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[硕士学位论文]Measurement of EVM (Error Vector Magnitude) for 3G

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0楼发表于: 2009-03-12 13:56:52

精彩尽在其中，
The aim of this thesis work is to measure the Error Vector Magnitude (EVM)
directly at the radio receiver of the 3rd Generation WCDMA base stations,
specifically at the gamma bus, and the output of the analogue to digital
converters. The EVM is a figure-of-merit for the down-conversion of the
modulated radio signal and is a measure of the signal to noise and distortion
ratio. The error vector is obtained by subtracting the received signal from an ideal
reference signal. The set-up consists of generating an RF signal using a signal
generator, feeding it into the receiver, and acquiring it from the interfaces of
interest using a logic analyzer. The ideal reference signal is created by means of
software. The work done in this project includes an algorithm proposal to
measure the received signal at the optimal position, this algorithm is based on the
eye diagram, specifically, in the analysis of the variance of the signal’s
magnitude. In addition, another algorithm was developed to compensate for the
effects of frequency offsets introduced by the RF local oscillator. The frequency
offsets can be visualized as phase variations of the IQ constellation in the time
domain, such phase variations were tracked and compensated using a one-tap
Least Mean-Square adaptive filter. Both algorithms were implemented in software
using Labview, resulting in an EVMRMS of 6.6% at the gamma bus, an ..

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