TV system

The video signal is an analog signal composed of video analog data and video synchronization data for the receiver to correctly display the image. The details of the signal depend on the video standard or "standard" of the application - NTSC (National Television Standards Committee), PAL (Phase Alternate Line), and SECAM (Sequential Transport and Storage Color Television System) , a TV system adopted by France, SEquential Couleur Avec Memoire). In the PC field, there are incompatibilities due to the different formats used. In terms of resolution, some systems have 625 lines (50 Hz) per frame, while others only have 525 lines (60 Hz) per frame. The latter is a standard adopted by North America and Japan, collectively referred to as NTSC. Usually, a video signal is generated by a video source such as a video camera, VCR, or TV tuner. To transmit images, the video source first generates a vertical synchronization signal (V SYNC). This signal resets the receiving device (PC monitor) and guarantees that new images are displayed starting from the top of the screen. After issuing the VSYNC signal, the video source then scans the first line of the image. After completion, the video source generates a horizontal synchronization signal again, resetting the receiving end so that the next line starts from the left side of the screen. For each line of the image, a scan line and a horizontal sync pulse signal are issued.

In addition, the NTSC standard also specifies that the video source needs to send 30 complete pictures (frames) per second. If you do not do other processing, the flicker phenomenon will be very serious. To solve this problem, each frame is divided into two parts, each with 2 62.5 lines. Some are all odd lines, and others are all even lines. When displaying, scanning odd lines first and then scanning even lines can effectively improve the stability of the image display and reduce flicker. At present, there are three main formats for color television in the world: NTSC, PAL, and SECAM. Currently, the three formats cannot be unified. Our country adopts PAL-D standard. General plasma is compatible with the above TV standard.