METHOD AND APPARATUS FOR DETECTING EDGES IN A SIGNAL OBTAINED FROM A BAR CODE SCANNED IN THE FRESNEL ZONE

A system for use in a bar code processing system using a combination of a first derivative signal and a second derivative signal to determine the bar edge. The predominant signal in determining the edge is the second derivative signal. A zero-cross of the second derivative signal occurs at the bar edge. The first derivative signal is used to qualify the point in time in the second derivative signal for which a zero-cross is examined the system is particularly suited for near filled operation.