Patent ID: 8824087

Claim:
A method for estimating a zero gain start bias in a read channel, the method comprising: receiving preamble samples within a fixed-length window selected for zero gain start calculation; calculating an energy associated with non-2T frequencies in the preamble samples; determining whether the energy associated with non-2T frequencies in the preamble samples is below a predetermined threshold; setting the zero gain start bias to zero when the energy associated with non-2T frequencies in the preamble samples is below the predetermined threshold; calculating an energy associated with a 2T frequency in the preamble samples when the energy associated with non-2T frequencies in the preamble samples is above the predetermined threshold; and calculating the zero gain start bias based on the energy associated with the 2T frequency in the preamble samples and the energy associated with non-2T frequencies in the preamble samples when the energy associated with non-2T frequencies in the preamble samples is above the predetermined threshold.