Apparatus for correcting quadrature error in a modulator and/or in a demodulator for a signal having a plurality of phase states, a corresponding transmitter, and a corresponding receiver
US5705958A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 26, 1996 |
| Grant date | Jan 6, 1998 |
| Priority date | — |
| Expiry date | Sep 26, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2027/0016
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
Apparatus for correcting quadrature error in a quadrature modulator and/or in a demodulator for a signal having a plurality of phase states, or of amplitude and phase states. The correction apparatus comprises a processor (51) which, when the apparatus is used to correct quadrature error in a demodulator, transforms the levels P and Q of the digital signals output by the demodulation stage into corrected levels P' and Q' that satisfy any one of the following eight relationships: ##STR1## These corrected levels are then applied to decision element (72), optionally after their maximum levels have equalized. The apparatus combines correction accuracy with cheapness, and it enables any quadrature error to be corrected.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.