A method for calibrating a single sideband (SSB) receiver, comprising: a) adjusting a mutual phase shift of I- and Q-signals to a first phase shift value; b) feeding a first, a second and a third test signal having a predetermined phase offset to an input to obtain respective SSB signals, and measuring a first and a second phase difference therefrom; c) calculating a first phase error on the basis of the first and second phase differences; d) repeating steps a)-c) with a second phase shift value to obtain a second phase error; and e) calibrating the SSB receiver by using that one of the first and second phase shift values that has yielded the smaller one of the first and second phase errors.

A method for channel aggregation and single sideband transmission executed in a broad-band communication system is suggested in which only I and Q versions of a purely sinusoidal local oscillator signals are needed, easing the system scaling when large numbers of channels must be aggregated. In addition to that, instead of phase shifting of an intermediate frequency broadband signal rather two intermediate frequency broadband signals are generated, which are phase shifted by +90 or by 90. As a result, the problems of frequency dependent phase shifting explained in the background section is not relevant for the method according to the present disclosure. Also, a corresponding method for image reject reception and channel separation as well as a transmitter and receiver for performing the methods are suggested.