Patent ID: 7230994

Claim:
An apparatus for performing multi-level modulation of an input data string to output a communication signal, said apparatus comprising: a data string number conversion circuit for converting said input data string into an input data signal composed by (3p+1) strings of binary signals, where p is an integer not less than 3, and for outputting said input data signal; a first data conversion circuit, receiving said input data signal output from said data string number conversion circuit, for converting said input data signal to output the converted input data signal; a second data conversion circuit, receiving said input data signal output from said data string number conversion circuit and an output signal of said first data conversion circuit, for converting the received signal into three sets of output signals, termed first, second and third output signals, each being a (p+1) string output signal; a parallel-to-serial conversion circuit, receiving and time-division multiplexing said three sets of (p+1) string output signals output from said second data conversion circuit, to output multiplexd signals; and a multi-level modulating unit, receiving said multiplexed signals of said parallel-to-serial conversion circuit, for effecting multi-level modulation to output the communication signal; wherein said first data conversion circuit outputs an output signal indicating a value from 1 to (11/8)×2 p , depending on the value of said input data signal; if the output signal of said first data conversion circuit takes on a value from 1 to 8×2 (p−3) , said second data conversion circuit sets, based on said input data signal, the value of the output signal of said first data conversion circuit as said first output signal and outputs signals representing predetermined (11/8)×2 p and (10/8)×2 p values as said second and third output signals, respectively; and if the output signal of said first data conversion circuit takes on a value from 1+8×2 (p−3) to 8×2 (p−3) +3×2 (p−3) , said second data conversion circuit sets the value of the output signal of said first data conversion circuit as said first output signal and outputs signals representing predetermined (8/8)×2 p and (6/8)×2 p values as said second and third output signals, respectively.