Method for demodulating an FM signal
US4859957A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 7, 1988 |
| Grant date | Aug 22, 1989 |
| Priority date | — |
| Expiry date | Oct 7, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03D2200/006
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A method for demodulating an FM signal (FM=Frequency Modulation), in which the FM signal is directly mixed down into an in-phase and a quadrature component of a complex frequency baseband and a modulation signal is determined from a phase relationship of the complex frequency baseband signal, and the phase relationship is determined from a curve length of the frequency baseband signal. The curve length is approximated by a length of a polygon curve which is spanned by successive sampled values of the complex frequency baseband signal. An estimated radius of an envelope curve of the complex frequency baseband is preferably used for normalizing the curve length. A signal receiver according to the invention comprises a direct converter (2), AC-coupled amplifiers (5a, 5b), a demodulator (6a) and a loudspeaker (8).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.