Device for automatically turning down volume during mobile phone call inside vehicle

The utility model provides a device for automatically turning down the volume during a mobile phone call inside a vehicle. If a phone call is detected inside the vehicle, the volume of vehicle sound equipment is automatically turned down, and when the phone call is finished, the volume is restored. Therefore, the defect that hand-operated muting operation of the driver causes distractions is overcome. A signal induction module is composed of an antenna, a frequency divider, a mobile phone signal processor and a frequency modulator. A processing module includes a single-chip microcomputer. An execution module includes a drive circuit and a vehicle sound equipment circuit. A mobile phone signal is divided by the frequency divider into four paths of signals: one path is subjected to TD-SCDMA processing and TD-SCDMA frequency modulation; one path is subjected to WCDMA processing and WCDMA frequency modulation; one path is subjected to CDMA2000 processing and CDMA2000 frequency modulation; and one path is subjected to GSM processing and GSM frequency modulation. The four paths of signals are integrated for digital processing and output. The obtained signal passes through a signal amplification circuit and the drive circuit, and is output to a sound equipment volume adjusting circuit.