Techniques For Providing DC-free Detection of DC Equalization Target

A hard disk drive comprising:

• a first filter that generates a short DC equalization target in response to a read back signal, wherein the read back signal is generated by reading magnetic patterns from a magnetic disk, the magnetic patterns being generated using perpendicular recording;
• a first detector that generates an output sequence in response to the short DC equalization target;
• a soft-input-soft-output high pass filter attenuating DC components of the short DC equalization target and passing low frequency components of the short DC equalization target that are above a cutoff frequency to generate a filtered signal, wherein the low frequency components comprise characteristics of the magnetic patterns;
• and
• an iterative detector that processes the output sequence in response to the filtered signal.

A method for detecting bits that are stored on a storage device, the method comprising:

• generating a short DC equalization target in response to a read back signal that is generated by reading magnetic patterns from a magnetic medium in the storage device, the magnetic patterns being generated using perpendicular recording;
• detecting a bit sequence in response to the short DC equalization target;
• attenuating DC components of the short DC equalization target and passing low frequency components of the short DC equalization target that are above a cutoff frequency using a high pass filter to generate a filtered signal, wherein the low frequency components comprise characteristics of the magnetic patterns;
• and
• processing the bit sequence in response to the filtered signal.