 Movement detection circuit for a PAL television signal |
| What is claimed is: 1. A movement detection circuit for a PAL television signal containing a ... |
|
| Phase-lock-loop lock indicator circuit |
| OF THE INVENTION Referring to FIG. 1, a block diagram illustrating a phase-lock-loop including the ... |
|
| Digital phase-locked loop circuit |
| Accordingly, it is an object of the present invention to provide a new and improved digital PLL ... |
|
| Chroma lock detector |
| A chroma lock detector circuit monitors charge pump control signals within a phase-lock loop to ... |
|
| Fax processor |
| Accordingly, it is the general purpose and object of the present invention to provide an autonomous ... |
|
| Copying machine |
| OF THE INVENTION The copying machine body has a housing 8 in which a reading section A for reading ... |
|
| Color television receiver AFPC circuit |
| Accordingly, it is an object of the present invention to provide a novel color television receiver ... |
|
| Synchronizing circuit for a television receiver |
| What is claimed is: 1. A synchronizing circuit for a television receiver comprising: a ... |
|
|
Method and apparatus for overlaying digitally generated graphics over an analog video signal
| Details |
Inventors: Zeidler, David E.; Simons, Robert M.; Zhu, Qiang;
Assignee: General Instrument (Hatboro, PA)
Primary Examiner: Metjahic; Safet
Assistant Examiner: Grant; Chris
Attorney, Agent or Firm: Ostroff; Irwin, Pfeifle; Erwin W.
A system for overlaying digital character signals on an analog video source signal including a predetermined color subcarrier includes a subcarrier phase lock loop, a digital character generating device, a digital video encoder, and a switching device. The subcarrier phase lock loop separately generates a color subcarrier and a system clock signal which are locked to the color subcarrier of the analog video source signal. The digital character generating device detects horizontal and vertical timing of pixel information in the analog video source signal, and generates digital character signals that are to be overlaid in predetermined pixels of the analog video source signal. The digital video encoder is responsive to the color subcarrier and system clock signals for generating a separate color subcarrier which is locked to the color subcarrier of the analog video source signal. The digital video encoder also converts the digital character signals from the digital character generating means into an analog video output signal that includes the color subcarrier generated in the digital video encoder. The switching means directs the analog video output signal from the digital video encoder or the analog video source signal to an output of the system during pixels times when a digital character is to be overlaid or not overlaid, respectively, on the analog video source signal. |
|
DETAILED DESCRIPTION It is to be understood that corresponding elements having the same function in the several views of the drawings are provided with the same designation numbers.
Referring now to FIG.
1, there is shown a block diagram of a system 10 for overlaying digitally generated graphics over an input analog video source signal in accordance with the present invention.
The system 10 comprises a horizontal/vertical (Horiz.
/Vert.
) Genlock device 12, a subcarrier Phase Lock Loop (PLL) 14 (shown within a dashed line rectangle), a digital video source/On Screen Display (OSD) generator 16, a digital video encoder 18 (shown within a dashed line rectangle), an optional burst window detector 20, a delta phase measurement device 22, and a switching means 24.
The input analog video source signal is, for example, a National Television System Committee (NTSC) video standard signal which is provided as an input to each of the horizontal/vertical Genlock device 12, the subcarrier PLL 14, and the switching means 24.
The horizontal/vertical Genlock device 12 and the digital video source/OSD generator 16 are components of a Digital Character Generating means 28 (shown within a dashed line rectangle).
The horizontal/vertical Genlock device 12 has an output which is coupled to a first input of the digital video source/OSD generator 16.
A digital graphics source signal comprising characters to be overlaid onto the input analog video source signal is provided as a second input to the digital video source/OSD generator 16 from a remote digital graphics source (not shown).
A first output of the digital video source/OSD generator 16 is coupled to the switching means 24 for providing control signals that control the switching position of the switching means 24 between the input analog video source signal and an analog video output signal from the digital video encoder 18.
A second output of the digital video source/OSD generator 16 is to coupled to an input of the digital video encoder 18 for delivering signals representing characters to be overlaid on the input video source signal
|
|
TV Signal 
