| 摘要 |
PURPOSE:To suppress the generation of the unwanted waves caused by the roll-off and to secure a simple and compact constitution of a device by filtering the phase modulated wave with the adverse characteristic of the roll-off before the n-multiplication. CONSTITUTION:A BRF 42 is provided before an 8-multiplication circuit 36. The circuit 36 applies the 8-multiplication to the output of the BRF 42 to set the phase transition at an integer multiple of 2pi. Then, an S.BPF 38 filters the output of the circuit 36 by the band pass characteristic of the central frequency 8f0. An 8-division circuit 40 divides the output of the S.BPF 38 into 8 pieces to reset the frequency at f0 and supplies a carrier to a demodulating part. The BRF 42 has a transfer function of 1/H (w), where H (w) shows the transfer function of the roll-off. In order words, the BRF 42 having an inverse characteristic 1/H (w) of the roll-off is put before the circuit 36. As a result, the phase transition and then the unwanted waves that are caused by the roll-off characteristic can be suppressed. |
