| 摘要 |
PURPOSE: To reduce the DC components of a base band signal and the charging of an AC coupling capacitor in a base band circuit, and to quicken a receiver recovering time by modulating the power of a vector component close to a carrier frequency, and diffusing the signal power of a narrow band width into a wide band width. CONSTITUTION: When an RF signal is received by a receiver being one of base stations with an antenna 12 of an AC coupling receiver 10, this is filtered by a block 14, and amplified by an amplifier 16, and the amplified RF signal is added to a mixer 18, and mixed with a first local oscillator frequency. A difference frequency from the mixer 18 is filtered by a block 20, and amplified by an AGC control intermediate frequency amplifier 22. The output of the amplifier 22 is supplied to mixers 24a and 24b, and the difference components from them are operated by filters 26a and 26b, AGC control amplifiers 28a and 28b, and A/D converters 30a and 30b, and outputs from the converters 30a and 30b are modulated by a signal processing circuit 32. Afterwards, the extracted information is stored in the RF channel list of an automobile. |
