The Spectrum Application (RF Measurements)
R&S
®
FPL1000
256
User Manual 1178.3370.02 ─ 09
CISPR Average detector (CISPR filter only)
The CISPR Average detector displays a weighted average signal level according to
CISPR 16-1-1.
The average value according to CISPR 16-1-1 is the maximum value detected while
calculating the linear average value during the specified dwell time.
The CISPR Average detector is only available for the CISPR filter.
The CISPR Average detector is applied to measure pulsed sinusoidal signals with a
low pulse frequency, for example. It is calibrated with the RMS value of an unmodula-
ted sinusoidal signal. The average value is determined by lowpass filters of the 2nd
order (simulating a mechanical pointer instrument).
The filter bandwidth and time lag of the detector depend on the measured frequency.
The time lag of the simulated pointer instrument reflects the weighting factor of the sig-
nal depending on its form, modulation, etc.
Table 7-17: Required parameters depending on frequency for CISPR 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 the
simulated pointer
instrument
160
ms
160
ms
100
ms
100
ms
Consider the following when defining the dwell time:
●
Unknown signals
: select a dwell time of at least 1
second to ensure that pulses
down to a frequency of 5
Hz are weighted correctly
●
Pulsed signals or signals that fluctuate slowly
: the dwell time must cover at
least the time until the first signal peak is measured; can require long dwell time
●
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 may replace
the quasipeak detector in the future.
Measurements and Results
