04425581 is referenced by 241 patents and cites 4 patents.

A system for overlaying a computer generated video signal on an NTSC video signal includes horizontal and vertical pulse processor circuits for generating a horizontal start signal and a vertical reset signal, respectively, in accordance with NTSC standards, and a clocking system for receiving the vertical reset signal and the horizontal start signal and for generating control signals to control the read out of video data from the video generator of a computer so that it is read out at an NTSC rate. The system further includes a video insert keyer circuit for combining the NTSC video signal and the computer generated video signal and for generating a composite video signal for transmission to a monitor or standard television.

Title
System for overlaying a computer generated video signal on an NTSC video signal
Application Number
6/255039
Publication Number
4425581
Application Date
April 17, 1981
Publication Date
January 10, 1984
Inventor
Hermann K Siegl
Lincoln
NE, US
Darrell L Schweppe
Lincoln
NE, US
Agent
Staas & Halsey
Assignee
Corporation For Public Broadcasting
DC, US
IPC
H04N 5/14
H04N 5/22
H04N 5/04
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