Eccentricity is an axis misalignment occurring in FO connectors, which leads to undesired attenuation of the infraredradiation guided in the optical fiber and has its cause in a lack of mechanical precision. The term eccentricity is also used for coaxial cables. It is the deviation of the inner conductor from the geometrical center of the dielectric. The deviation is expressed as a percentage of the radius of the dielectric. For compact disc(CD), eccentricity is the deviation of the distance from the center of the compact disc to the mean distance of the track spiral. For navigation satellites, the eccentricity is the ratio of the distances between the center of each ellipse and the two focal points on the principal axes.