Common Measurement Settings
R&S
®
ESW
177User Manual 1177.6298.02 ─ 08
1 Hz 1 GHz
1 MHz
Figure 10-7: Logarithmic x-axis scaling: the distance between measurement points is variable
In the spectrum from 10 Hz to 100 Hz, the distance is a few Hz. Between 100 MHz and
1 GHz, the distance is several MHz.
Thus, for logarithmic x-axis scaling, the number of measurement points must be suffi-
ciently high in order to distinguish high frequencies precisely. The resolution bandwidth
should cover at least one measurement point (that means: the distance between two
measurement points should not exceed the RBW). If this condition is not met, signals
or interferers could be missed, especially narrowband interferers.
Insufficient measurement points -
Filter may miss a signal
Resolution filter bandwidth
covers one measurement point
Resolution filter bandwidth covers
several measurement points
10.8.1.3 Keeping the Center Frequency Stable - Signal Tracking
Note: in the Receiver application, signal tracking is available for the IF analysis.
If the signal drifts on the display but you want to keep the center frequency on the sig-
nal peak, the center frequency can be adjusted automatically using signal tracking. In
this case, the signal trace is surveyed in a specified bandwidth around the expected
center frequency. After each sweep, the center frequency is set to the maximum signal
found within the searched bandwidth. If no maximum signal above a defined threshold
value is found in the searched bandwidth, the center frequency remains unchanged.
The search bandwidth and the threshold value are shown in the diagram by red lines
which are labeled as "TRK".
Frequency and Span Configuration
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