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Chapter 9 131
W-CDMA Measurement Application
Amplitude
Description Specifications Supplemental Information
Modulation Accuracy (Composite
EVM)
BTS Measurements
−25 dBm ≤ ML
a
≤ −15 dBm
20 to 30 °C
a. ML (mixer level) is RF input power minus attenuation.
RF input power and attenuation are set to
meet the Mixer Level range.
Composite EVM
Range 0 to 25%
Floor
1.6%
Accuracy
b
b. For 16 QAM or 64 QAM modulation, the relative code domain error (RCDE) must be
better than −16 dB and −22 dB respectively.
±1.0%
c
c. The accuracy specification applies when the EVM to be measured is well above the measurement floor.
When the EVM does not greatly exceed the floor, the errors due to the floor add to the accuracy errors.
The errors due to the floor are noise-like and add incoherently with the UUT EVM. The errors depend
on the EVM of the UUT and the floor as follows: error = [sqrt(EVMUUT
2
+ EVMsa
2
)] − EVMUUT,
where EVMUUT is the EVM of the UUT in percent, and EVMsa is the EVM floor of the analyzer in
percent. For example, if the EVM of the UUT is 7%, and the floor is 2.5%, the error due to the floor is
0.43%.
±0.5%
d
At EVM measurement in the range of
12.5% to 22.5%
Peak Code Domain Error
Accuracy ±1.0 dB
I/Q Origin Offset
DUT Maximum Offset −10 dBc (nominal)
Analyzer Noise Floor −50 dBc (nominal)
Frequency Error
Range
±3 kHz (nominal)
e
Accuracy
±5 Hz + tfa
f
Time offset
Absolute frame offset accuracy ±20 ns
Relative frame offset accuracy ±5.0 ns (nominal)
Relative offset accuracy
(for STTD diff mode)
g
±1.25 ns