Feed-Forward Filter for Imaginary Signal Estimation
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Solution Overview
Problem
Current communication systems face challenges in accurately estimating the imaginary-part component of complex signals, particularly in VSB signals, due to the complexity of equalizers and the inadequacy of conventional Hilbert transforms when phase errors are significant.
Innovation Solution
A communication signal receiver and method that utilize a feed-forward filter with adjustable tap coefficients based on phase error information to generate an estimated imaginary-part component signal, improving estimation accuracy by dynamically adjusting coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a Hilbert transform is used to estimate the imaginary-part component from the real-part component, then the device complexity is reduced by replacing the imaginary-part equalizer, but the measurement precision deteriorates when phase error is significant
Solution Approach 1:
The patent applies dynamics by making the tap coefficients of the feed-forward filter adjustable rather than fixed. The coefficients are dynamically updated based on phase error information through a coefficient adjusting circuit, allowing the filter to adapt to varying phase conditions and maintain high estimation accuracy across different operating scenarios
Solution Approach 2:
The patent changes the parameters (tap coefficients) of the feed-forward filter based on phase error information. By adjusting these coefficients according to measured or estimated phase errors, the system optimizes the Hilbert transform performance and maintains accurate imaginary-part component estimation even when phase errors are significant
2Measurement precision
If separate equalizers are used for real-part and imaginary-part components, then the measurement precision is improved, but the device complexity increases due to more parameters and tap numbers
Solution Approach 1:
The patent merges the function of separate real-part and imaginary-part equalizers into a single feed-forward filter that processes only the real-part component. By using a coefficient-adjustable feed-forward filter to generate the imaginary-part component, the system achieves comparable processing accuracy to separate equalizers while significantly reducing structural complexity
Solution Approach 2:
The patent introduces a coefficient adjusting circuit as an intermediary that uses phase error information to optimize the feed-forward filter performance. This intermediary enables the simplified single-filter structure to achieve accuracy levels previously requiring complex separate equalizers by dynamically adapting the filter coefficients
Data Source
AI summary
A communication signal receiver includes a feed-forward filter and a coefficient adjusting circuit. The feed-forward filter generates an estimated imaginary-part component signal according to a real-part component of a complex data signal by using tap coefficients of the feed-forward filter. The coefficient adjusting circuit adjusts the tap coefficients of the feed-forward filter according to a control information, wherein the control information comprises a phase error information. The phase error information changes as a phase of the complex data signal changes, wherein the phase is adjusted or not adjusted by the coefficient adjusting circuit.