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一、射频电路原理的概述 TCL9901寻呼机射频电路,由天线(ANT)接收无线电信号(RF),经射频放大电路放大后,送到第一混频器与第一本振信号进行混频,差拍出21.4 MHz的第一中频信号,放大后送第二混频器,差拍出455 kHz的第二中频信号,经限幅放大、鉴频和频率解调,输出FSK信号至逻辑处理单元。射频接收电路如图1所示。二、射频电路工作原理 1.天线与射频放大器:天线(L10)是一片环形的镀金金属片。与电容C7、C4和VC1组成并联谐振回路,谐振于寻呼机的工作频率,调节VC1可改变回路的谐振频率。C8为耦合电容,将天线接收下来的信号
First, the RF circuit schematic overview TCL9901 pager radio frequency circuit, the antenna (ANT) to receive radio signals (RF), amplified by the RF amplifier, sent to the first mixer and the first local oscillator signal mixing, beat The first intermediate frequency signal of 21.4 MHz is amplified and sent to the second mixer. The second intermediate frequency signal of 455 kHz is beat out, and the FSK signal is output to the logic processing unit after limited amplitude amplification, frequency discrimination and frequency demodulation. RF receiver circuit shown in Figure 1. Second, the RF circuit works Antenna and RF amplifier: Antenna (L10) is a ring of gold-plated metal. And capacitors C7, C4 and VC1 constitute a parallel resonant circuit, resonant in the pager operating frequency, adjust the VC1 loop can change the resonant frequency. C8 is a coupling capacitor, the antenna receives the signal down