An accuracy improving method of error vector magnitude measurement system for 78 GHz broadband modulated signals

With the high-speed development of millimetre-wave (mmW) communication, the mmW signal transmission quality problem has received corresponding attention. Error Vector Magnitude (EVM) is a crucial parameter to measure signal transmission quality, which is an important index to evaluate whether the communication system is reliable. In our previous work, the author proposed a method for measuring EVM parameters of W-band communication signals based on electro-optic sampling (EOS). This method avoids introducing additional nonlinear distortions and solves the problem of vector signal analyzers being unable to measure high-frequency broadband-modulated signals. Based on our previous work, this paper estimates the channel characteristics of the measurement system and performs postprocessing on the received measurement signal using the estimated results to obtain more accurate measurements. The experimental results indicate that the EVM of the 78 GHz signal is 24.41% @1 GBaud, which is reduced to 9.8%@1 GBaud after channel estimation. This improvement demonstrates the feasibility of the channel estimation correction method.