PWM Signal Generation With Dithering for Low Harmonic Distortion
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Solution Overview
Problem
Existing phased array systems face errors in digital signal generation due to the assumption that the base frequency equals the carrier frequency for all times, leading to frequency shifts and side-effects, which violate time-invariance requirements.
Innovation Solution
A hardware-efficient method using high-order polynomial interpolation to generate pulse-width modulated signals that allow for the free selection of amplitude and phase, preserving phase continuity while enabling carrier frequency variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the base frequency is assumed to equal the carrier frequency for all times, then the system can be treated as time-invariant and simplified, but frequency shifts occur and errors are introduced in the digital signals
Solution Approach 1:
The patent applies dynamics by making the signal generation system adaptive to frequency variations. Instead of assuming a fixed relationship between base frequency and carrier frequency, the system dynamically adjusts the phase angle calculations to account for frequency shifts, allowing the carrier frequency to vary while maintaining signal integrity and eliminating the time-invariance assumption.
2Adaptability or versatility
If the phase angle of the elements is changed to adapt the system state, then the system becomes more versatile, but the time-invariance requirement is violated causing frequency shifts and side-effects
Solution Approach 1:
The patent implements feedback by continuously monitoring the actual carrier frequency and adjusting the phase angle calculations accordingly. The system uses the relationship between phase angle changes and frequency shifts to compensate for variations, ensuring that signal reliability is maintained even when the system state changes and time-invariance is violated.
3Measurement precision
If high-order polynomial interpolation is used to generate PWM signals with free amplitude and phase selection, then signal accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent applies segmentation by breaking down the complex high-order polynomial interpolation into manageable computational steps. The phase angle calculations are divided into discrete updates based on frequency shifts, allowing the system to achieve high signal accuracy through systematic computation rather than monolithic complex calculations.
Data Source
AI summary
A digital signal generation assumes that a base frequency (the frequency with which the primitive phase angles are specified relative to) is equal to the carrier frequency for all relevant times. But this causes errors in the digital signals output to each array element transducer. Thus, it is necessary for the development of a signal generation system that is capable of producing a digital signal using the free selection of amplitude and phase. This is used to produce a substantially error-free signal that preserves the amplitude and phase relative to a constant base frequency while allowing the carrier frequency to vary.