Technical data

572 Chapter 19
W-CDMA or W-CDMA (with HSDPA) Analyzer
Interpretation of Measurement Results
W-CDMA or W-CDMA (with HSDPA)
Analyzer
Threshold
If the Threshold is not as expected, check the following:
Check the Threshold settings to make sure they are correct. (See “Setting the Active
Channel Threshold Level and Auto Threshold Level” on page 562 for more
information.).
• If the Threshold setting is Auto with no offset, it is an indication that there is a
poor signal to noise ratio.
• Check the Channel Power to ensure the level is as expected.
• If the power level is good, look for EVM and PCDE problems.
EVM Pilot and EVM Comp (Pilot (CPICH) and Composite Error Vector
Magnitude
An unexpectedly high EVM could be due to interfering signals, carrier feedthrough,
transmitter I/Q modulator, or signal path problems.
If you have not already done so, you can reduce the noise floor by activating the IF
Equalizer (See “Setting the IF Equalizer” on page 565.)
PCDE (Peak Code Domain Error)
An unexpectedly high PCDE could be due to interfering signals, carrier
feedthrough, transmitter I/Q modulator, or signal path problems.
Carr Feedthru (Carrier Feedthrough)
A good Carrier Feedthrough level is less than -25 dB. The 3GPP standard does not
specify Carrier Feedthrough; however, this measurement provides an additional tool
to troubleshoot the base station's transmitter.
In the frequency domain, Carrier Feedthrough can show up as an energy spike that
can be seen on the spectrum analyzer by closely spanning into the top of the
W-CDMA or W-CDMA (with HSDPA) signal. The effects of Carrier Feedthrough
can also show up as higher noise levels on the Code Domain Power screen. Carrier
Feedthrough can be caused by the lack of isolation across the mixer and cavity of
the transmitter's I/Q modulator.
Chan Pwr (Channel Power)
If the Channel Power level is not as expected, check pilot dominance and the
number of Scrambling codes visible. All visible sectors will contribute to channel
power. Also, check Amplifier Capacity and Utilization as they could have exceeded
the maximum capacity. A high power data call could be indicated by a very wide