
R3267 Series Spectrum Analyzer Operation Manual (Vol.1)
2.3.13 Measuring Modulation Index of FM Signals
2-124
Setting the measurement conditions
This changes the analyzer settings so that the input signal is displayed more clearly.
5.
Press FREQ, 1 and GHz.
A center frequency of 1 GHz is set.
6.
Press SPAN, 1, 0 and kHz.
A frequency span of 10 kHz is set.
7.
Press LEVEL, 5 and MHz(-dBm).
The reference level is set to -5 dBm.
8.
Press SRCH.
The normal marker is displayed on the trace peak.
9.
Press MKR and Delta Marker.
The delta marker is displayed.
10. Press SRCH and Next Peak.
The normal marker moves to the next highest peak.
Figure 2-140 FM Signal with Low Modulation Index
Calculating modulation index
11. Read the delta marker level.
Modulation index m is calculated from the following formula, using
∆
Level as
delta marker level.
m = 10
∆
Level + 6
20