Discrete Fourier transform via cross correlation charge transfer device

Claim 1

A signal processor to produce a Fourier transform of an analog signal having a plurality of data points comprising: digital shift register means having a plurality of cells for recirculating a digital clocking signal; a charge coupled device configured as an analog shift register means having a plurality of cells for receipt and circulation of an analog signal at a predetermined rate different from that of said digital shift register; a plurality of analog switch circuits each connected to a cell of said digital shift register by means of a direct, unweighted tap and connected to a corresponding cell of said analog shift register by means of a weighted tap which is weighted according to the expression; e.sup.i.sup.πk.spsp.2/2N where; k = integers between 0 and (N-1), and N = one-half the number of cells in said analog shift registers plus one; and summing means connected to each of said plurality of analog switches for receipt of the switched outputs therefrom, whereby a composite Fourier transform of the analog signal received by said analog shift register means is obtained.