Chapter 9 69
Modulation Accuracy (Composite EVM) Measurements
Measurement Procedure
Measurement Procedure
Step 1. Press Mode, TD-SCDMA with HSPA/8PSK to enable the TD-SCDMA with
HSPA/8PSK mode measurements.
Step 2. Press
Mode Preset to preset the analyzer.
Step 3. Select the signal inputs for the measurement.
For BBIQ measurements this will be the I or I input and the Q or Q
input. Use the procedure in “Using Option BBA Baseband I/Q Inputs.“
Step 4. Press
Input/Output, External Gain, BTS and enter the number and −dB
according to the external attenuator connected to the analyzer.
Step 5. Press
Mode Setup, Radio, Device to toggle the device to BTS.
Step 6. Press
Mode Setup, Analysis Timeslot to select the timeslot to be
measured.
Step 7. Press
Meas, Mod Accuracy (Composite EVM) to initiate the modulation
accuracy (composite EVM) measurement.
Step 8. Press
FREQ Channel, 2, GHz to set the center frequency to 2 GHz.
Step 9. Press
Meas Setup to check the keys available to change the measurement
parameters from the default condition.
When you need to estimate the S1/S2 phase on DwPTS, press
Result
Length
and enter the desired value. Result Length should be set to a
number no less than 4.
To specify which sub-frame is used for analysis within the acquired
Result Length, press
Analysis Subframe and enter the desired value.
To adjust the limit parameters, press
Limits to change the limit lines.
Step 10. Press
View/Display to select from the following views:
• I/Q Measured Polar Graph
• I/Q Error (Quad view).
•Code Domain Power
• Capture Time Summary
• Numeric Results.
For more information about changing measurement parameters, see
N9079A TD-SCDMA with HSPA/8PSK User’s and Programmer’s
Reference.
If you have a problem, and get an error message, see the “Instrument
Messages Guide”.
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