A model for bit error rate degradation during media thermal decay

A model is presented which relates medium grain size to the system BER degradation caused by media thermal decay. A simple model is used to calculate the magnetization and playback signal decay specifically focusing on grain size distributions. These results are utilized to determine signal to noise ratio (SNR) and bit error rate (BER) over a 10-year period for a recording density near 50 Gbit/in/sup 2/. In our calculation, both DC and transition noise are included. Typically, the DC noise increases more rapidly with storage time than the transition noise decreases. Because of the trade off between DC and transition noise, the relation between BER and SNR is complicated.