Secured scramble decoder filter
US4097894A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 1, 1976 |
| Grant date | Jun 27, 1978 |
| Priority date | — |
| Expiry date | Nov 1, 1996 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/161
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A secured scramble decoder filter comprised of a narrow band filter assembled on a fragile substrate and mounted in a housing wich automatically destroys the filter when any tampering is attempted. The filter is a series tuned network bridging a conductor coupled through a capacitor to a parallel tuned network, which is connected to ground. The coils for the filter are printed on a special electronic glass tube for temperature stability while the capacitors are deposited on the fragile substrate. The filter is mounted in a sealed housing in brackets with a spring, loaded to break the substrate when the device is tampered with to render it inoperative. The device is provided with a mounting screw requiring a special tool for removal so that when the device is mounted any prying in an attempt to remove the device will trigger the destruction of the filter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.