An radio frequency, RF, receiver, comprising: a quadrature mixer adapted for receiving an RF input signal and outputting in-phase and quadrature channels; analogue to digital converters for the in-phase and quadrature channels; an amplitude compensator adapted for adjusting the amplitude of one or both the channels to correct for amplitude mismatch, based on an amplitude correction coefficient; a phase compensator adapted for adjusting the relative phase between the two channels to correct for phase mismatch, based on a phase correction coefficient; a first mixer adapted for generating in-phase and quadrature desired signals from the amplitude adjusted and phase adjusted channels by mixing with a first frequency, and a first digital channel filter at the output of the first mixer adapted for generating a filtered in-phase desired signal and a filtered quadrature desired signal; a second mixer adapted for generating in-phase and quadrature image signals from the amplitude adjusted and phase adjusted channels by mixing with a second frequency, and a second digital channel filter at the output of the second mixer adapted for generating a filtered in-phase image signal and a filtered quadrature image signal; and a coefficient estimator adapted for generating the phase correction coefficient and the amplitude correction coefficient from the filtered in-phase and quadrature desired signals and the filtered in-phase and quadrature image signals, wherein the coefficient estimator comprises: a third mixer adapted for mixing the filtered in-phase and quadrature desired signals with a third frequency to generate shifted in-phase and quadrature desired signals; a fourth mixer adapted for mixing the filtered in-phase and quadrature image signals with a fourth frequency which is the negative of the first frequency to generate shifted in-phase and quadrature image signals; an adder adapted for combining the shifted in-phase and quadrature signals to generate a combined in-phase signal and a combined quadrature signal; an amplitude coefficient circuit (31,32,34,36) adapted for obtaining an amplitude difference between the combined in-phase signal and the combined quadrature signal; and a phase coefficient circuit (26,28,30) adapted for obtaining a phase difference between the combined in-phase signal and the combined quadrature signal. a quadrature mixer adapted for receiving an RF input signal and outputting in-phase and quadrature channels; analogue to digital converters for the in-phase and quadrature channels; an amplitude compensator adapted for adjusting the amplitude of one or both the channels to correct for amplitude mismatch, based on an amplitude correction coefficient; a phase compensator adapted for adjusting the relative phase between the two channels to correct for phase mismatch, based on a phase correction coefficient; a first mixer adapted for generating in-phase and quadrature desired signals from the amplitude adjusted and phase adjusted channels by mixing with a first frequency, and a first digital channel filter at the output of the first mixer adapted for generating a filtered in-phase desired signal and a filtered quadrature desired signal; a second mixer adapted for generating in-phase and quadrature image signals from the amplitude adjusted and phase adjusted channels by mixing with a second frequency, and a second digital channel filter at the output of the second mixer adapted for generating a filtered in-phase image signal and a filtered quadrature image signal; and a coefficient estimator adapted for generating the phase correction coefficient and the amplitude correction coefficient from the filtered in-phase and quadrature desired signals and the filtered in-phase and quadrature image signals, wherein the coefficient estimator comprises: a third mixer adapted for mixing the filtered in-phase and quadrature desired signals with a third frequency to generate shifted in-phase and quadrature desired signals; a fourth mixer adapted for mixing the filtered in-phase and quadrature image signals with a fourth frequency which is the negative of the first frequency to generate shifted in-phase and quadrature image signals; an adder adapted for combining the shifted in-phase and quadrature signals to generate a combined in-phase signal and a combined quadrature signal; an amplitude coefficient circuit (31,32,34,36) adapted for obtaining an amplitude difference between the combined in-phase signal and the combined quadrature signal; and a phase coefficient circuit (26,28,30) adapted for obtaining a phase difference between the combined in-phase signal and the combined quadrature signal. a third mixer adapted for mixing the filtered in-phase and quadrature desired signals with a third frequency to generate shifted in-phase and quadrature desired signals; a fourth mixer adapted for mixing the filtered in-phase and quadrature image signals with a fourth frequency which is the negative of the first frequency to generate shifted in-phase and quadrature image signals; an adder adapted for combining the shifted in-phase and quadrature signals to generate a combined in-phase signal and a combined quadrature signal; an amplitude coefficient circuit (31,32,34,36) adapted for obtaining an amplitude difference between the combined in-phase signal and the combined quadrature signal; and a phase coefficient circuit (26,28,30) adapted for obtaining a phase difference between the combined in-phase signal and the combined quadrature signal.