HIGH DENSITY OPTICAL RECORDING
Related Sites For a list of other companies and universities doing research in this area check out this site.
Introduction We have developed coding and signal processing methods to increase storage density on a optical disk. Our primary efforts are in the area of M-ary (or nonbinary) recording channels. A number of optical media have been proposed for nonbinary recording: electron trapping optical memory (by ETOM Technologies), pit depth modulation (by Calimetrics) magnetic multivalued (MMV) magneto-optic media (by Hitachi Maxell), nonbinary phase change materials (several companies).
Modulation Codes. We have developed numerous codes are of two general types: runlength limited (RLL) M-ary codes and partial response (PR) codes. A list of recent publications address in this area is here. We hold 14 US patents and have 8 patents pending in this area.
Fundamental Limits . We have also established fundamental (information theoretic) limits in optical recording. Chief among them is a result on the rationality of the capacity of M-ary RLL constrained channels. We have shown that the capacity is irrational except in a few special cases. In those cases where the capacity is rational, we have designed provably minimum complexity, capacity-achieving codes. Again, we have published numerous papers listed here.
Support Our work in this area has been generously supported by Optex Communication (now ETOM Technologies), The National Institute of Standards and Technology (NIST) Advanced Technology Program, The National Science Foundation PECASE award , and NSF Grant Opportunities for Aacademic Liason with Industry (GOALI) award . We are recently started a collaboration with three companies, Calimetrics , Polaroid , and Energy Conversion Devices , and are currently seeking funding to use our joint expertise in nonbinary recording media to develop new signal processing and and coding approaches.
HIGH DENSITY MAGNETIC RECORDING
Turbo codes for high density magnetic recording.. We applied turbo codes to partial response digital magnetic recording and showed that high rate turbo codes (4/5, 8/9 16/17) provide significant coding gain over conventional PR4 and EPR4. This work is supported by Western Digital Corporation. For a recent conference paper checkout CISS98_turbo_pr4.ps .
Coding for constrained channels . Full descriptions coming soon. For a few papers check out two recent conference papers here.