A method includes: producing a bit detection signal in response to a
plurality of islands located in a plurality of zones of a bit patterned
media, processing the bit detection signal to produce a synchronization
signal, wherein the processing is dependent on characteristics of the
islands in the zone containing the plurality of islands, and using the
synchronization signal to control timing of writing to the bit patterned
media. The synchronization signal can also be used to control timing of
reading from the bit patterned media.