What are the two kinds of TV systems? How many scan lines are designed for each system? What is the frame-rate? Which countries use these system standards?
電視系統有哪兩種？各多少掃描線？多少偵數？哪些國家使用？
NTSC is mainly used in USA and Japan. It requires 525 scan lines in each NTSC image, 30 frames per second, and each frame consists of 2 fields constructed in Interlace mode. PAL is a color signal standard first applied in Europe and later used in other areas, including China. PAL requires 625 scan lines in each image, 25 frames per second, and each frame consists of 2 fields constructed in Interlace mode.
NTSC，主要使用在美國、日本。NTSC每張影像使用525條掃瞄線，每秒30個Frames，每個Frame是由2個圖場以 Interlace方式構成。 PAL，彩色訊號標準，歐洲是先驅使用者，也被使用在世界其他地方，包含中國。PAL每張影像有625條掃瞄線，每秒有25 Frames，每個Frame是由2個圖場以Interlace方式構成。