Browse Prior Art Database

Peak Shift Measurements

IP.com Disclosure Number: IPCOM000073941D
Original Publication Date: 1971-Feb-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 3 page(s) / 58K

Publishing Venue

IBM

Related People

Peach, DF: AUTHOR [+4]

Abstract

It is desired to automatically measure and digitize peak-shift perturbations within a signal caused by processing the signal through a device, such as a magnetic head, which exhibits phase-shifting characteristics. This measurement method and circuit enables synchronization on the signal being measured.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

Peak Shift Measurements

It is desired to automatically measure and digitize peak-shift perturbations within a signal caused by processing the signal through a device, such as a magnetic head, which exhibits phase-shifting characteristics. This measurement method and circuit enables synchronization on the signal being measured.

Device or circuit 10 being tested receives input signal 11 and supplies output signal 12 which has peak-shift perturbations in that the peaks of signal 12 are time displaced from the transitions or state changes of signal 11. The amount of peak shift provided by device 10 (a magnetic head, for example) is measured by peak-detecting signal 12 in detector 13 and comparing the peak-detected signal with a zero-crossover signal supplied by clock circuit 15 and detector 17. Time duration of the hatched one-half wavelengths in signals 18 and 34 are an indication of positive peak shift. Similarly, duration of one-half wavelengths 18A indicate negative peak shift. The present description concerns measuring positive peak shift. Negative peak shift can be measured in a like manner.

Peak-detected signal 18, a three-cycle pattern, is repetitively supplied. Repeating a NRZI record pattern 00001000011 twice generates a three-cycle readback repetitive pattern. The caret marks at the top of the waveforms indicate the boundaries of the repeated data pattern.

Positive peak shift is measured by identifying and measuring the second- occurring short one-half wavelength in each three-cycle repetition (see the adjacent binary 1's in the above data pattern). In peak-detected signal 18, this is shown as the hatched one-half wavelength. The corresponding one-half wavelength in peak shift indicating signal 34 (AND 14) is also hatched.

To synchronize measurement of the hatched one-half wavelength, zero- crossover signal 19 is supplied to cycle binary trigger 20 such that it switches signal states at each positive-going transition generating cycle signal 23. Signal 23 is supplied to AND 21 with...