R3267 Series Spectrum Analyzer Operation Manual (Vol.1)
2.3.13 Measuring Modulation Index of FM Signals
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2.3.13 Measuring Modulation Index of FM Signals
This section describes the residual FM (FM signals with small modulation index).
The following formula holds if the FM signal modulation index m is less than approximately 0.8.
E
SB
: Level of the first sideband
E
C
:
Carrier level
For the logarithmic scale display,
∆
Level: Difference between the first sideband and the carrier levels [dB]
Measurement conditions: The target of the measurement below is a signal whose input signal character-
istics consist of an output frequency of 1 GHz, a level of -10 dBm, a modula-
tion frequency of 3 kHz and a modulation index of 0.2.
Use appropriate parameter values when making the measurements in the ex-
ample shown below.
Setup
1.
Connect the unit under test as shown in Figure 2-139.
Figure 2-139 Setup for Measuring Modulation Index
Power on
2.
Turn the analyzer and the unit under test power on.
Setting the unit under test
3.
Activate the signal output for the unit under test.
Initialization
This resets the current settings to the factory defaults or user-defined presets.
4.
Press SHIFT and CONFIG(PRESET).
This sets the analyzer to its presets values.
m =
E
C
2E
SB
m = 10
∆
Level + 6
20
