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:
Oct. 07, 1980
Filed:
May. 23, 1979
Dominique N Godard, Le Rouret, FR;
Philippe E Thirion, St-Paul-de-Vene, FR;
International Business Machines Corporation, Armonk, NY (US);
Abstract
A method and a device for training the equalizer of a receiver used in a QAM transmission system, by means of an unknown data signal, thereby enabling in particular said equalizer to be trained in the cases described above. In accordance with the method of the present invention, in a data receiver wherein, under normal operating conditions, the data is detected with respect to a first constellation, the equalizer is trained by detecting the data with respect to a second constellation which comprises fewer points than said first constellation and by adjusting the coefficients of the equalizer by means of an error signal produced as a result of the detection operation performed with respect to the second constellation. In accordance with a first embodiment of the present invention, the second constellation is comprised of those points of the first constellation that are farthest from its center. In accordance with a second embodiment of the invention, the points of the second constellation are obtained as follows: the first constellation is divided into L sets of points S.sup.l, l=1, 2, . . . , L and a point b.sup.l of the second constellation is associated with each set S.sup.l in accordance with the relation ##EQU1## where the a.sup.k 's are those points of the first constellation that belong to the set S.sup.l.