Technique to stabilize the chrominance subcarrier generation in a line-locked digital video system
a technology of chrominance subcarrier and line-locked digital video system, which is applied in the field of line-locked video system, can solve the problems of phase shift and consequently color stripe artifact, phase shift disturbance of sine wave, and continuous change of clk signal
Inactive Publication Date: 2010-06-29
SEMICON COMPONENTS IND LLC
View PDF21 Cites 0 Cited by
- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
Benefits of technology
The patent describes a technique to stabilize the generation of chrominance subcarriers in a line-locked digital video system. The technique involves calculating the time shift in the output waveform, converting it into an equivalent phase shift, and sending a phase correction number to a waveform generator block. This technique helps to improve the stability and accuracy of the video system.
Problems solved by technology
Due to the continuous changing of the clock(CLK) signal from the genlocking step, disturbance is usually created in the chrominance subcarrier PLL which will result in a phase shift and consequently in color stripe artifact.
Because of this arrangement, the problem which is readily encountered is a phase shift disturbance of the SINE wave in the chrominance subcarrier PLL in the receiver.
This disturbance is caused by the simultaneous locking of the genlock device, thereby causing continuous changing of the CLK signal.
Method used
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View moreImage
Smart Image Click on the blue labels to locate them in the text.
Smart ImageViewing Examples
Examples
Experimental program
Comparison scheme
Effect test
Embodiment Construction
[0020]In the preferred embodiment of the present invention, the system shown in FIG. 1 represents a simplified cable / satellite set-top box. It consists of a video decoder 101 which digitizes and conditions the analog input signal, an MPEG decoder 102 which decompresses the digital cable / satellite video stream, a mixing / overlay circuitry 103 which combines the two for picture-in-picture, overlaying menus, fading, etc., or simply switches from one to the other, and finally a digital video encoder 104 which takes the combined digital output of the overlay circuitry 103, converts it into the analog composite video format, which is then sent to a display unit 105. The system clock for the overlay circuitry 103, the digital video encoder 104 and the back-end of the MPEG decoder 102 is provided by the genlock circuitry embedded inside the video decoder. Before any mixing can be performed of the digital MPEG stream and the digitized analog video, the two must be synchronized horizontally an...
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More PUM
Login to View More Abstract
A technique to stabilize subcarrier generation in a line-locked digital video system, caused by simultaneous locking of the genlock device causing continuous changing of a shared clock signal, by calculating a time shift occurring in an output waveform, converting the time shift into an equivalent phase shift and sending a corresponding phase correction number to a waveform generator block to correct the time shift, and thus stabilize subcarrier generation.
Description
FIELD OF THE INVENTION[0001]The present invention relates to the field of line-locked video systems. More particularly, the present invention relates to the field of correcting phase shift in a chrominance subcarrier caused by the system in the process of genlocking.BACKGROUND OF THE INVENTION[0002]A line-locked video system is a digital system that acquires a line-by-line analog signal. An example of such a system would be a video decoder. Each line signal acquired by the system contains a synchronizing pulse and a “color burst,” neither of which carry information that is displayed on the screen. The synchronizing pulse is utilized so that a genlock PLL can locate the analog signal and lock onto it. The “color burst” is a series of eight cycles at the subcarrier frequency which appear in blanking intervals for synchronizing the television receiver to the chrominance signal. The display portion of the signal is transferred after both the synchronizing pulse and the “color burst” por...
Claims
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More Application Information
Patent Timeline
Login to View More Patent Type & Authority Patents(United States)
IPC IPC(8): H04N9/45
CPCH04N9/45
Inventor BICAKCI, ARA
Owner SEMICON COMPONENTS IND LLC