Modulation Error Ratio (MER)

The modulation error ratio (MER) is a measure of the signal-to-noise ratio (SNR) in a digitally modulated signal. Like SNR, MER is usually expressed in dB. MER over N number of symbols is defined as

where

I_j is the I component of the j-th symbol received
Q_j is the Q component of the j-th symbol received
is the ideal I component of the j-th symbol received
is the ideal Q component of the j-th symbol received