R&S 1129.7246.03, Operating Manual

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R&S ESU Instrument Functions
Receiver Mode
4.32 Operating Manual 1302.6163.12 - 03
• CISPR average and CISPR rms measurement:
With a CISPR average or a CISPR rms measurement, the maximum value of the
weighted signal during the measurement time is displayed. The relatively long
time constants used with CISPR average and CISPR rms detectors result in long
measurement times in order to obtain a correct measurement result. If unknown
signals are measured, the measurement time should be at least one second so
that pulses down to a frequency of 5 Hz are correctly weighted.
After a frequency change or a modification of the attenuation, the R&S ESU waits
until the lowpass has settled before the measurement time starts. The
measurement time is selected depending on the IF bandwidth and the
characteristics of the signal to be measured. Unmodulated sinusoidal signals as
well as signals with high modulation frequency can be measured within a short
time. Slowly fluctuating signals or pulse signals require longer measurement
times.
With measurement times shorter than 20 ms the detector weighting changes to
average or RMS.
• RMS measurement:
With RMS weighting the same applies to the measurement time as with the
average measurement.
• Quasipeak measurement:
With quasipeak measurements, the maximum value of the weighted signal during
the measurement time is displayed. The relatively long time constants used with
quasipeak detectors entail long measurement times to obtain correct results. With
unknown signals the measurement time should be at least 1 s. This ensures
correct weighting of pulses down to a pulse frequency of 5 Hz.
After internal switching, R&S ESU waits until the measurement result has
stabilized before it starts the actual measurement. Since the level does not
change during a frequency scan, known signals (e.g. broadband RFI) can be
correctly measured with a much shorter measurement time.
• Measurement with several detectors:
If several detectors are used simultaneously, a measurement time suiting the
slowest detector should be selected to obtain correct results for all detectors. It is
therefore recommended to set a measurement time that matches the average
detector when the peak and average detectors are used.