Hybrid modulation method for parametric audio system

摘要

A parametric audio system that permits greater control over the bandwidth of a modulated signal. The system includes a carrier signal generator for generating a carrier signal, at least one audio signal source for generating at least one audio signal, and a modulation component for generating an envelope signal based on the at least one audio signal, modulating the phase of the carrier signal based on a predetermined function to generate a first modulated signal, and multiplying the envelope signal and the first modulated signal to generate a second modulated signal. By selection of the predetermined function, the modulation component can alter the spectrum of the second modulated signal, thereby permitting greater control over the bandwidth of the second modulated signal.

主权项

1. A method of modulating a carrier signal in a parametric audio system, comprising the steps of:
generating an envelope signal based on at least one audio signal; generating the carrier signal, the carrier signal having a carrier frequency; modulating the phase of the carrier signal based on a predetermined function to generate a first modulated signal; multiplying the envelope signal and the first modulated signal to generate a second modulated signal, the second modulated signal having an associated spectrum; altering the spectrum of the second modulated signal by selection of the predetermined function; and amplifying the second modulated signal to generate an amplified signal, wherein the method further includes:
taking the natural logarithm of the envelope signal; andtaking at least an approximate Hilbert transform of the natural logarithm of the envelope signal to generate the predetermined function.