User Manual

The Spectrum Application (RF Measurements)
R&S
®
FPL1000
255User Manual 1178.3370.02 ─ 09
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Pulsed signals: the time must be long enough to capture several complete pulses
(at least 10)
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The time is determined by the lowest modulation frequency to be averaged
RMS detector
The RMS detector displays the root mean square (RMS) value over the specified dwell
time. The integration time is the specified dwell time.
The RMS detector is already available with the base unit.
The same considerations apply to the dwell time as for the average detector.
Sample detector
The sample detector displays the last value from the samples allocated to a pixel.
The sample detector is used for noise or phase noise marker calculation. However, it is
unreliable if the displayed span is much greater then the resolution bandwidth or if the
tuning steps of the local oscillator are too large. The sample detector is not recommen-
ded for EMI tests.
Quasipeak detector (CISPR filter only)
The quasipeak detector displays the maximum signal level weighted to CISPR 16-1-1
that was detected during the dwell time.
The quasipeak detector is only available for the CISPR filter, and not for an RBW of
1 MHz.
The filter bandwidth and time parameters of the detector depend on the measured fre-
quency. The time lag of the simulated pointer instrument reflects the weighting factor of
the signal depending on its form, modulation, etc.
Table 7-16: Required parameters depending on frequency for CISPR quasipeak detector
Band A Band B Band C/D
Frequency range < 150 kHz 150 kHz to 30 MHz > 30 MHz
Resolution bandwidth 200 Hz 9 kHz 120 kHz
Charge time 45 ms 1 ms 1 ms
Discharge time 500 ms 160 ms 550 ms
Time lag of the simulated
pointer instrument
160 ms 160 ms 100 ms
Consider the following when defining the dwell time:
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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
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Known signals: shorter dwell time possible, as the signal level does not change
during the final measurement
Measurements and Results