Coding method and apparatus using quaternary codes.

摘要

In digital data transmission and storage, binary data strings are encoded into symbols from a quaternary alphabet by a specific inventive use of finite-state machines. The novel, high-rate quaternary codes offer spectral shaping properties together with a significant increase in noise margin when used on channels which lend themselves to partial-response shaping. In principle, the encoding occurs in three steps: a u-state transition diagram (fig 2 ) generates quaternary symbols whose running digital sum assumes values from a given set; the u-state transition diagram is converted into a v-state machine (fig 3) each of the v states being associated with a number of transitions sufficient to encode the input data bytes into output code words; finally, the v-state machine is switched into a next state depending on its current state and the last encoded input data byte. <IMAGE> <IMAGE>