PWM Signal Generation for Phase-Stable Carrier Frequency Dithering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Phased array systems face errors due to frequency shifts when the phase angle of elements changes, violating time-invariance requirements, leading to frequency shifts and errors in digital signals output to array element transducers.
Innovation Solution
A hardware-efficient method using high-order polynomial interpolation to generate pulse-width modulated (PWM) digital signals that preserve amplitude and phase relative to a constant base frequency, allowing the carrier frequency to vary, by interpolating phase offsets and duty cycles to maintain continuity and reduce latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the phase angle of elements is changed to simplify system operation, then ease of operation is improved, but frequency shifts occur causing errors in digital signals
Solution Approach 1:
The patent changes the parameter representation from fixed time-invariant complex values to time-variant parameters including instantaneous frequency, phase angle, and amplitude. This allows the system to accommodate phase angle changes while maintaining signal accuracy by explicitly tracking and compensating for frequency shifts through continuous parameter updates.
Solution Approach 2:
The patent transitions from a static time-invariant model to a dynamic time-variant model where parameters such as carrier frequency, phase angle, and amplitude can change over time. This dynamic approach allows the system to adapt to phase angle adjustments while maintaining reliability by continuously updating signal parameters to reflect current system state.
2Device complexity
If time-invariance is assumed to simplify signal processing, then device complexity is reduced, but manufacturing precision of digital signals deteriorates due to frequency shifts
Solution Approach 1:
The patent replaces the simplified time-invariant assumption with explicit time-variant parameter tracking. Instead of assuming constant frequency and phase, the system continuously determines instantaneous frequency and phase angle parameters, allowing accurate digital signal generation even when operating conditions change, thereby maintaining manufacturing precision without excessive complexity.
Solution Approach 2:
The patent performs preliminary determination of instantaneous frequency and phase angle parameters before generating digital signals. By pre-calculating these parameters based on desired amplitude and phase specifications, the system prepares accurate reference values that guide subsequent signal generation, ensuring precision while managing complexity through structured preprocessing.
3Stability of the object's composition
If carrier frequency is held constant to maintain time-invariance, then stability of system behavior is improved, but adaptability to phase changes deteriorates
Solution Approach 1:
The patent introduces dynamic parameter adaptation where the carrier frequency, phase angle, and amplitude are allowed to vary over time based on system requirements. This dynamic model replaces the static time-invariant assumption, enabling the system to adapt to phase angle changes while maintaining stable and predictable behavior through controlled parameter evolution rather than rigid constants.
Solution Approach 2:
The patent performs preliminary specification of desired amplitude and phase characteristics, then derives the appropriate time-variant carrier frequency and phase angle parameters from these specifications. This preliminary action ensures that frequency and phase adapt to required phase changes while maintaining overall system stability through mathematically consistent parameter relationships.
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.