| 摘要 |
PURPOSE: A universal hands-free kit of a mobile phone for a car is provided to match transmit volume with receiving volume of each mobile phone manufactured in each manufacturer, thereby compatible with different mobile phones. CONSTITUTION: A send/end controller(102) outputs a hands-free mode detection signal. A TX(Transmit)/RX(Receive) signal level controller(106) inputs a signal for setting transmit/receive volume. A microprocessor(108) outputs a TX output level control signal and an RX input level control signal. An RX signal amplifier(112) amplifies an RX signal. An RX input level controller(114) controls an RX input level. An AGC unit(116) controls a gain of the RX signal. A TX signal amplifier(120) amplifies a TX signal. A signal processor(122) converts the TX signal into a digital signal. The first audio amplifier(128) receives the RX signal, and amplifies the RX signal. The second audio amplifier(130) re-amplifies an audio signal, and outputs the audio signal to a speaker(129). A TX signal amplifier(132) amplifies the digital signal. A TX signal output level controller(134) attenuates a portion of the amplified signals, and outputs the attenuated signal to a mobile phone(100).
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