Abstract: Method of generating a footprint for a useful signal, wherein the useful signal represents the evolution of a spectrum comprising useful signal frequencies, for example audio frequencies, over time, which allows automatic detection of identical or similar useful signals in a cost-efficient way and where the footprint is robust against modifications of the useful signal not perceptible to human users, wherein at least one data set comprising a part of the useful signal is processed by an analyzer according to a predetermined analyzing instruction, where the analyzer outputs as a result of the processing a footprint data vector depending on and identifying the processed data set.
Abstract: Method of embedding a digital watermark in a useful signal, wherein a watermark bit sequence is embedded into the frequency domain of the useful signal using adaptive frequency modulation of two given frequencies by tracking amplitudes of the chosen frequencies of the original signal and modifying them according to the current bit of watermark bit sequence.
Abstract: Method of generating a footprint for a useful signal, wherein the useful signal represents the evolution of a spectrum comprising useful signal frequencies, for example audio frequencies, over time, which allows automatic detection of identical or similar useful signals in a cost-efficient way and where the footprint is robust against modifications of the useful signal not perceptible to human users, wherein at least one data set comprising a part of the useful signal is processed by an analyzer according to a predetermined analyzing instruction, where the analyzer outputs as a result of the processing a footprint data vector depending on and identifying the processed data set.