Tegam 2411B, Operation Manual

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Chapter 2 About Arbitrary Waveforms
Waveform Generation
Waveform Generation
In an arbitrary waveform generator, you will define a waveform, using either the standard functions or
custom profile data files to load waveform memory. A set of start and stop addresses which correspond
to a waveform memory location is assigned with a waveform number. An address generator sequentially
presents data values from the specified memory location to the digital-to-analog converter (DAC). The
precision DAC converts the data into analog voltage values. This series of sequential voltage levels
describes the output waveform with the frequency determined by the sample clock rate divided by the
number of samples in the waveform. Changing the sample clock rate causes the address generator to
change the speed at which the data is presented to the DAC, thereby changing the output frequency.
The waveforms you create are a series of data points consisting of X- and Y-axis values. For 16-bit gen-
erators, such as the TEGAM 2411B, the Y values b32767 and -32768 are used. In describing
the first point, 0, is given a Y value. The next point has another Y value, and so on up to the last address
in your waveform. This series of points make up the waveshape.
Waveform Cycle
All the data points in the specified waveform memory location make up one waveform cycle. The wave-
form generator will output all the points in the waveform at the sample clock rate specified. The result-
ing frequency is equal to the sample clock rate divided by the number of data points in the waveform. If
more than one cycle of the waveshape is entered into a waveform, the output frequency will be a multi-
ple of one waveform generator cycle. For example, if you create a waveform with 3 triangle wave cycles
using the same number of data points and the sample clock rate, the frequency will be 3 times higher.
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