Phase Precorrection for Constant Envelope Signals
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Solution Overview
Problem
Constant envelope signals, such as FM/PM signals, face significant distortion due to linear filtering effects, leading to amplitude and phase errors, which existing equalizers can only partially mitigate, requiring large and expensive equipment for high power broadcast transmitters.
Innovation Solution
A phase precorrection system that applies a calculated phase correction to the constant envelope signal without introducing amplitude modulation, using a phase precorrection component to adjust the signal's phase and mitigate phase distortion caused by linear distortion sources, allowing the signal to be amplified by a limiting amplifier and passed through filtering elements with reduced distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a constant envelope signal is transmitted through a linear filter (filterplexer), then the signal can be combined with other signals, but linear distortion occurs causing phase errors and audio distortion
Solution Approach 1:
The patent applies preliminary phase correction to the constant envelope signal before it enters the linear filter (filterplexer). A phase correction algorithm calculates the inverse phase response of the filter and applies this correction in advance, so that when the signal passes through the filter, the combined phase shifts result in the desired output phase, eliminating audio distortion and phase errors
Solution Approach 2:
The patent replaces the need for complex physical equalization hardware with a digital signal processing approach. Instead of using large, expensive analog equalizers that require manual tuning, the invention uses computational algorithms to calculate and apply phase corrections in the digital domain, substituting mechanical/electrical hardware with software-based processing
2Manufacturing precision
If practical equalizers are used to mitigate distortion, then some phase distortion is corrected, but the equalizers are physically large, expensive, and require manual tuning
Solution Approach 1:
The patent replaces complex physical equalization hardware with a digital signal processing approach. Instead of using large, expensive analog equalizers that require manual tuning, the invention uses computational algorithms to calculate and apply phase corrections in the digital domain, substituting mechanical/electrical hardware with software-based processing
Solution Approach 2:
The phase correction algorithm automatically adapts to the filter's characteristics by calculating the inverse phase response. The system self-configures by analyzing the filter's actual performance and generating the appropriate correction, eliminating the need for manual tuning and making the system self-adjusting to environmental variations
Data Source
AI summary
Systems and methods are provided for precorrecting a constant envelope input signal. A phase precorrection component generates a precorrected input signal by applying a phase precorrection to the input signal. The applied phase correction alters an associated phase of the input signal without applying amplitude modulation to the signal. A linear distortion source applies amplitude distortion and phase distortion to the precorrected input signal. The applied phase correction mitigates the phase distortion applied by the linear distortion source.