Parametric Signal Processing for High-Volume Low-Distortion Audio
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Solution Overview
Problem
Existing parametric audio systems face challenges in achieving high volume outputs with low distortion, as they often require intense emitter drive levels that exceed physical limitations, leading to emitter failure and distortion issues, and previous solutions like square rooting, Single Side Band modulation, and recursive error correction have not effectively addressed these problems.
Innovation Solution
A parametric signal emitting system that includes audio input processing with compressors, equalization networks, low and high pass filters, and modulators to optimize audio signals for efficient emission, along with strategically placing inductors near the emitter to reduce voltage radiation and allow flexible system design, using a pot core inductor to minimize interference and heat, and optimizing emitter configuration with a protective screen to enhance output and reduce distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the emitter is driven at intense levels to achieve high volume output, then the output volume increases, but distortion increases and emitter failure rate increases
Solution Approach 1:
The patent applies preliminary action by pre-processing the audio signal through compression and equalization before modulation. The compressor reduces dynamic range to prevent overload, and the equalization network pre-compensates frequency response, allowing the emitter to operate at lower intense levels while still achieving high volume output with reduced distortion and failure rate.
Solution Approach 2:
The patent changes operating parameters by using optimized modulation indices and frequency ratios in the parametric modulation process. By carefully selecting carrier and modulator frequencies and their relationship, the system achieves efficient parametric interaction that produces high volume output without requiring excessive drive levels that would cause emitter failure.
2Productivity
If the emitter is driven at intense levels to achieve high volume output, then the output volume increases, but distortion increases
Solution Approach 1:
The compressor and equalization network perform preliminary signal conditioning to prevent distortion before it occurs. The compressor limits peak levels to stay within linear operating ranges, while the equalization network pre-corrects frequency imbalances, resulting in clean high-volume output without the distortion that would normally accompany intense emitter operation.
Solution Approach 2:
The system employs feedback mechanisms through the compressed signal path where output levels are monitored and fed back to the compressor and equalization stages. This automatic gain control and frequency response adjustment ensures the emitter operates in an optimal range that maximizes volume output while minimizing distortion generation.
3Productivity
If conventional signal processing techniques are applied to achieve high volume, then output volume increases, but system complexity increases
Solution Approach 1:
The patent merges multiple signal processing functions into integrated circuits and modular blocks. The compressor, equalization network, and modulators are combined in a unified signal path architecture, reducing the number of separate components and interconnections needed. This integration achieves high volume output while keeping system complexity manageable through functional consolidation.
Solution Approach 2:
The signal processing system is designed with universal blocks that can handle multiple functions. For example, the compressor also serves as a limiter and level controller, while the equalization network provides both frequency correction and tone shaping. This multi-functionality reduces the total number of components needed to achieve high volume output.
4Productivity
If intense drive levels are used to achieve useful volume magnitude, then output volume increases, but power consumption increases
Solution Approach 1:
By pre-compressing and pre-equalizing the signal, the system prepares the input signal to maximize parametric conversion efficiency. This preliminary processing allows the emitter to convert electrical energy to acoustic energy more efficiently, achieving useful volume magnitude with lower power consumption than would be required without such optimization.
Solution Approach 2:
The system optimizes operating parameters including modulation depth, carrier frequency, and modulator frequency to maximize the efficiency of parametric sound generation. By operating at optimized frequency ratios and modulation indices, the system achieves higher acoustic output per watt of electrical input, reducing overall power consumption while maintaining useful volume levels.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves significantly higher output volume with lower power consumption and reduced distortion, operating efficiently with minimal component cost and complexity, capable of producing high-quality binaural sound without the need for headphones, while consuming as little as 9 watts per channel compared to conventional systems which consume 80-130 watts.
Implementation Method 1
Non-linear transduction, such as a parametric array in air, results from the introduction of sufficiently intense, audio modulated ultrasonic signals into an air column. Self demodulation, or down-conversion, occurs along the air column resulting in the production of an audible acoustic signal.
Implementation Method 2
This process occurs because of the known physical principle that when two sound waves with different frequencies are radiated simultaneously in the same medium, a modulated waveform including the sum and difference of the two frequencies is produced by the non-linear (parametric) interaction of the two sound waves.
Implementation Method 3
strategically placing inductors near the emitter to reduce voltage radiation and allow flexible system design, using a pot core inductor to minimize interference and heat
Data Source
Figure 1
Figure 2~3A
Figure 3B
AI summary
A signal processing system (10) for generating a parametric signal comprises an audio compressor (14a, 14b), operable to compress a dynamic range of an audio input signal, and an equalization network (16a, 16b), operable to equalize the audio signal. A low pass filter (18a, 18b) is operable to remove high portions of the audio signal and a high pass filter (20a, 20b) is operable to remove low portions of the audio signal. An oscillator circuit (22 a, 22b) is operable to generate a carrier signal, and a modulation circuit (23) is operable to combine the audio signal with the carrier signal to produce at least one modulated carrier signal.