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Measurements
R&S
®
FSW
126
User Manual 1173.9411.02 ─ 19
Fig. 5-8: Measurement of two equally-leveled RF sinusoidal signals with a resolution bandwidth
(1
kHz) which is significantly smaller than their frequency spacing
5.2.4.2
Measuring the Modulation Depth of an AM-Modulated Carrier in the Frequency
Domain
In the frequency range display, the AM side bands can be resolved with a narrow
bandwidth and measured separately. The modulation depth of a carrier modulated with
a sinusoidal signal can then be measured. Since the dynamic range of a signal ana-
lyzer is very large, extremely small modulation depths can also be measured precisely.
For this purpose, the R&S
FSW provides measurement routines that output the modu-
lation depth numerically in percent directly.
Signal
Generator
R&S FSW
Fig. 5-9: Test setup
Table 5-4: Signal generator settings (e.g. R&S SMU)
Frequency
128 MHz
Level
-30 dBm
Modulation
50 % AM, 10 kHz AF
Basic Measurements