DI-770 Oscilloscope provides five virtual instruments in one

DI-770 and WINDAQ/Scope Manual
Setting up a channel
The two channels of the spectrum analyzer are completely configurable. Both channels are identical, each has its own
menu item in the main menu. The possibilities of the vertical axes in the spectrum analyzer are the same as in the
oscilloscope, so only the differences are discussed here. Since the possibilities for both channels are equal, channel 1
is explained here.
Setting the input sensitivity
The input sensitivity of a channel determines how large a certain signal will be displayed, the lower the full scale
value, the larger the signal will be displayed. It is possible to enable an autoranging function.
Note: The vertical axis in the spectrum analyzer has a range that is twice the input sensitivity. This is done because
the frequency components of which a signal is built, can have a larger amplitude than the input sensitivity. So if an
input sensitivity of 8 Volt full scale is selected, the axis will have values from 0 to 16 Volt full scale.
The sensitivity can be set through the Sensitivity menu. The Sensitivity menu is called by enabling the Ch1 menu and
then selecting the Sensitivity menu. In this menu the input sensitivities are available. In the spectrum analyzer also an
Autoranging setting is available. The Sensitivity menu can also be entered by clicking the right mouse button over
one of the Ch1 or Ch2 controls and readouts.
To switch on Autoranging, a special button is available. When autoranging is switched on, the button caption is Auto,
otherwise it holds the current set input sensitivity. Pressing the right mouse button on this button will bring up a menu
with all sensitivities.
Note: When Autoranging is switched on, several measurements might be needed to set the input sensitivity properly,
depending on the input signal.
Another way to set the sensitivity is by using the keyboard. A few keys have been reserved for setting the input sensitivity
of the channels. These keys are:
Increase Ch1 sensitivity
Decrease Ch1 sensitivity
Increase Ch2 sensitivity
Decrease Ch2 sensitivity
Logarithmic or linear vertical axis
The vertical axis of the spectrum analyzer can be set to linear or to logarithmic.
When set to linear, the normal axis is used, running from 0 to 2 x Sensitivity. When set to logarithmic, the position on
the linear axis that is mark-ed Sensitivity will get the value
Value = 20 x 10 log Sensitivity
The rest of the labels will get a value that is related to this value and differ from it with 10 dB per division (when Software
gain is set to 1). The measured data will be transformed to logarithmic data as well.
Selecting the axis type can be done by entering the Ch1 menu, choosing the Axis type menu and selecting the axis
type.
The axis type can also be set by the keyboard using the following keys:
toggle the Ch1 axis between Linear and Logarithmic
toggle the Ch2 axis between Linear and Logarithmic
The Spectrum Analyzer
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