Modem apparatus, image communication apparatus and...

Details Modem apparatus, image communication apparatus and... Modem apparatus, image communication apparatus and...

2005-10-11

2005-10-11

Chin, Stephen (Department: 2631)

Pulse or digital communications

Transceivers

Modems

C375S261000, C375S324000

Reexamination Certificate

active

06954493

ABSTRACT:
When a communication is started through a control channel in a half-duplex communication compliant with the Recommendation V.34, the modem apparatus of the present invention demodulates reception symbols subjected to quadrature amplitude modulation and thereby finds their coordinates on a signal space diagram. Then, the modem apparatus calculates a cross product of two vectors from the origin to the coordinates of two consecutive symbols and identifies a control signal from a polarity array configured by polarities of the calculation result arrayed over a span of a plurality of consecutive symbols.

REFERENCES:
patent: 4608703 (1986-08-01), Kaga et al.
patent: 4796279 (1989-01-01), Betts et al.
patent: 6310926 (2001-10-01), Tore
patent: 6311233 (2001-10-01), Nishioka et al.
patent: 6728308 (2004-04-01), Chu et al.
patent: 95/13675 (1995-05-01), None
“Recommendation V.34”, Feb., 1998, pp. 27-66.
International Telecommunication Union: “ITU-T V.34”, pp. 1-73, downloaded from http://www.mirror.itu.int/dms/pages/itu-t/rec/v/T-REC-V.34-199802-1.html on May 13, 2004.

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