Interdiction method and apparatus with programmable jamming effectiveness

摘要

An off-premises method and apparatus for the interdiction of unauthorized channels of a broadband cable television signal includes common circuitry for adjusting the amplitude and equalization levels of the broadband CATV signals and one or more subscriber modules for generating jamming signals of different frequencies which are used to interdict one or more unauthorized channels. Each subscriber module is associated with a subscriber and is programmable and addressable to adjust the jamming parameters of that subscriber independently of other subscribers. Each subscriber module circuit comprises a plurality of latches, each of which is associated with one of a plurality of digital to analog converters. Each of the digital to analog converters drives one or more frequency agile oscillators with its analog output to generate the jamming signals. The subscriber module is based on a sequential state machine which loads frequency control words corresponding to the jammed channels from a frequency control memory into each latch on a cyclic basis. According to one illustrated implementation, the system is adapted to perform with various jamming factors, including pulsed or continuous mode jamming, variable dwell time, and variable hopping rates depending upon the channel line-up of a particular CATV system. Generally, heavy jamming factors are combined with fast hopping rates while light jamming factors are combined with slow hopping rates. Pulsed mode jamming is combined with slow hopping rates and light jamming factors. Using a combination of jamming parameters based on a channel line-up for a particular subscriber improves overall jamming effectiveness.