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Abstract

A method and system for reducing the sampling rate of a signal for use with high modulation index frequency modulated signals reduces the power consumption and processing requirements of the digital signal processing equipment which performs the demodulation. In a preferred embodiment, a high modulation index FM signal is divided into in-phase and quadrature phase components by a downconverter (FIG. 1, 10). These components are sampled by analog to digital converters (20, 21) and input to a delay element (40, 41). The resulting delayed and undelayed samples are conveyed to downsamplers (60-63) where the sampling rate is reduced. The undelayed in-phase and delayed quadrature phase components are multiplied together by a first multiplier (70) while the undelayed quadrature phase and delayed in-phase components are multiplied together by a second multiplier (71). The output of the second multiplier (71) is then subtracted from the output of the first multiplier (70) by a subtractor (80) which outputs baseband audio or data.

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First Claim