Patent ID: 6310926
Filing Date: 2001-10-30
Classification: H04L

Abstract:
A receiver of a multicarrier QAM system for receiving and demodulating an analog multicarrier QAM signal TM into a digital output signal (R.sub.x) consisting of successive bits, comprising:a) analog/digital conversion means (7, 8) for converting said analog multicarrier QAM signal TM into a digital time-domain multicarrier QAM signal (DS) using a predetermined sample frequency (f.sub.sampR) from a receiver clock generator (NCO, 15);b) time-domain/frequency-domain conversion means (10) for converting said digital time-domain multicarrier QAM signal (DS) into a digital frequency-domain multicarrier QAM signal consisting of a plurality of complex QAM data values (Y.sub.1, Y.sub.2 . . . Y.sub.k ; Y.sub.00, Y.sub.01, Y.sub.10, Y.sub.11);c) decoding means (11, 12) for respectively selecting a complex default QAM data value (C.sub.k, C.sub.00, C.sub.01, C.sub.10, C.sub.11) representing a known digital data symbol (00, 01, 10, 11) on the basis of said complex default QAM data values and for decoding said complex default QAM data values into said digital output signal; andd) timing recovery means (14, 16, 19-21) for adjusting a phase of said receiver clock generator (NCO, 15) such that the sample timing in said analog/digital conversion means (7, 8) coincides with that (f.sub.sampT) used in a transmitter (1-6) which generates said analog multicarrier signal; characterized in thate) said timing recovery means (14, 16, 19-21) comprises:e1) phase rotation direction determining means (221-224) for determining a plurality of phase rotation direction values (-1, +1, 0; d.sub.1, d.sub.2, d.sub.3, d.sub.k) of a respective complex QAM data value (Y.sub.k) with respect to a corresponding complex default QAM data value; ande2) average phase rotation direction determining means (219) for determining an average phase rotation direction value (d.sub.k') by averaging all respective rotation direction values; and whereinf) said phase of said sample frequency (f.sub.sampR) is adjusted on the basis of said average phase rotation direction value (d.sub.k).