Agilent Technologies E4428C, User Manual

Page: 519 / 700

Chapter 16 495
W-CDMA Uplink Digital Modulation for Receiver Test
Setting Up a Multiple PRACH Signal
Viewing a Multiple PRACH Signal
This procedure uses the Agilent E4440A PSA Spectrum Analyzer for measuring the ESG output. Figure
16-1 on page 447 shows the connections between the ESG and the PSA. The signal shown in Figure 16-33
on page 496 was built using the procedures from the section “Setting Up a Multiple PRACH Signal” on
page 479 . If you have used other parameters, your signal output may show different characteristics.
1. Preset the spectrum analyzer.
2. Select the Spectrum Analysis mode.
Press
Mode
>
Spectrum Analysis
.
3. Set the center frequency.
Press
Frequency Channel
>
Center Freq
>
1.95
>
GHz
.
4. Select the zero Hertz span.
Press
Span
>
Zero Span
.
This sets the PSA to function like an oscilloscope measuring in time rather than frequency.
5. Set the sweep time to 80 ms.
Press
Sweep
>
40
>
ms
.
6. Set the resolution bandwidth for a quick response time that captures the bursting nature of the PRACH
components.
Press
BW/Avg
>
8
>
MHz
.
Whenever you make a measurement in the zero Hertz span, you need to set the resolution bandwidth to
its maximum value to ensure capturing all of the signal characteristics.
7. Trigger the spectrum analyzer from the rear trigger input using the ESG trigger signal selected in the
section, “Selecting the Rear Panel Output Trigger” on page 480 .
Press
Trig
>
Ext Rear
.
8. Set the PSA to average the signal measurement.
Press
Det/Demod
>
Detector Auto Norm
>
Average
.
9. Lower the reference level to
−
10 dBm.
Press
Amplitude Y Scale
>
Ref Level
>
10
>
-dBm
.
10. Resolve the display for a closer view of the signal.
Press
Scale/Div
>
5
>
dB
.