Browse Prior Art Database

Transfer Function Measurement

IP.com Disclosure Number: IPCOM000116948D
Original Publication Date: 1995-Nov-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Fukushima, Y: AUTHOR [+2]

Abstract

Disclosed is a method for measuring a transfer function of actuator servo in Hard Disk Drive (HDD), which has a function of noise injection into the servo loop by a command through the interface. Using this function of the HDD, the transfer function can be measured without additional hardware.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 81% of the total text.

Transfer Function Measurement

      Disclosed is a method for measuring a transfer function of
actuator servo in Hard Disk Drive (HDD), which has a function of
noise injection into the servo loop by a command through the
interface.  Using this function of the HDD, the transfer function can
be measured without additional hardware.

      Fig. 1 shows the block diagram of the servo system.  Open loop
transfer function is calculated using following equation.  (Open loop
transfer function) = Gc * Gp = (-U)/V

      Fig. 2 shows the configuration of this measurement.  There is a
Personal Computer (PC) and a HDD connecting to the PC.  The HDD has
following functions to measure the transfer function.
  1.  HDD has a noise table on the memory.  The length of noise table
       is 512 points or proper value.  The address is usually
assigned
       on a sector buffer memory.
  2.  Noise data can be transferred from PC to the HDD by a interface
       command.
  3.  Each noise value can be added to the controller output (U) by a
       interface command.
  4.  During the noise injection, the controller output (U) and the
       result of injection (V) are stored into the memory.
  5.  After the noise injection, the collected data (U, V) are
       transferred to the PC by a interface command.

      Transfer function is usually measured using swept sine noise.
To implement swept sine, the test sequence can be describ...