Calibration of magnetic tape drive

In a method of calibrating a helical scan magnetic tape drive, a dual scan calibration tape having a calibration stripe is loaded into the tape drive. As a head traverses differing paths along the calibration stripe, a series of calibration signal waveforms is obtained. For each calibration signal waveform in the series, a voltage measurement is made at a predetermined position within each waveform. A maximum one of the voltage measurements is used to generate a measured overlap scale factor (MOV) indicative of an overlap of the read head relative to the calibration stripe. As a subsequent calibration stripe on the calibration tape is read in a dual scan calibration mode, the measured overlap scale factor is utilized to generate a track position error vector. The track position error vector is used to adjust a tape path guide of the tape drive.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of calibrating a helical scan magnetic tape drive, the method comprising:

(1) loading a calibration tape into a tape path of the helical scan drive, the calibration tape having a calibration stripe recorded thereon;

(2) obtaining a series of calibration signal waveforms from the calibration stripe as a head traverses differing paths along the calibration stripe, the differing paths occurring at differing linear positions of the calibration tape relative to the head;

(3) for each calibration signal waveform in the series, obtaining a voltage measurement at a predetermined position within each waveform;

(4) determining a maximum one of the voltage measurements obtained in step (3); and,

(5) using a selected one of the voltage measurements to generate a measured overlap scaling factor indicative of an overlap of the read head relative to the calibration stripe.

2. The method of claim 1, further comprising using the measured overlap scaling factor to obtain a track position error vector.

3. The method of claim 2, further comprising using the track position error vector to adjust a tape path guide of the tape drive.

4. The method of claim 1, wherein the selected one of the voltage measurements is a maximum one of the voltage measurements.

5. A method of calibrating a helical scan magnetic tape drive, the method comprising:

(1) loading a calibration tape into a tape path of the helical scan drive, the calibration tape having a calibration stripe recorded thereon;

(2) using a read head to obtain a calibration signal waveform from the calibration stripe while the calibration tape has essentially no linear velocity in the tape drive;

(3) stepping the calibration tape a predetermined distance in a linear direction in the tape path, and then repeating step (2) to obtain another calibration signal waveform;

(4) repeating step (3) a plurality of times in order to obtain a series of calibration signal waveforms;

(5) for each calibration signal waveform in the series, obtaining a voltage measurement at a predetermined position within each waveform;

(6) determining a maximum one of the voltage measurements obtained in step (5); and,

(7) using the maximum one of the voltage measurements to generate a measured overlap scaling factor indicative of an overlap of the read head relative to the calibration stripe.

6. The method of claim 5, further comprising using the measured overlap value to obtain a track position error vector.

7. The method of claim 6, further comprising using the track position error vector to adjust a tape path guide of the tape drive.

8. The method of claim 5, wherein the predetermined distance at which the calibration tape is stepped a same distance for all read paths.

9. The method of claim 5, wherein the predetermined position within each waveform at which the voltage measurement is obtained is determined with reference to a time at which the head crosses a beginning of the calibration stripe.

10. A method of calibrating a helical scan magnetic tape drive, the method comprising:

(1) loading a calibration tape into a tape path of the helical scan drive, the calibration tape having a calibration stripe recorded thereon;

(2) imparting a slow creeping linear velocity to the calibration tape;

(3) using a read head to obtain a calibration signal waveform from the calibration stripe while the calibration tape moves at the slow creeping linear velocity;

(4) periodically repeating step (3) to obtain a series of calibration signal waveforms;

(5) for each calibration signal waveform in the series, obtaining a voltage measurement at a predetermined position within each waveform;

(6) determining a maximum one of the voltage measurements obtained in step (5); and,

(7) using the maximum one of the voltage measurements to generate a measured overlap scaling factor indicative of an overlap of the read head relative to the calibration stripe.

11. The method of claim 10, further comprising using the measured overlap value to obtain a track position error vector.

12. The method of claim 11, further comprising using the track position error vector to adjust a tape path guide of the tape drive.

13. The method of claim 10, wherein the predetermined position within each waveform at which the voltage measurement is obtained is determined with reference to a time at which the head crosses a beginning of the calibration stripe.