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:
Feb. 02, 1999
Filed:
Mar. 03, 1997
Paul Dana Cole, Fairfield, CT (US);
General Datacomm, Middlebury, CT (US);
Abstract
A shaping filter for a PAM mapper is provided which manipulates incoming PAM code level signals to produce outgoing PAM code level signals whose frequency spectrum is shaped to meet desired criteria. In manipulating input code level values in(t), the shaping filter preferably utilizes previous output signal values without using previous incoming signal values. In a preferred embodiment, the output code level values out(t) are constrained to an output alphabet which is a predefined subset of code levels within the .mu.-law constellation, and are obtained by manipulating the input signals according to an integer-valued shifting function such that out(t) are code level values within the output alphabet. The preferred shifting function S 'shifts' in(t) by a number of places in the output alphabet in the direction opposite the sign of ##EQU1## to provide out(t), where out(t) are .mu.-law code output level values at times t, and a.sub.i are weighting factors chosen to shape the frequency spectrum of out(t). The shaping filter may be used with multidimensional PAM constellations.