Get Agilent Pn 89400-14 Using Error Vector Magnitude Measurements Bb

The relationship between EVM(Vector Magnitude) and SNR(Signal to Noise Ratio), also known as MER (Modulation Error Ratio), is relatively straightforward as EVM is a voltage ratio of the error signal to the peak state voltage, and SNR is a ratio of the signal power to the error power.

EVM is defined as (6.22)EVM (dBc)=Mean(|q−q^|2)/Mean(|q|2),where q is a QAM symbol at the very edge of the burst, which consists of two PAM symbols, respectively, from the last and second last real-valued PAM OQAM/FBMC symbols, and q^ is the estimation of q at the receiver output, when the wireless channel is free of ...

In general, EVM is calculated by finding the ideal constellation location for each received symbol, as shown in Figure 1b. The root means square (rms) of all error vector magnitudes between the received symbol locations and their closest ideal constellation locations constitute the EVM value of the device.

EVM (Error Vector Magnitude) is a measure of how accurately a radio is transmitting symbols within its constellation. EVM is a measure of signal quality, which is a function of noise, interfering signals, nonlinear distortion and the load of the radio.

evm = lteEVM( x , r ) returns a structure, evm , containing error vector magnitude (EVM) information for the input array, x , given the reference signal array, r . The EVM is defined using the error, or difference, between the input values, x , and the reference signal, r .

An error vector is a vector in the I-Q plane between the ideal constellation point and the point received by the receiver. In other words, it is the difference between actual received symbols and ideal symbols.

3GPP TS 34.122 section 5.7. 1 states "The Error Vector Magnitude is a measure of the difference between the reference waveform and the measured waveform. This difference is called the error vector. Both waveforms pass through a matched Root Raised Cosine filter with bandwidth 1.28 MHz and roll-off alpha =0.22.