Ceyear 4041 Series, User Manual

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Chapter IV Spectrum Analyzer Mode
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span is proportional to the channel power bandwidth (ratio range: 1~10). This ratio will
remain unchanged when the channel power bandwidth is changed. Changing the
channel power span may change this ratio. For example, when the channel power
bandwidth is doubled, the spectrum analyzer will also double the channel power span.
i) Enable the average function:
Press
【
BW
】
and [Average Off On] successively, set the average number of times to 16, and then enable the
average function.
After the channel Power meter function is enabled, the detector mode will be switched to the RMS mode if the
spectrum analyzer is in auto detector mode. The two vertical white lines displayed on the screen indicate the
bandwidth of channel power and the results are displayed at the bottom of the screen. The channel Power
measurement is as shown in Fig 4-2.
Fig 4-2 Channel Power meter of FM signal
4.1.2 Occupied bandwidth measurement
In this section, the occupied bandwidth measurement of FM signal is taken as an example to demonstrate the
method to measure the occupied bandwidth of signals with the occupied bandwidth measurement function of 4041
series spectrum analyzer.
1) Definition of occupied bandwidth
Occupied bandwidth refers to the frequency bandwidth containing a certain percentage of the total transmitted
power and is centered on the center frequency of designated channel. The occupied bandwidth measurement
function of 4041 series spectrum analyzer can give measurements quickly, clearly and accurately. There are two
calculation methods for occupied bandwidth according to the modulation mode.
a) Power percentage method:
Calculate the bandwidth of those frequencies containing a certain percentage of the total power of transmission