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Microprocessor-Generated Digital Transfer Function Analysis

IP.com Disclosure Number: IPCOM000101912D
Original Publication Date: 1990-Sep-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Jansen, RE: AUTHOR [+3]

Abstract

Modern disk drive control systems consisting of a digital signal processor (DSP) and highly integrated support circuits are becoming state of the art. Described is how transfer function measurements of these systems can be performed without a Transfer Function Analyzer by using an external computer attached to the DSP bus.

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This is the abbreviated version, containing approximately 84% of the total text.

Microprocessor-Generated Digital Transfer Function Analysis

       Modern disk drive control systems consisting of a digital
signal processor (DSP) and highly integrated support circuits are
becoming state of the art.  Described is how transfer function
measurements of these systems can be performed without a Transfer
Function Analyzer by using an external computer attached to the DSP
bus.

      Fig. 1 shows a block diagram of a control system with an analog
summing junction (a) used for measuring the open and closed loop
response of the control system.  An external transfer function
analyzer (b) makes the measurement by adding an analog noise signal
to the loop via the summing junction and measuring the response at
the output of the digital-to-analog (D to A) converter (c).  Fig. 2
shows the same control system, but with the A to D converter
integrated with the Power Amplifier that drives the actuator.  This
integration leaves the DSP bus as the only interface between modules
with no analog summing junction. However, the summing junction can be
programmed within the DSP control algorithm and a transfer function
computed using digital data sent to an external computer via the DSP
bus.

      The noise source is either generated within the DSP in response
to a command over the normal interface or is input from the computer
to the DSP via a high-speed interface to the DSP bus.  Control system
response at the position demodulator output, power amp input or a...