The Spectrum Application (RF Measurements)
R&S
®
FPL1000
257
User Manual 1178.3370.02 ─ 11
●
Unmodulated signals or signals with a high modulation frequency
: the dwell
time must cover at least the time until the first signal peak is measured; usually
shorter than for pulsed signals
RMS Average detector (CISPR filter only)
The RMS Average detector is a combination of the RMS detector (for pulse repetition
frequencies above a corner frequency) and the Average detector (for pulse repetition
frequencies below the corner frequency). It thus achieves a pulse response curve with
the following characteristics:
●
10
dB/decade above the corner frequency
●
20
dB/decade below the corner frequency
The average value is determined by lowpass filters of the 2nd order (simulation of a
mechanical pointer instrument).
The RMS Average detector is only available for the CISPR filter.
The detector is used, for example, to measure broadband emissions and will possibly
replace the quasi-peak detector in the future.
The detector parameters depend on the measured frequency. The time lag of the simu-
lated pointer instrument reflects the weighting factor of the signal depending on its
form, modulation, etc.
Table 6-18: Required parameters depending on frequency for RMS Average detector
Band A
Band B
Band C/D
Band E
Frequency range
<150
kHz
150
kHz to 30
MHz
30
MHz to 1
GHz
>1
GHz
IF bandwidth
200
Hz
9
kHz
120
kHz
1
MHz
Time lag of simula-
ted pointer instru-
ment
160
ms
160
ms
100
ms
100
ms
Corner frequency
10
Hz
100
Hz
100
Hz
1
kHz
The same considerations apply to the dwell time as for the CISPR average detector.
Required sweep time in FFT mode
In FFT mode, the sweep time is divided among the required subspans. To ensure the
required dwell time at each frequency, the sweep time must be at least:
<sweep time>
min
= <required_dwell_time> * <number_of_FFT_subspans>
The number of FFT subspans is indicated in the "Sweep" settings, see
on page 330. It is also returned for the
query.
Frequency Resolution - Sweep Points and Scaling
The number of sweep points defines the number of measurement values collected dur-
ing one sweep. Thus, increasing the sweep points also increases the accuracy of the
results regarding the frequency resolution.
Measurements and Results
