Coefficient tap leakage for fractionally-spaced equalizers
US4237554A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 1, 1979 |
| Grant date | Dec 2, 1980 |
| Priority date | — |
| Expiry date | Mar 1, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/01
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A quadrature amplitude modulated (QAM) data signal transmitted at T symbols per second is sampled in a data receiver at a rate of 2/T samples per second and applied to a transversal-type equalizer structure (25, 46, 34, 35) having taps spaced at T/2 second intervals. A demodulated equalized signal (a.sub.j, b.sub.j), generated once every T seconds, is quantized to form a decision (a.sub.j *, b.sub.j *) as to the value of the original modulating data symbol. An error signal (e.sub.j, e.sub.j) is formed in response to the pre- and post-quantized values of the demodulated equalized signal. Tap coefficients (c.sub.i (j), c.sub.i (j)) used in generating the equalized signals are updated in response to (a) a correction term which is a function of the error signal and (b) a predetermined tap leakage term which has a constant magnitude. The introduction of the tap leakage term maintains the coefficient values at minimum levels.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.