Patent ID: 8144809

Claim:
A modulating apparatus in a mobile communication system that performs data communication at a rate for transmitting 2400 symbols per second, each of the symbols having multi-level, characterized by comprising: a base band filter that blocks an unnecessary frequency component of a multi-level symbol inputted and outputs a waveform signal; and frequency shifting and modulating means for shifting to modulate a frequency of an output signal according to a magnitude of an amplitude of the waveform signal inputted from the base band filter, and in that when a positive symbol and a negative symbol each of which has a maximum absolute value are alternately and repeatedly inputted, the frequency shifting and modulating means is adjusted so as to have a frequency shift within a range between a frequency shift which is decided by a modulation index adapted to an emission mask determined based on a condition that the positive symbol and the negative symbol each of which has the maximum absolute value are alternately and repeatedly inputted and a frequency shift which is decided by a modulation index adapted to the emission mask determined based on a condition that pseudo-random data is inputted.