Patent ID: 6421445
Filing Date: 2002-07-16
Classification: H04H,H04K,H04L

Abstract:
An apparatus for including a code having a plurality of audio signal frequency components, wherein the code comprises a plurality of code frequency component sets, each of the code frequency component sets representing a respectively different code symbol and including a plurality of respectively different code frequency components, the code frequency components of the code frequency component sets forming component clusters spaced from one another within the frequency domain, each of the component clusters having a respective predetermined frequency range and consisting of one frequency component from each of the code frequency component sets falling within its respective predetermined frequency range, component clusters which are adjacent within the frequency domain being separated by respective frequency amounts, wherein the predetermined frequency range of each respective component cluster is smaller than the frequency amounts separating the respective component cluster from its adjacent component clusters, the plurality of code frequency components including a first code frequency component having a first frequency and a second code frequency component having a second frequency different from the first frequency, comprising:first masking evaluation means for evaluating a masking ability of at least one of the plurality of audio signal frequency components to mask a code frequency component having the first frequency to human hearing to produce a first respective masking evaluation; second masking evaluation means for evaluating a masking ability of at least one of the plurality of audio signal frequency components to mask a code frequency component having the second frequency to human hearing to produce a second respective masking evaluation; amplitude assigning means for assigning a respective amplitude to the first code frequency component based on the first respective masking evaluation and for assigning a respective amplitude to the second code frequency component based on the second respective masking evaluation; and code inclusion means for including the plurality of code frequency components with the audio signal.