Broadcast segment recognition systems and methods are provided in which a signature representing a monitored broadcast segment is compared with broadcast segment signatures in a data base representing known broadcast segments to determine whether a match exists. Criteria for determining the validity of such a match are provided. In addition, signatures characterizing respective intervals of a broadcast signal exhibiting correlation are produced by generating a difference vector for each respective interval and carrying out vector transformations of the different vectors to reduce such correlation. Also, a broadcast segment recognition data base is updated by monitoring a broadcast signal to detect signal events indicating possible broadcast segments of interest in which at least two alternative segments of interest are detected by assigning priority to one of the two segments based upon predetermined criteria. A signature characterizing a broadcast signal interval is produced including a plurality of digital words each characterizing a respective sub-interval thereof by selecting at least one such digital word based on predetermined digital word distribution criteria, match probability and a degree of signal difference between the respective sub-interval and adjacent portions of the signal.