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manually.
d)
Increase the sweep time of the spectrum analyzer
Press
【
Sweep
】
and [Sweep Time Auto Man] and increase the sweep time with the step key
【
↑
】
. By increasing
the sweep time, there may be more time for averaging data at each trace pixel point.
3.3.4 Measuring small signals by using video average
In video average function, digital method is used to average the mean values of current trace point for
sweeping and previous same trace position. Enable video average to set the number of video average.
The video average gets different result from the average detector.
a)
Reset the spectrum analyzer
Press
【
Preset
】
key to restart the spectrum analyzer.
b)
Set the center frequency, the span, and the reference level
Set the frequency of the external signal generator to 300MHz and set the amplitude to -80dBm, and connect the
radio frequency output end of the signal generator to the radio frequency input end of the spectrum analyzer. Set
the center frequency of the spectrum analyzer. Press
【
Freq
】
and select [Center Freq] to set the center
frequency to 300MHz, and then select
【
Span
】
to set the span to 5MHz. Press
【
Ampt
】
and select [Ref Level]
to set the reference level to -40dBm.
c)
Enable the video average function
Press
【
BW
】
and [Average On Off]. As the average program averages the trace, the small signal becomes
clearer. The default number of averages is 16.
d)
Set the number of averages to 25
Input the number 25 by the numerical keypad on the front panel and press [ok], or
【
Enter
】
key on the soft menu,
as shown in Fig. 3.10. The Remarks window at the left of the screen will display the number of average. Once the
set number of average is reached, the Spectrum Analyzer will continue to perform average computation on this
data basis. If you want to stop the measurement after the number of average is reached, you may use single sweep
function. Press
【
Sweep
】
and [Sweep Cont Single].
