Digital demodulator for quadrature amplitude and phase modulated signals
US5767739A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 21, 1997 |
| Grant date | Jun 16, 1998 |
| Priority date | — |
| Expiry date | Jan 21, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04S1/007
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Digital demodulator for a quadrature-modulated signal (sq) which transmits a combination signal by amplitude and phase modulation. A quadrature-signal source provides a digitized in-phase component (I) and a digitized quadrature component (Q) of low frequency. A resolver converts the two components (I,Q) into a magnitude signal (b) and a first phase signal (p1). A first feedback control loop and a second feedback control loop that maintains the slope (mp) of the first phase signal (p1) at the zero value and the time average (pm1) at the zero phase position, whereby a third phase signal (p3) is formed. From the resulting signals (b, p3, p3') a decoder forms at least one of the required components (R,L,P).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.