Patent ReferencesSynchronous radio or television receiver with analog high frequency section followed by digital low frequency section Carrier reproducing circuit for phase shift keying signals Dual conversion FM receiver using phase locked direct conversion IF Baseband demodulator for FM and/or AM signals Digital zero IF selectivity section Digital FM demodulator using delayed signal product with arctangent Method of, and demodulator for, digitally demodulating an SSB signal Method of receiving frequency-modulated stereo multiplex signals Dual port FM demodulation in phase locked receivers Nearly DC IF phase locked transceiver InventorAssigneeApplicationNo. 430467 filed on 11/02/1989US Classes:455/209, Plural local oscillators or mixers455/316, With frequency stabilization for at least one local oscillator455/324Homodyne (i.e., zero beat or synchrodyne reception)ExaminersPrimary: Eisenzopf, Reinhard J.Assistant: Charouel, Lisa Attorney, Agent or FirmInternational ClassH04B 001/30AbstractA direct conversion FM receiver that comprises a quadrature mixer, an A to D converter, a digital demodulator, a digital phase lock loop, and frequency offset setting means is disclosed. The quadrature mixer receives FM signals and mixes them with a local oscillator signal to produce an analog in-phase baseband signal and an analog quadrature baseband signal. The analog in-phase baseband signal and the analog quadrature baseband signal are converted into digital signals by the A to D converter. The digitally converted baseband and quadrature signals are digitally demodulated and filtered by the digital demodulator such that modulation information is produced. The modulation information is used, at least in part, to control the phase lock loop means. In addition, the phase lock loop is offset by the frequency offsetting means such that the desensing components of the analog devices are minimized, thus, substantially reducing the need for tight component tolerance of DC sensing components and the need for manufacturing adjustments of DC desensing components.Field of SearchWith plural conversionWith synchronized or controlled local oscillator Plural local oscillators or mixers With particular discriminator or detector With local oscillator synchronization or locking Discriminator or detector With frequency stabilization for at least one local oscillator Homodyne (i.e., zero beat or synchrodyne reception) | |