The present invention relates to a method receiving frequency-modulated (FM) stereo multiplex signals transmitted at radio frequencies (RF) wherein during conversion from the RF band to the intermediate frequency (IF) band, the demodulated signal serves as a negative feedback signal to reduce the frequency deviation in the IF band, and wherein adjacent-channel selectivity is provided by low-pass filtering after the conversion to the IF band.
Such a method of FM reception and a circuit for carrying out the same are described in Auslegeschrift DE-B No. 12 63 113. FIG. 5 of that publication shows an embodiment for receiving a frequency-modulated signal and converting it into the range of audibility using negative feedback for reducing the frequency deviation in the IF band, with the adjacent channels being suppressed. The channels to be received contain stereo signals with a stereo subcarrier frequency of 38 kHz, and the complete stereo multiplex signal is transmitted in the respective radio-frequency channel with a peak frequency deviation of +/-75 kHz. FIGS. 1a to 3b of that publication show how the provision of adjacent-channel selectivity by means of low-pass filters can be simplified if the heterodyning frequency for the signal to be received is chosen so that the center frequency of the frequency-modulated IF signal is lower than twice the value of the peak frequency deviation of the signal to be received. Therefore, this frequency conversion method is also called "low IF method."