Abstract: A method of generating an encoded signal from a sequential stream of digital data, where the encoded signal has a non-power carrying null state and a power carrying active state with two opposing polarities. Logical one bits are distinguished from logical zero bits by inverting the encoded signal's polarity at the start of only the logical one bits. The encoded signal is set to the active state during a bit set-up period before, and held in the active state during a bit hold period after each polarity inversion. At other times the encoded signal is set to the null state. The method may include the addition of equalization pulses during strings of consecutive logical zero bits to keep the encoded signal from remaining in the null state for extended periods. Each equalization pulse may be preceded by an equalization set-up period and followed by an equalization hold period where the encoded signal is in the active state.

Abstract: Method and apparatus for detecting valid data peaks read from a magnetic medium. Signals representing the peaks are entered into a shift register. Logic circuitry including comparator are connected to stages of the shift register to determine the relative magnitude of a peak sampled at time N versus subsequently sampled peaks. The generated magnitude information is used to determine which of the signals represent valid data peaks and which represent noise and the like.