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b) Power drop XdB:
The occupied bandwidth in this calculation method is defined as follows: spacing between two frequency points
corresponding to signal power drop by XdB on both sides of the frequency point where the signal peak power is.
The signal power drop XdB can be set by the user.
2) Measurement procedures
The occupied bandwidth can be measured with S3302 series spectrum analyzer according to the following
procedures:
a) Set the signal generator to output the FM signal:
Use the signal generator to generate one FM signal. Set the frequency as 1GHz, power as -10dBm, FM offset as
500kHz and demodulation rate as 10kHz. Connect the output of the signal generator to the RF input end of the
spectrum analyzer through one cable, as shown in Fig. 4-1. Enable the ON state of the modulation output and radio
frequency.
b) Reset the spectrum analyzer into the default state:
Press [Reset].
c) Set the center frequency:
Press [frequency] and [Center Freq] to set the center frequency with number keys. Set the center frequency of the
spectrum analyzer as the frequency of the tested signal, i.e. 1GHz.
d) Set the resolution bandwidth:
Press [BW] and [RBW Auto Man
], and set the resolution bandwidth as an appropriate value.
e) Set the video bandwidth:
Press [BW] and [VBW Auto Man
], and set the video bandwidth as an appropriate value.
In order to improve the measurement accuracy, it is recommended to set the ratio of the resolution bandwidth to
video bandwidth to be more than 10. Press [RBW/VBW] to change this ratio.
f) Enable the occupied bandwidth measurement mode of the spectrum analyzer:
Press [Measure], [OBW] and [OBW Off On
].
After the occupied bandwidth measurement function is enabled, the spectrum analyzer will change into the
occupied bandwidth measurement interface, and measurement results will be displayed at the bottom of the screen.
Refer to Fig. 4-3 for the schematic diagram of occupied bandwidth measurement. Two vertical white lines on the