| 摘要 |
<p>Presently, almost all commercially available data storage systems use saturation recording and binary signaling schemes. Earlier data channels for storage systems utilized various forms of bit by bit peak detection. More recently, various forms of PRML (partial response maximum likelihood) or DFE (decision feedback equalization) have appeared in products. These improvements are still limited by the fact that the storage data channel is a saturation channel, and as such, has a significantly reduced information handling capacity compared to a linear data channel. Recording media defects are currently mapped out at the factory and skipped under normal device usage, while remaining errors are corrected by error correction code. However, at higher aerial densities, defects in the media tend to become a greater problem. The above-incorporated applications teach a linearization technique for linearizing magnetic recording channels without suffering signal to noise loss and not suffering bandwidth loss. Given this, the objective is to take the channel recording as close as possible to the theoretical capacity limit. Spread spectrum communication systems are also known. As originally designed by actress Heddy LaMar and musician George Antheil and described in U.S. Patent 'Secret Communication System', U.S. Patent 2,292,387 of August 11, 1942, the frequency of the carrier was pseudo randomly changed in discrete steps to spread the spectrum at the transmitter. The received carrier frequencies were demodulated out by synchronization with the known transmitted pseudo random modulation to despread the spectrum. To a non-synchronized receiver, the spread spectrum signal looked like noise, but the intended receiver can despread the spectrum and recover the information. An added benefit to communication systems was robustness against narrow band jamming as well as atmospheric fading and multipath cancellations. The present inventor has recognized that this communication system can be adapted to efficiently store linearized data in a magneto-optical storage system.</p> |
