1. A method of improved impairment covariance matrix estimation for a received signal in a Generalized Rake receiver arrangement, said method comprising: providing a plurality N of despread pilot symbols representative of said signal; determining an estimate of an impairment covariance matrix R for said received signal; providing an estimate of scaling parameters α, β for said estimate R according to a weighted least squares estimate based on the color of a residual noise vector for said impairment covariance matrix estimate R, and forming an improved estimate of said impairment covariance matrix based on at least said weighted least squares estimate.