Chapter 16 471
W-CDMA Uplink Digital Modulation for Receiver Test
Generating a Single PRACH Signal
Setting Up the LF Output as the AICH Signal
This task sets up the LF output so the results of the AICH trigger signal can be viewed on the PSA display
(see “Viewing the PRACH Message Using an AICH Trigger”). By following the steps in this task, the
message part will appear intermittently after each displayed preamble as the AICH trigger is received.
1. Press
LF Out > LF Out Source > Function Generator.
2. Press
LF Out Waveform > More (1 of 2) > Pulse.
3. Press
LF Out Period > 21 > msec.
4. Press
LF Out Width > 1 > msec.
5. Press
LF Out Amplitude > 5 > Vp.
6. Press
LF Out Off On to On.
Viewing the PRACH Message Using an AICH Trigger
This procedure guides you through configuring the PSA for making a spectrum analysis measurement. This
is being done to familiarize you with the different measurement modes that exist for the PSA. You could use
the W-CDMA mode, time domain measurement, to achieve the same results.
1. Preset the spectrum analyzer.
2. Select the spectrum analysis mode.
Press
Mode > Spectrum Analysis.
3. Set the center frequency to 1.95 GHz.
Press
Center Freq > 1.95 > GHz.
4. Set the span to zero hertz for close-in viewing of the PRACH signal.
Press
Span > 0 > Hz.
5. Set the sweep time to 50 ms.
Press
Sweep > Sweep Time > 50 > ms.
6. Set the spectrum analyzer to trigger from the ESG’s PRACH pulse trigger signal.
Press
Trig > Ext Rear.
You now see the message part moving across the display as the AICH trigger is received after each
preamble. Figure 16-18 shows the message part as it appears after the third preamble transmission.
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