Power Measurements – MEAS Key R&S FSL
1300.2519.12 4.100 E-11
Sweep Time
Opens an edit dialog box to enter the sweep time. With the RMS detector, a longer sweep time
increases the stability of the measurement results.
The function of this softkey is identical to the Sweeptime Manual softkey in the bandwidth
menu.
Remote: SWE:TIM <value>
Fast ACP On/Off
Switches between the IBW method (Fast ACP Off) and the zero span method (Fast ACP On).
When switched on, the R&S FSL sets the center frequency consecutively to the different
channel center frequencies and measures the power with the selected measurement time (=
sweep time/number of channels). The RBW filters suitable for the selected standard and
frequency offset are automatically used (e.g. root raised cos with IS 136). For details on
available channel filters see "List of available RRC and channel filters" on page 4.20.
The RMS detector is used for obtaining correct power measurement results. Therefore this
requires no software correction factors.
Measured values are output as a list. The powers of the transmission channels are output in
dBm, the powers of the adjacent channels in dBm.
The sweep time is selected depending on the desired reproducibility of results. Reproducibility
increases with sweep time since power measurement is then performed over a longer time
period. As a general approach, it can be assumed that approx. 500 non–correlated measured
values are required for a reproducibility of 0.5 dB (99% of the measurements are within 0.5 dB of
the true measured value). This holds true for white noise. The measured values are considered
as non–correlated if their time interval corresponds to the reciprocal of the measured bandwidth.
With IS 136 the measurement bandwidth is approx. 25 kHz, i.e. measured values at an interval
of 40 Ms are considered as non–correlated. A measurement time of 40 ms is thus required per
channel for 1000 measured values. This is the default sweep time which the R&S FSL sets in
coupled mode. Approx. 5000 measured values are required for a reproducibility of 0.1 dB (99%),
i.e. the measurement time is to be increased to 200 ms.
Remote: POW:HSP ON
ACP Abs/Rel
Switches between absolute and relative power measurement in the adjacent channels.
Abs The absolute power in the adjacent channels is displayed in the unit of the y–axis,
e.g. in dBm, dBMV.
Rel The level of the adjacent channels is displayed relative to the level of the
transmission channel in dBc.
Remote: POW:ACH:MODE REL
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