Fast edge detection system tolerant of high degree of intersymbol interference
US6499662B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 13, 1999 |
| Grant date | Dec 31, 2002 |
| Priority date | — |
| Expiry date | Sep 13, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K7/1452
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A system and method for improving the accuracy of edge detection under high Inter-Symbol Interference, or ISI, conditions is disclosed. The amplified and filtered first derivative signal is offset by equal amounts in both directions to generate positive and negative offsets which serve as inputs to negative and positive peak detectors, respectively. The offset is determined by a fast adaptive peak detector provided by attenuating and AC-coupling the first derivative signal to the positive supply to drive a peak detector with a fairly short attack time, such that its output is nearly settled on the first peak of the first derivative signal, but having a decay time long enough to keep the threshold level approximately constant across the label. Peaks are qualified if the peak in question differs in amplitude from the previously qualified peak by the offset amount. Thus, peaks are qualified if their modulation depth exceeds a threshold, regardless of the absolute level of the peaks (such qualification strategy is referred to as modulation depth gating).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.