en:if
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— | en:if [2018/10/29 19:19] (aktuell) – angelegt - Externe Bearbeitung 127.0.0.1 | ||
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+ | ===== Intermediate Frequency ===== | ||
+ | In the **[[wpen> | ||
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+ | The intermediate frequency usually is amplified in several IF amplifier stages and finally fed to the demodulator, | ||
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+ | The engineers choose the intermediate frequency depending on the frequency range of the receiver and the selection of IF filters. In a VLF or longwave receiver a low intermediate frequency is more efficient, as cheaper LC (coil - capacitor) filters can be used with good results and the risk for mirrors (the tuned signal can be heard a second time on the dial with a distance of the double of the intermediate frequency) is small. On shortwaves, this is more a problem, as coil filters offer not such a good selectivity and disturbing " | ||
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+ | To prevent " | ||
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+ | A typical intermediate frequency used in AM broadcasting receivers is 455 kHz. | ||
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+ | In a double conversion receiver, the antenna signal is mixed with a much higher oscillator signal, so that a first high intermediate frequency, for exemple at 5 MHz, is generated. This IF has to pass through a bandpass filter, then it's amplified and converted in a second mixer stage to generate the second intermediate frequency. The final filtering and amplification, | ||
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+ | In FM broadcasting receivers, a typical intermediate frequency of 10,7 MHz is used. | ||
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en/if.txt · Zuletzt geändert: 2018/10/29 19:19 von 127.0.0.1