Magnetic recording techniques for buried servos

A continuous servo system that shares the surface area of the medium with data on the same track, to improve the accuracy of servo-track following, uses only conventional media and a single head. A long-gap head records low-frequency servo signals deeply into the medium coating, and a short-gap head then erases the surface portion to stabilize the servo amplitude. Short-gap read-write heads then write and read high-frequency data signals without interference. Using frequency-separation filters and an ac-biased pulse-write method, an inductive head reads servos while simultaneously writing data. Servo-signal amplitude increases during data-write operations. Servo signals, which do not degrade after stabilization, provide information needed for track following and for various timing and control functions. Data reliability is unimpaired.