Patent ID: 6590733
Filing Date: 2003-07-08
Classification: G11B

Abstract:
A process for digitally representing an amplitude of each of at least two pilot tone signals having mutually exclusive frequencies, the at least two signals indicating a relative position of a servo controlled device and being part of an input signal set whose amplitude is represented in an input digital representation, the process comprising:deriving a digital representation of a frequency of each of the at least two signals; deriving a digital representation of a sine function and of a cosine function of the frequency of each of the at least two signals based on the digital representations of frequency; mixing the digital representations of each of the sine and cosine functions of the frequency of each of the at least two signals with the input digital representation to derive digital representations of sine and cosine components of each of the at least two signals; and processing the digital representations of the sine and cosine functions of each of the at least two signals to derive a digital representation of the amplitude of each of the at least two signals.