Approximated parameter adaptation

1. An apparatus comprising:

a circuit including a Soft-Output Viterbi Algorithm (SOVA) detector configured to process an input signal using a selected set of channel parameters being branch biases of the SOVA detector, the circuit further configured to:

produce, using a first adaptation algorithm, a first set of channel parameters for use by the circuit as the selected set of channel parameters in processing the input signal;

approximate a second set of channel parameters of a second adaptation algorithm for use by the circuit as the selected set of channel parameters in processing the input signal based on the first set of channel parameters and a relationship between a third set of channel parameters generated using the first adaptation algorithm and a fourth set of channel parameters generated using the second adaptation algorithm;

process the input signal using the second set of channel parameters as the selected set of channel parameters; and

the first adaptation algorithm being a minimum mean squared error (MMSE) adaptation algorithm and the second adaptation algorithm being a Minimum Bit-Error Rate (MBER) adaptation algorithm.

2. The apparatus of claim 1 , further comprising a memory storing the third set of channel parameters generated using the first adaptation algorithm and the fourth set of channel parameters generated using the second adaptation algorithm.

3. The apparatus of claim 1 further comprising the circuit further including a detector that performs the processing of the input signal using the selected set of channel parameters, the circuit further configured to:

perform processing of the input signal using a fifth set of channel parameters generated using the second adaptation algorithm as the selected set of channel parameters in processing the input signal to produce a detection result;

determine that a decoding of one or more detection results produced by the detector using the fifth set of channel parameters has failed a threshold number of times; and

at least partly in response to the determining the decoding has failed the threshold number of times, perform the processing of the input signal using the second set of channel parameters as the selected set of channel parameters.

4. The apparatus of claim 3 , further comprising the circuit configured to:

determine that a decoding of one or more detection results produced by the detector using the second set of channel parameters has succeeded; and

at least partly in response to the determining the decoding has succeeded, adapt, using the second adaptation algorithm, the second set of channel parameters using the successful decoding result.

5. The apparatus of claim 1 , further comprising the circuit further including a detector that performs the processing of the input signal using the selected set of channel parameters, the circuit further configured to:

perform processing of the input signal using a fifth set of channel parameters generated using the second adaptation algorithm as the selected set of channel parameters in processing the input signal to produce a detection result;

determine that a decoding of one or more detection results produced by the detector using the fifth set of channel parameters has succeeded after less than a threshold number of failures; and

at least partly in response to the determining the decoding has succeeded, adapt, using the second adaptation algorithm, the fifth set of channel parameters using the successful decoding result.

6. The apparatus of claim 1 , further comprising:

a memory storing the third set of channel parameters generated using the first adaptation algorithm and the fourth set of channel parameters generated using the second adaptation algorithm;

the input signal being a readback signal read from a sector of a magnetic storage medium; and

the third set of channel parameters and the fourth set of channel parameters corresponding to an area of the magnetic storage medium including the sector and being generated during a manufacturing process including reading back known data written to the area of the magnetic storage medium including the sector.

7. A system comprising:

a channel circuit including a Soft-Output Viterbi Algorithm (SOVA) detector configured to process an input signal using a selected set of parameters being branch biases of the SOVA detector;

an adaptation circuit configured to:

produce, using a first adaptation algorithm, a first set of channel parameters for use by the circuit as the selected set of parameters in processing the input signal;

approximate a second set of channel parameters of a second adaptation algorithm for use by the channel circuit as the selected set of parameters in processing the input signal based on the first set of channel parameters and a relationship between a third set of channel parameters generated using the first adaptation algorithm and a fourth set of channel parameters generated using the second adaptation algorithm; and

output the second set of channel parameters to the channel circuit as the selected set of parameters to process the input signal with; and

the first adaptation algorithm being a MMSE adaptation algorithm and the second adaptation algorithm being a MBER adaptation algorithm.

8. The system of claim 7 further comprising:

a memory storing the third set of channel parameters generated using the first adaptation algorithm and the fourth set of channel parameters generated using the second adaptation algorithm;

the input signal being a digitized sample sequence corresponding to a sector of a magnetic storage medium; and

the third set of channel parameters and the fourth set of channel parameters corresponding to an area of the magnetic storage medium including the sector and being generated during a manufacturing process including reading back known data written to the area of the magnetic storage medium including the sector.

9. The system of claim 8 further comprising:

an analog-to-digital converter (ADC) circuit configured to generate one or more ADC samples based on an readback signal corresponding to the sector;

an equalizer circuit configured to receive digital samples from the ADC circuit and to equalize the digital samples to generate the digitized sample sequence; and

a decoder configured to receive an output of the SOVA detector processing the input signal using the set of parameters and to perform decoding on the output of the SOVA detector.

10. The system of claim 7 further comprising the channel circuit being a detector and the adaptation circuit being further configured to:

output a fifth set of channel parameters to the channel circuit for use as the selected set of parameters in processing the input signal to produce one or more detection results, the fifth set of channel parameters generated using the second adaptation algorithm;

determine that a decoding of the one or more detection results produced by the detector using the fifth set of channel parameters has failed a threshold number of times; and

at least partly in response to the determining the decoding has failed the threshold number of times, perform the processing of the input signal using the second set of channel parameters as the selected set of parameters.

11. The system of claim 7 further comprising the channel circuit being a detector and the adaptation circuit being further configured to:

output a fifth set of channel parameters to the channel circuit for use as the selected set of parameters in processing the input signal to produce one or more detection results, the fifth set of channel parameters generated using the second adaptation algorithm;

determine that a decoding of the one or more detection results produced by the detector using the fifth set of channel parameters has succeeded after less than a threshold number of failures; and

at least partly in response to the determining the decoding has succeeded, adapt, using the second adaptation algorithm, the fifth set of channel parameters using the successful decoding result.

12. A method comprising:

producing, by a circuit including a Soft-Output Viterbi Algorithm (SOVA) detector configured to process an input signal using a selected set of channel parameters and using a first adaptation algorithm, a first set of channel parameters for use by the circuit as the selected set of channel parameters as branch biases of the SOVA detector to perform processing of the input signal;

approximating a second set of channel parameters of a second adaptation algorithm for use by the circuit as the selected set of channel parameters in processing the input signal based on the first set of channel parameters and a relationship between a third set of channel parameters generated using the first adaptation algorithm and a fourth set of channel parameters generated using the second adaptation algorithm;

processing the input signal using the second set of channel parameters as the selected set of channel parameters; and

the first adaptation algorithm being a minimum mean squared error (MMSE) adaptation algorithm and the second adaptation algorithm being a Minimum Bit-Error Rate (MBER) adaptation algorithm.

13. The method of claim 12 further comprising:

the input signal being a digitized sample sequence corresponding to a sector of a magnetic storage medium;

the third set of channel parameters and the fourth set of channel parameters corresponding to an area of the magnetic storage medium including the sector and being generated during a manufacturing process including reading back known data written to the area of the magnetic storage medium including the sector; and

the relationship between the third set of channel parameters and the fourth set of channel parameters being a difference.