Patent ID: 6191906
Filing Date: 2001-02-20
Classification: G11B

Abstract:
In a data storage disk drive, a method of determining a phase angle between a phase angle between a clock signal and a data signal having a cosine component of amplitude (v) and sine component of amplitude (u) comprising:storing a set of log(u) and log(v) values in a first lookup table;storing a set of arctan(log(v)-log(u)) values in at least a second lookup table;looking up a log(u) value in the first lookup table;storing the log(u) value;looking up a log(v) value;subtracting the stored log(u) value from the log(v) value to form an intermediate result;addressing the second lookup table with the intermediate result to return a result including an arctan(v/u) value; anddetermining the phase angle from the arctan(v/u) value.