R&S 1129.7246.03, Operating Manual

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Operating Manual 1302.6163.12 - 03 4.139
R&S ESU Instrument Functions
Analyzer Mode
Average detector
The average detector forms the average value of the measured values within a
pixel.
To this effect, R&S ESU uses the linear voltage after envelope detection. The sam-
pled linear values are summed up and the sum is divided by the number of samples
(= linear average value). For logarithmic display the logarithm is formed from the
average value. For linear display the average value is displayed. Each pixel thus
corresponds to the average of the measured values summed up in the pixel.
The average detector supplies the average value of the signal irrespective of the
waveform (CW carrier, modulated carrier, white noise or impulsive signal).
Quasipeak detector
The quasipeak detector resembles the behavior of an analog voltmeter by evaluat-
ing the measured values in a pixel.
The quasipeak detector is especially designed for the requirements of EMC mea-
surements and is used for evaluating pulse-shaped spurious.
CISPR RMS detector
The CISPR RMS average detector supplies a weighted reading of the input signal.
When measuring the RMS-average according to the proposed amendment of
CISPR 16-1-1 (CISPR/A/628/CD), the maximum value of the RMS-average during
the measurement time is displayed. The detector is used, for example, to measure
pulsed sinusoidal signals with a low pulse repetition frequency. It is calibrated with
the RMS value of an unmodulated sinusoidal signal. Averaging is with lowpass fil-
ters of the 2nd order (simulation of a mechanical instrument). The CISPR RMS
detector is available in zero span.
CISPR average detector
The CISPR average detector supplies a weighted average. When measuring the
average according to CISPR 16-1-1, the maximum value of the linear average dur-
ing the measurement time is displayed. The detector is used, for example, to mea-
sure pulsed sinusoidal signals with a low pulse repetition frequency. It is calibrated
with the rms value of an unmodulated sinusoidal signal. Averaging is with lowpass
filters of the 2nd order (simulation of a mechanical instrument). The CISPR Average
detector is available in zero span.
During a frequency sweep, R&S ESU increments the 1st local oscillator in steps
that are smaller than approximately 1/10 of the bandwidth. This is to ensure that
the signal level is correctly measured. For narrow bandwidths and wide frequency
spans a very large number of measured values is thus obtained. The number of
frequency steps, however, always is a multiple of 625 (= number of pixels that can
be displayed). With the sample detector selected, only every n
th
value is dis-
played. The value of n depends on the number of measured values, i.e. on the fre-
quency span, the resolution bandwidth and the measurement rate.