A correction network comprising: an in-phase input port, a quadrature input port, an in-phase output port and a quadrature output port, wherein each input port (2i, 2q) is connected to each output port (3i, 3q) by a digital filter network, the digital filter network comprising a set of filter tap coefficients and configuration means for configuring values of the set of filter tap coefficients,: wherein a first instance of the correction network is configurable as a pre-corrector coupled to an up-converter and controllable by a correction controller via first control signals in such a way as to reduce effects of a frequency dependent quadrature error between a transmission characteristic of an in-phase signal transmit path and a transmission characteristic of a quadrature signal transmit path, wherein the quadrature signal transmit path is for transmission of in-phase and quadrature portions of a signal; and wherein a second instance of the correction network is configurable as a post-corrector coupled to a down-converter and controllable by the correction controller via second control signals in such a way as to reduce effects of a frequency dependent quadrature error between a reception characteristic of an in-phase signal receive path and a reception characteristic of a quadrature signal receive path, wherein the quadrature signal receive path is for reception of in-phase and quadrature portions of a signal. an in-phase input port, a quadrature input port, an in-phase output port and a quadrature output port, wherein each input port (2i, 2q) is connected to each output port (3i, 3q) by a digital filter network, the digital filter network comprising a set of filter tap coefficients and configuration means for configuring values of the set of filter tap coefficients,: wherein a first instance of the correction network is configurable as a pre-corrector coupled to an up-converter and controllable by a correction controller via first control signals in such a way as to reduce effects of a frequency dependent quadrature error between a transmission characteristic of an in-phase signal transmit path and a transmission characteristic of a quadrature signal transmit path, wherein the quadrature signal transmit path is for transmission of in-phase and quadrature portions of a signal; and wherein a second instance of the correction network is configurable as a post-corrector coupled to a down-converter and controllable by the correction controller via second control signals in such a way as to reduce effects of a frequency dependent quadrature error between a reception characteristic of an in-phase signal receive path and a reception characteristic of a quadrature signal receive path, wherein the quadrature signal receive path is for reception of in-phase and quadrature portions of a signal. wherein a first instance of the correction network is configurable as a pre-corrector coupled to an up-converter and controllable by a correction controller via first control signals in such a way as to reduce effects of a frequency dependent quadrature error between a transmission characteristic of an in-phase signal transmit path and a transmission characteristic of a quadrature signal transmit path, wherein the quadrature signal transmit path is for transmission of in-phase and quadrature portions of a signal; and wherein a second instance of the correction network is configurable as a post-corrector coupled to a down-converter and controllable by the correction controller via second control signals in such a way as to reduce effects of a frequency dependent quadrature error between a reception characteristic of an in-phase signal receive path and a reception characteristic of a quadrature signal receive path, wherein the quadrature signal receive path is for reception of in-phase and quadrature portions of a signal.