PURPOSE: To prevent the spread of unnecessary waves of a burst signal, by switching when a code of modulation input is inverted at the leading and tailing edges of a burst signal, delaying or lapping the signal by ≥2-bit to generate the burst signal.

CONSTITUTION: A burst signal controller 5 controls a code generator 6 with an inputted rectangular wave. This generator 6 generates a rectangular wave, which is applied to a synthesizer 7 where it is synthesized with an input data. An output of the synthesizer 7 is applied to a modulator 2, where a phase or amplitude modulation wave is generated. The output of the modulation wave is applied to a switching device 3, which performs switching based on a switching signal from a controller 5. In this case, the switching signal from the controller 5 rises with a lead for a time longer than the leading edge of a data signal input by 2-bit, and falls down with a time delay longer than the trailing edge of the data input signal by 2-bit. Thus, the spread in unnecessary waves of the burst signal can be narrowered by switching the modulation wave.