To demodulate a W-CDMA signal
This task shows you how to demodulate the W-CDMA signal that you
loaded in the previous task. If you are using your own W-CDMA signal
instead of the one from the previous task, you may need to change some
of the parameters set in step 5 to match those of your signal.
1. Load the W-CDMA signal as instructed in the previous task.
2. Turn on Wideband CDMA demodulation.
Press [
Instrument Mode
], [
demod type], [Wideband CDMA].
3. Set the maximum W-CDMA span to 5 MHz.
Press [
System Utility
], [
memory usage
], [
configure meas memory
]
Press
[
mx WCDMA span
], 5MHz.
4. Verify that the maximum number of time points is 4096:
Press [
max time pts], 4096 [enter].
If necessary, reallocate memory until you can set [max time pts] to 4096 points.
Smaller values limit the number of symbols that the analyzer can
demodulate and display.
5. Set demodulation parameters for this signal:
Press [
Instrument Mode
], [
demodulation setup
].
Press [
demod format], [3GPP forward link], [W-CDMA 5 MHz], [return], [return].
Selecting [
3GPP forward link] configures the analyzer to make base-station,
W-CDMA measurements, as proposed in the 3GPP 1999 forward link
standard. Pressing the [
W-CDMA 5 MHz] standard-setup softkey automatically
sets the chip rate (3.84 MHz), main length (15 slots), scramble code (0),
and filter alpha (0.22) to match that of a 5 MHz, 3GPP 1999 forward-link
signal. For details about standard setups softkeys, see online help for the
[
3GPP forward link] softkey.
6. If necessary, mirror the frequency spectrum.
Press [
Instrument Mode
], [
demodulation setup
], [freq spectrum mirror]
As mentioned in the previous task, some W-CDMA signals may have a
flipped (mirrored) frequency spectrum. If this is true for your signal, you
must perform this step.
7. Select the composite code-domain power display:
Press [
Measurement Data
], [code domain], [composite].
8. Start the measurement:
Press [
Pause/Single
].
9. After the measurement finishes, autoscale the results:
Press [
Auto Scale
].
Using Wideband CDMA (Options B73, B79, and 080)
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