Apparatus and method to derive a television color subcarrier fre

Details Apparatus and method to derive a television color subcarrier fre Apparatus and method to derive a television color subcarrier fre

1995-05-15

1996-06-11

Groody, James J.

Television

Synchronization

Locking of computer to video timebase

348540, 348453, H04N 945

Patent

active

055260551

ABSTRACT:
A technique to derive a television color subcarrier frequency signal from a computer video signal is described. A computer generates a computer video signal including a horizontal synchronization signal component. The horizontal synchronization signal component is applied to a subcarrier frequency generator to produce a pixel clock signal and a subcarrier relative phase signal which are applied to a digital encoder. The digital encoder processes the computer video signal, the pixel clock signal, and the subcarrier relative phase signal to generate an analog baseband television signal. The subcarrier frequency generator includes a frequency conversion circuit, a timing source, and a deviation compensator. The conversion circuit receives the horizontal synchronization signal and generates the pixel clock signal. The timing source is used to generate a reference clock signal. The deviation compensator includes a signal comparison circuit to process the pixel clock signal and the reference clock signal and derive a count signal. A ratio counter circuit then processes the count signal and generates a subcarrier relative phase signal, for processing by the digital encoder.

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patent: 5455628 (1995-10-01), Bishop
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TMC22090/22091 Digital Video Encoders, Preduct Literature, Raytheon Semiconductor Corporation.
CXA1145P/M RGB Encoder Product Literature, Sony Corporation.
B+855 12-18M.Hz RGB/YCrCb to NTSC/PAL Encoder Products Literature, Brooktree Corporation.

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