Importance

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Abstract

Periodic components of a data signal are generated from a periodic original signal in a manner to cause the periodic components to represent not only the data but also information about characteristics of the original signal; subsequently both the data and the information about the original signal characteristics are derived from the periodic components. The periodic components of a data signal are generated at frequencies within a frequency band and in a manner such that the components precisely define a fixed frequency outside the spectral band. Unauthorized access to a device (of the kind that receives data in the form of a data signal having periodic components) is detected by generating the periodic components using a modulation scheme, involving no encryption, whereby the data may be recovered from the data signal directly by demodulation even by an unauthorized party; imparting inherent authentication information to the periodic components; and permitting authorized access and detecting unauthorized access on the basis of the inherent authentication information.

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First Claim