System to cancel ghosts generated by multipath transmission of television signals
US5341177A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 1, 1992 |
| Grant date | Aug 23, 1994 |
| Priority date | — |
| Expiry date | Jun 1, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N5/211
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A ghost-canceling reference signal for inclusion in a television signal is provided by cyclically inserting ones of extended-length complementary-sequence pairs into a prescribed scan line in each of the vertical blanking intervals of successive fields of the television signal. By definition, a pair of binary (.+-.1) sequences of similar length to each other are complementary sequences only if the sum of the linear autocorrelation functions of the sequences is identically zero for all shifts other than zero but provides a high correlation gain at zero shift. A television receiver is described for receiving television signals containing such ghost-canceling reference signals, separating the ghosted complementary-sequence pairs from the received television signals, linearly correlating the ghosted complementary-sequences with corresponding ghost-free complementary-sequences previously stored in the receiver, and adjusting the filtering parameters of ghost-canceling video filters in accordance with the sum of the linear correlation results.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.