Optimum amplitude and frequency of jamming carrier in interdiction program denial system

• US 5,142,574 A
• Filed: 12/06/1989
• Issued: 08/25/1992
• Est. Priority Date: 03/10/1988
• Status: Expired due to Term

• Current Assignee: Moonbeam LLC (Intellectual Ventures LLC)
• Original Assignee: Scientific-Atlanta Incorporated (Cisco Systems, Inc.)
• Inventors: West, Lamar Jr., Blusiewicz, Philip A., Farmer, James O.
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US07/446,602
• Time in Patent Office: 993 Days
• Field of Search: 380/7, 380/20, 455/1
• US Class Current: 380/209
• CPC Class Codes: H04K 2203/14 for the transfer of light or images, e.g. for video-surveillance, for television or from a computer screen
• CPC Class Codes: H04K 3/41 characterized by the control of the jamming activation or deactivation time control of jamming activation and deactivation time only for the purpose of alternating between jamming mode and target monitoring mode H04K3/45
• CPC Class Codes: H04K 3/42 characterized by the control of the jamming frequency or wavelength
• CPC Class Codes: H04K 3/43 characterized by the control of the jamming power, signal-to-noise ratio or geographic coverage area
• CPC Class Codes: H04K 3/825 by jamming
• CPC Class Codes: H04N 7/166 Passage/non-passage of the television signal, e.g. jamming, band suppression scrambling and descrambling H04N7/167
• CPC Class Codes: H04N 7/167 Systems rendering the television signal unintelligible and subsequently intelligible

Abstract

Off premises cable television interdiction apparatus comprises a microprocessor actuation and control means for actuating and controlling one or more frequency agile voltage controlled oscillators. The voltage controlled oscillators selectively jam only unauthorized premium programming transmitted in the clear from a headend to a particular subscriber. Each voltage controlled oscillator is allocated a continuous band of frequencies consistent with the elimination of jamming signal frequency harmonics which may disturb authorized programming at a higher channel frequency. The microprocessor actuation and control means provides a calibration mode and a normal mode of operation. The method of interdiction comprises the steps of generating and storing voltage control words for operating the oscillators consistent with a head end selected jamming factor for a particular channel to be jammed and addressably transmitted and stored premium programming authorization data. An optimum frequency amplitude window for the jamming signal is disclosed.

Claims

1. Cable television premium channel interdiction apparatus for selectively jamming unauthorized premium programming transmitted to a subscriber comprising:

microprocessor actuation and control means for selectively actuating and controlling a plurality of n jamming frequencies provided by a plurality of m controlled oscillators, each of said oscillators separately interdicting with a continuous portion of a boardband cable television spectrum, m being less than or equal to n, a maximum of m jamming frequencies being applied for jamming unauthorized premium programming transmitted to a particular subscriber at one point in time, the microprocessor actuation and control means having a calibration mode of operation and a normal mode of operation, and, during said normal mode of operation, providing a frequency hopping rate on the order of four thousand hertz;

wherein said jamming frequency is limited to be within a range of frequencies extending from approximately 100 KHz below the frequency of a video carrier of a premium channel to be jammed to approximately 200 KHz above the frequency of a video carrier of a premium channel to be jammed and wherein the amplitude of a jamming signal is within the range of approximately -2.5 dB to approximately 6.5 dB of the power level of the video carrier power level of the premium channel to be jammed.

2. The cable television premium channel interdiction apparatus of claim 1 wherein the amplitude of the jamming signal is within the range of approximately -2.5 dB to +5.0 dB.

3. The cable television premium channel interdiction apparatus of claim 1 wherein the jamming signals are calibrated periodically during premium program transmission.

4. A cable television premium channel interdiction method for selectively jamming unauthorized premium programming transmitted to a subscriber comprising the steps of:

receiving globally transmitted frequency and jamming factor data for each premium channel,

receiving addressably transmitted channel or premium programming authorization data,

generating and storing control word data responsive to the frequency, jamming factor and authorization data and

sequentially applying jamming signals to unauthorized premium programming responsive to the stored control word data;

wherein the jamming signals are applied anywhere within a range of approximately 100 KHz below to 200 KHz above the video carrier of a particular premium channel to be jammed.

5. The cable television premium channel interdiction method of claim 4 wherein the amplitude of the jamming signal is within the range of approximately -2.5 dB to +5.0 dB.

6. A cable television channel interdiction apparatus for selectively jamming unauthorized programming transmitted to a subscriber comprising:

means for selectively actuating and controlling a plurality of n jamming frequencies provided by a plurality of m controlled oscillators, each of said oscillators separately interdicting within a continuous portion of a broadband cable television spectrum, m being less than or equal to n, a maximum of m jamming frequencies being applied for jamming programming transmitted to a particular subscriber, the microprocessor actuation and control means having a calibration mode of operation and a normal mode of operation, and, during said normal mode of operation, providing a frequency hopping rate on the order of four thousand hertz;

wherein said jamming frequency is limited to be within a range fo frequencies extending from approximately 100 KHz below the frequency of a video carrier of the unauthorized channel to be jammed to approximately 200 KHz above the frequency of a video carrier of the unauthorized channel to be jammed, and the amplitude of a jamming signal is within the range of approximately -2.5 dB to approximately +6.5 dB of the power level of the video carrier of the channel to be jammed.

7. The cable television channel interdiction apparatus of claim 6 wherein the amplitude of the jamming signal is within the range of approximately -2.5 dB to +5.0 dB.

8. The cable television channel interdiction apparatus of claim 6 wherein the jamming signals are calibrated periodically during premium program transmission.

9. A cable television channel interdiction method for selectively jamming unauthorized programming transmitted to a subscriber comprising the steps of:

receiving globally transmitted frequency and jamming factor data for each channel;

receiving addressably transmitted channel or programming authorization data;

generating and storing control word data responsive to the frequency, jamming factor, and authorization data; and

sequentially applying jamming signals to unauthorized programming responsive to the stored control word data, said jamming signals are applied anywhere within a range of approximately 100 KHz below to approximately 200 KHz above the video carrier of a particular channel to be jammed.

10. The cable television channel interdiction method of claim 9 wherein the amplitude of the jamming signal is within the range of approximately -2.5 dB to +5.0 dB.