Equalizer for
US4995031A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 19, 1989 |
| Grant date | Feb 19, 1991 |
| Priority date | — |
| Expiry date | Jun 19, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q2213/36
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A receiver for a digital data transmission system comprises a sampling device for sampling digital data signals received from a subscriber loop. A precursor equalizer connected to the output of the sampling device equalizes, in effect filters, the sampled digital data signal. A timing recovery circuit connected to the output of the precursor equalizer controls the sampling device in dependence upon the filtered digital data signal. The precursor equalizer has a difference equation such that the equalized digital data signal has at least one zero-crossing occurring substantially one baud before the main cursor of each pulse. For twisted wire pair subscriber loops, the precursor equalizer may have a different equation: ##EQU1## which produces a single precursor zero-crossing. Alternatively, the precursor equalizer may have a difference equation: ##EQU2## which produces two precursor zero crossings, y(n) being the input to the filter, w(n) its output, h.sub.0 the main cursor height before equalization and h.sub.-1 the precursor height before equalization. The latter precursor equalizer may be modified by multiplying each of the coefficients (h.sub.-1 /h.sub.0).sup.2 and h.sub.-1 /h.su…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.