Spectrum Measurements
R&S
®
ESR
309
User Manual 1175.7068.02 ─ 12
The example is based on the following configuration.
Center frequency
100 MHz
Span
Zero span (0 Hz)
Unit
dBm
Reference Level
-30 dBm
Attenuation
20 dB
RBW
1 MHz (EMI)
VBW
10 MHz
Sweep time
100 ms
Detector
Auto Peak
All other settings are in their default (preset) state.
The first picture shows the resulting noise characteristics in the time domain (zero
span). The x-axis shows the time. The y-axis shows the level of the "signal" in dBm.
P
max
is the highest level that has been measured, P
min
is the lowest level.
The second picture shows the corresponding CISPR APD function. Here, the x-axis
represents the disturbance levels in dBm. The scale of the axis is arbitrary. By default,
its range is a 100 of the unit you are working with. The end point of the x-axis repre-
sents the reference level.
The y-axis represents the statistical frequency that a particular level value will turn up
with. The y-axis is a logarithmic axis by default. Like the x-axis, its scale is arbitrary.
As you can see, the probability that levels above P
max
will occur is zero. With falling
level values, the probability that a particular level occurs increases (until P
min
has been
reached). Because the noise has no spikes, the APD curve is falling (more or less)
smoothly.
Measurements
