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:
Nov. 14, 1978
Filed:
Jun. 16, 1977
Hendrik A VAN Essen, Eindhoven, NL;
Petrus J VAN Gerwen, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
A non-recursive discrete filter for simultaneously realizing for example two band-pass filter characteristics starting from a given lowpass transfer characteristic, wherein one bandpass filter has an in-phase transfer characteristic and the other filter the quadrature transfer characteristic of this in-phase filter. The central frequency of these filters is f.sub.o and the output sampling frequency is f.sub.s = 8f.sub.o. This discrete filter comprises multiplying means in which input signal samples x(n) are modified by an associated filter coefficient a(i) for generating modified input signal samples z(n,i) = a(i)x(n-i). The coefficients a(i) are the same for both transfer characteristics and are given by: ##EQU1## WHEREIN H.sub.1 (I) REPRESENTS THE DISCRETE IMPULSE RESPONSE OF THE LOWPASS FILTER. To realize the in-phase transfer characteristic the samples z(n,i) are thereafter multiplied by a factor sgn[cos (.pi.i/4)] and the products thus obtained are accumulated. This results in the output signal sample ##EQU2## To realize the quadrature transfer characteristic the samples z(n,i) are thereafter multiplied by a factor sgn[sin(.pi.i/4)] and the products thus obtained are accumulated. This results in the output signal sample ##EQU3##