Boots – shoes – and leggings
Patent
1979-02-15
1981-01-13
Malzahn, David H.
Boots, shoes, and leggings
370 23, G06F 1531
Patent
active
042453259
ABSTRACT:
Disclosed is a digital multifrequency signaling receiving system in which a first operation device executes an operation to multiply multifrequency signals composed of N samples as input signals by a window function including coefficients required for fast Fourier transform. An output produced at the first operation device, as a sample signal, is subjected to fast Fourier transformation at a second operation device which includes a subtractor and a logic circuit. In the subtractor, the sample signals are delayed N/2 samples to halve the number of sample signals. The logic circuit executes an operation for the sample signals, taking advantage of the fact that some frequencies of the outputs of the Fourier transform are represented as the conjugate complex of the other outputs of the Fourier transform. The sample signals fast-Fourier-transformed and produced at the second operation device are subjected discrete Fourier transformation in a processor, where an output for detecting the multifrequency signals is obtained.
REFERENCES:
patent: Re29460 (1977-10-01), Mills
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patent: 3824471 (1974-07-01), Mills
patent: 3863030 (1975-01-01), Mills
patent: 3976843 (1976-08-01), Buchner et al.
patent: 4021653 (1977-05-01), Sharp et al.
patent: 4109109 (1978-08-01), Molleron
Imagawa Hitoshi
Iwase Yasumasa
Kikuchi Shiro
Malzahn David H.
Nippon Telegraph and Telephone Public Corporation
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