Analysis of Servo System Parameters with Data Error Rate for CD- ROM Drives

• Main Authors: Chuang, Yao-Lung, 莊曜隆
• Other Authors: Yung-Yaw Chen
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/32526843852304879359

碩士 === 國立臺灣大學 === 電機工程學系 === 85 === The Compact Disc (CD), introduced more than a decade ago, has become a successful medium for the distribution and storage of digital information. The CD-ROM has the advan-tage of large storage capacity and portability etc.; Therefore it is popular with computer users, publishers and game makers etc. On CD, data is pre-stored and must be read by the optical pickup head. The lens has to focus the laser beam on CD surface, then following the data track reading. Prestored data read from CD is analog signal and is called RF signal. In order to decide 0 or 1, system has to transfer analog data signal to digital EFM signal, then use Data Phase Locked Loop (Data PLL) to get corrected data. If the transfer path has some trouble or becomes unstable, there may be some reading error. Reading reliability is important in CD-ROM systems. We will analyze the problem and find the solution to improve it. Here, let me simply describe the CD driver data read error reason: (1) Focusing offset (2) Tracking offset (3) Data slicer bandwidth setup (4) Data PLL''s loop filter design (5) Focusing compensator design The chapter of focusing offset is discuss when the laser beam do not focus on the focus-ing center, what will cause the data error rate. We will also describe the relationship between focusing offset and jitter. The chapter of tracking offset explain when the laser beam do not lock on the center of data track, it will make how many data error in this case, and the rela-tionship between tracking offset and jitter is in our research also. The details will be described in chapter 5. In chapter 6, we will use the data slicer bandwidth set value with data error rate curve in different speed to find a right setting value. The effect of Data PLL on the data error rate will be shown in chapter 6, too. Finally, in chapter 7, we will use the experimental result to check our focusing compensator to see if it can reduce the focusing error and makes (C1,C2) error minimal.