User Manual

The Spectrum Application (RF Measurements)
R&S
®
FPL1000
244User Manual 1178.3370.02 ─ 03
Figure 7-8: Measurement of two equally-leveled RF sinusoidal signals with a resolution band-
width (1 kHz) which is significantly smaller than their frequency spacing
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 FPL1000 provides measurement routines that output the
modulation depth numerically in percent directly.
Figure 7-9: Test setup
Table 7-4: Signal generator settings (e.g. R&S SMW)
Frequency 128 MHz
Level -30 dBm
Modulation 50 % AM, 10 kHz AF
Measurements and Results