An apparatus for reading a non-volatile memory includes a tracking module operable to calculate means and variances of voltage level distributions in a non-volatile memory and to calculate at least one reference voltage to be used when reading the non-volatile memory based on the means and variances, a likelihood generator operable to calculate at least one other reference voltage to be used when reading the non-volatile memory, wherein the at least one other reference voltage is based at least in part on a predetermined likelihood value constellation, and to map read patterns from the non-volatile memory to likelihood values, and a read controller operable to read the non-volatile memory using the at least one reference voltage and the at least one other reference voltage to yield the read patterns.