R&S FSMR, Руководство по эксплуатации, Страница: 264 / 955

MKR FCTN - Analyzer R&S FSMR
1166.3363.12 4.14-2 E-2
Activating the Markers
Menu MKR FCTN :
SELECT
MARKER
The SELECT MARKER softkey activates the numerical selection of the
marker in the data entry field. Delta marker 1 is selected by input of ' 0 '.
If the marker is switched off, then it is switched on and can be moved later
on.
IEC/IEEE-bus command:
CALC:MARK1 ON;
CALC:MARK1:X <value>;
CALC:MARK1:Y?
PEAK
The PEAK softkey sets the active marker/delta marker to the peak of the
trace.
IEC/IEEE-bus command:
CALC:MARK1:MAX
CALC:DELT1:MAX
Measurement of Noise Density
NOISE MEAS
The NOISE MEAS softkey switches the noise measurement for the active
marker on or off. The corresponding marker becomes the NORMAL
marker.
During noise measurement, the noise power density is measured at the
position of the marker. In the time domain mode, all points of the trace are
used to determine the noise power density. When measurements are
performed in the frequency domain, two points to the right and left of the
marker are used for the measurement to obtain a stable result.
The noise power density is indicated in the marker field. With a logarithmic
amplitude units (dBm, dBmV, dBm
8 V, dB 8 A) the noise power density is
output in dBm/Hz i.e. as level in 1 Hz bandwidth with reference to 1 mW.
With linear amplitude units (V, A, W) the noise voltage density is evaluated
in
8 V/ Hz, the noise current density in 8 A/ Hz or the noise power density
in 8 W/Hz.
The following settings have to be made to ensure that the power density
measurement yields correct values:
Detector: Sample or RMS
Video bandwidth:
0.1 x resolution bandwidth with sample detector
(corresponds to RBW / VBW NOISE)
3 x resolution bandwidth with RMS detector
(corresponds to RBW / VBW SINE)
In the default setting, the R&S FSMR uses the sample detector for the
noise function.
With the sample detector, the trace can additionally be set to AVERAGE to
stabilize the measured values. With RMS detector used, trace averaging
must not be used since in this case it produces too low noise levels which
cannot be corrected. Instead, the sweep time can be increased to obtain
stable measurement results.