2-15
77
Figure 2-10.—Frequency deviation versus bandwidth.
From table 2-1 we see that there are 16 significant sidebands for a modulation index of 5. To
determine total bandwidth for this case, we use:
The use of this math is to illustrate that the actual bandwidth of an fm transmitter (240 kHz) is
greater than that suggested by its maximum deviation bandwidth (75 kHz or 150 kHz). This is
important to know when choosing operating frequencies or designing equipment.
Q-4.
What characteristic of a carrier wave is varied in frequency modulation?
Q-5.
How is the degree of modulation expressed in an fm system?
Q-6.
What two values may be used to determine the bandwidth of an fm wave?
