| 摘要 |
PURPOSE: To prevent the degradation of transmission characteristics due to distortion by simple constitution even when a power supply voltage drops by controlling modulation signals so as to lower the peak value of modulated waves corresponding to the drop amount of the detected power supply voltage and performing input to a modulation part. CONSTITUTION: A value for which the output voltage Vcc of a power source 4 is detected by a voltage detection circuit 11 is A/D converted by an A/D converter 12 and inputted to a digital signal processor(DSP) 10. The DSP 10 inputs communication data and generates the modulation signals Sm so as to lower the peak value of the modulated waves St corresponding to the drop amount of the voltage Vcc corresponding to a program stored in a built-in ROM. Corresponding to the signals Sm, the modulated waves St for which carrier waves are orthogonally transformed by an orthogonal transformer 13 are amplified by the supply power of the power source 4 by a transmission power amplifier 3 and outputted. Thus, waveform distortion is eliminated even when the power supply voltage drops and the degradation of the transmission characteristics due to the distortion is prevented by the simple constitution. |
