78 Chapter2
Making Measurements
Example 5: Third-Order Intermodulation Distortion
b. Set the reference level to this value by pressing MKR →,
MARKER → REF LVL. Figure 2-23 on page 78 illustrates the
resulting display.
Figure 2-23 Signal Peak Set to Reference Level
Maximize dynamic range
12.Distortion-free dynamic range is important for this type of
measurement. To maximize such dynamic range:
a. Set the mixer input level to −30 dBm by pressing
AMPLITUDE,
MORE 1 OF 3, MAX MXR LEVEL.
b. Enter −30 dBm.
The spectrum analyzer automatically sets the attenuation so the
maximum signal level is −30 dBm at the input mixer when the signal is
at or below the reference level (see Example 1). You will hear the input
attenuator click; notice that the value of the attenuator is now 20 dB
(see Figure 2-24 on page 79).
This change to the maximum mixer level can affect the noise, so you
may need to adjustment the resolution and video bandwidths.
Set a second marker and measure the distortion product
Once a marker is activated, the marker delta function activates a
second marker and displays the difference between the two markers.
Relative measurements can then be performed easily.
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