Instrument Functions
R&S
®
NRP2
117User Manual 1173.9157.02 ─ 03
Unit
Sets the result unit.
4.5.3.3 Filtering settings
You can smooth the trace in the "Average" display by means of an averaging filter. For
this purpose, a number of sweeps are recorded and the power of points of the same
position in time is averaged ("Trace Averaging"). The averaging process substantially
improves zero offset and linearity of the measurement result.
In the "Peak" display, a maximum search is performed over the number of curves corre-
sponding to the averaging number. If signals of stochastic envelope are applied, filtering
may increase the measurement accuracy. The fluctuations of results caused by the
inherent noise of the sensor will also be reduced, but this is unfavorable for a higher
systematic deviation (measured values are too high). Remedy: Reduce the video band-
width (see below).
The averaging filter does not affect the "Random" display.
To prevent results from being falsified due to instable trigger conditions, you should
always check whether the trace is stable in its time axis. This should be done without
averaging ("Trace Avg No = 1").
To meet the requirements for higher reproducibility and accuracy of numeric results,
measured power values for gates can be averaged even more by "Numeric Averaging",
irrespective of "Trace Averaging".
The measurement accuracy for the peak power, in particular for low power levels, can
be increased by reducing the effect of the inherent noise. You can do this by using a
smaller channel bandwidth ("Video Bw"). For the R&S NRP-Z8x wideband power sen-
sors, this can be done in several steps between 300 kHz and 30 MHz (FULL). Reducing
the video bandwidth also increases the trigger sensitivity. As a rule of thumb, the trigger
threshold ("Level") can be reduced by 3 dB if the video bandwidth is reduced by a factor
of 4.
The video bandwidth must never be smaller than the RF bandwidth of the signal.
►
Select "Filt..." in the trace control panel opened via the Window→Graph→"Display"
dialog box ("Trace&Statistics" sensor mode).
Displaying traces
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