A method is proved for analyzing frequency distribution of a reflection from a surface of a body to determine a type of body surface. Initially, a plurality of data points from a sensor that senses the reflection of the body's surface are provided. A first series of terms are summed together to provide a first magnitude, each term including a plurality of data points; wherein the plurality of data points being spaced apart by a first spacing. A second series of terms are summed together to provide a second magnitude, each term including a plurality of data points; wherein the plurality of data points being spaced apart by a second spacing. The first magnitude is compared to the second magnitude to determine the type of body surface.