Digitally modulated data signal DC-free transmission method in e.g. magnetic storage

摘要

The method involves including, in the signal, a train of code words, whose transit length is limited to that of symbols (1,7). The code signal is delayed for a duration of n bits, where n is an integer greater than unity. From respective blocks of non-delayed and delayed code signal are determined two digital sum variations (DSV1,2). The variations are compared for their signs for generating sign dependent separating words with a given bit pattern. The separating words are inserted between adjacent blocks. The code signal is then inverted, based on NRZI coding, in dependence on the respective bit pattern of the separating words.