The Spectrum Application (RF Measurements)
R&S
®
FPL1000
255
User Manual 1178.3370.02 ─ 09
●
Pulsed signals
: the time must be long enough to capture several complete pulses
(at least 10)
●
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:
●
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
●
Known signals
: shorter dwell time possible, as the signal level does not change
during the final measurement
Measurements and Results
