Radio receiver for demodulating both wideband and narrowband modulated signals

摘要

A radio receiver is disclosed for demodulating both wideband and narrowband frequency-modulated signals. The radio receiver improves the capacity of a system by reducing the bandwidth occupancy of analog frequency modulation systems. The radio receiver comprises a superheterodyne frequency device which converts the received frequency-modulated signal to a fixed intermediate frequency signal. A filter then filters the intermediate frequency signal with a first filter bandwidth adapted to a wideband frequency-modulated signal. The filtered wideband frequency-modulated signal is demodulated in a demodulator using a frequency discriminator. The intermediate frequency signal is then filtered using a second and third filter bandwidth adapted to a narrowband frequency-modulated signal. Finally, the further-filtered intermediate frequency signal is demodulated using a frequency discriminator.