Agilent Technologies E4428C, Руководство пользователя

Страница: 608 / 700

584 Chapter 17
W-CDMA Downlink Digital Modulation for Receiver Test
Using W-CDMA Downlink
Generating the Baseband Signal
This procedure builds upon the previous procedure.
Press
Mode Setup
>
W-CDMA Off On
to On.
This generates the real-time downlink W-CDMA signal. The signal generator experiences a slight delay
while the signal is being built. During this time,
Baseband Busy
appears on the display. After the signal
generation is completed, the display reads
WCDMA On
and the
WCDMA
and
I/Q
annunciators appear. The
signal is now modulating the RF carrier.
The signal’s configuration data resides in volatile memory and is not recoverable after an instrument preset,
power cycle, or another signal generation.
Applying New Settings
The steps in this procedure build upon the previous procedure.
Signal parameters changes are not always automatically applied to the current signal being transmitted.
When this condition occurs, an annunciator appears informing you that the new changes must be applied to
the signal. This procedure demonstrates how these types of changes are applied to the current signal output.
1. Press
Link Control
>
5
>
Enter
.
2. Press
PhyCH Setup
.
3. Move the cursor to highlight the
On
value for DPCH data channel 1.
4. Press
Edit Item
to toggle the channel off.
Notice that with the personality already turned on, as soon as a data channel parameter is changed, the
Apply Needed
annunciator appears (see Figure 17-6 ). This indicates that the new setting has not yet
taken effect in the active baseband signal.