Abstract: Width of a write track for a magnetic tape head is measured by writing a foreground magnetic track signal on a magnetic tape having a dissimilar background signal. A magnetic tape read head is moved from beyond one edge, laterally across, and beyond the opposite edge of the foreground track signal. Logic detects the read head encountering the one edge and the opposite edge of the foreground track signal; and determines, from an independent position sensor, the width of the foreground track signal as the lateral distance between the lateral position of the read head at one edge, and at the opposite edge of the foreground track signal.

Abstract: Dynamic tension control for tape transported along a tape path between supply and take-up reels, driven by supply and take-up motors, and having tachometers for determining linear speed of the tape. A controller accelerates the tape toward a target speed, initially operating the motors in static acceleration tension control; and if the linear speed of the tape is within a predetermined range of the target tape speed, operating the motors in composite tension control employing static tension control and delta velocity control.

Abstract: Width of a write track for a magnetic tape head is measured by writing a foreground magnetic track signal on a magnetic tape having a dissimilar background signal. A magnetic tape read head is moved from beyond one edge, laterally across, and beyond the opposite edge of the foreground track signal. Logic detects the read head encountering the one edge and the opposite edge of the foreground track signal; and determines, from an independent position sensor, the width of the foreground track signal as the lateral distance between the lateral position of the read head at one edge, and at the opposite edge of the foreground track signal.

Abstract: Dynamic tension control for tape transported along a tape path between supply and take-up reels, driven by supply and take-up reel motors. Rotational angular velocities of the supply and take-up reels are determined from tachometers, and therefrom a linear speed for the tape at the supply reel, and a linear speed for the tape at the take-up reel are each determined. The tape linear speeds at the reels are compared to determine a delta velocity between the linear speeds. The motors are operated in accordance with a function of the delta velocity to provide a torque to at least one of the reels tending to reduce the delta velocity.

Abstract: Dynamic tension control for tape transported along a tape path between supply and take-up reels, driven by supply and take-up motors, and having tachometers for determining linear speed of the tape. A controller accelerates the tape toward a target speed, initially operating the motors in static acceleration tension control; and if the linear speed of the tape is within a predetermined range of the target tape speed, operating the motors in composite tension control employing static tension control and delta velocity control.

Abstract: Dynamic tension control for tape transported along a tape path between supply and take-up reels, driven by supply and take-up reel motors. Rotational angular velocities of the supply and take-up reels are determined from tachometers, and therefrom a linear speed for the tape at the supply reel, and a linear speed for the tape at the take-up reel are each determined. The tape linear speeds at the reels are compared to determine a delta velocity between the linear speeds. The motors are operated in accordance with a function of the delta velocity to provide a torque to at least one of the reels tending to reduce the delta velocity.

Abstract: A servo position detector and a method for detecting and following an index position displaced at an offset with respect to an edge of a servo track, an edge comprising an interface between two dissimilar recorded servo signals. The servo track has two edges on opposite lateral sides of a middle recorded servo signal, the edges separated by a predetermined distance. A servo read element has an active sensing region which is no more than and is substantially the entire predetermined distance separating the edges, thereby.sensing no more than two of the dissimilar recorded servo signals at one of the edges. An independent position sensor senses the coarse position of the servo read element, indicating which edge or which index position is aligned with the servo read element. Logic compares the two sensed servo signals to determine the ratio therebetween, and determines an error between the compared ratio and a predetermined ratio.

Abstract: Servo errors can be avoided in a bi-directional reel-to-reel tape transport in which magnetic tape is moved in either of two opposite directions for data recording by providing a fine-line tachometer for each reel and a directly coupled tension sensor. Control of tape speed is implemented in a servo algorithm that uses tachometer inputs to determine parameter values for generating reel motor drive currents. If the linear velocity of both reels is the same then the tension output must be within a tolerable range. The directly coupled tension output provided an is indication of the actual current of the tension sensor. The difference between the linear velocities of the tape from each reel is calculated and monitored together with the tape tension. A trip level is set when an error occurs to stop tape motion and permit recovery without damaging the tape.

Abstract: Servo elements contained within a tape head detect a lateral displacement the magnetic tape relative to the tape head and generate position error signals corresponding to such lateral displacement. To aid in servo monitoring, the position error signals are sampled at predetermined times and the samples output or stored in machine-readable form. Each sample is classified as bad if it exceeds a predetermined threshold. Samples are analyzed to determine, for each time a bad position error signal occurs, how many successive position error signals are also bad. Samples are also analyzed to determine the relationship between bad position error signals samples and total samples. This data may be used for a number of different purposes. For example, this information may be used to identify differences between performance on top and bottom servo edges, or problems with the servo writing mechanism. Performance variations among different servo elements may also be identified.

Abstract: A high resolution, independent position sensor is provided, having application in a magnetic tape drive and other environments in which a linear or angular position is to be monitored. Analog outputs from an inexpensive, low resolution optical encoder are processed to correct gain and offset distortions and are used as the basis for an interpolation process. If a code strip having a 127-micron grating is used, a resolution of about 0.125 microns can be achieved.

Abstract: An improved and apparatus is provided in a tape drive for servo-controlling a tape head position relative to a magnetic tape as the magnetic tape travels past the tape head thereby reducing track mis-registration on the magnetic tape. Servo elements contained within the tape head detect a lateral displacement of the magnetic tape position relative to the tape head and generate position error signals corresponding to such lateral displacement. The position error signals are then filtered to generate a low frequency position error signal, a midrange frequency error signal, and position reliability signals. The tape head is then positioned by a head actuator according to the low frequency position error signal to adjust to the lateral movement of the magnetic tape. The midrange frequency error signal is compared to a distortion threshold to determine if errors exist due to tape edge vibrations or distortion of the magnetic tape.