Abstract: The signal-to-noise ratio of a demodulated received signal is estimated by measuring the error vector magnitude (EVM) of the demodulated signal; and processing the measured EVM in combination with a correction term to estimate the signal-to-noise ratio of the demodulated signal. The correction term is a polynomial function of the measured EVM. The signal-to-noise ratio is estimated in accordance with the formula: E S N 0 ? 10 · LOG 10 ? ( ? · ? E S ? 4 ? [ ? ^ z + C ? ( ? ^ z ) ] 2 ) ? ? ? ( dB ) wherein {circumflex over (?)}z is the measured EVM based on the mean of a Rayleigh density of EVM measurements; and C is the correction term. For QPSK modulated signals, C is calculated in accordance with the formula: CQPSK({circumflex over (?)}z)?2.71×10?3{circumflex over (?)}z3?7.54×10?2{circumflex over (?)}z2+0.7{circumflex over (?)}z?2.25 For BPSK modulated signals, C is calculated in accordance with the formula: CBPSK({circumflex over (?)}z)?1.