Simultaneous and orthogonally interactive clock recovery and D.C. null equalization in high density digital magnetic recording

A detection system for saturation digital magnetic recording is described and analyzed which consists of two simultaneously operating feedback loops whose error signals are interactive, but orthogonal to one another so that stability is readily achieved. The technique involves the generation of two error signals, namely (1) phase, and (2) D.C. offset. Thus, both the horizontal (time) and vertical (offset) errors in the system\´s decision thresholds are theoretically forced to zero in steady state since both feedback loops are third order. Thus, the entire magnetic "read"/"write" channel is fully equalized including the DC null. In the more conventional "read"/"write" channels, the "read" detection process occurs before and is independent of the subsequent clock recovery process resulting in a significant sacrifice in theoretically achievable overall performance.