Abstract: Methods and apparatus are disclosed for detecting PR4 equalized Gray codes, providing phase tolerant Gray codes and detection thereof. A Gray code detector is provided, which receives a PR4 equalized Gray code input signal and provides a binary detector output. The detector comprises a plurality of filters providing Euclidean distance values based on the input signal. A logic component selectively provides the detector output based on one or more of the Euclidean distance values from the matched filters, according to one or more criteria, such as the detector mode.

Abstract: A detector (55) and method for detecting a synchronization servo mark (SSM) in a data stream of mass data storage device (10) has a matched filter (56) to receive the data stream. The filter (56) produces a maximum output when the SSM is applied. A delay element receives (64) the matched filter output to produce a delay element output (72). When the delay element output (72) is greater than a predetermined threshold value (Vth) and is larger than the output value (74), the (SSM) is in a current time location. When the “D” element output (72) is greater than the predetermined threshold value (Vth) and less than the output value, the SSM is in the next time location. The threshold may be established to be less than maximum if the phase of the SSM is within a predetermined phase range.

Abstract: A detector (55) and method for detecting a synchronization servo mark (SSM) in a data stream of mass data storage device (10) has a matched filter (56) to receive the data stream. The filter (56) produces a maximum output when the SSM is applied. A delay element receives (64) the matched filter output to produce a delay element output (72). When the delay element output (72) is greater than a predetermined threshold value (Vth) and is larger than the output value (74), the (SSM) is in a current time location. When the “D” element output (72) is greater than the predetermined threshold value (Vth) and less than the output value (73), the SSM is in the next time location. The threshold may be established to be less than maximum if the phase of the SSM is within a predetermined phase range.

Abstract: Methods and apparatus are disclosed for detecting PR4 equalized Gray codes, providing phase tolerant Gray codes and detection thereof. A Gray code detector is provided, which receives a PR4 equalized Gray code input signal and provides a binary detector output. The detector comprises a plurality of filters providing Euclidean distance values based on the input signal. A logic component selectively provides the detector output based on one or more of the Euclidean distance values from the matched filters, according to one or more criteria, such as the detector mode.