Readback recovery of run length limited codes

Abstract From the Canadian patent

Run length limited codes such as (1,7) codes are, recovered with a dual channel recovery system in which the high resolution channel normally supplies the output (recovered) signal. The low resolution channel includes detection means such as a delay device and gate, to detect a predetermined absence of transitions in the low resolution signal (which is indicative of long strings of successive zeros) to inhibit the high resolution channel from supplying the output. The result is to effectively block the high resolution channel from providing a false output.