Method for evaluating the suitability for reception of the frequency-modulated broadcast transmissions received in an FM broadcast receiver, and circuit arrangement for carrying out the method

摘要

To evaluate the suitability for reception of a frequency-modulated broadcast transmission in a mobile broadcast receiver, the field strength indicating signal is evaluated. It is applied at the same time to a first high-pass filter (30), the cut-off frequency of which is approximately 1 kHz and which is connected in series with an inverting amplifier (32) which is connected via a rectifier diode (34) to an RC section (36), furthermore to a second high-pass filter (38), the cut-off frequency of which is about 80 kHz and which is connected in series with a further inverting amplifier (40), the output of which is connected to the RC section (36) via a rectifier diode (42), and to a bandpass filter (48), the cut-off frequencies of which are about 8 kHz and about 50 kHz and which is connected in series with a high-gain amplifier (46), the output of which is connected to the RC section (36) via a fullwave rectifier (50). The variable charging voltage occurring across the capacitor (C) of the RC section (36) is a measure of the suitability for reception, which includes multi-path reception, adjacent-channel reception and common-channel reception disturbances. IMAGE