2201R Mobile Tester User Guide
Chapter 3 Performing manual tests and measurements in GSM mode
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Freq. Error
This result field indicates how the actual carrier frequency deviates from the nominal frequency. It is measured in
hertz. According to the specifications, the maximum allowable relative error is 10
-7
; that is, approximately ±90 Hz in
the GSM 850 and GSM 900 bands, ±180 Hz in the GSM 1800 band and ±190 Hz in the GSM 1900 band.
EVM Peak
The key measurement for EDGE modulation is the error vector magnitude or EVM for short, which is the distance in
the I/Q diagram between the measured signal and the ideal one, relative to the ideal signal vector magnitude; the EVM
is measured separately for each symbol. The peak EVM measurement determines the maximum EVM within the
burst. The result is expressed as a percentage and always positive.
EVM RMS
The RMS EVM is the RMS-averaged value over all symbols of a burst. The result is expressed as a percentage.
Phase Err. Peak
The peak phase error is the magnitude of the maximum phase error that occurred within a single burst. This value is
always positive.
Phase Err. RMS
The RMS phase error is calculated from the phase errors of all bits within a burst, by root-mean-square-averaging
them. This value is always positive.
EVM 95th %
The 95th percentile EVM is the error vector magnitude that is not exceeded by 95% of the symbols of the burst. The
95th percentile EVM is expressed in %.
Origin Offset
The origin offset indicates the accuracy of the I/Q modulator’s DC setup; it usually is an undesired leakage produced
due to a DC offset in the phone’s I/Q modulator. It is measured in dBc.
Multislot Class
This field indicates the multislot class number, along its meaning. The multislot class indicates the maximum number
of downlink slots, the maximum number of uplink slots and the maximum number of concurrent downlink and uplink
slots.
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