Feedback Filter Block Switching to Reduce Boundary Discontinuities
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Solution Overview
Problem
Feedback filters used in digital signal processing face challenges in parallelization due to signal dependency and discontinuity issues when dividing input signals, leading to reduced signal-to-noise ratios.
Innovation Solution
A filter circuit that divides input signals into blocks with overlapping data, allowing feedback filtering on a sample-by-sample basis and coupling output blocks to minimize discontinuities by adjusting switching timing based on signal comparisons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If input signals are divided into blocks by time domain for parallel processing, then parallelization is achieved and flexibility in filter design is improved, but discontinuity occurs at block boundaries which degrades signal-to-noise ratio
Solution Approach 1:
The input signal is divided into multiple blocks that can be processed in parallel by multiple feedback filters. Each block contains overlapping samples where the tail end of one block overlaps with the head end of the next block, enabling parallel processing while maintaining continuity through the overlap region.
Solution Approach 2:
The head end data of each block is duplicated and added to the tail end of the previous block before processing. This preliminary action ensures that when blocks are processed in parallel, the overlapping regions contain consistent data, preventing discontinuities at block boundaries and maintaining signal-to-noise ratio.
2Manufacturing precision
If polyphase decomposition is used to achieve parallelization, then signal processing equivalence is maintained, but signal dependency between filters restricts feasible order and filter properties
Solution Approach 1:
Instead of using polyphase decomposition that creates signal dependency, the patent segments the input signal into time-domain blocks with overlapping regions. This segmentation allows each feedback filter to process independent blocks without signal dependency constraints, enabling flexible selection of filter order and properties.
Solution Approach 2:
By pre-duplicating head end data and adding it to the tail end of previous blocks, the patent eliminates signal dependency issues that would otherwise restrict filter design flexibility. This preliminary data preparation allows independent parallel processing while maintaining signal continuity.
3Adaptability or versatility
If simple time domain division is used for parallel processing, then no signal dependency exists between filters, but discontinuity at block boundaries lowers signal-to-noise ratio
Solution Approach 1:
The patent applies preliminary action by duplicating head end data of each block and adding it to the tail end of the previous block before parallel processing. This ensures that overlapping regions contain consistent data, eliminating discontinuities at block boundaries while maintaining the independence of parallel filter processing.
Solution Approach 2:
The patent merges the tail end of one block with the head end of the next block by adding duplicated data. This merging creates overlapping regions that ensure continuity when blocks are processed in parallel, maintaining signal-to-noise ratio while preserving filter independence.
Data Source
AI summary
A filter circuit includes: a division unit that divides an input signal and adds, to a tail end of a division block, of head data of the next division block, to generate an input block; a plurality of signal processing units that perform filtering of a feedback type on input blocks to generate output samples, and generate and output blocks; and a coupling unit that couples the output blocks. The signal processing unit outputs first output samples generated until a switching timing, and outputs second output samples generated by the signal processing unit after the timing. The switching timing is a timing within a period corresponding to the duplicated data, at which timing a difference between a first signal generated by the signal processing unit and a second signal generated by the signal processing unit is less than or equal to a threshold consecutively for a second data length.