Track following servo demodulation

Abstract

The present invention provides an apparatus and method for precise servo tracking of a multi-track magnetic tape head. The magnetic tape has at least one servo area with at least two servo tracks. Adjoining servo tracks have different servo patterns recorded thereon, one being a single frequency, constant amplitude signal, the other alternating between a zero amplitude null signal and a constant amplitude signal of a second frequency. A servo element in the tape head senses and combines the signals from both of the tracks. A detector outputs the peak-to-peak amplitude values of the combined signal and two register modules detect and store the maximum and minimum peak-to-peak values over a predetermined period of time. These maximum and minimum values are provided to a signal processor which determines their ratio. The ratio indicates the amount and direction of any position error of the servo element relative to the edge between the two adjacent servo tracks and is used to direct an actuator to adjust the position of the tape head to minimize the error.