Importance

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Abstract

An FM receiver includes an IF unit followed by an LF unit. The receiver has circuitry for changing the signal transmission characteristic of the IF and/or LF units, including a detector module with detector circuits for detecting values characteristic of receiving or interference states, with the inputs of these detector circuits each being connected with a circuit point of the IF or LF unit carrying the signal to be processed and with the outputs of these detector circuits providing signal characterizing receiving the interference states. The circuitry for changing the signal transmission characteristic also includes an evaluation circuit for processing the signals characteristic of receiving or interference states, the evaluation circuit having an input portion with at least one amplitude and/or time threshold circuit connected with the detector module and having a logic unit which is connected to the input portion and which provides processed signals characteristic of receiving and interference states as control signals to influence individual stages of the IF or LF unit. One of the detector circuits in the detector module determines if the demodulated signal undergoes a voltage leap exceeding a predetermined value, and if so a follow-up voltage for controlling the center frequency of a relatively narrow-banded IF filter is cut off.

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First Claim