Function introduction
86 AFG31000 Series Arbitrary Function Generator User's Manual
InstaView overview
InstaView
TM
technology (real-time waveform monitoring) allows you to see the waveform of the device
under test (DUT) in real time, without the need for an oscilloscope and probe. This eliminates the
uncertainty caused by unmatched impedance.
To use InstaView:
1. Select Basic on the touch screen.
2. Press the InstaView button.
NOTE. The dialog box that opens indicates that there is a cable propagation delay. You can measure the
delay using the Auto Measure feature. Also note that every time you change a cable on the instrument,
the cable propagation delay must be auto-measured or manually updated.
3. To measure the cable delay between the channel 1 output and trigger input, connect the cable
appropriately and select Auto Measure. You can measure channel 2 the same way.
4. Once you have measured the delay, you can turn on InstaView by choosing the channel and
selecting OK.
NOTE. In the InstaView dialog box, you have an option to add Manual Input for the cable propagation
delay. Use the Delay input box to indicate the cable delay. This should only be used when you know the
amount of time of the delay, otherwise your measurements will not be accurate when using this feature.
Tutorial: InstaView
Most waveform generators insert a 50 Ω serial resistor on the output signal path (which requires the
output to be connected to a 50 Ω load through a cable with 50 Ω characteristic impedance) to ensure
maximum power transmission and minimize the reflection of high-speed signals. This is called
impedance matching and the nominal settings shown on the generators are based on the assumption
that all stages in the signal path are a perfect 50 Ω.
Many users, however, use devices under test (DUTs) that are not 50 Ω terminated. This impedance
mismatch causes the waveform at the DUT to be different from the nominal settings on the generator.
For example, if you set a 3.3 V square waveform as a clock to trigger on a TTL circuit, you may get a
6.6 V square waveform at the device end, because a TTL circuit typically has an input impedance of
several kOhms. Additionally, if there is parasitic capacitance or inductance, it will lead to distortion of
the waveform; it is not a square waveform anymore. The challenge is the screen still shows a 3.3 V
square waveform.
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