MULTILEVEL QUADRATURE AMPLITUDE MODULATOR CAPABLE OF REDUCING A MAXIMUM AMPLITUDE OF A MULTILEVEL QUADRATURE AMPLITUDE MODULATED SIGNAL REGARDLESS OF TRANSMISSION DATA INFORMATIONOF REDUNDANT INFORMATION

摘要

Abstract of the Disclosure:In order to produce first and second Lee-errorcorrecting code sequences in a multilevel quadratureamplitude modulator comprising a code converting unit(10) for converting first and second 2m-level inputdigital signals into first and second major convertedsignals by rearranging a square signal point arrangementinto an approximately circular arrangement on a phaseplane, each of the first and the second major convertedsignals consisting of m binary bits numbered from afirst (least significant) bit through an m-th (mostsignificant) bit, a first error correcting codeproducing circuit (21) carries out error correctingcalculation for the first through an n-th bits of thefirst major converted signal to produce the firstLee-error correcting code sequence where n represents aninteger which is not less than two and is not greaterthan m. Similarly, a second error correcting codeproducing circuit (22) produces the second Lee-errorcorrecting code sequence. The first and the secondmajor converted signals are multiplexed with the firstand the second error correcting code sequence into afirst and a second major multiplexed signal, respec-tively. The first and the second major multiplexedsignals are modulated into a multilevel quadratureamplitude modulated signal. In a counterpart multilevel(Abstract of the Disclosure continued)quadrature amplitude demodulator, an inverse operationis carried out to produce the first and the second inputdigital signals.