Spectrum Measurements
R&S
®
ESR
252
User Manual 1175.7068.02 ─ 12
Note that in the I/Q Analyzer the channel bandwidth does not change the measure-
ment span or sampling rate; it merely defines the range for the carrier-to-noise analy-
sis.
Remote command:
[SENSe:]POWer:ACHannel:ACPairs
Adjust Settings ← C/N, C/No
Enables the RMS detector (see also
Chapter 6.3.1.5, "Detector Overview"
on page 399) and adjusts the span to the selected channel bandwidth according to:
"4 x channel ban measurement margin"
The adjustment is performed once; if necessary, the setting can be changed later on.
Note
: in the I/Q Analyzer, this function is not available. The channel bandwidth defines
the range for the carrier-to-noise analysis.
Remote command:
6.1.1.4
Measuring the Occupied Bandwidth
An important characteristic of a modulated signal is its occupied bandwidth. In a radio
communications system for instance the occupied bandwidth must be limited to enable
distortion-free transmission in adjacent channels. The occupied bandwidth is defined
as the bandwidth containing a defined percentage of the total transmitted power. A per-
centage between 10 % and 99.9 % can be set.
The measurement principle is the following: The bandwidth containing 99% of the sig-
nal power is to be determined, for example. The routine first calculates the total power
of all displayed points of the trace. In the next step, the points from the right edge of
the trace are summed up until 0.5 % of the total power is reached. Auxiliary marker 1 is
positioned at the corresponding frequency. Then the points from the left edge of the
trace are summed up until 0.5 % of the power is reached. Auxiliary marker 2 is posi-
tioned at this point. 99 % of the power is now between the two markers. The distance
between the two frequency markers is the occupied bandwidth which is displayed in
the marker field.
Measurements