Polyphase Rate Converter Reconfiguration for Incommensurate Sampling
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Solution Overview
Problem
Traditional rate conversion methods, especially those using poly-phase filters, face challenges with high computational complexity and inflexibility, particularly when dealing with incommensurate sampling rates and requiring large filter coefficients, which can lead to increased costs and resource demands.
Innovation Solution
A flexible poly-phase filter structure that adjusts filter coefficients based on the phase index and allows for interpolation or approximation, enabling efficient rate conversion across different sampling rates by using a generalized poly-phase architecture with multiple subfilters and interpolation techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional rate conversion using least common multiple is used, then rate conversion between different sampling rates is achieved, but computational complexity and resource requirements increase significantly
Solution Approach 1:
The patent segments the rate conversion process into multiple poly-phase subfilters instead of using a single complex filter operating at the least common multiple rate. Each subfilter operates at a lower rate, dividing the overall computational burden into manageable parts while maintaining the ability to convert between arbitrary sampling rates.
Solution Approach 2:
The patent changes the operational parameters by having each poly-phase subfilter operate at the input sampling rate rather than the least common multiple rate. This parameter change dramatically reduces computational complexity while still achieving the desired rate conversion through the combination of multiple subfilters.
2Measurement precision
If large filter coefficients are used for accurate rate conversion, then conversion accuracy is improved, but memory requirements and computational load increase
Solution Approach 1:
The patent divides the filter into multiple poly-phase subfilters, each with a smaller set of coefficients. This segmentation reduces the memory required to store coefficients while maintaining overall conversion accuracy through the combined output of all subfilters.
Solution Approach 2:
The patent uses a finite number of poly-phase subfilters (partial action) rather than requiring an excessively large single filter. This partial approach achieves sufficient accuracy for practical applications while dramatically reducing memory and computational requirements.
3Device complexity
If poly-phase filters are used for rate conversion, then computational complexity is reduced, but flexibility for incommensurate sampling rates is limited
Solution Approach 1:
The patent creates a universal rate conversion system where the same poly-phase subfilter structure can handle any pair of sampling rates, whether commensurate or incommensurate. This multi-functional approach eliminates the need for different filter designs for different rate pairs while maintaining computational efficiency.
Solution Approach 2:
The patent introduces dynamic selection of which poly-phase subfilter to use based on the specific input and output sampling rates. This dynamic adaptation allows the system to efficiently handle any rate conversion scenario while maintaining low computational complexity through the use of pre-computed subfilters.
Data Source
AI summary
Poly-phase filters are used to offer an efficient and low complexity solution to rate conversion. However, they suffer from inflexibility and are not easily reconfigured. A novel design for rate converters employ poly-phase filters but utilize interpolation between filter coefficients to add flexibility to rate conversion. This interpolation can be implemented as an interpolation of the poly-phase filter results. Additional approximations can be made to further reduce the amount of calculations required to implement a flexible rate converter.