Measurement Computing Medallion Rotate rev.2.3 - Manual (Page 21)

October 2000 Medallion Rotate Manual
21
C
HAPTER
T
HREE
M
EDALLION
R
OTATE
A
PPLICATIONS
This chapter describes the analysis methods available in Medallion Rotate.
The chapter begins with some notes on collecting data. It then lists some uses
for each method, then goes on to present a sample application of the method.
You can use this chapter as a guide to selecting the best method to analyze
data for a particular type of problem. However, this chapter is not meant to be
the last word on analysis using Medallion Rotate. You are likely to discover
other applications for Medallion Rotate after you have been using it for a while.
N
OTES ON
C
OLLECTING
D
ATA
S
AMPLE
R
ATE
Guidelines for the sample rate for each type of application are described
under the application. One thing to note is that the sample rate of the
tachometer signal does not have to be the same as the sample rate for a data
channel. For example, the sampling rate on the tachometer channel can be much
higher than the sampling rate on a vibration transducer channel.
In general, the sampling rate must be at least 2.5 times the maximum
frequency of interest to avoid aliasing effects (described below). Note that most
analyzers require that you use the sample rate, not the maximum frequency, in
setting up to collect time waveform data. So for a maximum frequency of 400 Hz,
set the sampling rate at 1000 samples/second.
400 Hz < 1000
2.5
=
Sampling rate
2.5
400 Hz x 2.5 < 1000 = Sampling rate