Method and system for producing a signature characterizing an audio broadcast signal

A system for producing a signature characterizing an audio broadcast signal for use in broadcast signal recognition, comprising:

• means for forming a plurality of frequency band values each representing portions of said audio broadcast signal within a respective predetermined frequency band;
• means for comparing each of a first group of said plurality of frequency band values with a respective one of a second group of said plurality of frequency band values representing portions of said audio broadcast signal within the same respective predetermined frequency band, each respective one of the second group of said plurality of frequency band values representing portions of said audio broadcast signal at least a part of which was broadcast prior to the portions of said audio broadcast signal represented by the corresponding one of said first group of said plurality of frequency band values;
• and
• means for forming said signature based upon the comparisons of the first and second groups of said plurality of frequency band values.