Zenith Electronics Corporation

Michael E Long

Richard W Citta

Frederick H Auld, Jr

Vito Brugliera

Dennis M Mutzabaugh

Caitlin B Bestler

Paul A Snopko

Larry K Moreland

Barry Hardek

George R Green

Peter Stramello

A video communication system includes a microprocessor for operating a tuner to select desired television channels in response to the input of corresponding channel numbers. A video data application program is Stored in a memory that is accessible to the microprocessor for providing an on-screen display generator with the video data program information for display. The microprocessor identifies the video data application program by a phantom channel number and when that channel number is input by the user, the microprocessor decodes it and accesses the memory location of the video data application program and activates the on-screen display generator.

Use of transmitter assigned phantom channel numbers for data services

A cable television plant scrambling system incorporates video inversion with a pair of mode signals included in the vertical blanking interval of a scrambled television signal for identifying the proper mode for a video inverting/non-inverting amplifier at a subscriber station. An encoded mode control signal in the form of a byte of data is sent periodically with the scrambled television signal for selecting which of the mode signals is operative. In the receiver, the mode signals are applied to the inverting/non-inverting video amplifier and the encoded mode control signal is supplied to a microprocessor which is provided with a decoding algorithm from the cable head-end. The microprocessor decodes the mode control signal and tells the inverting amplifier which mode signal to look to for proper operation. A new decoding algorithm is periodically downloaded to subscriber stations on an out-of-band basis to enable the encoded mode control signal to be changed.

Enhanced security for a cable system

A television signal receiving apparatus with a channel tuner, such as a television, VCR, or cable box has circuitry for extracting nonprogram type information such as may be carried in the vertical blanking interval of a broadcast signal. In order to ensure a reliable signal source for the nonprogram type information the apparatus has a controller for setting the channel tuner to the proper channel and selecting the proper signal source to receive the nonprogram type information when the apparatus is not used for receiving regular programming signals selected by the viewer.

Non-program signal acquisition system for a television signal receiver

A dual in-band/out-of-band CATV receiver includes a coupler that couples input signals to a tuner and decoder for demodulation and recovery of in-band data and to an FSK receiver for recovery of out-of-band data. The recovered data outputs of the decoder and of the FSK receiver are coupled to a data switch that has a common output that is coupled to a tuner/decoder microprocessor. The tuner/decoder microprocessor in turn supplies information to a switch microprocessor for controlling operation of the data switch to couple either in-band or out-of-band data to the tuner/decoder microprocessor. The data switch defaults to the in-band data position whenever a channel change occurs.

Dual in-band/out-of-band CATV system

A method of operating a pay per view (PPV) television system includes transmitting global data packets alternately encrypted with two different session keys. Subscriber terminals store three session keys, and automatically sequence through the session keys in an ateempt to decrypt the data packets. A program tag in the global data packet identifies a television program and a memory location in the subscriber authorization memory and may also include a tag identifying an upcoming program for which the subscriber may self-authorize his terminal by accessing the memory location identified by the PPV tag. The program tag is required to enable the subscriber terminal descrambling means to descramble the accompanying television program. Subscriber terminals are periodically polled by addressed data packets whereupon the contents of their authorization memories are sent to the cable heat-end for billing purposes. After successful polling, a new session key is downloaded to the subscriber in an addressed data packet. After polling of all subscribers, the memory location identified by the PPV tag is cleared by means of a global data packet encrypted in the new session key which only polled subscriber terminals have. An unpolled subscriber terminal needs to be polled before it receives the new session key.

Television signal scrambling system and method

A TV decoder low loss switching system includes relay operated switch contacts for directly connecting an input signal without loss to a decoder tuner in the normal or enabled mode or bypassing the input signal to a TV in the bypass mode. The switch is parallelled by an impedance to permit a small amount signal singal to be applied to the tuner (in the bypass mode) for data purposes. In one embodiment, a second set of simultaneously actuated contacts connects the output of the decoder to the output terminal. In another embodiment, a channel 3/4 modulator is supplied by the decoder and its output connected via a PIN diode to the output terminal. The PIN diode is biased into conduction by actuation of a transistor switch responsive to the microprocessor enabling the decoder. The conduction of the PIN diode permits the channel 3/4 modulator signal to pass to the output terminal.

Television signal decoder bypass switch

One version of a microprocessor based auto dialer for a PPV television system includes an IR receiver for receiving impulse 'buy' decisions, in the form of one or more key pad entries from a portable IR transmitter, and a number generator for adding the appropriate digits to a partial ANI telephone number stored in memory. In another version, the auto dialer is connected to the serial port of a PM type CATV decoder and a PPV identifier and telephone number may be downloaded to the ANI auto dialer to eliminate the permanent storage of the telephone number and to simplify subscriber interaction. The auto dialer dials the telephone number of the cable head end. Further embodiments include carrier current interfaces between the IR receiver/detector and the auto dialer, and between the decoder and the auto dialer.

ANI auto dialer with carrier current interface

A television encoding system passes a modulated video carrier through a pair of SAW filters for attenuating and reversing the phase of the carrier during horizontal intervals. Another pair of SAW filters impart intermediate amplitude and phase changes to the video carrier during transitions into and out of the horizontal intervals to minimize switching transients and frequency disturbances in the color and audio carriers.

Television signal encoder with reduced transient switching effects

A cable converter for a television signal transmission having a stereo audio signal includes a coaxial output jack supplied with a 4.5 MHz aural intercarrier and a DC voltage for volume control and mute purposes. An interface circuit includes a pair of transistors connected in series for controlling the DC voltage level on the output jack as a function of desired volume level. One of the two transistors functions as a switch that may be operated from the cable head-end to provide a mute voltage level at the output jack for disabling the audio for nonauthorized channels. Optionally, a head-end control signal may operate another transistor for preventing coupling of the 4.5 Mhz aural intercarrier to the output jack.

Cable converter for television signals with stereo audio signal

A video system includes a VCR coupled to the output of a summation circuit that has two inputs. The first input is supplied from an active splitter and the second from a UHF modulator/upconverter which has its input connected to the active splitter through a decoder/converter. The output of the summation circuit is coupled through a passive splitter to the VCR and the VCR is connected to the TV receiver in normal fashion. The arrangement permits full use of the VCR capabilities.

Video system with programmable VCR

A decoder for a television signal encrypted with randomly inverted video and randomly suppressed sync pulses includes inverting and noninverting amplifiers for inverting the inverted video and a sync pulse restoration circuit for restoring suppressed sync pulses, all under control of decoder logic. A comparator is coupled to the noninverting amplifier and changes its output voltage in the presence of signal portions extending beyond the mid sync level of the video signal. The output of the comparator is connected to the emitter of a transistor that has its collector supplied through a voltage divider load from a source of blanking level voltage. The junction of the voltage divider receives the decoded video signal. The transistor is driven conductive in response to flyback pulses, corresponding to the occurrence of sync pulses, applied to its base. The transistor conducts only during sync pulse intervals and the level of the decoded video signal during these intervals is brought to a common point, thus restoring all sync tips to the same height. For negative noise spikes, the transistor is not driven conductive and the level of the decoded video signal is held at blanking level.

Synchronizing pulse restoration circuit

A television signal converter includes ON/OFF means and channel selection means responsive to remotely transmitted infra-red command signals. The signal channel frequency output of the converter is coupled to the input of a VCR having program means enabling a user to determine a recording time schedule. A microprocessor driven programmable remote command signal transmitter supplied ON/OFF and channel selection command signals to the converter.

Time programmable control system for a converter/VCR system

A CATV decoder for receipt of television stereo audio includes a shunt path having a 4.5 MHz filter and amplifier for translating the 4.5 MHz audio signal to a modulator thus bypassing the normal audio baseband detector and 4.5 MHz oscillator circuit. A switch acts through an OR gate for selectively enabling the shunt path and normal audio path. Control from the cable head end is provided by a signal to the OR gate for returning operation to the normal audio path if reception is not authorized. In a similar manner, a remote audio mute signal may be supplied to the OR gate by the viewer.

Baseband CATV decoder with stereo bypass

A VCR includes a single two-way signal splitter and a plurality of RF switches for interconnecting a source of television signals, a television receiver, and a decoder or converter to enable complete flexibility in viewing of any channel while recording of any channel, including a channel requiring a decoder without incurring additional signal loss.

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Oakbrook, IL, United States of America

Michael E Long