Abstract:
Binary coded data is represented on a record medium by alternate regions of differing characteristics. Adjacent regions form equal width pairs, thus the total width of the representations is not dependent on code content. Machine reading of the code is accomplished by timing a scan of the representation in the adjacent regions of the pairs of regions of alternate characteristics and comparing the scan times in both regions of each pair to determine which region in each pair is larger to thereby assign a binary one or zero value to the encoded binary bit represented by the pair.