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:
Aug. 10, 1993
Filed:
Aug. 25, 1991
Ronald W Potter, Snohomish, WA (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A method and apparatus for interpolating between data samples (V.sub.S) that preserves the frequency spectrum of a sampled analog signal (V.sub.O) is provided. Data samples (V.sub.S) are interpolated to produce interpolated values (V.sub.IV) that contain frequency domain information that accurately replicates an original frequency spectrum (24) of the analog signal (V.sub.O) is disclosed. A signal processor (10) reads data samples (V.sub.S) which occur at sampling times (t.sub.S) and resample times (t.sub.R) at which the V.sub.S values are interpolated. A set of t.sub.S times are found near each t.sub.R time. A digital FIR filter having a frequency function (H(fT)) and a continuous impulse response function ##EQU1## is embodied in software form within a program that controls the signal processor (10) where T is the width of the filter impulse response. The signal processor (10) convolves an offset continuous impulse response function ##EQU2## with the V.sub.S values. A plurality of convolved values (V.sub.C) are summed at each t.sub.R time to produce an interpolated value (V.sub.IV) at each t.sub.R time. The frequency response function (H(fT)) of the digital FIR filter reduces aliasing errors introduced by spectral images (25a and 25b) of the original frequency spectrum (24) and reduces amplitude errors caused by the filter's pass band ripple (38). The V.sub.IV values contain frequency domain information that accurately replicates the original frequency spectrum (24).