| 摘要 |
In a radio receiver comprising a battery (60), a local oscillator (104), a mixer (103), a demodulator (201) and a controller (401), a voltage level (Ps) of the battery is detected within the rise time of the local oscillator after the power is supplied thereto. The power is intermittently supplied to the local oscillator and other circuits. Before the rise of the local oscillator, the voltage level is selected to check the battery. After the rise of the local oscillator, the demodulated signal (S3) is selected to perform usual receiving operation. The rise of the local oscillator is detected by comparing an amplitude of the intermediate frequency signal (S1) with a reference value (Vref1). The voltage level (S4) and the demodulated signal (S3) are transferred to the controller (401) through a single port (Po). <MATH> |
