Agilent Technologies 8560E - Figure 2-13 FM Signal with Carrier at a Null; Figure 2-14 FM Signal with First Sidebands at a Null

66 Chapter2
Making Measurements
Example 3: Modulation
Figure 2-13 FM Signal with Carrier at a Null
Figure 2-14 FM Signal with First Sidebands at a Null
NOTE Incidental AM from a source signal can cause the frequency null to shift, resulting in
errors to the procedure above. Incidental AM is very low for most RF signal generators,
but can be significant in microwave signal generators. Nonsymmetrical side lobes
indicate the presence of incidental AM. In such cases, the best technique for measuring
FM is to down-convert and use a modulation analyzer such as the Agilent 8901A/B.