Duplicate Decoding of Data With Both Clock Phases
Original Publication Date: 1985-Feb-01
Included in the Prior Art Database: 2005-Feb-18
The reading of information from a magnetic medium requires the reconstruction of clock and data signals. The phase relationship between the clock and the data is initially unknown. The duplication of a small set of logic permits both data collection and clock phase identification. Data is stored on magnetic media by recording a sequence of flux changes. These changes must be decoded into clock and data signals to retrieve this information. The clock and data information is then used to buffer the data and ultimately transmit it to a host. Referring to the figure, a phase-locked loop (PLL) 10 can generate a clock by synchronizing itself to the frequency of the flux changes 11. This clock will then have the proper frequency, but the clock may be 180 degrees out of phase.