Parametric signal processing systems and methods
A method for generating a modulated carrier signal that can be emitted as a parametric wave includes measuring an average amplitude of an audio signal, and adjusting an average amplitude of a carrier signal based on the average amplitude of the audio signal. The carrier signal is then modulated with the audio signal to generate a modulated carrier signal. Various circuits, components and software are also provided for implementing the modulated carrier signal generation scheme.
1 . A method for generating a modulated carrier signal that can be emitted as a parametric wave, comprising:
determining an average amplitude of an audio signal;
adjusting an average amplitude of a carrier signal based on the average amplitude of the audio signal to create an adjusted carrier signal, wherein the average amplitude of the carrier signal increases as the average amplitude of the audio signal increases, and wherein the average amplitude of the carrier signal decreases as the average amplitude of the audio signal decreases; and
modulating the adjusted carrier signal with the audio signal to generate a modulated carrier signal.
2 . The method of claim 1 , further comprising rectifying the audio signal prior to measuring the average amplitude of the audio signal.
3 . The method of claim 1 , further comprising delaying the audio signal prior to modulating the adjusted carrier signal with the audio signal.
4 . The method of claim 3 , wherein the audio signal is delayed between about 0.25 to about 1 second prior to modulating the adjusted carrier signal with the audio signal.
5 . The method of claim 3 , wherein the audio signal is delayed by an amount of time such that adjustments in amplitude of the adjusted carrier signal substantially coincide with a corresponding portion of an audio waveform for which the average amplitude used to create the adjusted carrier signal was determined.
6 . The method of claim 1 , wherein the average amplitude of the audio signal is measured over a period of about 0.5 seconds to about 3 seconds.
7 . The method of claim 6 , wherein the average amplitude of the audio signal is measured over a period of about 1 second to about 2 seconds.
8 . The method of claim 6 , wherein the average amplitude of the audio signal is measured over a period of about 1.5 seconds.
9 . The method of claim 1 , further comprising emitting the modulated carrier signal from an emitter.
10 . A system for generating an ultrasonic signal, comprising:
an audio source, operable to provide an audio signal;
a measuring circuit, operable to measure an average amplitude of the audio signal;
an amplitude modifying circuit, operable to modify an average amplitude of a carrier signal based on the measured average amplitude of the audio signal to create a modified carrier signal, wherein the average amplitude of the carrier signal increases as the average amplitude of the audio signal increases, and wherein the average amplitude of the carrier signal decreases as the average amplitude of the audio signal decreases; and
a modulation circuit, operable to modulate the modified carrier signal with the audio signal to generate a modulated carrier signal.
11 . The system of claim 10 , wherein the measuring circuit includes an audio to DC converter.
12 . The system of claim 10 , wherein the measuring circuit includes a time delay component operable to delay the audio signal prior to modification of the carrier signal.
13 . The system of claim 12 , wherein the time delay component delays the audio signal between about 0.25 to about 1 second prior to modulating the modified carrier signal with the audio signal.
14 . The system of claim 12 , wherein the time delay component delays the audio signal by an amount of time such that adjustments in amplitude of the modified carrier signal substantially coincide with a corresponding portion of an audio waveform for which the average amplitude used to create the modified carrier signal was determined.
15 . The system of claim 10 , further comprising an ultrasonic emitter, operable to emit the modulated carrier signal into a non-linear medium.
16 . The system of claim 10 , wherein the measuring circuit measures the average amplitude of the audio signal over a period of about 0.5 seconds to about 3 seconds.
17 . The system of claim 16 , wherein the average amplitude of the audio signal is measured over a period of about 1 seconds to about 2 seconds.
18 . The system of claim 16 , wherein the average amplitude of the audio signal is measured over a period of about 1.5 seconds.
19 . A method for generating a modulated carrier signal for an ultrasonic audio system, the method comprising:
determining an average amplitude of an audio signal over a sampling period;
adjusting an amplitude of a carrier signal based on the determined average amplitude of the audio signal to create an adjusted carrier signal, wherein the average amplitude of the carrier signal increases as the average amplitude of the audio signal increases, and wherein the average amplitude of the carrier signal decreases as the average amplitude of the audio signal decreases; and
modulating the adjusted carrier signal with the audio signal to generate a modulated carrier signal.