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2025-01-27 01:57本頁面
【正文】 or 88 ~ 108MHz 2. Receiver sensitivity as the ability to receive weak signal sensitivity, usually the size of the input signal voltage, said input signal received smaller, higher sensitivity. FM radio sensitivity is usually 5 ~ 30uV. 3. Selective receiver from a variety of signals and interference signals required to select (or attenuation of unwanted signals) capacity as selective units with dB (decibels) that the higher the dB number, the better selectivity. FM radio frequency interference should be greater than 50dB. 4. Frequency range of the frequency response of the receiver frequency characteristics or the pass band is called. FM Machine passband typically 200KHz. 5. Receiver output power maximum load output without distortion (or nonlinear distortion factor for a given value) power as the output power. FM receiver with FM receiver works Figure 1 Block diagram of FM receiver Ordinary FM receiver block diagram shown in Figure 1. Its working principle is: highfrequency antenna receives the signal, selected by the input frequency tuning circuit for the f1, and then amplified by highfrequency amplification stage into the mixer stage. The local oscillator output frequency f2 is also another level into the mixer, the mixer output level with f1, f2, (f1 + f2), (f2f1) and other frequency ponents of signals. Mixer stage circuit output then select FM IF signal (f2f1), then amplified by IF, was sufficiently high gain, then Kamfrequency lowfrequency modulated signal is demodulated, amplified by the low frequency amplifier stage. Due to the high frequency antenna signal through the mixing of a fixed frequency, plus to zoom, so the higher the receiver sensitivity, good selectiv
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