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This chapter describes procedures, components, and features you will use
in HP BenchLink/Arb.
About Arbitrary Waveforms
The waveforms you create in HP BenchLink/Arb are a series of data
points. The first point, 0, is given a Y value between -1 and +1. The next
point has another Y value, and so on, to the maximum number of data
points in your waveform. Taken together, these points make up a
waveshape.
All the data points in the waveform edit window make up one function
generator output cycle. When you send the waveform to the function
generator, it will attempt to output all the points at the frequency you
specify. For example, if you create a waveform with 10 sine wave
segments and set a 1 kHz output frequency when you send the waveform
to the function generator, the output will appear to be a 10 kHz sine wave.
The function generator samples the data points at 40 Msamples/second.
The maximum output is determined by the sample rate divided by the
number of points. A full waveform edit window (16,000 data points)
appears to have an upper frequency limit of 2.5 kHz , since
40 Msamples/16,000 = 2500. When higher frequencies are reached, the
function generator automatically samples the points so the full wave is
output. The function generator will sample no fewer than 8 points per
waveshape. Refer to chapter 7 in the HP 33120 User’s Guide for
additional information about sampling.
When possible, you should always send the maximum number of data
points. The more data points you send, the greater the fidelity of the
function generator output. HP BenchLink/Arb contains a special
function to allow you to expand any waveform to the maximum number
of data points.
The relative amplitude (Y values) of your waveform can range from -1 to
+1. This is a ‘relative’ amplitude because the function generator output
voltage will be scaled to these values. You set the desired output
peak-to-peak voltage when you send the waveform to the function
generator. For example, a square wave in the waveform edit window
that ranges from -1 to +1 can be output as a 1 volt peak-to-peak
waveform. The +1 relative amplitude is scaled to +0.5 volts and the -1
relative amplitude is scaled to -0.5. The square wave will be centered
around 0 volts.
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Chapter 3 Using HP BenchLink/Arb
About Arbitrary Waveforms
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