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Chapter 1 Introduction to Measurement Analysis in LabVIEW
LabVIEW Analysis Concepts 1-2 ni.com
By analyzing and processing the digital data, you can extract the useful
information from the noise and present it in a form more comprehensible
than the raw data, as shown in Figure 1-2.
Figure 1-2. Processed Data
The LabVIEW block diagram programming approach and the extensive set
of LabVIEW Measurement Analysis VIs simplify the development of
analysis applications.
Data Sampling
Sampling Signals
To use digital signal processing techniques, you must first convert an
analog signal into its digital representation. In practice, the conversion is
implemented by using an analog-to-digital (A/D) converter. Consider an
analog signal x(t) that is sampled every ?t seconds. The time interval ?t is
known as the sampling interval or sampling period. Its reciprocal, 1/?t, is
known as the sampling frequency, with units of samples/second. Each of
the discrete values of x(t) at t = 0, ?t, 2?t, 3?t, and so on, is known as a
sample. Thus, x(0), x(?t), x(2?t), …, are all samples. The signal x(t) can
thus be represented by the following discrete set of samples.
{x(0), x(?t), x(2?t), x(3?t), …, x(k?t), …}
Figure 1-3 shows an analog signal and its corresponding sampled version.
The sampling interval is ?t. Notice that the samples are defined at discrete
points in time.

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© National Instruments Corporation 1-1 LabVIEW Analysis Concepts
1
Introduction to Measurement
Analysis in LabVIEW
Digital signals are everywhere in the world around us. Telephone
companies use digital signals to represent the human voice. Radio, TV,
and hi-fi sound systems are all gradually converting to the digital domain
because of its superior fidelity, noise reduction, and signal processing
flexibility. Data is transmitted from satellites to earth ground stations
in digital form. NASA’s pictures of distant planets and outer space are
often processed digitally to remove noise and extract useful information.
Economic data, census results, and stock market prices are all available in
digital form. Because of the many advantages of digital signal processing,
analog signals also are converted to digital form before they are processed
with a computer.
This chapter provides a background in basic digital signal processing and
an introduction to the LabVIEW Measurement Analysis VIs.
The Importance of Data Analysis
The importance of integrating analysis libraries into engineering stations is
that the raw data, as shown Figure 1-1, does not always immediately
convey useful information. Often, you must transform the signal, remove
noise disturbances, correct for data corrupted by faulty equipment, or
compensate for environmental effects, such as temperature and humidity.
Figure 1-1. Raw Data