DI-770 Oscilloscope provides five virtual instruments in one

DI-770 and WINDAQ/Scope Manual
The voltmeter has a limited frequency range in which the measurements are performed correctly. If the periodical
time of the input signal is much larger than the measuring time, a wrong value is measured. See the next illustration.
If the time in which the 200 samples are taken is too long in relation to the periodical time of the input signal, aliasing
can occur (see also the chapter about the oscilloscope).
Setting the frequency range
To avoid errors like the ones mentioned above, the frequency range of the voltmeter has to be set properly. The sampling
frequency is then changed. By activating the choice Frequency range from the Settings menu, a popup menu
appears, in which several frequencies are available. The frequencies indicate the center frequency of a frequency
range in which the voltmeter measures properly. The size of the frequency range is determined from 0.2 x f center to 5
x f center .
When Auto freq. is chosen, the voltmeter determines the best frequency setting by itself. For each measurement the
frequency has to be determined, resulting in a longer time before updating the displays.
Note: The Auto frequency setting overrides the sample frequency setting in the oscilloscope and the spectrum analyzer.
This will result in a less usable display in those instruments.
To avoid this, the choice Scope freq. is available in the menu. The voltmeter will use the same sample frequency as
the oscilloscope or spectrum analyzer.
Displaying channels
The voltmeter has several modes to display the two channels. To select the measure mode, enter the Settings menu
and select Channels. Use the Measure channel option to enable or disable measuring from a channel. Measuring takes
place from at least one channel.
When only one channel is measured, the controls of the other channel are disabled or removed from the display.
Setting up a channel
The channels of the voltmeter can be setup in several ways. Both channels have the same settings, so only channel 1
is discussed here.
Setting the input range
In the voltmeter, the input range or sensitivity can be set through the channels settings dialog.
The channels setting dialog is called by selecting the Channels option from the Settings menu. In this dialog, the input
sensitivities are available, as well as an autoranging setting.
The Voltmeter
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