1. A method for removing quadrature imbalance errors in received data, the method comprising: accepting an unbiased training sequence in a quadrature demodulation receiver, the unbiased training sequence having a uniform accumulated power evenly distributed in a complex plane, and including predetermined reference signals (p) at frequency +f and predetermined mirror signals (p m ) at frequency −f; processing the unbiased training sequence, generating a sequence of processed symbols (y) at frequency +f, representing complex plane information in the unbiased training sequence; multiplying each processed symbol (y) by the mirror signal (p m ); and, obtaining an unbiased quadrature imbalance estimate B m at frequency −f.