Measuring Am-Modulated Signals - R&S ESR Series User Manual

®
R&S ESR
Table 3-6: Signal generator settings (e.g. R&S SMU)
Frequency
Level
Modulation
1. Set the signal analyzer to the default state by pressing the [PRESET] key.
The R&S ESR is set to its default state.
2. Select "Spectrum" mode.
3. Set the center frequency to 128 MHz and span to 50 kHz.
a) Press the [FREQ] key and enter 128 MHz.
b) Press the [SPAN] key and enter 50 kHz.
4. Activate the marker function for measuring the AM modulation depth.
a) Press the [MEAS] key.
b) Press the "More" key.
c) Press the "AM Mod Depth" softkey.
Figure 3-14: Measurement of the AM modulation depth
The modulation depth is displayed as "MDepth". The frequency of the AF signal can be
obtained from the frequency display of the delta marker.
3.5.3.3

Measuring AM-Modulated Signals

The signal analyzer rectifies the RF input signal and displays it as a magnitude spec-
trum. The rectification also demodulates AM-modulated signals. The AF voltage can be
displayed in zero span if the modulation sidebands fall within the resolution bandwidth.
Displaying the AF of an AM-modulated signal (Zero Span)
Test setup
User Manual 1175.7068.02 ─ 12
The R&S ESR automatically sets a marker to the carrier signal in the center of
the diagram and one delta marker each to the upper and lower AM sidebands.
The R&S ESR calculates the AM modulation depth from the level differences of
the delta markers to the main marker and outputs the numeric value in the
marker field.
Basic Measurement Examples
128 MHz
-30 dBm
50 % AM, 10 kHz AF
Quick Start
104