Method and apparatus for the measurement of defects in magnetic recording disks using a logarithmic amplifier
US5838510A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 31, 1996 |
| Grant date | Nov 17, 1998 |
| Priority date | — |
| Expiry date | Oct 31, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B33/10
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The present invention relates to a method and apparatus for the measurement of defects in magnetic recording disks using a logarithmic amplifier. A magnetic head senses a magnetic field of a magnetic disk and creates a read signal having a varying amplitude. The test apparatus has a squarer which receives and squares the read signal. A logarithmic amplifier coupled to the squarer converts the squared signal to a logarithmic signal. The logarithmic signal is filtered by a first filter. A second filter coupled to the logarithmic amplifier provides an average of the peaks of the logarithmic signal. A digital-to-analog converter coupled to the second filter scales the output of the second filter. The test apparatus further comprises a comparator having a first input and a second input, where the first input is coupled to the first filter, and the second input is coupled to the digital-to-analog converter. The comparator provides an output signal in response to receiving a signal from the first filter having an amplitude that is lower than an average of a predetermined number of peak values of the signal, thereby indicating an error in the disk. In another embodiment, the test apparatus…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.