Hi guys, I am currently generating LTE signal and receiving it through Agilent MXA signal analyzer and demodulating it in VSA 89601. How can I measure the SNR or Q factor in VSA? Because LTE demodulation only shows constellation diagram and I cant find a way to get the eye-diagram due to the nature of OFDM I guess...
Can anyone please advice or share your experience.
Thank you.
Can anyone please advice or share your experience.
Thank you.
EVM is the most commonly used figure of merit for LTE signals. The EVM result displayed by the 89600 VSA software gives an aggregate measure of signal quality by including errors due to noise as well as other impairments (symbol clock error, amplitude compression or distortion, carrier frequency offset, etc.). If white noise is the dominant impairment present, the EVM displayed in dB will be approximately equal to the reciprocal of the SNR. If other error sources are present though, it becomes prohibitively difficult to back out even a rough estimate of SNR value.
Because OFDM signals are made up of many subcarriers being transmitted simultaneously, the traditional idea of a single signal transitioning from one point to the next in a sequential manner doesn’t really apply. I suspect this is why you’re not getting the typical eye diagram that you’re expecting. However, the VSA software will show you how close the states are to each other at the moment the symbol is valid.
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