| 摘要 |
PURPOSE:To realize the FM modulation with a digital signal processing only using a conventional signal processor without the need for any large capacity ROM by introducing a sinusoidal wave from a cyclic digital filter generating the said signal. CONSTITUTION:In the embodiment, the circuit is constituted in a way that a multiplication circuit 5 whose multiplication coefficient is 2 cosA in a cyclic digital filter shown in figure A is replaced into a multiplier circuit 5, a multipler circuit 8 whose multiplication coefficient is sinA is removed and an output of an adder circuit 1 is extracted externally by a signal w1. Thus, since the FM modulator is realized by a cyclic digital filter using a filter constant calculated from the parameter of an FM modulation wave to be outputted and including a multiplication coefficient changing timewise, any large capacity ROM is not needed but the circuit is constituted by a conventional signal processor.
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