Abstract: A program control system for controlling access to premium programming and/or premium channels comprises a program control apparatus which may incorporate one or more subscriber modules. The subscriber modules may use one or more different types of program control technologies to provide different subscribers with different levels of access as well as different levels of security. One subscriber module may comprise a program control apparatus for interdicting premium programming signals transmitted "in the clear". Other modules may comprise positive or negative traps or bandstop filters. The program control apparatus allows a cable television provider to apply new or different program control technologies on a subscriber by subscriber basis.

Abstract: 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.

Abstract: Off premises cable television interdiction apparatus comprises a microprocessor actuation and control means for actuating and controlling at least one frequency agile voltage controlled oscillator. The voltage controlled oscillator selectively jams only unauthorized premium programming transmitted in the clear from a headend to a particular subscriber. The voltage controlled oscillator generates a jamming signal carrier at a frequency 1/N between the video and audio carriers where N is an integer, preferably small. The microprocessor provides a calibration mode and a normal mode of operation. During the normal mode of operation, a frequency hopping rate on the order of four thousand hertz is achievable. the method of interdiction comprises the steps of generating and storing voltage control words for operating the oscillator consistent with a headend selected jamming factor for a particular channel to be jammed and addressably transmitted and stored premium programming authorization data.

Abstract: An off premises CATV system is disclosed. A headend transmits programming including pay-per-view programming and a cable distribution system distributes the programming. An off premises unit is coupled to the cable distribution system for supplying the programming to at least one subscriber. A subscriber terminal is coupled to the off premises unit over a communication link. The subscriber terminal including an input device for inputting subscriber-supplied signals indicative of a pay-per-view event to generate a message. A transmitter responsive to the subscriber-supplied signals transmits the message to the off premises unit over the communication link. The message is transmitted at a plurality of random times within a predetermined period of time.

Abstract: A method of transferring a data message from a remote unit to a central location is provided. A plurality of data channels is selected for transmitting the data message from the remote unit to the central location. At least one random transmit time is generated for transmitting the data message for each of the plurality of data channels. The data message is transmitted over the plurality of data channels at the transmit times. An apparatus for transferring a data message from a remote unit to a central location is also provided.

Abstract: A off-premises CATV system includes a compensation control including a picture carrier controlled automatic gain control and an automatic slope control. A broadband television signal output from a variable gain device is distributed by a radio frequency signal splitter to a number of subscribers for interdiction by the generation of a number of jamming signals. The variable gain device and a variable impedance device which is frequency dependent are connected in series for automatic gain control and automatic slope control, respectively. A first feedback control is used to compare a first portion of the broadband television signal to a reference power level and to control the variable gain device to null the error. A second feedback control is used to compare a second portion of the broadband signal to a second reference power level and to control the variable impedance device to null the error.

Abstract: An off-premises i.e. a negative or positive trap, jamming cable television or interdiction system, includes a picture carried controlled automatic gain control circuit. A broadband television signal output of a variable gain device is distributed by a radio frequency signal splitter to a number of subscribers. A portion of the output of the variable gain device comprising at least two contiguous television channels is passed to a power level detector. A detected power level is compared with a predetermined power level reference for adjusting the gain of the variable gain device. The predetermined power level reference is set to equal the attenuation between the off-premises equipment and the subscriber premises plus the desired level at the entrance to the subscriber's premises. The power level of a jamming or interdicting signal for denying access to unauthorized television programs is set to fall within a predetermined range of power levels related to the predetermined power level reference.

Abstract: Automatic level calibration apparatus for transmitting data from a cable television terminal to the headend of a cable television system comprises programmable transmitter apparatus of the terminal, programmable receiving apparatus at the headend and a calibration controller. Responsive to an addressed command from the headend, the programmable transmitter apparatus returns a sequence of levels at a particular calibration frequency. The programmable receiver apparatus determines an indication of the received signal strength of each of the levels of the sequence of levels. The controller determines an optimum level for transmissions from the terminal.

Abstract: A three terminal compensation network for frequency dependent attenuation has a control terminal, an input terminal, and an output terminal. The network is particularly useful for an off-premises CATV system for slope compensation of a broadband television signal. The control terminal is supplied with a voltage indicative of the amount and direction of the slope in the actual television signal. The voltage oppositely biases a set of diodes which are used as controlled resistances in a pair of tuned circuits in the network. One series tuned circuit provides for varying degrees of negative slope compensation and a parallel tuned circuit provides for varying degrees of positive slope compensation. The network elements are connected in a modified bridge T configuration such that the characteristic impedance of the CATV system (75 ohms) can be approximately matched for the input and output of the broadband television signal.

Abstract: A cable television reverse manifold system is coupled between first and second diplexers of off-premises subscriber service providing equipment. The diplexers separate the transmission path between a headend and a subscriber into downstream or forward and upstream or reverse transmission paths. In one embodiment, the reverse manifold apparatus combines signals from at least one subscriber for transmission to the headend. In another embodiment including a data receiver and a controller, the off premises service providing equipment may be controlled by the subscriber. In yet a third embodiment, a radio frequency transmitter is coupled between the controller and the upstream diplexer which may actuate a plurality of simultaneous data transmissions over separate data channels in the notoriously noisy subsplit 5-30 megahertz transmission spectrum.

Abstract: Networks which remove the jamming signal from the television signal supplied to subscribers for a premium T.V. channel in a cable (CATV) or other subscription television system utilizes surface accoustic wave (SAW) devices arranged to provide a broadband all pass response across the entire band covered by all of the transmitted television channels except for a notch at the frequency of the jamming signal. The narrow band response of the filter in the premium channel is such that the notch presents insertion loss at the jamming signal frequency and over a frequency range to accommodate shifts in the frequency response of the SAW devices with respect to the frequency of jamming signal, which insertion loss is about 100 times the insertion loss at the picture carrier frequency of the television signal, even though the picture carrier and the jamming signal frequency may be within about 200 KHz apart from each other.

Abstract: A BPSK modulator for modulating a data signal onto a carrier signal comprises first and second transistors connected in a mirror configuration and a center tap transformer. The collectors of the first and second transistors are coupled to a first winding of the center tap transformer and the BPSK modulated carrier signal is provided at the output of the transformer. Unmodulated data is input to each of the bases of the first and second transistors. The emitters of the first and second transistors are coupled to the collector of a third transistor whose base receives the carrier signal. A programmable gain control circuit is also coupled to the base of the third transistor for step-wise adjustment of the transmit level of the BPSK modulated carrier signal. In this manner, the transmit output level of the modulator may be adjusted when necessary in the event of changing environmental or other considerations.

Abstract: An off-premises cable television interdiction apparatus provides a microprocessor controller for controlling and switching one or more variable frequency voltage controlled oscillators. The variable frequency oscillators selectively jam only unauthorized premium programming transmitted on particular channels of a broadband signal in the clear from a headend to a subscriber. The microprocessor controller controls the variable frequency oscillators to hop between jamming frequencies and jam particular channels under control from the headend. A frequency calibration routine is executed periodically upon power-up to determine gain parameters for the oscillators. A heterodyned variable frequency oscillator may be provided for the interdiction system which moves the frequency of the variable frequency oscillator out of the television band and mixes the variable frequency oscillator output with a fixed local oscillator output to provide a jamming signal that falls in the television band.

Abstract: Off premises cable television interdiction apparatus comprises a microprocessor actuation and control means for actuating and controlling a plurality of 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. During the normal mode of operation, a frequency hopping rate on the order of four thousand hertz is achievable.

Abstract: Scrambling and descrambling systems utilizing jamming signals provide improved pictures with minimal distortion due to ghosts and artifacts. The television signal is combined with a jamming signal or signals located preferably in the vestigial sideband (VSB) of the modulated picture carrier and at about a null in the spectrum of the modulation of the picture carrier by the horizontal sync. The jamming signal or signals also preferably are placed between the harmonic components of the horizontal sync which define the horizontal sync spectrum and at frequencies which comply with governmental regulations respecting frequency locations of strong signals of CATV purposes. The jamming signals are generated by phase locking to the horizontal sync signals of the television signals or to a submultiple of the horizontal sync frequency.

Abstract: In order to prevent a communications failure in a communications network wherein many terminals share a common communications channel or bus and respond to a network controller over the communications bus to enable the terminals to have access to the bus sequentially and for predetermined intervals, the command which enables the terminal to transmit is connected to an "anti-babbling" circuit which processes the enabling command and prevents the terminal from transmitting its local messages onto the bus when the enabling command does not conform to either of two critical communication protocol timing parameters. Thus, if the enabling command extends longer than the predetermined interval, or occurs at a frequency higher than the predetermined frequency required for normal communication, the "anti-babbling" circuit times-out and causes the terminal to stop transmitting.