User Manual

The Spectrum Application (RF Measurements)
R&S
®
FPL1000
455User Manual 1178.3370.02 ─ 09
7.14 Optimizing Measurements
7.14.1 Minimizing the Measurement Duration
If you want to minimize the measurement duration, try the following methods to opti-
mize the measurement:
●
Reduce the span of the measurement to the relevant parts of the signal only.
●
Increase the RBW to minimize the measurement time; however, consider the
requirements of the standard if you need to measure according to standard!
●
Reduce the sweep time and thus the amount of data to be captured and calcula-
ted; however, consider the requirements regarding the standard deviation.
●
To determine average (or peak) values, use an RMS detector (or peak detector)
with a higher sweep time instead of trace averaging to obtain better average
power results in less time. Furthermore, enforce the use of the sweep type "FFT"
(as opposed to "Auto"; in Sweep mode, the averaging effect of the RMS detector
may be less efficient).
●
When performing multiple measurements, use multiple channel setups to switch
between measurements rather than changing the settings within one channel
repeatedly.
Additional information
An application note discussing measurement speed optimization is available from the
Rohde & Schwarz website:
1EF90: Speeding up Spectrum Analyzer Measurements
7.14.2 Improving Averaging Results
Instead of trace averaging, use an RMS detector with a higher sweep time to obtain
better average power results in less time. Furthermore, enforce the use of the sweep
type "FFT" (as opposed to "Auto"; in Sweep mode, the averaging effect of the RMS
detector may be less efficient).
In FFT mode, FFTs are calculated per bin and combined using the RMS detector. For
trace averaging, on the other hand, the local oscillator must be switched repeatedly for
each trace, which takes additional time.
Generally, a higher sweep time leads to more data to be averaged and thus stabilizes
the results. In FFT mode, a higher sweep time means more FFTs are calculated and
combined per bin.
Thus, in the same capture time, the FFT mode with an RMS detector can provide bet-
ter results than an averaged trace.
Optimizing Measurements