Chapter 3 WCDMA Non-Call Mode
RF Analyzer for modulation quality
WCDMA Options Version 6.20
91
Reading the results The modulation quality parameters are displayed in a table showing the current,
minimum, average and maximum values of the measurements taken. The Count
field shows the number of iterative tests over which average values are calcu-
lated. To the right-hand side of the table a bar display allows for a quick and easy
identification of limit violation by providing violation indicators. For a detailed
description of the bar display refer to section “Display fields” on page 25.
EVM Peak [%] — Shows the peak value determined for the the EVM (Error
Vector Magnitude). The EVM measures the modulation quality of the RF signal
transmitted by the UE. It shows the deviation of the measured signal vector from
an ideal, calculated signal vector, i.e. the error vector (magnitude and phase). The
EVM is expressed as a percentage value.
EVM RMS [%] — Shows the RMS value of the Error Vector Magnitude, i.e. the
RMS value of the error vector measured divided by the RMS value of the refer-
ence signal, also expressed as a percentage value. As the error vector value
changes countinously and besides the peak value a mean value is needed for
facilitating the assessment of modulation quality, the root mean squared Error
Vector Magnitude is determined as a measure of modulation accuracy at the
decision points. The RMS value is an average of all the decision points (symbols)
across a whole measurement interval.
The EVM value shall not exceed 17.5% at an output power of equal to or greater
than –20 dBm and a power step size of 1 dB under normal operating conditions.
Mag. Error Peak [%] — Shows the peak value determined for the difference
between the measured vector’s and the ideal vector’s magnitude. The value is
normalized to the magnitude of the ideal modulated signal vector and expressed
as a percentage value.
The magnitude error value shall not exceed 50 %.
Mag. Error RMS [%] — Shows the RMS value determined for the magnitude
error, also expressed as a percentage value. The root mean squared magnitude
error is a measurement of the error in the mobile’s transmit signal size (magni-
tude) at the decision points.
Phase Error Peak [deg] — Shows the peak value determined for the phase
difference, i.e. for the angle difference, between the signal vector measured and
the ideal signal vector, expressed in degrees.
The phase error peak value shall be in the range of ±45°
Phase Error RMS [deg] — Shows the RMS value determined for the phase error.
The root mean squared phase error is a measurement of the phase component of
the vector error of the UE’s transmit signal at the decision points. It is expressed
in degrees.
The phase error RMS value shall not exceed ±10°.
Frequency Error [Hz] — Shows the value determined for any difference between
the UE’s RF-modulated carrier frequency and the assigned carrier frequency in
Hertz.
According to WCDMA specifications the UE’s carrier frequency shall not deviate
from the assigned frequency by more than ±0.1 ppm. Thus the value displayed in
this field shall be in the range of ±200 Hz.
To Next Page
Loading...
