Talk:Run Length Limited
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are bytes encoded individually or as a stream?????
The question is unclear. BITS are encoded as a stream.
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This article is silly. All magnetic media recording codes are RLL codes. If it imposes a limit on the run length, it's RLL! For example, FM is a rate-1/2 (0,1) RLL code and MFM is a rate-1/2 (1,3) RLL code. Group Code Recording is, as the article says, a rate-4/5 (0,2) RLL code. Other popular ones are the rate-1/2 (2,7) RLL code (the original "RLL") and the rate-2/3 (1,7) RLL code.
Then folks developed PRML techniques that made (0,k) RLL codes more feasible, and that's what everyone uses on hard drives these days.
A lot of these techniques were developed at IBM, who were always pushing storage capacity limits in their mainframe heyday.
The other thing that needs to be mentioned is that all such codes assuming NRZI encoding afterwards, so a 1 bit is a transition, and a 0 bit is no transition. The minimum spacing between transitions d by (n+1 in an (n,k) code) is limited by the high-frequency response of the channel, while the laximum spacing (k+1 in an (n,k) RLL code) is limited by the clock-recovery jitter. (Even if the electronics have zero jitter, there is some in the source signal.)
