| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a two-point frequency modulation apparatus capable of reducing an input timing difference between two-point modulations, and also, capable of improving modulation accuracy, and its modulation method. <P>SOLUTION: The two-point frequency modulation apparatus 10 comprises a PLL circuit 11; a frequency division ratio generating part 13, which sets a frequency division ratio of a frequency divider 111 on the basis of a first digital base band signal S1 and a carrier wave signal; an adder 114 for adding a second digital base band signal S2 to an output signal of a loop filter 113; a delay index calculating means (a filter coefficient calculating part 17), which calculates a delay index on the basis of a change magnitude of the amplitude of an output signal output from the adder 114; and a delay adjusting means (a digital filter 18) which shifts the phase of either of the first/second digital base band signals S1, S2 in response to the delay index and reduces a phase difference. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
