Apparatus for demodulating and decoding multi-level amplitude modulation signal conveying digital data
US5233479A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 1, 1990 |
| Grant date | Aug 3, 1993 |
| Priority date | — |
| Expiry date | Oct 1, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B20/10
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An apparatus for demodulating and decoding a multi-level amplitude modulation signal used to convey digital data, such as a QAM signal, having amplitude modulated carrier components differing in phase. The apparatus derives demodulated data values from that signal, and derives from average values of sets of these data values a set of compensated reference point data respectively corresponding to signal reference points of the multi-level modulation signal which are expressible as a symbol constellation in the I-Q plane. The compensated reference point data are used to obtain correct digital code values from the demodulated data, even if there is considerable distortion of the multi-level amplitude modulated signal, as is the case for such a signal when recorded and reproduced from a magnetic recording medium.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.