North American Philips Corporation

Edwin R Meyer

David C Greene

Larry G Phillips

Saiprasad V Naimpally

A method and apparatus for synchronizing a received television signal to a subcarrier locked signal is provided. The apparatus includes a comparison block for determining whether the received television signal and subcarrier locked signal are related by a predetermined fixed frequency relationship and for providing indications of the same, and a signal generation block for dividing down the subcarrier locked signal according to the predetermined fixed frequency relationship so as to provide an output signal which is synchronized with the subcarrier locked signal, and at a frequency determined according to the fixed frequency relationship when the signals are related. The apparatus is particularly useful in PIP applications where the received television signal is a horizontal signal and the subcarrier locked signal is a four times multiple of the subcarrier frequency. The comparison block preferably includes a counter and a windowing circuit for determining whether edges of horizontal signal pulses are received within or outside a predetermined time window, and a decision circuit for determining whether the occurrences (counts) of in and out of window edges are indicative of related or unrelated signals. The entire apparatus preferably includes only flip-flops, simple logic gates such as AND, NAND, or OR gates, inverters, multiplexer switches, and resettable counters. The apparatus also preferably further includes a standard combination of flip-flops and a NAND gate for providing a synchronized horizontal reset output signal when the comparison block determines that the received horizontal clock and the subcarrier locked clock are not related.

Apparatus and method for generating a horizontal reset signal

Apparatus and methods for remodulating digital luminance and color difference components for display as PIP information, or together with other composite video components for multi-PIP and test pattern applications are disclosed. A digital encoder is used for conducting a digital quadrature modulation on the color difference components and for digitally adding the luminance signal thereto prior to the converting of the remodulated information into an analog format. Preferably, the digital video information output by the encoder is in the form Y1+(R-Y)1, Y1 +(B-Y)1, Y2-(R-Y)1, Y2-(B-Y)1, Y3+(R-Y)2. Y3+(b-Y)2, Y4 -(R-Y)2, . . . , where Y is the luminance component, R-Y and B-Y are color difference components, and where the numbers index received samples of the video components with the luminance component being sampled at twice the frequency of the color difference components. Where digitally modulated composite video is desired, fixed black level, burst, and background values are multiplexed with the active R-Y and B-Y signals, while fixed sync tip, black level, and background values are multiplexed with the active Y signals prior to encoding.

Apparatus and method for creating digitally remodulated video from

A stabilized gated oscillator that provides pulses at a predetermined repetition rate in phase coherence with a gating signal includes a ceramic resonator in a feedback resonant circuit between the output terminal and the input terminal of a linear amplifier. The resonant circuit, which establishes the repetition rate, is constructed to provide an oscillator frequency in a frequency range between two resonant frequencies of the ceramic resonator wherein the ceramic resonator acts as an inductance.

Stabilized gated oscillator utilizing a ceramic resonator

A digital television processing section capable of picture enhancement, progressive scanning, and multiple picture-in-picture processing is provided. The preferred digital television processing section preferably comprises a picture enhancement processor (PEP), a progressive scan processor, a picture in picture processor, at least one multiplexing means, and a common memory means. The PEP broadly comprises a parameter control means, a memory input select means, and mixer for obtaining current video data, delayed video data from the common memory, and control information from the control means, and for processing the obtained data and information to provide a signal to the progressive scan processor. In various modes of operation, the mixer also provides the signal to the memory input select means which forwards the information to the common memory. The common memory is used as a field delay device and feeds a delayed signal forward to the progressive scan processor. The progressive scan processor then utilizes the current signal and the delayed signal to provide a non-interlaced display. The delayed signal from the common memory may also be fed back to the mixer of the PEP so that noise reduction and/or cross-color effect reduction may be accomplished or so that stored pictures may be displayed. The picture-in-picture (PIP) processor together with a first multiplexer permits main and secondary (PIP) video data to be supplied as current video data to the PEP. Or if desired, up to nine PIPs may constitute the video field.

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Knoxville, TN, United States of America

Edwin R Meyer