that Siemon's algorithm is better than other, and when we have more than 4 frequencies the Differential's algorithm has the best depth result. Also the Homogenous's algorithms has the worst result for inversion HEM data, and Pseudo laxyer algorithm is more better than homogenous algorithms. At long last, these softwares are in initial stages, and we hope to plan perfect software in the future.