The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 23, 1980
Filed:
Apr. 10, 1979
Hiroshi Sakaki, Tokyo, JP;
Sotokichi Shintani, Tokyo, JP;
Kokusai Denshin Denwa Co., Ltd., Tokyo, JP;
Abstract
An apparatus for reducing a sampling frequency which derives information with the bandwidth f.sub.B /N (N is an integer) having a sampling frequency of 2f.sub.B /N from an input FDM signal with a bandwidth up to f.sub.B having the sampling frequency 2f.sub.B has been found. The present apparatus comprises a pair of partial frequency reduction systems and a switch for alternately selecting the outputs of said partial frequency reduction systems to provide the output signal. Each of said partial frequency reduction systems comprises a DFT means for performing the discrete Fourier transform for every G sampling points (G is the multiple of N) to said input signal, a multiplication means for multiplying the predetermined frequency characteristics with the output of said DFT means, linear conversion means for linear conversion of the output of said multiplication means and for providing G/N number of data, and means for performing the inverse discrete Fourier transform to the output of said linear conversion means. The present invention reduces sampling frequency by performing a smaller number of multiplications than a prior art, thus, the structure of an apparatus can be simple.