Patent ID: 6813359
Filing Date: 2004-11-02
Classification: H04B

Abstract:
A method for minimizing multipath interference in the broadcast of FM signals that use secondary signals in a QAM format comprising the steps of:a) generating an FM stereo pilot signal of a predetermined median frequency and secondary signals in a quadrature amplitude modulation format; a1) receiving said FM stereo pilot signal of said predetermined frequency; b) tracking a time series of phase measurements of the received FM stereo pilot signal; c) determining the proper phase reference of the FM pilot signal for demodulation of the QAM secondary signals at approximately the center of the time series; d) comparing the phase measurements over the time series to detect changes in said phase based upon multipath signal interference and relative movement between transmitter and receiver; e) selecting the appropriate phase modulation for demodulation of said QAM secondary signals; e1) demodulating the QAM secondary signals without multiple path interference.