Method and device for digital modulation with low transition density

摘要

The present invention relates to a digital modulation method and a corresponding modulator. The modulator comprises a transcoder (110) followed by a FIFO register (120) and a 2-PSK modulator (130). The transcoder codes a binary word of fixed size into a code word of variable size using a transcoding table. The transcoding table codes at least one first binary word, leading to a first number of phase transitions at the output of the modulator, into a second word of size greater than that of the first word, leading to, at the output of the modulator, a second number of phase transitions less than the first number of phase transitions.

主权项

1. A digital modulation method for transforming a sequence of input words (wk), each constituted of m information symbols, into a sequence of M-PSK modulation symbols where M=2m, wherein said method comprises:
a step of transcoding wherein each input word (wk) is coded into a code word (w′k) of variable length by means of a transcoding table, the transcoding table coding at least one first input word, leading to a first number of phase transitions in said sequence of modulation symbols, into a second word of size greater than m, leading to a second number of phase transitions less than said first number in said sequence; a step of concatenation of the code words (w′k) obtained at the preceding step to supply a sequence of output words (w″k), each output word being constituted of m information symbols; and a M-PSK modulation supplying for each output word of the sequence a corresponding M-PSK symbol.