Detection of Minor Disk Asperities Using Successively an all Ones Pattern and an all Zeroes Pattern
Original Publication Date: 1981-Mar-01
Included in the Prior Art Database: 2005-Feb-11
Asperity detection is particularly useful in connection with phase encoding of data on a disk 10 (Fig. 1) by means of which flux changes 16 and 18 are at the centers or edges of bit cells. A transition 16 written at the center of a bit cell 14 is recognized as a 1 bit, and a transition 18 at the edge of a bit cell 14 is recognized as a 0 bit. Writing of this data is keyed from a predetermined reference point, such as index 20; hence, a 1 bit being written is virtually written in the same area of each bit cell each time. The same is true of a 0 bit.