Abstract: A system for enhancing the clarity of video images by changing the pulse response characteristics. A correcting signal that is proportional to the slope of the rise time is generated, processed and then added to the original signal. The combined signal is then monitored with a device that has the ability to check for the presence of overshoots on fast rise time high amplitude signals. When such overshoots are detected, the system switches to a component of the signal which has no overshoot for the duration in time that the overshoot exists, thereby greatly diminishing or eliminating the overshoots.

Abstract: A video scrambling and descrambling arrangement utilizes plural scrambling characteristics including a predetermined scrambling waveform and a selectable one of a plurality of phase relationships with respect to the video signal to be scrambled. Descrambling is achieved by combining with the scrambled video signal a correspondingly phase shifted, inverted version of the scrambling signal. Scrambling and descrambling can be implemented in analogue or digital forms. The information required to achieve descrambling is contained in the scrambled video signal, preferably in an unscrambled portion thereof.

Abstract: A system for transmitting multiple video signals via a single video channel, each video signal having a luminance component in respective sequential horizontal line periods. Luminance components of the video signals are separated and compressed. An output video signal having sequential output horizontal line periods is formed and the compressed luminance components are inserted in the output horizontal line periods. Chroma components are compressed by a higher compression factor and inserted in the blanking intervals. The two color video signals are compressed into one standard 4.2 MHz channel, permitting the system to replace directly any existing 6 MHz audio/video transmission system. An encoder aspect of the invention combines plural video source channels to form an output video channel for transmission, using first and second decoders for separating the input video signal into respective luminance and chroma signals.

Abstract: A system for scrambling and descrambling complex data signals, such as video signals, employs a system for encoding the decoding information, in the form of two security keys, directly onto the scrambled signal being transmitted, without the need of a second communications link for delivering one of the keys. The data signal is encoded with identification information which identifies a specific one of multiple decoders at the receiving stations, and a scrambled security code. The security code can only be descrambled by the decoder which is specifically identified in the identification code. A security code descrambling algorithm which is specific to the respectively associated decoder is permanently installed in the decoder along with the identification information. The relationship between the security code descrambling algorithm and the identification code for each of the decoders is stored in a memory at the transmitting station.

Abstract: A system for scrambling and descrambling complex signals, such as video signals, employs a system for encoding the decoding information, in the form of two security keys, directly onto the scrambled signal being transmitted, without the need of a second communications link for delivering one of the keys. In a video embodiment, several of the video lines during the vertical scan period are encoded with identification information which identifies a specific one of multiple decoders at the receiving stations, and a scrambled security code. The security code can only be descrambled by the decoder which is specifically identified in the identification code. A security code descrambling algorithm which is specific to the respectively associated decoder is permantently installed in the decoder along with the identification information. The relationship between the security code descrambling algorithm and the identification code for each of the decoders is stored in a memory at the transmitting station.

Abstract: A system for scrambling and descrambling the image associated with a video signal employs the shifting in time of a video image after removal of vertical and horizontal synchronization, and color burst reference signals. Coded data which contains information necessary for unscrambling the video image is transmitted in the video signal itself during the vertical blanking interval. A high level of simplification in the decoding is achieved by merely restoring synchronization and color reference data without the need for returning the video image to its original timing. This system provides the significant advantage of permitting unscrambling by unlocking vertical and horizontal synchronization of the video image using inexpensive circuitry at the decoder end, while affording the operator of the transmitter the ability to select whether the unscrambled signal is recordable by a conventional video tape recorder at the receiving end.

Abstract: A system for scrambling and descrambling the image associated with a video signal employs the shifting in time of a video image after removal of synchronization and color burst reference signals. Coded data which contains information necessary for unscrambling the video image is transmitted in the video signal itself during the vertical blanking interval. A high level of simplification in the decoding is achieved by merely restoring synchronization and color reference data without the need for returning the video image to its original timing. This system provides the significant advantage of permitting unscrambling of the video image using inexpensive circuitry at the decoder end, while affording the operator of the transmitter to select whether the unscrambled signal is recordable using a conventional video tape recorder.

Abstract: When the output of a number of color television signal generators is to be combined, all of these outputs must be correctly timed with respect to one another. To accomplish this, the output of a signal generator is applied to a phase-adjusting device and then to a sync separator. Horizontal synchronization pulses and/or color bursts are separated from the signal and applied to a switcher which alternately supplies these synchronization signals and reference synchronization signals to an adder circuit. The other input of the adder receives the incoming signal without the synchronization signals to be timed. The output of the adder is thus the incoming television signal, but with reference synchronization pulses substituted for its synchronization pulses half the time. The output of the adder is then applied to a monitor. The display on the monitor has a distinct flicker when the synchronization pulses of the incoming signal are not in phase with the reference synchronization pulses.

Abstract: Keying signals controlling the switching from a first to a second available signal source are available at the output of a comparator. The input of the comparator receives the output of a presettable up/down counter. The comparator has a first reference input which receives a first reference count (generally one half of the maximum count) at which the counter is switched from up to down operation. The second reference input receives a clip reference count which is less than the first reference count. If the oscillator oscillates at a frequency which is a predetermined multiple of the line frequency, and if the counter is reset at the line frequency, the keying signal will cause a vertical bar containing the picture information from the second signal source to appear within the remaining display which corresponds to the first signal source. The position of the bar can be varied by changing the preset input of the main counter, while its width can be varied by changing the clip reference.

Abstract: Each of the video signals to be combined to create the special effect is applied to the first input of the corresponding one of a plurality of mixing units. The outputs of the mixing units are connected in common. Each mixing unit has a second input. The synchronization and burst signals of one of the video signals is applied to the second input of one of the mixing units. The gain of each mixing unit relative to the applied signal at the first input varies as a function of a corresponding control signal. Each control signal has an amplitude varying directly with the amplitude of an externally applied input signal and inversely with the amplitude of the next following input signal.

Abstract: For phase matching a first and second television signal, both signals are applied to the inputs of an electronic switching circuit, whose output is connected to a standard television monitor. The switching circuit applies the video portion of the first television signal to the monitor. For matching the phase of the synchronizing signals, the synchronizing signals from the first television signal are applied to the monitor for the first half of each field, those from the second television signal during the second half of each field. A visually detectable shift occurs between the top and bottom half of the picture displayed on the monitor if the synchronizing signals of the second television signal are not in phase with those of the first television signal.

Abstract: Each decoder has a random access memory storing program code numbers, a security number, a customer identification number, and program identification numbers utilized for billing purposes. Communication between each decoder and a central computer is subscriber-initiated. The program code numbers must be updated periodically by means of a computer-decoder transmission which takes place only after the program identification numbers have been transmitted from the decoder to the computer. During predetermined cycles in the system sequence, the read-out of the random access memory takes place in reverse order and starting at an arbitrary start point hard-wired into each decoder. Confusion signals are transmitted while program identification numbers already transmitted to the computer are erased in the decoder memory. The communication through the telephone network takes place by frequency shift keying.

Abstract: Each decoder has a random access memory storing program code, a security number, a customer identification number, and program identification numbers utilized for billing purposes. Communication between each decoder and a central computer is subscriber-initiated. The program code codes must be updated periodically by means of a computer-decoder transmission which takes place only after the program identification numbers have been transmitted from the decoder to the computer. During predetermined cycles in the system sequence, the read-out of the random access memory takes place in reverse order and starting at an arbitrary start point hard-wired into each decoder. Confusion signals are transmitted while program identification numbers already transmitted to the computer are erased in the decoder memory. The communication through the telephone network takes place by frequency shift keying.

Abstract: At the sending end randomly generated binary code number signals are inserted into predetermined lines of the vertical retrace interval. The code number signals are also processed in accordance with a program assignment code to change or leave unchanged a predetermined characteristic of the television signal. Periodically, program identification signals, each signifying a program identification number, are inserted into the television signal instead of the binary code number signals. At the receiving end, the program identification signals are utilized to address a random access memory which furnishes program assignment signals. The program assignment signals control logic circuits to process the code number signals in accordance with the same program assignment code utilized at the transmitter. The output of these logic circuits is then utilized to decode the received encoded signal.

Abstract: Due to unavoidable timing and slope errors in the leading and trailing edges of invert pulses utilized in encoding and decoding of the television signal by inversion of the picture signal portion relative to the synchronizing signal portion, transients are generated. A clamping circuit clamps the television signal to a predetermined reference level for short time intervals around each desired switching time instant. The time intervals are sufficiently long to include the maximum possible variation in the actual timing of the switching time instants. A grey level is thus inserted at the encoder. At the decoder, a clamping circuit clamps the television signal to ground potential during the grey level intervals thereby balancing the DC components of the signal portions.