Tektronix NetTek YBT250, User Manual, Page: 201 / 338

Taking Measurements
YBT250 Field Transmitter & Interference Tester User Manual
3- 99
5.
Tap the
Forward Link
button.
6. Select a channel.
Figure 3- 48: A W-CDMA Signal Quality display (option WD2)
Tap the online help link to display more information about a
measurement.
The EVM measurement is most accurate when using the confor-
mance test model for EVM, Test Model 4. Test Model 4 specifies
that the only active channels are the P-CCPCH and SCH channels,
with the P-CPICH channel present as an option. The P-CPICH must
be present for the YBT250 to make an EVM measurement.
The EVM measurement can be made on signals other than Test
Model 4, but the result is an estimate of the true EVM value. The
YBT250 attempts to determine the spreading factor of all active
codes and the power levels during one time slot. Changing power
levels or codes with low power levels decreases the accuracy of the
EVM estimate.