Northrop Grumman Systems Corporation

Jeffrey B Warner

Ronald P Smith

Hanna S-h Hsu

Maneesh Goyal

A discrete Fourier transform (DFT) filter bank with stack shift capability, configured, for example, as an analyzer, but equally applicable to a synthesizer, and implemented as a polyphase filter. The DFT filter bank includes a complex modulator for multiplying the input signals x(m), x(m) . . . x(m) by a complex modulator e(m). In order to keep the coefficients for the polyphase filter real, the coefficients are modulated by a DFT twiddle factor e. The use of the DFT twiddle factor enables the hardware to be reduced significantly. For example, for an 8 phasetap filter, only 8 selectable negators are required as opposed tofor known DFT filter banks.

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Hermosa Beach, CA, United States of America

Jeffrey B Warner