Method and apparatus for multi-level quadrature amplitude modula

Details Method and apparatus for multi-level quadrature amplitude modula Method and apparatus for multi-level quadrature amplitude modula

1996-07-11

1998-10-20

Ghebretinsae, Temesghen

Pulse or digital communications

Transmitters

Quadrature amplitude modulation

375264, 332103, H04L 2736

Patent

active

058258280

ABSTRACT:
A method and an apparatus is provided for a multi-level quadrature amplitude modulation system, in which the DC level of the output is "0" even when the modulation multi-level number is varied and mean electric power becomes almost the same. The multi-level quadrature amplitude modulation system is capable of modulating at different modulation multi-level numbers. The method of operating the system includes the steps of converting all of the input bit numbers into the same bit number based on a prescribed conversion rule for each orthogonal channel irrespective of the modulation multi-level number of the system, filtering the converted signal by a digital filter, converting the output of the digital filter into an analog signal by a D/A converter, and modulating the analog signal by a quadrature modulator.

REFERENCES:
patent: 4665532 (1987-05-01), Fukuda et al.
patent: 4965536 (1990-10-01), Yoshida
patent: 5200978 (1993-04-01), Lo Curto et al.
patent: 5363410 (1994-11-01), Hayashi

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