Chapter 17 583
W-CDMA Downlink Digital Modulation for Receiver Test
Using W-CDMA Downlink
Managing Noise
The tasks in this procedure build upon the previous procedure.
The following tasks teach you how to set the overall carrier-to-noise (C/N) ratio for the downlink W-CDMA
setup and to set the E
c
/N
o
value for individual physical channels.
• “Setting the Carrier to Noise Ratio” on page 583
• “Setting Ec/No” on page 583
Setting the Carrier to Noise Ratio
1. Press
Mode Setup to return to the first-level real-time W-CDMA menu.
2. Press
Link Control > 8 > Enter > Channel State Off On to On.
3. Press
PhyCH Setup.
4. Move the cursor to highlight the C/N value field.
5. Press
10 > dB.
NOTE Noise values less than 10 dB may not be visible on a spectrum analyzer.
You have now set the overall carrier to noise ratio to 10 dB and turned on noise. This is done to apply a
discernible level of noise across the entire channel space.
Setting E
c
/N
o
1. Move the cursor to highlight the Ec Ref field.
2. Press
Edit Item > DPCH 2.
3. Move the cursor to highlight the Ec/No value field.
4. Press
15 > dB.
You have now set the E
c
/N
o
value for the DPCH 2 channel to 15 dB. Note that modifying the E
c
/N
o
value for
a channel will change the overall carrier to noise ratio and the E
c
/N
o
value for all other active channels. For
reliable results when making hand calculations to determine or verify E
c
/N
o
values, it is recommended that
you first scale the code domain power to 0 dB to display the normalized relative channel power levels (see
“Scaling to 0 dB” on page 581).
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