公开(公告)号：CA1285650C

公开(公告)日：1991-07-02

申请号：CA490980

申请日：1985-09-18

Applicant: IBM

Inventor： COPPERSMITH DON ,  KITCHENS BRUCE P

IPC: H03M7/14 ,  H03M5/14 ,  G11B20/14 ,  H03M7/40 ,  H04L25/49

Abstract: YO984052 RUN-LENGTH LIMITED CODE WITHOUT DC LEVEL Code modification circuitry alters the end portion of each block in a sequence of code blocks, and also inserts additional bits at the junction between contiguous blocks. The codes to be processed are runlength limited (RLL) codes having a DC component which is to be removed for certain applications such as magnetic recording. The modification circuitry retains the RLL format. Charge (or the integral of the waveform) accumulated by the sequence of bits of one block is compensated by selecting the sense of charge accumulation in next block to be of opposite sense. This is accomplished by the code modification circuitry using a relatively small set of possible combinations of digital words at the junctions of the blocks.