R&S FSW Series, Руководство пользователя

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Measurements and Results
R&S
®
FSW
204 User Manual 1173.9411.02 ─ 43
7.2.7.3 Measurement Example 3 – Measuring the Intrinsic Noise of the R&S FSW with
the Channel Power Function
Noise in any bandwidth can be measured with the channel power measurement func-
tions. Thus the noise power in a communication channel can be determined, for exam-
ple.
If the noise spectrum within the channel bandwidth is flat, the noise marker can be
used to determine the noise power in the channel by considering the channel band-
width. However, in the following cases, the channel power measurement method must
be used to obtain correct measurement results:
●
If phase noise and noise that normally increases towards the carrier is dominant in
the channel to be measured
●
If there are discrete spurious signals in the channel
Test setup:
► Leave the RF input of the R&S FSW open-circuited or terminate it with 50 Ω.
Procedure:
1. Preset the R&S FSW.
2. Set the center frequency to 1 GHz and the span to 1 MHz .
3. To obtain maximum sensitivity, set RF attenuation to 0 dB and the reference level
to -40 dBm .
4. Select the "Channel Power ACLR" measurement function from the "Select Mea-
surement" dialog box.
5. In the "ACLR Setup" dialog box, set up a single Tx channel with the channel band-
width 1.23 MHz .
6. Select the "Adjust Settings" softkey.
The settings for the frequency span, the bandwidth (RBW and VBW) and the
detector are automatically set to the optimum values required for the measure-
ment.
7. Stabilize the measurement result by increasing the "Sweep Time".
Set the "Sweep Time" to 1 s .
The trace becomes much smoother because of the RMS detector and the channel
power measurement display is much more stable.
Channel Power and Adjacent-Channel Power (ACLR) Measurement