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JD780A Series Analyzers
a.
Press the Average soft key.
b.
Enter a value between 1 and 100.
c.
Press the Enter soft key.
Setting limit
Procedure
1.
Press the LIMIT hot key.
2.
Press the Occupied BW soft key to set the limit parameters.
3.
Toggle the Test Limits soft key between On and Off to enable or disable the Pass/Fail indication.
4.
Set the upper threshold:
a.
Press the High Limit soft key.
b.
Enter a value for the upper limit.
c.
Select the unit: MHz, kHz, or Hz.
5.
Optional. Go to SAVE/LOAD > Save, and then select Limit to save the limit settings.
See "Using save" on page 31 for more information.
Measurement example
The Occupied Bandwidth measurement shows both of power across the band and power bandwidth in
a user specified percentage to determine the amount of spectrum used by a modulated signal.
Occupied bandwidth is typically calculated as the bandwidth containing 99% of the transmitted power.
Figure 12
Occupied bandwidth measurement with spectrum analyzer
Spectrum emission mask (SEM)
The Spectrum Emission Mask (SEM) measurement is to identify and determine the power level of out-
of-band spurious emission outside the necessary channel bandwidth and modulated signal. It
measures the power ratio between in-band and adjacent channels. The JD780A series indicates either
Pass or Fail based on the specified limit of the signal.
72
Using Spectrum Analyzer
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