en:selectivity
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— | en:selectivity [2018/10/29 19:42] (aktuell) – angelegt - Externe Bearbeitung 127.0.0.1 | ||
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+ | ===== Selectivity ===== | ||
+ | The capability of a receiver to separate one signal from another on an adjacent frequency channel is referred to as selectivity. | ||
+ | In the technical documentation, | ||
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+ | In the shortwave range, the radio stations appear relatively close to each other with a channel spacing of 5 kHz. A station a channel only 5 kHz away from the operation frequency can severely affect the signal, causing an unpleasant whistling tone in this example with a pitch of 5 kHz. On medium waves, this phenomenon with a channel spacing of 9 kHz (international) resp. 10 kHz (in the US) is less pronounced, on FM with a channel spacing of 50/100 kHz, adjacent channel interference is only a problem with very weak signals in the vicinity of a " | ||
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+ | It is important to choose the optimum bandwidth for reception: For AM reception of broadcasting stations, IF filters with a width of 4 - 6 kHz perform well, for SSB reception 1.8 - 3 kHz, for CW reception are very narrow filters of 250 - 500 Hz used. | ||
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+ | Coil filters can be produced cheaply, but they perform well only on low intermediate frequencies, | ||
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+ | In some receivers, a continuously variable bandwidth (BWC) has been realized; with the modern DSP technology (digital signal processing), |
en/selectivity.txt · Zuletzt geändert: 2018/10/29 19:42 von 127.0.0.1