METHOD AND DEVICE FOR DIGITALLY DEMODULATING A FREQUENCY MODULATED SIGNAL

摘要

The present invention represents a new approach in the field of digitally demodulating a frequency modulated signal as it is used for example for fm-audio broadcasting. The inventive algorithm improves the signal to noise ratio of the demodulated signal for carrier to noise ratios below the fm-threshold. According to the present invention the spikes in the demodulated signal which are typical to occur for carrier to noise ratios below the fm-threshold are detected and eliminated. The detection is done by interpolation and other criteria of the unwrapped phase ~u of the frequency modulated signal. The unwrapped phase ~u is calculated as the absolute phase which is not limited to the range ¢-.pi.,..., .pi.!.