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AssigneeInternational Business Machines Corporation
InventorsDominique N. Godard, Philippe E. Thirion
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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.
In a data receiver for a data transmission system using a QAM technique, of the type wherein the received signal is, in particular, equalized by an adaptive equalizer and then fed as an input signal to a data detection device which supplies the detected data after comparing said input signal with a first constellation, a method of training said equalizer, characterized in that it includes the steps of:
In a data receiver for a data transmission system using a QAM technique, of the type that includes an adaptive equalizer and a data detection device which receives as input signal the received signal after the latter has been, in particular, equalized, and provides the detected data after comparing said input signal with a first constellation, a device for training the equalizer, characterized in that it includes:
In a data receiver for a data transmission system using a QAM technique, of the type that includes an adaptive equalizer, means for subtracting an estimated phase error from the phase of the equalized signal and for supplying a signal called input signal, a data detection device which receives said input signal as input and supplies the detected data after comparing said input signal with a first constellation, and means for supplying said estimated phase error, a device for training the equalizer, characterized in that it includes:
Dependencies are inferred from the claim text.