Anti-demodulator circuit, filtering device and demodulator circuit
US6937871B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | May 7, 2002 |
| Grant date | Aug 30, 2005 |
| Priority date | — |
| Expiry date | Jul 24, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03D3/06
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
The invention relates to an anti-demodulator circuit which is fundamentally built up in the same way as a demodulator circuit but, instead of a bandpass filter as generally used in a demodulator, comprises a notch filter which receives an input signal comprising a useful signal and an interference signal, and generates a filtered signal. The notch filter has a center frequency which approximately corresponds to the frequency of the input signal so as to suppress at least a part of the useful signal. The anti-demodulator circuit further comprises a mixer circuit which receives the filtered signal and a phase-shifted input signal and supplies a demodulated output signal which substantially corresponds to the interference signal.The invention can be particularly used in connection with a filtering device for suppressing interference signals based on adjacent channel disturbances in FM radios, in which the bandwidth of the filtering device is controlled in dependence upon the output signal of the anti-demodulator circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.