Methods and structures for a general purpose, discrete time sample, interval accumulating filter for measuring any of a plurality of parameters associated with operation of a digital read channel. The general purpose interval accumulating features and aspects hereof permit flexible configuration for measuring a variety of operational characteristics and parameters of a digital, discrete time sample, read channel. The interval accumulating filter may sense harmonic frequencies associated with mechanical and electrical noise in the read channel operation. Other features and aspects hereof permit monitoring of multiple signal frequencies of a read channel in a disk drive, error recovery of a bad sector in a disk drive, and measurement of numerous other operational aspects of a discrete time digital sample read channel.