Abstract: An apparatus for interpreting digital output signals from a Code 39 bar code data system wherein all of the bars and spaces in a signal code character are measured for time duration, minimum and maximum widths bars and spaces are identified, first bar cutoff and space cutoff values are respectively produced having a time duration approximately 1.5 times the time duration of the minimum width bar and space, second bar cutoff and space cutoff values are respectively produced having a time duration approximately equal to one-half of the sum of the time duration of the minimum and maximum width bars and spaces and means are provided for respectively comparing the first and second bar cutoff values and space cutoff values and for using the greater of such values as a reference against which all of the bars and spaces in said characters are respectively measured.