PWM Carrier Frequency Shifting for Dynamic Phased Array Phase Control

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Solution Overview

Problem

Phased array systems face errors in digital signal output due to frequency shifts caused by phase changes, which violate the time-invariance requirement, leading to side effects such as frequency shifts and errors in signal generation when the phase of drive signals changes dynamically.

Innovation Solution

The solution involves reconstructing digital signals by explicitly inducing frequency shifts away from a base frequency implied by phase changes, allowing the carrier frequency to shift while preserving timing and phase accuracy, using a novel algorithm and hardware-efficient method for generating pulse-width modulated signals that respect and interpret changes in frequency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the phase angle of phased array elements is changed dynamically, then the system can adapt to different operational requirements, but frequency shifts occur that cause errors in digital signal generation

Engineering Contradiction:

Improvephase angle adjustment capabilityVSAvoidsignal generation accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent changes the parameter being modulated from phase angle to frequency. By using frequency modulation instead of phase modulation, the system can dynamically adjust the phase angles of phased array elements without causing frequency shifts that would error digital signal generation. The PWM signal generator modulates frequency directly, eliminating the frequency shift problem inherent in phase-based approaches.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If a constant base frequency is assumed for digital signal generation, then the system design is simplified, but errors occur when the carrier frequency varies due to phase changes

Engineering Contradiction:

Improvesignal generation system complexityVSAvoidsignal output accuracy

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent makes the base frequency dynamic rather than constant. The PWM signal generator continuously adjusts the base frequency to match the varying carrier frequency caused by phase changes in the phased array elements. This dynamic adaptation allows the system to maintain signal accuracy without requiring complex compensation circuits, achieving both simplicity and precision.

Inventive Principle:

Principle #15Dynamics

3Ease of operation

If phase changes are used to control phased array elements, then operational flexibility is improved, but time-invariance is violated causing side effects including frequency shifts

Engineering Contradiction:

Improvephased array control flexibilityVSAvoidtime-invariance property

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent substitutes phase-based control with frequency-based control. Instead of using phase changes to control phased array elements (which violates time-invariance), the system uses frequency modulation through PWM signaling. This substitution maintains operational flexibility while preserving time-invariance, eliminating the harmful side effects of phase-based control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11378997B2Variable phase and frequency pulse-width modulation technique

Publication Date: 2022.07.05 SIM IP HXR LLC

AI summary

Phased array systems rely on the production of an exact carrier frequency to function. Reconstructing digital signals by specified amplitude and phase is accomplished explicitly by inducing frequency shifts away from a base frequency implied by phase changes. Shifting the carrier frequency of a digitally controlled phased array while preserving the timing of the individual phase pulses enables more efficient driving of the phased array system when the phase of the drive signals change dynamically in time.