Phase-Compensated Decision Feedback Equalizer for Ghost Removal
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Solution Overview
Problem
Digital broadcasting receivers face challenges in maintaining consistent ghost removal performance due to phase differences between carrier frequencies and ghosts, leading to degradation in ISI/ghost channel capturing/tracing and increased hardware size from higher tap counts in feedback filters.
Innovation Solution
A phase-compensation decision feedback channel equalizer is implemented, comprising a feedforward filter, feedback filter, and phase compensator, which removes phase distortions by equalizing the phase of decision and input signal constellations, thereby maintaining consistent ghost removal performance and reducing hardware size by optimizing bit usage in feedback filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase compensation is not applied to equalize the phase of decision and input signal constellations, then the hardware structure remains simple, but ghost removal performance degrades due to phase differences between carrier frequencies and ghosts
Solution Approach 1:
The phase compensator uses feedback from the decision signal constellation to adjust and equalize the phase of the input signal constellation. By continuously monitoring the phase difference and applying compensatory adjustment, the system maintains consistent ghost removal performance while managing the complexity through a closed-loop control mechanism.
2Reliability
If higher tap counts are used in feedback filters to improve ghost removal performance, then ghost removal efficiency improves, but hardware size increases
Solution Approach 1:
The patent optimizes the number of bits used in the feedback filter by analyzing the actual precision requirements for ghost removal. By adjusting the bit depth parameter to the minimum necessary level, the system achieves effective ghost removal while minimizing the hardware resources required, thus resolving the contradiction between performance and hardware size.
3Stability of the object's composition
If phase equalization is implemented to maintain consistent ghost capturing/tracing performance, then performance consistency improves, but the number of processing steps increases
Solution Approach 1:
The phase compensator performs preliminary phase equalization by pre-adjusting the decision signal constellation to match the input signal constellation phase before the main processing stages. This preliminary alignment prevents subsequent performance variations and reduces the need for iterative adjustments, thereby maintaining consistency while minimizing processing time loss.
Data Source
AI summary
There are provided a phase-compensation decision feedback channel equalizer. The phase-compensation decision feedback channel equalizer equalizes phases of signals outputted from a feedforward filter and a feedback filter regardless of a phase distorted by a carrier wave and a ghost, thereby satisfying the same ghost removal performance.