Feedback nonlinear equalization of modulated data signals
USRE31351E · kind E · reissue
Assignee
Inventor
Key dates
| Filing date | Dec 24, 1981 |
| Grant date | Aug 16, 1983 |
| Priority date | — |
| Expiry date | Dec 24, 2001 |
Classification
- Technology area (CPC —)General
Abstract
A receiver for a quadrature amplitude modulated data signal impaired by linear and nonlinear distortion, phase jitter and additive noise includes circuitry which compensates for these impairments. In particular, the receiver includes a processor (FIG. 1 44; FIG. 2, 44') which subtracts a feedback nonlinear signal (FIG. 1, D(n); FIG. 2, D'(n)) from each sample of the received signal, either prior or subsequent to demodulation, providing compensation for nonlinear intersymbol interference. The feedback nonlinear signal subtracted from each sample is comprised of a weighted sum of products of individual data decisions and/or the complex conjugates of data decisions, each such product, in turn, being multiplied by a predetermined harmonic of the carrier frequency. In an illustrative embodiment, compensation for second- and third-order intersymbol interference is provided by including two- and three-multiplicand weighted products in the feedback nonlinear signal. Weighting coefficients for each product are adaptively updated in a decision-directed manner.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.