The "Time Domain" plot is a powerful
tool to use for analysis since it is as close to the raw (analog) data
as you are likely to get. It also can be quite intimidating to learn to
use (with good reason) and many analysts do not use it at all. Even more
than the FFT, it creates a number of questions for the analyst:
-
How is it interpreted
?
-
How is one set
up ?
-
Should I use it
everywhere ?
-
Why do I need
it at all when I have the FFT to use ?
This section of the manual will provide
you with information on how to use and interpret the time domain plot.
More importantly (since it is from this signal that an FFT plot is produced)
this section will attempt to give you a general understanding of how the
FFT process views the signals we feed into it and how these signals impact
what we see when we look at an FFT. |
| The time domain, of course, is where
the reading begins - an analog measurement of how the surface is moving.
This analog signal is fed from the transducer to the analyzer where it
is converted to a digital signal - it goes through an A/D converter. The
result of this process can be seen above in the plot above. |
| It is important to realize that
it is experience (i.e. practice)
that creates a 'comfort' level for the analyst in interpreting the time
domain plot. Experience in setting it up properly and experience in being
able to recognize what you are seeing - the pattern of what you
are seeing. Let's zoom in on this plot. |
