The Zoom Walsh Transform
Patrick C. Y. Yip · IEEE Transactions on Electromagnetic Compatibility · 1976
A special case of FWT is examined where a scheme is devised to replace a single high-order FWT by consecutive FWT's of much lower order. This special case of the usual decimation-in-frequency approach to fast transforms [1] results in a reduction of transform order, which may have useful applications in processing signals in localized sequency regions.