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Course Outline no. 197-5 .
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Digital Data Acquisition,
Signal Processing and Analysis

Course No. 197-5

(Course Outline shown below.)

For Whom Intended

Testing laboratory personnel who want to expand their analysis capabilities, perhaps in the interest of improving their test designs;
analysis personnel responsible for the interpretation of data acquired in the laboratory;
test requesters/designers who want to know what tools are available and what to expect from them.

Brief Course Description The objective of the first portion of the course (also available separately as Course 196, Digital Data Acquisition) is to provide participants with the knowledge required to specify, evaluate and use a wide variety of digital data acquisition systems in laboratory and field applications. Basic principles of sampling and digitizing theory are presented and reinforced with practical examples from everyday testing operations.

Hardware discussions concentrate on performance capabilities and practical problems that arise in laboratory and field applications. Heavy emphasis is placed on new technologies and system concepts that will be available in the near future. The aim is to prepare participants to design and procure state-of-the art systems that will satisfy their technical requirements efficiently and economically. Literature describing the latest available hardware will be used as examples of good (and bad) practice. Particular emphasis will be placed on critical evaluation of commercially-available hardware and software systems.

The objective of the second part of the course is to provide participants with a working knowledge of the tools available for analysis of data acquired by digital data acquisition systems for a variety of laboratory and field applications. Basic analysis principals and methods are presented and reinforced with practical examples from everyday testing operations. The interaction between test design, data acquisition and analysis is emphasized.

The lectures and discussions are designed to promote understanding of the concepts involved through “mechanical feel” rather than mathematics. Participants are encouraged to offer problems from their own activities for discussion and solution by the class. The course is presented as a series of highly interactive lecture /discussion sessions. Problems for individual and group solution are interspersed throughout the course to act as training aids and to evaluate class progress. Special-interest discussions are encouraged outside of the regular course sessions.

Demonstration programs written in LabView are used during the course to illustrate the concepts. These demonstrations are available for download, free of charge. Students are encouraged to download the demonstration programs prior to class, and install them on a laptop computer they can bring with them to class and use to follow along with the instructor when the demonstrations are presented.

Certificate Programs This course is an elective for any of TTi’s specialist certificate programs.

Related Courses The data acquisition portion of Course 197-5 is available separately in Course 196, Digital Data Acquisition, which runs concurrently. Either Course 197-5, or Course 196 may be presented on-site, at your facility.

Prerequisites A good understanding of the engineering problem to be analyzed is expected. An understanding of basic computer and data acquisition principles will be useful.

Text Each student will receive a course workbook, including most of the viewgraphs used in the course presentation.

Course Hours, Certificate and CEUs Open courses meet seven hours per day. Upcoming presentation dates can be found on our current open course schedule. Class hours/days for on-site courses can vary from 14-35 hours over 2-5 days as requested by our clients. Upon successful course completion, each participant receives a certificate of completion and one Continuing Education Unit (CEU) for every ten class hours.

Course Outline No. 197-5

Part I, Digital Data Acquisition

Also available separately as Course 196

Overview of the Measurement Process — The System Approach
- The role and function of digital data acquisition.
- Testing and experiment types — what capabilities are required?
- Accuracy, Dynamic Range, Headroom
Basic Concepts
- Basic calculations
- The Fourier Transform as a “Black Box”
- Data presentation in time and spectral domain
Sampling and Digitization Theory
- Data acquisition speed and accuracy/resolution considerations
- Aliasing (download TTi’s Aliasing Demonstration program)
- Noise and other data corruption problems
Data Acquisition Hardware
- Signal Conditioning
- Amplifiers
  - Common-mode rejection
  - Transducer wiring practice
- Anti-alias filters (download TTi’s Aliasing Demonstration program)
- Sample-and-hold amplifiers
- Multiplexers
- Analog-to-digital converters
  - Flash, Successive-approximation, Multi-pass, Sigma-Delta, Integrating
The Computer System
- Candidate computer systems — tradeoffs
- Interface concepts — speed, implementation ease and robustness
- Data storage — speed, volume considerations
Types of Digital Acquisition Systems
- Applications, Special considerations, Performance and limitations of available system architectures
Data Analysis
- Engineering-Unit Conversions
- Data Interpolation
- Correction of Anti-Alias filter distortion
Evaluating Data Acquisition Systems
- Simple tests to evaluate system accuracy/capability
Specifying a system
- How do you specify a system to get what you want?

Part II, DSP and Data Analysis

Introduction and Overview
Review of Basic Concepts
- The time and frequency domains
- Time histories and time series analysis
- Sampling theory; acquiring good data
- Linear systems; transform concepts
- Spectra
"Static" (Load/Deflection) Test Analysis
- Basic curve fitting
  - Least squares techniques, linear regression, polynomial regression
  - Spline fitting
  - Yield point determination
Oscillating-Signal Analysis
- Basic characterization
- Decibels
- Data smoothing, averaging, trend removal...
- Random signals
- Probability distribution
- Correlation
Spectral Domain Operations
- Calculating and displaying the spectrum
  - The Fourier Transform... as a Black Box
  - — What it does (and doesn't) do
  - — Fast Fourier Transform (FFT)
  - — Basic relationships and rules
  - — Spectral "arithmetic"
  - "1/N" Octave analysis
  - Spectral graphing formats
- Engineering applications
  - Power Spectral Density (PSD)
  - Transfer functions
  - Forced-response analysis
Data Filtering
- Filtering in the spectral domain
- Time-domain filtering
  - FIR, IIR filters
- When to use time-domain and spectral-domain filters
Signal Integration and Differentiation
- Practical problems with real data
Transient Data Analysis: Spectral Analysis
- Shock Response Spectra
Continuous-Data Analysis
- Finite measurement-length effects
  - Gibb's Phenomenon...Ringing
  - Windowing, window types/uses/advantages and disadvantages
Data Averaging
- Time block averaging
- Spectral averaging, PSD
- Average transfer-function calculation
- Coherence
Special Topics
- Anti-alias filter-correction techniques
- Data interpolation
  - Averaging and derivative techniques
  - Spectral extension
- Data Acquisition System Calibration
Using the tools
Class problems
Final Examination
Award of Certificates for successful completion

Printable (.pdf) version of course outline no. 197-5 ( Adobe Acrobat Reader required).

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