Secured scramble decoder filter
First Claim
1. A circuit device for removing an interfering signal purposely injected between the video carrier and audio carrier of a television transmission signal, said interfering signal having a frequency substantially in the range of one-fourth to three-fourths of the frequency interval between the video carrier and the audio carrier comprising:
- a housing;
a narrow band notch filter mounted in said housing;
means for tuning said filter to the optimum frequency for eliminating the interfering signal, the latter having a frequency substantially in the range of one-fourth to three-fourths of the frequency interval between the video carrier and the audio carrier; and
means for mounting said housing, said mounting means including means for securing said filter against unauthorized removal from said mounting.
1 Assignment
0 Petitions
Accused Products
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.
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Citations
12 Claims
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1. A circuit device for removing an interfering signal purposely injected between the video carrier and audio carrier of a television transmission signal, said interfering signal having a frequency substantially in the range of one-fourth to three-fourths of the frequency interval between the video carrier and the audio carrier comprising:
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a housing; a narrow band notch filter mounted in said housing; means for tuning said filter to the optimum frequency for eliminating the interfering signal, the latter having a frequency substantially in the range of one-fourth to three-fourths of the frequency interval between the video carrier and the audio carrier; and means for mounting said housing, said mounting means including means for securing said filter against unauthorized removal from said mounting. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A circuit device for removing an interfering signal purposely injected between the video and audio of a television transmission comprising:
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a housing; a frangible substrate mounted in said housing; a narrow band notch filter mounted in said housing upon said frangible substrate; tuning means for tuning said filter to the optimum frequency for eliminating the interfering signal; mounting means for mounting said housing containing said filter; said mounting means including breaking means for breaking said frangible substrate when said device is tampered with, the breaking means comprising a spring, means for cocking said spring, and means for triggering said spring whereby said spring breaks said frangible substrate rendering said filter inoperative. - View Dependent Claims (9, 10, 11)
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12. A circuit device for removing an interfering signal purposely injected between the video and the audio of a television transmission comprising:
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a housing; a narrow band notch filter mounted in said housing, said filter comprising a series resonant inductance and capacitance circuit and a parallel resonant inductance and capacitance circuit, conductors for said filter being deposited upon a substrate; tuning means for tuning said filter to the optimum frequency for eliminating the interfering signal, said tuning means comprising tunable capacitor means in said series and said parallel resonant circuits, said tunable capacitor means comprising at least one capacitor for the series and parallel resonant circuits, said at least one capacitor being deposited upon a temperature stable member attached to said substrate, said at least one capacitor comprising a plurality of strips deposited upon said substrate and being coarse tunable by removal of all or a portion of said strips.
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Specification