Unlike most other signal analysis applications, SIGVIEW does not merely provide a fixed user
interface for all purposes. It is rather designed as a collection of tools which can be combined in
many different ways to create a user interface and functionality customized to your analysis.
Once you have created your toolchain, you can save your application-specific “workspace” or
"tool" and reuse it later. To be able to use the full power of SIGVIEW, it is very important to
understand a several basic concepts:
Analysis chain: All signals or signal analysis results in SIGVIEW are connected to other
windows to form a chain of functional blocks: file input, data acquisition, FFT, instruments…You
can imagine signals or analysis results to “flow” through that chain from one tool to another one,
following your analysis path. Each time the content of one window changes, all its child windows
will recalculate and redraw its content. The analysis chain could look like this (Control Window
display): Visible part of the signal: If you perform any analysis on a signal window, it will be performed
only on the currently visible part of the signal. Consequently, if you change the visible part of
the signal (by moving through the signal, zooming in or out,…),
all child windows will recalculate
and redraw its content accordingly. This feature, together with different playback/navigation
functions, provides a very powerful method to control control the analysis and simulate real-time
analysis with offline signals.
Every array of values is a “signal”: Each sequence of X/Y values is considered to be a "signal"
(audio signal, spectrum, etc.). Consequently, each sequence has its sampling rate, even if it was
not actually created by digitally sampling some analog signal. Sampling rate of an FFT is simply a
number of its values (bins) in one X-axis unit, Hz. Following this logic, it is possible to perform, for
example, FFT analysis on an FFT result. Even if it seems like it does not make sense, it can
sometimes be interesting to see the results. The important thing is that SIGVIEW does not
impose any artificial limitations, telling you what you should and what you should not do. You are
free to experiment and to find you own way to get the results you want.
Signal graph/Linked windows :
If one window is created as a result of the analysis from any
other window, then those two windows are linked. The network of linked windows works like a
complex analysis machine where output of each window is the input for its child windows. It
means that all changes in one window will cause its child windows to recalculate and redraw their
content. A good example is a part of the signal and its FFT; if you slide a part of the signal
through the whole signal, its FFT result window will recalculate on each move to show FFT result
of each new signal segment. Moving through signals: You will usually work and perform analysis on a small part of a longer
signal. If your signal is zoomed-in to a smaller part, you can use arrow keys or playback
commands to move through the signal and observe changes in analysis results. One of the
standard procedures for working with signals would be:
1. Load one long signal and zoom-in to some power-of-2 length segment.
2. Perform some analysis on that segment, for example FFT
4. Return to the signal window and use left/right arrow keys to move the segment through
the whole signal
5. That way, you will be able to observe spectral changes in a signal through time and to
"record" consecutive spectra in a 3D graphics.
Data acquisition/monitoring : You
can work with a data acquisition window as you would with
any other static signal window. The only difference is that the signal you are recording will change
(if data acquisition is started) in regular intervals, depending on your data acquisition settings.
That will cause your signal analysis system to recalculate and redraw all windows connected with
data acquisition window. If your PC is fast enough, you will be able to create or change your
analysis system while data acquisition is running; otherwise it might be better to create the
system first and than start the data acquisition and observe the results.
Control window : Working with many
signals and analysis windows at the same time can
become quite confusing. In those situations, you can use Control window to display your signal
analysis system in a tree-view form where you can easily understand signal flow, perform
operations on multiple signals, hide and show windows and choose which signals to show as
overlay. Properties: You can change parameters for most analysis windows even after they are created.
If this is possible, Edit/Properties menu options will be enabled in the main menu or in the context
menu for specific window. By using this option, you will be able to change window properties like
cutoff frequencies for filtered signal, spectral analysis settings
for FFT and Time-FFT, scale limits
for instruments, etc.