Hands-free device for cellular phone using frequency modulation

摘要

A hands-free device (100) for a cellular phone using frequency modulation (FM) which is capable of transmitting the user's voice to a call-connected party over the cellular phone (200) and outputting the call-connected party's voice to the user through an existing FM radio (300) installed in a vehicle when the user uses the cellular phone while driving the vehicle. When the user uses the cellular phone (200) while driving the vehicle, he can apply his voice to a microphone (120) and listen to the call-connected party's voice through the FM radio (300), thereby avoiding potential traffic accidents during the use of the cellular phone in the vehicle. Aradio transmitter (182) of a phase locked loop (PLL) system transmits a voice signal with a high quality of sound to the FM radio (300) so that it can be reproduced by the FM radio.