Pulse or digital communications – Transceivers – Modems
Reexamination Certificate
2005-11-08
2005-11-08
Liu, Shuwang (Department: 2634)
Pulse or digital communications
Transceivers
Modems
C375S232000, C375S260000, C375S295000, C370S206000, C370S248000
Reexamination Certificate
active
06963603
ABSTRACT:
An apparatus and method is provided for minimizing frequency distortion in the transmit path of an XDSL modem implementing digital multi-tone (DMT) line code. The current invention provides a means for both determining and correcting for distortion in the frequency domain. The apparatus may be incorporated in an existing X-DSL architecture without additional circuitry. In an embodiment of the invention the apparatus may include a calibration phase which may be implemented using the existing analog-to-digital (ADC) conversion and demodulation capabilities on the receive path of the modem. This calibration phase takes place before the training phase associated with establishing communications with a remote site. During the calibration phase a calibration sequence with known spectral characteristics in the frequency domain is injected digitally at the beginning of the transmit path into each of the tone bins of the inverse Fourier Transform engine (IFFT). The receive path is configured to receive feedback of a resultant analog output signal from the transmit path. A frequency analyzer is used to determine the spectral properties of the feedback from the analog output signal and a normalizer is used to compute a local gain table with gain factors for each tone bin which effect the required normalization.
REFERENCES:
patent: 5113414 (1992-05-01), Karam et al.
patent: 5574990 (1996-11-01), Flanagan
patent: 5825826 (1998-10-01), May et al.
patent: 6075411 (2000-06-01), Briffa et al.
patent: 6141377 (2000-10-01), Sharper et al.
patent: 6263077 (2001-07-01), Zuranski et al.
patent: 6295326 (2001-09-01), Tonissen et al.
patent: 6366554 (2002-04-01), Isaksson et al.
patent: 6381268 (2002-04-01), Polley et al.
patent: 6389062 (2002-05-01), Wu
patent: 6411657 (2002-06-01), Verbin et al.
patent: 6480532 (2002-11-01), Vareljian
patent: 6512739 (2003-01-01), Heidari et al.
patent: 6516049 (2003-02-01), Heidari et al.
patent: 6549512 (2003-04-01), Wu et al.
patent: 6754261 (2004-06-01), Liu et al.
Heidari Sam
Rezvani Behrooz
Smith Dale
Cary Charles C.
Ikanos Communication Inc.
IP Creators
Liu Shuwang
LandOfFree
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