Joseph P Creekmore

US Patent:

7027942, Apr 11, 2006

Filed:

Oct 26, 2004

Appl. No.:

10/972461

Inventors:

Jeffrey Woodard - Reston VA, US
Joseph Creekmore - Reston VA, US

Assignee:

The Mitre Corporation - McLean VA

International Classification:

G06F 19/00

US Classification:

702 76, 324 7619

Abstract:

A multirate spectral analyzer receives a data sequence through a tapped delay line () onto a plurality of filter channels, each of which includes a first decimator (), a polyphase filter (), and a second decimator (). Each filter channel is coupled to a transform processor () which modulates the frequency response of the polyphase filters to a plurality of identical bandpass filters spaced evenly at 2πk/M intervals, where k=1, 2,. . . , M−1, and M is the number of filter channels. The transform processor () outputs a plurality of time series representative of the frequency component for each of the corresponding filter channels. By choosing a prototype filter order to be much larger than the number of filter channels, the effects of aliasing in the output are greatly reduced. The reduction in aliasing further allows, by prudent selection of the two decimators, for fractional temporal overlap to be implemented in the spectral estimates.