Frequency estimation based on constellation error in QAM modems

Details Frequency estimation based on constellation error in QAM modems Frequency estimation based on constellation error in QAM modems

2006-07-18

2006-07-18

Kim, Kevin (Department: 2638)

Pulse or digital communications

Receivers

Automatic frequency control

C375S322000

Reexamination Certificate

active

07079605

ABSTRACT:
A method for frequency estimation in a QAM modem comprising the following steps: (1) receiving inphase and quadrature components of a QAM symbol from a carrier recovery block; (2) mapping received QAM symbol to a nearest QAM plant point using a slicer; (3) determining an instant error power of the received QAM point; (4) averaging the instant error power over a plurality of incoming QAM symbols in time domain; (5) excluding a DC component from the averaged error power; (6) translating the averaged error power without DC component from time domain into a frequency domain in order to determine the frequency spectrum of the averaged error power; (7) selecting the frequency spectrum component of the averaged error power with the maximum amplitude by using a peak detection; and (8) determining the frequency offset as the maximum frequency spectrum component of the averaged error power.

REFERENCES:
patent: 5309481 (1994-05-01), Viviano et al.
patent: 5940450 (1999-08-01), Koslov et al.
patent: 6041085 (2000-03-01), Anzai
patent: 6603821 (2003-08-01), Doi
patent: 6882691 (2005-04-01), Chiodini
patent: 2001/0017896 (2001-08-01), Murakami et al.

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