Four new runlength constrained recording codes

Four simple runlength constrained codes for digital optical or magnetic recording are presented. Parameters are R=1/3, (d ,k)=(1,2), R=1/4, (d,k)=(4,8), R=1/4, (d,k)=(4,7) and R=1/4, (d ,k)=(5,9). Both the finite-state transition diagrams for the encoders and sliding-block decoders are presented