Signal-To-Noise Ratio (SNR) For Reliable Data Recording

Due to the nonlinear nature of the thermal optical recording process and the inherent difficulty in tracking and maintaining focus of a submicron-sized light spot, peak-shift values of 40 to 50% are likely to occur during the use of an optical data storage system. Wideband SNR of 30 dB or more will, therefore, be required to attain acceptable phase margin (i.e., reliable operation). Similarly, magnetic recorders working at high linear density will experience peak-shift values of 20 to 30%; wideband SNR from 23 to 29 dB will be required in those machines, depending upon whether or not error correction coding (ECC) is employed.