Use of wideband DTV overlay signals for brevity signaling and public safety
US6498627B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 21, 1999 |
| Grant date | Dec 24, 2002 |
| Priority date | — |
| Expiry date | Oct 21, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N21/478
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A brevity signaling module for a digital television (DTV) receiver enables the reception of emergency broadcast messages. The overlay signal received at the receiver front end is squared in a squaring loop, producing spectral lines at DC and twice the overlay signal frequency, or 2&ohgr;, where &ohgr;=2&pgr;f and f is the center frequency of the overlay signal. The squared signal is passed through a narrow band filter having a bandwidth sufficient to pass a spectrum containing a plurality of tones 2&ohgr;, 2&ohgr;1, 2&ohgr;2, . . . , 2&ohgr;n, where 2&ohgr;1, 22, . . . , 2&ohgr;n are different frequency tones assigned to different auxiliary functions. The detected tone is used by a control module to determine whether normal multipath processing should be performed or whether this processing should be suppressed and auxiliary functions performed, including turning on the DTV receiver power in order that an emergency broadcast message might be conveyed to persons in the vicinity of the DTV receiver.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.