Wave digital filter
A wave digital filter (engl. Wave digital filter ) is a digital filter , which in the field of digital signal processing is used. The specialty of this filter type is that, starting from passive analog filters , which are electrical circuits with capacitors , inductors and electrical resistors , the structure of the digital filter structure and the determination of the filter parameters are derived. Wave digital filters were developed by Alfred Fettweis in the early 1970s .
construction
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Wave digital filters are recursive digital filters in their structure. These are filters which have feedback and loops in their structure and belong to the class of IIR filters . Wave digital filters do not manage with the minimum possible number of filter coefficients. The structure of these filters is more complex than the canonical direct forms 1 and 2 and more arithmetic operations are required with a comparable filter order.
The advantage of wave digital filters is their greater insensitivity to quantization errors in the filter parameters. Passive analog filters, also known as LC branch circuits, are known to be insensitive to component tolerances. These component tolerances of analog filters correspond to the limited accuracy of the filter parameters in the digital filter. For this reason, based on the insensitive analog filter structures, corresponding digital filter structures are derived, which then have an equally high insensitivity to the parameters to be implemented. In the case of specific implementations in signal processors and FPGAs , shorter word lengths can be used in the signal paths under certain circumstances, which minimizes computing effort and circuit size.
The field of application of wave digital filters covers the same areas as ordinary digital filters in the normal forms.
literature
- Kammeyer, Kroschel: Digital signal processing - filtering and spectral analysis with MATLAB exercises . Teubner, 2006, ISBN 3-8351-0072-6 .
- Stefan Bilbao and Julius O. Smith: Wave Digital Filters, Lecture 12. (PDF; 100 kB) Stanford University, 2013, accessed on March 18, 2013 .