BNC 7000 Series User Manual - Manual (Page 25)

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Figure 8 “More” Configuration Menu allows choosing reference source
After clicking on the Measure button, the phase noise measurement is started. A couple of
calibration steps are automatically performed and phase noise data is acquired from SERIES
7000. In the Measurement tab of the plot window the red trace shows the intermediate result as
shown in Figure 8.
Once the measurement is completed, the GUI returns into idle state. During the idle state, the
“beat” signal of the two measurement channels can be observed in the “Time Domain” tab of
the measurement window as shown in Figure 9.
Upon measurement start the SERIES 7000 will adjust the input step attenuator to avoid power
compression and maximize dynamic range, calibrate the phase detector and phase lock the internal
references. The “Status Window” tab will indicate measurement progress and provide status and error
messages..
The loop bandwidth is adaptively set to ensure stable and reproducible measurements with maximum
dynamic range. The gain of the IF amplifiers is adjusted to measure at lowest sensitivity without driving
the stages into compression.
Note that the measurement time needed largely depends on the offset range measured and the total
number of correlations.
Figure 10 shows a screenshot of the GUI after a completed measurement. Below the actual
(red) measurement trace, a gray polygon (shade trace) is visible. This polygon indicates the
measurement floor for the current measurement. With increasing number of correlation, this
noise floor will decrease. If the measurement trace at a given offset is above the noise floor the
measured trace has reached a steady-state value at the same offset. Increasing number of
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