WaveCAD Arbitrary Waveform Creation Software
WaveCAD is a powerful Windows-based design tool that enables the user to create waveforms
from mathematical expressions, from combinations of other waveforms, “freehand”, or using a
combination of all three techniques.
WaveCAD creates waveforms that are up to 65536 points long with a vertical resolution of 12-
bits. Waveforms can be stored in either a binary (.WAV extension) or ASCII format (.ASC
extension); .WAV files are smaller than .ASC files for the same waveform.
The waveform is downloaded to the generator using the Waveform Download command on Wave
CAD’s System menu, having first set the interface and interface parameters (also on the System
menu) to match the generator’s settings shown on the
remote…
menu of the UTILITY screen.
The arb waveform name shown in the list (accessed by the ARB key after download) will be the
same as the WaveCAD file name (without the extension).
Waveform download times depend on waveform size, file format and interface used. GPIB
transfers at about 1,500 points per second, RS232 at 9,600 Baud transfers at about 200 points
per second.
The operation of WaveCAD is intuitive and the built-in HELP provides further information where
operation is not self-explanatory. A short time spent exploring the software should reveal all the
main capabilities; the notes that follow are intended to draw attention to one or two important
features which might be overlooked at a first browse.
All “freehand” commands are available directly from the Toolbar or from the Edit menu. When
neither Autoline nor Sketch are selected, clicking the left-hand mouse button and dragging
defines a “zoom” rectangle which expands that part of the waveform to the full window size
enabling viewing or modification of the waveform to be carried out with greater resolution. To
return to the full view of the waveform select View All from the View menu. “Anchors” can be
dragged from left or right, using the arrows at the top of the Y-axes, to define a section of
waveform which can be Smoothed, Filtered, Inverted or replaced by another wave defined from
the Wave menu, see below.
Apart from Edit and View the only other menu of importance is Wave. A number of “standard”
waveforms (sine, sawtooth, sinx/x, exponential, etc.) can be selected directly; selecting any one
brings up a self-explanatory dialogue box in which all appropriate parameters can be set. The
most powerful WaveCAD facility, the Equation Editor, is also accessed from the Wave menu.
The Equation Editor, opened by selecting
Equation…
in the Wave menu, permits a waveform to
be defined both directly as a mathematical expression and as a combination of previously defined
waveforms. Pressing the Operands button in the Equation Editor window gives the full choice of
operations and functions that can be used in the equation. This list is largely self-explanatory
although it does require an understanding of the appropriate mathematics. The following simple
examples should give a taste of the possibilities.
In these examples note that:
‘amp’ is the waveform Amplitude set in the Level Adjuster field.
‘omg’ (omega) = 2
∗
pi
∗
f (
2π
f) radians, where f = 1/per (1/period)
‘per’ (period) is defined as the difference between the defined start and end 1, e.g. start
point 0, end point 1023, period 1024.
‘p’ (or ’t’) is the x-axis variable; the function is calculated point-by-point for the range of ‘p’ defined
by the start and end points.
Example 1 : Sinewave
Ampl (p) = amp
∗
sin (omg
∗
p)
Sin (omg
∗
p) will generate a single sinewave in the period defined by the start and end
points. The value of the sine function varies in the range ±1; multiplying by amp makes the
sinewave amplitude that defined by the Amplitude parameter. Instead of using amp, a
fixed amplitude can be defined numerically, e.g.
Ampl (p) = 256
∗
sin(omg
∗
p)
gives a sinewave with an amplitude of ±256 points.
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