unit:
1. dB: power gain, a pure counting symbol, indicating a relative value, where the conversion relationship between power and dB is as follows
xdB = 10lg (Po / Pi)
3dB means that Po is twice the Pi
2. dBm (decibel milliwatt):
Describe the absolute value of power, the calculation formula of power P (mW) and x (dBm) is as follows.
Therefore, dBm will have positive and negative, where 1mW corresponds to 0dBm, when the power is greater than 1mW, The value of dBm is positive, otherwise it is negative. The subtraction of the two units of power in dBm is actually the division of the corresponding power
symbol:
1. EVM (error vector amplitude, unit percentage):
the root mean square of the ratio of the average error vector signal power and the average reference signal power. The smaller the percentage value, the better the signal quality after transmission.
2. SNR (signal-to-noise ratio, same as S / N):
signal to noise power ratio, unit dB
