Variable Tap Equalizer for Multipath Ghost Signal Removal
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Solution Overview
Problem
Conventional equalizers face limitations in effectively handling strong short ghost signals and require significant hardware resources, while their ability to adapt to changing multipath information is inefficient due to the need for coefficient initialization.
Innovation Solution
The implementation of a variable tap length equalizer with an N-tap feed forward filter, an M-tap feed backward filter, and an L-tap filter, controlled by a unit that dynamically connects these filters based on multipath information to extend the handling range for pre-ghost, strong short ghost, and post-ghost signals, thereby optimizing hardware usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional fixed tap length equalizers use sufficient tap length to cover most possible lengths of ghost signals, then the handling range for multipath information is improved, but hardware resources are significantly increased
Solution Approach 1:
The patent implements variable tap length equalizers where the tap length is dynamically adjusted based on the detected ghost signal characteristics. Instead of using a fixed large tap length to cover all possible cases, the system adapts the tap length to match the actual ghost signal length, thereby reducing hardware resources while maintaining adequate handling range.
Solution Approach 2:
The patent changes the parameter of tap length from a fixed value to a variable value that can be adjusted according to the multipath conditions. By detecting the ghost signal profile and adjusting the tap length parameter accordingly, the system achieves optimal performance with minimal hardware resources.
2Adaptability or versatility
If conventional main tap moving equalizers move the main tap to increase pre-ghost signal handling range, then the adaptability to long pre-ghost signals is improved, but the ability to remove strong short ghost signals behind the main tap deteriorates
Solution Approach 1:
The patent segments the equalizer structure into multiple independent equalizers with different tap lengths. One equalizer is configured for handling long pre-ghost signals while another is configured for removing strong short ghost signals. This segmentation allows each equalizer to specialize in specific ghost signal types without compromising the other functionality.
Solution Approach 2:
The patent creates a multi-functional equalizer system that can handle both long pre-ghost signals and strong short ghost signals simultaneously. By combining multiple equalizers with different configurations, the system achieves universal capability to address various multipath conditions that a single equalizer cannot handle effectively.
3Adaptability or versatility
If conventional equalizers initialize coefficients of all taps when multipath information changes beyond the limit, then the adaptability to changing channels is improved, but the processing time and complexity are increased
Solution Approach 1:
The patent changes the tap length parameter dynamically in response to multipath conditions without requiring full coefficient initialization. By adjusting the tap length parameter to match the detected ghost signal characteristics, the system adapts to channel changes efficiently without the time penalty of re-initializing all coefficients.
Data Source
AI summary
Equalizers are provided including an N-tap feed forward filter, an M-tap feed backward filter, an L-tap filter, a control unit and an accumulator. The control unit is configured to connect the L-tap filter to the N-tap feed forward filter or the M-tap feed backward filter based on multipath information present in a communications channel. The accumulator is configured to sum output signals from at least one of the N-tap feed forward filter, the M-tap feed backward filter and the L-tap filter and to output a summation result. Related digital receivers, methods and computer program products are also provided.