HP 8901B - Page 27

Model 8901B General Information
modulation index. If the peak amplitude is called P and the trough amplitude is called T, the modulation
index
rn (usually expressed in %) is defined as
P-T
m=- + x 100%.
In the example of Figure 1-3, P = 1.5 and T = 0.5; therefore,
1.5 - 0.5
m= x 100% = 50%.
1.5 + 0.5
Figure 1-4 shows AM signals with modulation indexes varying from 0 to 100%.
(a) 0% AM (CW)
(b) 30% AM
(c) 70% AM
(d) 100% AM
Figure 1-4. AM for Various Depths
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