Simplified encoding apparatus and method for pilot tone modulation in automatic-track-following

摘要

A 24/25 modulation encoding device for generating a power spectrum of a binary sequence using spectrum peak and notch power monitoring (SPNPM) modulation is disclosed in this invention. The encoding device includes a dual polarity up-down counter for generating digitized step functions for replacing sine and cosine functions recruited by the SPNPM modulation. The encoding device further includes a bit shifter and an accumulator for generating an estimator of expectation for approximating a real and an imaginary part of a work value for obtaining a power spectrum required by the SPNPM modulation. The encoding device further includes an absolute accumulator for receiving said estimator of expectation approximating said real and imaginary parts of said work value for generating an absolute work value to replace a work-square value required for generating a power spectrum. The encoding device further includes a linear circuit with an input terminal designated as a DC terminal looping back for extra-weighting an input therefrom. The encoding device further includes a comparator coupled to said linear sum circuit for determining a smaller sum value for monitoring a notch required by the SPNPM modulation for reducing circuit complexity of the encoding device.