Recursive-Transversal Digital Filter for Sinusoidal Burst Extraction
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Solution Overview
Problem
Existing digital filters for extracting periodic alternating signals, such as sinusoidal burst signals, require high hardware expenditure due to the complexity of signal curve description and numerous multiplication operations, making them economically unfavorable for practical realization in circuit technology.
Innovation Solution
A digital optimal filter design comprising a transversal filter with a first shift register and recursive filter structure, utilizing a pole-zero pair at z=ej2nf for finite pulse response, and implementing the FIR portion using Canonical Signed Digit (CSD) coding to reduce hardware requirements and operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a transversal filter with many coefficients is used to describe complex signal curves, then the filtering precision is improved, but the hardware expenditure increases
Solution Approach 1:
The patent divides the complex optimal filter into two separate simpler filters: a recursive filter and a transversal filter. The recursive filter handles the periodic signal extraction using fewer coefficients, while the transversal filter processes the remaining signal. This segmentation reduces the total number of coefficients needed compared to a single comprehensive transversal filter, thereby reducing hardware expenditure while maintaining filtering precision.
2Measurement precision
If the signal curve is described with high precision using many sample values, then the extraction accuracy is improved, but the number of multiplication operations increases
Solution Approach 1:
By splitting the filtering task between recursive and transversal filters, the patent reduces the number of multiplication operations. The recursive filter structure inherently requires fewer multiplications than a full transversal filter with many coefficients, while still achieving high extraction accuracy through the combined action of both filters.
Solution Approach 2:
The patent changes the structural parameters of the filter system by introducing a recursive component with specific pole-zero placement. This parameter change allows the system to achieve the same extraction accuracy with fewer multiplication operations, as the recursive structure exploits the periodic nature of the signal to reduce computational complexity.
3Ease of manufacture
If a simple filter design is used to reduce hardware expenditure, then the ease of manufacture is improved, but the filtering capability deteriorates
Solution Approach 1:
The patent uses segmentation to create two simpler filter modules that are easier to manufacture individually than a single complex filter. Despite the simplicity of each module, their combination maintains strong filtering capability, as the recursive filter captures the periodic signal characteristics while the transversal filter handles the detailed signal curve matching.
Solution Approach 2:
The patent merges the outputs of the recursive filter and the transversal filter to achieve the final filtering result. This combining of two simpler filter designs produces a system with filtering capability comparable to or exceeding that of a single complex filter, while benefiting from the ease of manufacture of the simpler components.
Data Source
AI summary
A digital optimal filter having an especially sinusoidal pulse response uses a filter structure with a recursive and a transversal portion. The transversal portion comprises filter coefficients for the representation of scan results of half a period of the sinusoidal pulse response signal. The recursive filter structure is used to change the sign after generation of the scan results for half a period and to mark the start and the end of the pulse response. A plurality of periods can lie in between the start and the end of the pulse response, this is why the digital optimal filter can be used to extract especially sinusoidal burst signals from an original signal, namely in digital technology, which is advantageous for the implementation of IC's.