Dual loop sinewave descrambler and method of descrambling
US4920566A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 1, 1989 |
| Grant date | Apr 24, 1990 |
| Priority date | — |
| Expiry date | Feb 1, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/167
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus are provided for descrambling a sinewave scrambled television signal. The television signal is applied to a dual loop circuit that detects AM sinewave modulation on the television signal sound carrier. The detected modulation is applied to the picture carrier of the television signal in a first loop of the circuit to cancel the AM sinewave modulation therefrom. The detected modulation is applied to the sound carrier of the television signal in a second loop of the circuit to increase the AM sinewave modulation on the sound carrier within the loop. The net loop gain of the first loop is then lowered to minimize the application of noise from the sound carrier to the picture carrier.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.