Modern communications theory has played a major role in increasing the efficiency and reliability of communication systems. The aim of the proposed research is to achieve efficiency and reliability for the storage and retrieval of digital data in magnetic recording systems. Specifically the aim is to increase the packing density of the digital data, that is, the amount of data that can be stored in a unit area of the magnetic media. This can be achieved by increasing the linear density (i.e. the number of bits per inch along a track) and/or by increasing the density of the tracks (i.e., the number of tracks per inch). All of this must be done without sacrificing the reliability of the retrieved data. The principal investigator will explore two distinct techniques for utilizing modulation and coding for increasing the packing density for magnetic recording systems. The first is an improvement of a presently used techniques, including a class of codes called modulation codes, as well as error detection and correction codes. The second ignores the present systems and uses techniques that have worked with channels with characteristics similar to magnetic recording channels. The PI will continue the search for modulation codes that gave good error correction properties. In particular, he will study trellis codes that have good Hamming distance and satisfy run length constraints. Second he will attempt to improve his model for channel errors to better reflect the actual performance of real systems. Third the PI proposes research that includes a experimental program in which he will make measurements on disk drives and of the burstiness of errors that occur in magnetic recording systems. This part of the research also includes building circuitry to implement new signal processing algorithms such as adaptive equalizers, and new modulation and coding systems. Finally the PI proposes to continue research on new codes for insuring the reliability of digital data recorded on magnetic and optical media.
